ISEE-3 Reboot Project Update: BULLSEYE! and More

Project Update June 1, 2014

We have returned from our foray (probably not the last) at Arecibo.  It was a wonderful trip, the people down there are marvelous, and Arecibo is the crown jewel of American radio astronomy.  Did you know that the Chinese are building a bigger one, modeled after ours?  The NSF keeps trying to cut their budget but this is truly an amazing asset to the American people and the world and it should be supported!!  I want to thank Mike Nolan, Phil Perillat, Dana Whitlow, Victor Negron, and all the great crew down there.

Technical Progress, Contact Made!

Commanding The Spacecraft

As we put out in our project very brief note on Friday, we have successfully contacted the bird!  At the time of the contact we had Morehead State University Space Science Center’s 21 meter dish, the 20 meter dish at Bochum Radio Observatory in Germany, and the SETI  Allen Array were all listening.  This was not without problems.  The spacecraft has two transponders, which are oddly enough called transponder A and Transponder B. Transponder B is normally the engineering telemetry transponder and transponder A is the ranging transponder.  The final state of the spacecraft at last contact was to have both of the transponders transmitters active and that is what people around the world have been tracking.  However, the spacecraft is set up with a lot of redundancy so you can use either transponder A or B to send telemetry or to range.

We tried several times to command the spacecraft’s B transponder at 2041.9479 MHz into the mode where it normally sends engineering telemetry, which is our first task.  It did not work.  We tried several variations of the proper commands and we tried several operational approaches such as scanning across the receive transponder band to make sure that there was not some offset that we did not know about or that the receive frequency had drifted over the years.  Nothing worked.   Then we tried the same process on transponder A and BINGO, telemetry! Well not really telemetry itself, but modulation from the output of the telemetry system.  The initial command was just to turn engineering telemetry on at 512 bits/second.  This was successful.  Figure one, generated by Achim Volhardt from AMSAT DL and Bochum, shows the modeled spectrum for a 512 bits/sec telemetry rate overlaid on the received signal, which is what we commanded:

Figure 1: Simulated (Solid Line) vs Received Spectrum from ISEE-3/ICE A Transponder

Figure 1: Simulated (Solid Line) vs Received Spectrum from ISEE-3/ICE A Transponder

The second image, figure 2, shows a waterfall plot that clearly shows the sidebands of the expected signal, as recorded from our Ettus Research USRP N 210 receiver as processed through GNU radio by Balint Seeber:

Figure 2: Waterfall Plot of Signal Showing Sidebands

Figure 2: Waterfall Plot of Signal Showing Sidebands

This provided our initial verification that we indeed had successfully commanded the spacecraft into engineering telemetry mode.  We later also, working through the A transponder’s receiver, we commanded through the B transponder’s command decoder to output engineering telemetry through transponder B’s transmitter.  Thus we have verified so far the following systems on the spacecraft.

1. Transponder A receiver

2. Transponder A’s Command Decoder and Data Handling Unit

3. Transponder B’s Command Decoder and Data Handling Unit

We reviewed some of our documents and found that neither of the ISEE-3/ICE receivers had met their specification in testing.  The specification was for -120 dbm sensitivity.  However, we found that receiver A was tested at about -114 dbm, and Receiver B at -111 dbm.  A difference of 6 and 9 db gain respectively.  Working the numbers backward with our 400 watt power amplifier and the gain of the Arecibo dish, we found that we were marginally ok with the A receiver and probably slightly short with the A receiver, calculating in radiated power vs db Eb/No.  Normally NASA and the Deep Space Network (DSN) uses transmitters in the tens of kilowatts range.  Since we could neither acquire one that big in the time that we had, or could afford to buy one, this had driven our decision to use Arecibo rather than a larger power amplifier at a smaller dish.

Our biggest disappointment was that we then tried to command the spacecraft into 64 bits/second mode, which was a mode that is much more complicated to set up, we did not get working successfully during the limited time that the spacecraft is visible from Arecibo.  We need to do this so that the smaller dishes at Morehead State and Bochum will have a positive signal margin so that we can record several hours of data.

THEN WE HAD AN EARTHQUAKE.  As many know who follow our social media, on Thursday after our end to end systems test we had an earthquake.  I was on the central part of the Arecibo dish, 450 feet in the air with Dana and Anthony, another engineer at the site when this happened.  We had just chatted about how observations could be affected by vibrations in the dome structure as it translates during an observation and then that happened!  The azimuth tracking system, which is the curved structure on the underside of the top part of the dish, was slewing while we were there as well as the dome.  We were sitting in a safe area when everything started shaking.  I was doing a video at the time but stopped it to hold on during the shaking!

Demodulating and Decoding the Received Signal

The first miracle was to command the spacecraft.  The second is to understand what it says.  Figure 3 shows a scope plot of the resulting data and clock plotted in time:

Figure 3: Clock and Data Recovery from Demodulator

Figure 3: Clock and Data Recovery from Demodulator

If you look at the bottom of this figure you can see 1’s an zero’s, the bits that come out of this process.  Now our guys are super exited about this and yesterday morning (Saturday) Austin Epps sent out an email based on the first set of bits that Balint got out of the demodulator:

I searched for the synch bits ‘11111010111100110011010000000000’ per the SIRD document.  That string was found in two locations…starting at bit 575 and again at bit 2623.  Note that the two locations are 2048 bits apart, exactly as expected.

We got our synchronization bits, which provides the framing indicator for a frame of data, out of the demodulator!  Not to be outdone, (actually everyone is collaborating and working beautifully together), our new volunteer, a very old hand at demodulating satellite data, Phil Karn, jumped on the data that Balint provided and we have the following fully processed first frame of data!

Gentlemen, feast your eyes on this:

7c 02 02 02 02 02 02 02 7c 02 02 02 02 02 02 02
7c 00 02 00 00 f2 00 00 7c 02 02 79 a0 00 00 00
7c 00 02 33 c8 02 4d 02 7c 4b 02 76 00 00 00 00
7c 02 02 53 01 02 39 02 7c 44 02 00 b1 49 00 00
7c 00 02 5a 00 19 5c 64 7c 4b 02 0e a0 00 00 00
7c 0e 02 4b 47 63 91 1d 7c 42 02 4d 36 00 00 00
7c 45 02 44 4e 8a 89 02 7c ce 02 50 a4 00 00 00
7c 48 02 32 4b b5 d2 ad 7c 33 02 12 fc 81 9f be

This is my very first Viterbi-decoded frame of ISSE-3 telemetry,
extracted from the first frame of the recording I received this morning.

Note that it ends with the 12 fc 81 9f be sequence, the 3-byte encoder
dump sequence 12fc81 followed by the 2-byte sync sequence 9fbe.

I forced the Viterbi decoder to end in the state 819fbe so those last
three bytes could not have been anything else, regardless of what was
received. HOWEVER, the 12 fc decoded just before that actually came from
the received symbol stream, and since that matches the values given in
the documentation this is a strong indication of correct decoding.

As another indication of correct decoding, I re-encoded the
Viterbi-decoded data and compared the encoded symbols to the raw symbols
received from the spacecraft. There were no errors. None.

I think we have it. Now I just need to polish this off so it’s useful.

Fantastic work!  Phil later processed our first day’s data dump from the spacecraft and we received 49 full frames of data at a bit rate of 512 bits/second.  Until the very end there were no errors on the downlink, and only then when the spacecraft was going beyond the horizon for Arecibo.  These are the milestones related to commanding and receiving data from the spacecraft that have been achieved:

1. Successful commanding multiple times of ISEE-3/ICE

2. Received engineering telemetry from both data multiplexing units on the spacecraft.

3. Successful demodulation on the ground of the received data, through the output of bits.

4. Verification of good data at 512 bits/sec, including frame synchronization, correct number of bits/frame, and with no errors, showing a very strong 30+ db link margin through Arecibo.

These milestones alone would be praiseworthy but there is more!

UPDATE: Sunday night.  Phil Karn sent me an email to say that he has now processed over a 1000 frames of telemetry from the ISEE-3 spacecraft.  We are going to have a LOT of fun decoding and displaying the data this week!


The Trajectory Problem

One of the major problems that we have, that has to be solved, is to update the range to the spacecraft so that its position, velocity, and trajectory into the Earth Moon system can be properly plotted so that we can then plot a course, and fire the engines for a  maneuver to target a lunar flyby at the proper altitude (around 50 km) on August 10, 2014.  The last trajectory solution that we have from the DSN is from 2001 and it is this one that is provided by NASA JPL in its Horizons prediction program that everyone has been using.

The problem is that this solution has been shown to be inaccurate when we are using the extremely narrow beam width (~2 arc minutes), at Arecibo.  When plotted out to the approximate distance of the spacecraft, 2 arc minutes is only about 16,800 km wide, meaning that if the spacecraft is more than about half this distance (assuming that we point exactly at the right location), then the spacecraft falls outside of this beam and the signal vanishes.  This is except for the fact that the Arecibo telescope is so powerful that the minor lobes of the main beam are still more powerful than most smaller telescopes and that was how we were receiving the spacecraft in the first few days at Arecibo.

Then, Phil Perillat who handles the hard problems in operating the telescope at Arecibo, performed a search to lock on the main beam of the spacecraft.  He was able to do this, and our signal level was over 50 db above the noise, a very strong signal for transponder A, and a bit less, around 45 db for transponder B.  Phil continued to do this almost every day when we could get time on the extremely busy telescope.

There is a huge side benefit to this technique.  In the scientific community for asteroid research radar and optical sighting of Near Earth Objects is used as the only means to determine orbits.  This community has gotten extremely good at this method.  The spacecraft engineering community uses coherent transponders (which is what transponder A is on ISEE-3/ICE) to lock on and do a two way ranging to allow the engineers to calculate a good orbit ephemeris for a spacecraft.

Amazing Accuracy of the 1986 Trajectory

Using the data from Phil’s daily targeting of the spacecraft, Mike Loucks at Space Exploration Engineering, along with the folks at Applied Defense, and then further verified by volunteers from APL working on their own time, we have narrowed down the location of the spacecraft.  It turns out that it is far closer to the Moon than the JPL Horizons propagated trajectory, and very near being on the course intended for it by the ICE trajectory team in 1986!  This is shown in figure 4:

Figure 4: Newly Plotted ISEE-3/ICE Course Compared to Horizons and JPL 2001 Trajectory

Figure 4: Newly Plotted ISEE-3/ICE Course Compared to Horizons and JPL 2001 Trajectory

The Blue Circle is the orbit of the Moon with the Moon’s location show at the right side of the circle (August 10, 2014 location).  The Yellow Horizons trajectory is shown intersecting the Moon’s orbit but no where near the Moon on that date.  The white line was a re-propigation of the JPL Horizons orbit in Systems Tool Kit (Satellite Tool Kit).  The dark blue trajectory is the intended trajectory of the ICE navigation team in 1986.  The red/green trajectory is the plotted trajectory based on Phil Perillat’s pointing data from the Arecibo telescope!

Consider this, the spacecraft has completed almost 27 orbits of the sun since the last trajectory maneuver. That is 24.87 billion kilometers.  They are off course by less than 30,000 km.  I can’t even come up with an analogy to how darn good that is!!  That is almost 1 part in ten million accuracy!  We need to confirm this with a DSN ranging, but if this holds, the fuel needed to accomplish the trajectory change is only about 5.8 meters/sec, or less than 10% of what we thought last week!

We truly stand on the shoulders of steely eyed missile men giants…

What is Next

If we can maneuver the spacecraft by June 17th we get the very small delta V number for the maneuver above.  However, this starts to climb rapidly as the spacecraft gets closer  to the moon.  Also we cannot at this time rule out a lunar impact.  It is imperative that we get a ranging pass as soon as possible.  We also need time to not only evaluate the health of the spacecraft, but to test the systems, the catalyst bed heaters for the propulsion system, the valve heaters, analyze the rest of the propulsion, power, and attitude control system as rapidly as possible.  This will be a lot of commanding so we have to move into high gear next week.

This is a very fluid situation and we have made amazing progress, thanks to the support of those who believed in us in our crowd funding and the support of our NASA sponsors at NASA Ames and NASA headquarters.  We also want to thank the members of the original ISEE-3/ICE engineering and science team.  Without their marvelous efforts, and without the documents that they saved and stored lovingly for decades in their homes this would have been a far more difficult task!  We also appreciate their looks over our shoulders and we will be relying on them to do this more as we work to successfully command the spacecraft to fire its engines.  More to come soon!!



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ISEE-3 Reboot: Updates from the Front at Arecibo….

Sunday May 25 2014

We have had a very active week since we arrived and got started work.  We arrived on Saturday the 17th and checked into the visiting scientists quarters near the big dish.  And then we saw it…..

The Arecibo dish is too big to be taken in in one photo so here are a couple to give some sense of scale.

Figure 1: Central Focus of the Arecibo Dish

Figure 1: Central Focus of the Arecibo Dish

See the ring in the middle?  This picture below is what it looks like with people on it looking down to the center of the ring.

Figure 2: Arecibo Dish Rotating Section

Figure 2: Arecibo Dish Rotating Section

Those are people down in the center there.  That gives you a slight bit of sense of the size of the place.

Mike Nolan and the folks at the dish are just the best people imaginable.  There are several scientists in residence at this time running experiments and there are several who do things remotely.  One scientist showed us some amazing pictures of a celestial body that are amazing (keeping it quiet until the findings are published) that were obtained with the radar at the site.  The power amplifier that we had shipped to the site puts out about 400 watts on S-Band.  The one on site here, running at half power, is a megawatt.  We can’t use that one as it is very precisely tuned to its frequency and can’t be changed. The days kinda run together down here so the days are estimates for what we did starting but here are our day to day accomplishments while down here.


Since the power amplifier from Germany was a bit late, we started out by conferring with the staff here on the best approach to be able to use the dish.  Mike Nolan, Phil Perillat, and Dana Whitlow, Victor Negron, and the group are all outstanding technical and scientific people and helped us figure out the ins and outs of using the dish down here.  The dish requires near constant maintenance and so it is near the end of these times, after the work is finished, that we have opportunities to receive signals from the spacecraft.  We brought our own transceivers down here, the Ettus Research USRP 210’s which use the GNU radio Software Defined Radio (SDR) open standards.  Operated by the right people, such as Ettus engineer Balint Seeber (Ettus graciously allowed Balint to come down here with us).


We began by replicating the basic reception of the spacecraft using the dish and using their equipment in parallel with ours.  The first day, which I think was Tuesday, Phil saw that the signal from the spacecraft was weaker than before.  We had some time to work and Balint did some configuring of the USRP receiver.  However, not much more than that happened and we were somewhat concerned about the signal.  Was the spacecraft failing as it approached Earth?  So we asked the folks at Morehead State to monitor the spacecraft on Wednesday in parallel with Arecibo in order to see what they could see.


On Wednesday we got the great news that the power amplifier had been shipped from Germany, next day Fedex!  The team worked during the day writing software that would be used for receive testing at the dish.  When the pass started, we were very surprised to see that the signal from the spacecraft was basically missing.  We consulted with Morehead and found that they were receiving the signal stronger than ever.  We also were receiving signal from the 6 meter dish at SETI in California.  Phil Perillat then did some investigating and found the signal, but at a very weak signal strength on a side lobe of the dish.  (Lobes are part of the spread of received energy from the dish).  Some calculations indicated that if Morehead could hear the signal in its main lobe but we could not, then there was a divergence between the position of the spacecraft and the ephemeris file provided by the NASA JPL Horizons server.  We did not have enough time on Wednesday to find the spacecraft on the main lobe.


Huzzah!  We received the tracking number for the power amplifier and instead of waiting for it to be delivered around 5:00 pm, we and the film crew with us took off to the west end of the island to pick up the amplifier at Fedex.  We were greeted by Wilson at the office (if you don’t know who or what Wilson is, watch the Tom Hanks movie about the crash of a Fedex plane):

Figure 3: Wilson Greets us at Fedex in Puerto Rico

Figure 3: Wilson Greets us at Fedex in Puerto Rico

We picked it up early and got back to Arecibo before 1:30 in the afternoon, when it started raining which halts all activities in the center focus of the dish for safety reasons.  However, we did remove it and its power supply from their crates and set up the system to begin testing at the control center on Thursday evening.

We also were able to get some quality time in on the system for a receive test.  The ever diligent Phil Perillat initiated a search for the spacecraft and was able to lock onto it, but with an offset of -0.47 degrees in Right Ascension (RA) and 0.08 degrees in Declination (Dec).  After some calculations this indicated that the spacecraft was approximately 250,000 km away from its expected location.  With this information the signal was solidly locked to the spacecraft with approximately 55 db of signal to noise on one frequency and approximately 45 db on the other.  The difference is due to polarization differences between the two signals principally.  We were also able to lock onto the signal using the Ettus USRP 210 radios of ours.  This is shown in figure 4:

Figure 4: FFT and Waterfall Plot of ISEE-3/ICE Signal.

Figure 4: FFT and Waterfall Plot of ISEE-3/ICE Signal.

We had some very happy campers in the control room!:

Figure 4: The ISEE-3 Reboot Crew After Signal Confirmation on USRP Radio

Figure 5: The ISEE-3 Reboot Crew After Signal Confirmation on USRP Radio

With the successful reception of the signal on the USRP radio we confirmed at least the entire receive chain and processing through our laptops the signals in GNU radio.  Balint did a marvelous job there and we had help from John Malsbury who had been with us the previous two days.


On Friday the team from Arecibo lifted the Dirk Fischer Electronics power amplifier from the bottom of the dish up to the central focus and installed in the transmitter room. Figure 6 shows the power amplifier and its power supplies installed and ready to go:

Figure 6: Dirk Fischer Electronics Power Amplifier Installed in the Arecibo Transmitter Room

Figure 6: Dirk Fischer Electronics Power Amplifier Installed in the Arecibo Transmitter Room (in the Dome)

During the previous few days discussions had been had with Dana Whitlow and Victor Negron about how to get our transmitter signal from the USRP up to the power amp.  There are several fiber optic cables (as stray RF is a big no no there) that could carry the signal from the control room to the dome.  Then there was a coax to go from there to the power amp.  This created a lot of signal loss so preamplifiers were installed on top of the power amp that would allow us to boost the signal to the proper level to drive the transmitter to full power.  All of the transmit path from the control room to the preamps were tested and shown to be operational.

Final Testing Late Friday

With everything installed we then decided to do a final end to end test of the system.  We sent signals up to the preamps that then allowed Dana Whitlow adjust them and to monitor the output of the power amp.  After some trial and error this was accomplished and all four of the amplifiers that made up the combined power amp were tested and it was confirmed that they operated at full power while remaining relatively cool in the transmitter room.  This is the same room where the big megawatt klystrons are located.  In this test we found a couple of configuration issues to deal with which were successfully fixed.  Thus by the end of the day, we had a completely successful end to end test of our transmission and reception system.

Discussion and Agenda for Next Week

Originally we were going to head home this past Friday.  However, with the inevitable delays that are part of doing real work, we reached our first major success milestone here at Arecibo on Friday.  Thus we have extended our stay for another week in order to actually transmit to and attempt to command the spacecraft.  The end to end test revealed a couple of operational issues that we have to deal with such as that with a dish with this fine of a main transmit lobe, that we may have to offset the dish to “lead” the spacecraft so that it will be where it should be when it receives the signal.  This is doubly true as we now know that the spacecraft is off course compared to the existing ephemeris.

The error in position has just elevated the concern level greatly.  We know approximately what the offset error is from the existing ephemeris but we don’t have enough information yet to plot a new course and generate a new ephemeris file.  This has become extremely important as there is a solid statistical chance that the spacecraft could impact the moon or even by off course enough to threaten other spacecraft in Earth orbit.  We are working with Mike Loucks of Space Exploration Engineering (SEE) our trajectory guy on this issue.  An east coast company, Applied Defense (ADS) has also offered their help and engineering support to derive a new ephemeris from our new position reports.  ADS and SEE did the trajectories for NASA’s just completed LADEE mission.  It won’t be perfect but it will be an improvement over what we have now.

This is a necessary improvement as we are far enough off course that if we fired the engines now for a course correction, it could easily make matters worse.  So we have just had the level of concern increase dramatically!  We will know more when we are able to get time on the dish again, maybe Monday at best but definitely Tuesday so that we can have multiple plot points along an arc to give to Applied Defense for them to work with creating a new orbit plot.

We hope that if all of the stars align (some of the stars are paperwork), that we can attempt transmission to the spacecraft to command it into engineering mode on Tuesday.  It is imperative for us to do this and to attempt to range to the spacecraft to further refine the orbit.  Reading the engineering telemetry, debugging the demodulator and the telemetry system software are our biggest tasks this week.  We will have Morehead State and the SETI Allen Array (or some subset), listening to see if the telemetry is being transmitted.  This will allow several hours of reception instead of just the 2.5 hours here at Arecibo.

This is all for now.  Watch our @ISEE3Reboot twitter feed and website for the latest!!

Oh, and thanks to all of those who donated to our project.  As you can see, your money is being well spent!



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ISEE-3 Reboot Project: Aiming for First Contact

Date 5/13/14

Today’s update regards the progress of the ISEE-3 Reboot Project team in our preparations to contact the spacecraft.  We started this effort 32 days ago on on April 12 2014.  Below is what we have accomplished in that time.

Technical Progress

The Learning Curve

Perhaps the toughest part of doing something like this in a very limited timespan is to climb the learning curve – and to do so with a spacecraft you knew very little about.  Early on we did a preliminary evaluation of the spacecraft and its systems so as to better understand it.  This was a long jump into deep water.   As we did with our Lunar Orbiter Image Recovery Project which concerns the 1960s era Lunar Orbiter spacecraft, the search for ISEE-3 documents has been intense and not without failure.

Most of the best information that we have been able to find has been from the people who worked on the project in the 1980’s when the spacecraft was fully operational.  This image shows the trajectory of ISEE-3/ICE during that period:

Figure 1: ISEE-3/ICE Trajectory through 1986

Figure 1: ISEE-3/ICE Trajectory through 1986

We have also obtained several documents from NASA as part of the development of our Space Act Agreement. Yet many holes still remain in our knowledge of the spacecraft that we have to deal with.  For example, we don’t really know the last state of the spacecraft.  In digging through documents and consulting with those who should know we have yet to find a record of the last commands sent to ISEE-3.  We know that both transmitters (2270.4 Mhz and 2217.6 Mhz) are fully operational but they are not sending telemetry.  Clarity is finally coming to us as our team (Austin, Cameron, Marco, and Tim) have diligently gone through the documents we have.  They are coming up with a series of commands that we will need to send to the spacecraft to set up its engineering telemetry mode.

Since there is no computer on board the ISEE-3 spacecraft our task is actually much easier since we are going to be directly commanding various subsystems. Our team has made a lot of progress in this area.  We are going to be ready to head off to Arecibo this weekend to attempt the first commanding of the spacecraft using their 305 meter dish, the largest in the world.

Hardware Status


We now have our Ettus Research Software Radio’s inhouse at ISEE-3 Mission Control.  Figure 2 shows the spectrum of our signal at a ISEE- 3/ICE receiver frequency of 2090.66 Mhz:

Figure 2: Ettus Research USRP N210 Output at ISEE-3/ICE Receiver B Frequency

Figure 2: Ettus Research USRP N210 Output at ISEE-3/ICE Receiver B Frequency

We have a baseline configuration completed by the engineering team at Ettus to modulate (using GNU Radio) the waveforms required by the ISEE-3/ICE spacecraft.  We expect to be ready for receiving and debugging the demodulated stream if we are able to command the engineering telemetry mode to “on” aboard ISEE-3.  We have a couple of questions related to parity generation and convolutional coding that we hope that we have right. However, since things are all in software, we can play around with parameters while we are in a window waiting to see the spacecraft.

Command Generation Console and Telemetry Screens

Tim Reyes in Mountain View, California and Matt Sachs from Huntsville, Alabama have been working together to develop the consoles for commanding the spacecraft.  Figure 3 shows a mockup of the screens without the commands present:

Figure 3:

Figure 3: ISEE-3/ICE Command Console Screen (Tim Reyes and Matt Sachs)

We are ready to go with the commanding structure but we are still working on exactly what commands to send.  Since we don’t completely know the current state of the ISEE-3 spacecraft we are going to make some assumptions and then work from there with a contingency plan of multiple commands, being extremely careful!

The telemetry screens are coming along as well.  Our team has been focusing on climbing the steep learning curve for understanding the telemetry system.  In this effort details are everything.  We have to understand the calibrations required for things such as temperature and pressure sensors, solar array voltages and currents, attitude determination sensors, etc..  This is an ongoing process and we have, as usual, dug some of the pertinent information out of 35 year old IEEE or AIAA papers that are publicly available.  Figure 4 is from the old 1978 Mission Operation Plan that we obtained from Bob Farquhar:

Figure 4: Original Telemetry Screen from the ISEE-3 Mission

Figure 4: Original Telemetry Screen from the ISEE-3 Mission

Depending on how much time we have, we will do a very quick and dirty system that Austin Epps will build. Ideally  we will use a Labview version, provided to us by Eddie Rodriquez from National Instruments.  The people that make Labview have been incredibly supportive of our efforts and long term we will use Labview for our operational support of the spacecraft for engineering and science.

Another issue we have is that we have no idea what has failed on the spacecraft since telemetry was last obtained.  There are no surviving records that we can find of what was working the last time the spacecraft was operated.  This makes things more difficult in that we have to debug not only our telemetry system, our modulator and demodulator, but we also have to determine whether or not to believe what is coming back from ISEE-3’s telemetry indicators.  This makes things more complicated, but not impossible.

We are not going to use exactly the conventions that you see above for the telemetry system.  We may start out that way but we want something that is much more in keeping with modern graphical systems.  Keep in mind that all of this is being done on a rapid basis, and much of the work is being done by volunteers.  All of the folks working on this, whether they are volunteers, NASA folks helping us with the Space Act Agreement, or our own internal team, have done a marvelous job in getting rapidly up to speed on what is necessary to pull this off.  The next miracles that need to occur are related to transmitting to- and then commanding the spacecraft.

Ground Station Transmitters

We have two ground station power amplifiers that we are currently working with. These amplifiers are being sent to our ground station partners.  One amplifier is from AR RF/Microwave Instrumentation of Souderton, Pennsylvania.  This unit is a 700 watt transmitter (Model 700S1G4) that AR is loaning the project to be used on the big dish at the Morehead State University Space Science Center (MSU-SSC).  The Model 700S1G4 is a portable, self-contained, air-cooled, broadband, completely solid-state amplifier designed for applications where instantaneous bandwidth, high gain and linearity are required.  The model 700S1G4 is a 700 watt minimum output power amplifier at S Band frequencies ( GHz for our application).  The folks at AR RF/Microwave have graciously loaned us the transmitter for when the spacecraft is close enough to the Earth (around mid July) for a link to close for commanding ISEE-3/ICE.  The power amplifier will be driven by a Ettus Research USRP N210 software radio transceiver.

The second power amplifier is coming from Dirk Fischer Electronics in Senifurt, Germany.  This power amplifier is being built specifically for us and will be shipped to Arecibo to be installed next week.  Figure 5 shows parts of this transmitter under construction:

Figure 5: DK2FD Power Amplifiers Ready for Testing

Figure 5: DK2FD Power Amplifiers Ready for Testing

The power amplifier as well as the Ettus Research Radio’s and other equipment has been purchased with the Rockethub-provided funding (well we are borrowing against it right now).

 Other Equipment

We have purchased a laptop onto which we are loading GNU Radio software and Linux operating system. As soon as we get our Labview developer software we will start working with it as well and integrating the work that Eddie and Mike have done for us in that area. We may not have everything working by next week but we will have the critical parameters loaded. There will probably be more hardware to buy but for now and for next week this will work.

Operational/Program Management

 Space Act Agreement

All the T’s are crossed and the I’s have been dotted for the Space Act Agreement (SAA) with NASA. The document has been put into the SAA formatter and (in theory) it will be forwarded to the lawyers for a final review before signing sometime in the next day or two. NASA has already provided us with the documentation from Goddard Space Flight Center and did it early so as to help foster our success in the effort.

The spacecraft is traveling at a quarter million miles per day, and with this in mind everyone is working together to fulfill the terms of the agreement as if it was already signed. Since what we are doing is setting a precedent for future activities of this type we are sure that they are just making sure that they have assured themselves that everything is done just right.


Our first official attempt to contact the spacecraft will be at the Arecibo antenna in Puerto Rico the week of the May 19.. The folks down there are working to fit us into their busy schedule of radar observations of Near Earth Objects. That kind of stuff is interesting to me as well so it will be a lot of fun to see a place that I’ve seen on TV and in movies for most of my life. We are working out an arrangement whereby to where the ISEE-3 Reboot Project will donate the power amplifier that we are getting from Germany to Arecibo in consideration for their support of our project.

Morehead State University

The Morehead State University Space Science Center 21 meter dish is going to be our primary ground station for the activities leading up to and including everything required to put the spacecraft into its final science operating state. However, until the spacecraft is within about 2-3 million kilometers of Earth, which will be in mid to late July, it does not have the wherewithal to close the link with the spacecraft so as to allow two way communications. During our time at Arecibo we will be commanding the spacecraft from there. If we are successful in putting the spacecraft into engineering telemetry mode, one of the USRP N210 radios and our software will be there to process and store the telemetry received. We will be shipping a radio there on Thursday to be ready for next week.

Bochum Observatory and AMSAT-DL

The Bochum Observatory, located in Bochum, Nordrhein-Westfalen, Germany is a private institution set up in 1946 by professor Heinz Kaminski. The observatory has a 20 meter dish that is used for radio science, amateur radio operations, and as a science receiver to receive data from many different satellites. The Amateur Radio Satellite Organization in Germany (AMSAT-DL) works closely with the Bochum observatory. It was this group that in early March of this year detected the signals from ISEE-3/ICE which first generated our interest in communicating with the spacecraft.

The group there with Achim Vollhardt and Mario Lorenz have been working with us and providing signal strength readings from the spacecraft. Independently of our effort they have developed a demodulator for the signals from ISEE-3/ICE. Due to ITAR limitations we have been careful in developing their site for commanding the spacecraft but we are working out a way to do so without compromising our requirements in the ITAR regime. What we hope to do is to have them receive the signals from the spacecraft, demodulate, store, and forward them to us after we command the spacecraft into engineering telemetry mode. With sites in Germany, Kentucky, and Arecibo we will have  good coverage, though the Arecibo dish only sees the satellite until the Earth turns away.

 Other Ground Stations

We are working to get on other ground stations. The SETI Institute in California has been tracking the signal as a means to calibrate and troubleshoot the Allen Array. We are working with them and hope to be able to provide them with a radio and or software so that they can demodulate the signal.

 Mystery Station

We have a another station here in California that we are talking to in order to get their support. Can’t report anything until we close that effort but things are in negotiation now.

Surprise! Google Creative Labs and the ISEE-3 Reboot Project

 Some folks had mentioned and recommended to us to get a film crew to go with us to Arecibo as this will be a very noteworthy event. We were recently contacted by the folks at Google Creative Labs about our project and we have worked out a collaboration for them to film us in operation at Arecibo! We have created a Google + page as well and are working to turn this into a longer term means of better communicating and disseminating our educational and scientific product for the ISEE-3 Reboot project.

We hope to be able to do a live stream from Arecibo with the Google Creative Lab folks for our attempt to command the spacecraft. It looks like we are also going to be there when the transmitter arrives from Germany so we will work with the Arecibo folks to get it installed as soon as possible.

Funding Status

On the evening of May 14, 2014 we reached our fundraising goal for the project! First of all a hearty thanks to everyone for your support and as soon as the funding gets to us we will start putting together the goodies to everyone. When we started this we only had a very vague idea of how much we would need to do this. We have spent about $35,000 so far with more spending coming as we go to Puerto Rico to Arecibo to attempt the first contact. We had to borrow and get terms to pay for some items that we will have to pay for when the funds arrive.

In all probability we will need more funds so we would like to ask for folks to continue to give as you can until the funding window ends on Saturday morning 17t May, at just about the time we get on an airplane to Puerto Rico. We will take a hiatus for fund raising but there is a strong possibility that we may have to pay for the Deep Space Network to do a ranging to the spacecraft for us. If so we will definitely have to do more fund raising. I still marvel at the technical ability of the DSN and how it does interplanetary spacecraft ranging. It is absolutely a non-trivial task!

Next Week’s Activities

Next week is crucial to the success of our project. Using the dish at Arecibo gives us the best chance of being able to command the spacecraft in the very near term. Every day is exceedingly important to us right now. The spacecraft gets about the distance from the Earth to the Moon closer each day and now every day the amount of propulsion burn it takes to make the trajectory correction grows.

The ISEE-3/ICE spacecraft was never really designed to be an interplanetary cruiser and thus the thrusters on board are very small. We estimate that if we wait until mid-June to do the course correction that it will take 17 hours of thrusting to get the course change of about 40 meters/second that we will need at that time. As such, everyday we wait, the risk increases. You see, as we have to continually command the spacecraft to fire for every 512 pulses, thus increasing the chance that something will go wrong.

Figure 6 shows the track of the spacecraft against the sky right now and the distance that it travels per day shown as the tick marks. It is pretty much impossible to see it now, but at least you can get an idea of its track in the sky as it approaches the Earth:

  Figure 6: Track of the ISEE-3/ICE Spacecraft The Sky Mid May 2014

Figure 6: Track of the ISEE-3/ICE Spacecraft The Sky Mid May 2014

Our flight operations engineer Tim Reyes put this graphic together.

Our team has done a marvelous job getting everything together and climbing an incredibly steep learning curve.  We have another new person Cameron Woodman, who has also done just a stellar job in helping everyone else get up to speed and to help with the back and forth engineering thought process related to getting the telemetry system going.  Marco Colleluori is putting in an incredible amount of effort to get Matlab to do what the old ICEMAN program did 35 years ago.

We have a great group of other people as well from our artist Mark Maxwell, who put together our logo, the folks at the ground stations, the team of ISEE-3/ICE alumni, without whom this would have been impossible to do!

And of couse without my project co-lead Keith Cowing, we would have never generated the immense public interest that the project has developed or collected donations from so many interested supporters that is going to translate our plans into reality.

This is a very interesting spacecraft and I think that this process has been a great learning experience for our team and we look forward to the possibility of being able to return this truly historic spacecraft to science operations.



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ISEE-3 Reboot Project Near Term Objectives


The ISEE-3 Reboot project is an effort to contact, evaluate, command, and place back into  operation in an Earth orbit the International Sun-Earth Explorer #3 (ISEE-3) spacecraft. In 1978 the ISEE-3 spacecraft was launched as part of a trio of spacecraft to monitor and understand the properties of the Earth’s magnetosphere (the Earth’s magnetic field) as it relates to how it is influenced by the various forms of radiation emitted by the Sun.  ISEE-3 basically wrote the book and invented the term heliophysics.  Later the spacecraft was renamed the International Cometary Explorer (ICE) and was the first to visit a comet (Gaicobini-Zinner on Sept 11, 1985), and Halley’s comet in March of 1986.

In 2014 this venerable spacecraft returns to Earth’s orbit and our primary objective is to regain control of the spacecraft and command its engines to fire on a trajectory that will result in a capture into a permanent Earth orbit.  following this, we hope to return the spacecraft to science operations, using its instruments as they were originally designed.  The data from the spacecraft will be open to the public and will be used by the heliophysics community and will be a tool for teaching operations and science data gathering from a spacecraft by students and the public.  In the following sections we will detail the engineering objectives of the project until it is in its final Earth orbit.

Engineering Objectives for the Recovery of ISEE-3

Problem Statement

Figure 1 shows the trajectory of the ICE/ISEE-3 spacecraft from its last propulsive maneuvers in 1986 until its return to the Earth in 2014:

Figure 1: ICE/IESS-3 Trajectory Through August 10, 2014

Figure 1: ICE/IESS-3 Trajectory Through August 10, 2014 (Tick Marks are 14 Day Intervals)

NASA has gotten rid of all of the hardware that understood how to talk to ISEE-3 around 1999.  The spacecraft was last commanded in 1986 or 1987.  The last time it was listened to, with a carrier only, was in 1999 and 2008.  Also, NASA has determined that it does not have the funding to recover the spacecraft and thus on April 12, 2014 the ISEE-3 Reboot Project was born.

Engineering Questions to Be Answered

The principal questions that have to be answered in order to successfully place the spacecraft into a stable Earth orbit and return to science operations are:

  1. Is the spacecraft still operational in the same state as for the previous reception by the   NASA Deep Space Network (DSN) in 2008 and can we receive signals without the support of the DSN?
  2. If the spacecraft is still operational can the equipment and software required to command the spacecraft and read its telemetry be reconstituted on a rapid basis?
  3. If the answer to (2) is positive, are there non DSN assets that can be used to command the spacecraft?
  4. if the answer to (2) and (3) are positive, can the spacecraft be commanded back into telemetry mode in order to debug the telemetry software system, and determine the health of the spacecraft for a thruster firing?
  5. If the answer to (2,3, and 4) are positive, can we obtain an updated ranging to the spacecraft in order to improve on the existing trajectory information.
  6. If all of the above are positive, can we reconstitute the programming necessary to fire the thrusters to modify the spacecraft’s trajectory as desired?
  7. After the spacecraft is placed into a stable Earth orbit, can we return it to science operations.

In the questions above, there are a plethora of subquestions within each one.   This is a summary document explaining where we are currently at in the process and to provide an abbreviated path to answering the questions posed above.

Spacecraft Operational Status (Question 1)

We have multiple reception reports from various telescopes around the world.  These include Arecibo, the Bochum radio observatory in Germany (AMSAT-DL), the big dish at Morehead State University Space Science Center (MSU-SSC) in Kentucky, and the SETI Allen Array telescope in California.  Both transponders have been received and a cursory analysis of the carrier signals indicate that  the spacecraft is still in a stable spinning mode with a rotation rate of 18.6 RPM, close to its last known values.  Thus question 1 has been answered in the affirmative.  The ISEE-3 reboot team now includes the above dishes, with the exception of the Allen array.  We expect to add more dishes in the following week.  Thus we can consider this question answered in the affirmative

Equipment and Software to Talk to the Spacecraft and Do We Have the Assets to Do So? (Question’s 2 and 3)


Since we only started this on April 12th of this year, designing a hardware modulator/demodulator was out of the question.  In an extremely fortunate happenstance, Ettus Research has its office less than three miles from ours, and they are experts in the design of software radio systems.  Beyond this, the engineers at Ettus think that this is a cool project and they have developed, based upon information that we have obtained from public sources, the modulator that will allow us to talk to the spacecraft.  Additionally, the demodulator is under development now and will be available very soon.  We are reconstructing this from the documents that we have available.  However, soon we hope to have other documents from NASA that will possibly help to clarify things further so that we don’t make any mistakes.  We have ordered the hardware for four of these Software Defined Radios (SDR’s) and should have them in our possession before the 15th of this month from National Instruments, of Austin Texas, the company that owns Ettus Research.  Thus the answer to this question is that it is in an advanced state of progress.

Command/Telemetry System

We have been able to obtain the most current list of command codes and most of the information that we need for reconstructing the telemetry system for ISEE-3.  We obtained these from sources other than NASA.  Our internal team has converted the command lists and we have an internal and an external team developing the program to process the command codes.  This is obviously the most important part of the system and it will interface with the modulator/demodulator combination.

We are also diligently reading all of the telemetry documentation that we have been able to obtain from public sources.  We are going to develop telemetry screens for mission operations for the propulsion, the attitude determination and control system, and the power system.   Right now we have a team of experts in Labview, the graphical instrumentation software from National Instruments, developing these screens.  We will integrate our data regarding the calibrations, constants, variables, and other outputs from the spacecraft with the Labview telemetry display system.  The Ettus SDR system interfaces directly with Labview so we are able to develop this entire system in a fraction of the time otherwise needed. So the answer is that we are moving forward toward integrating the work of several people, spread around the country, in the next week.

Ground Stations

As of May 4th, we have three ground stations in our network.  The first and most important in the near term is the 305 meter in diameter big dish at Arecibo.  This is the largest radio dish in the world and the team down there, led by Mike Nolan, has graciously agreed to provide support to the project on a non interference basis.

The second ground station, and that we will be working with over the next few months, is the dish at the Morehead State University Science center.  This 21 meter dish is not large enough to contact the spacecraft now, but will be able to after the spacecraft gets within about 2-3 million kilometers distance.

Our third core ground station is at the Bochum Radio Observatory, and is operated in concert with the Amateur Radio Satellite Organization Germany (AMSAT-DL).   We are still working the numbers required to be able to do ranging as well as receiving telemetry at this station.

We are working now with another organization that will be named should our negotiations be successful that is an educational institution that has control over some very impressive dishes.  If this works, this may be our prime ground station in California. So this is an ongoing process.


Key to being able to command the spacecraft is the ability to transmit to it on the appropriate frequency.  We have two efforts ongoing at this time in this area.  The first is that we have a transmitter under construction now, from Dirk Fischer Elektronik in Germany.   Dirk is an expert in the design, development, and construction of microwave systems.  Microwave is still a black art and Dirk’s products are used around the world in the amateur radio community.  This transmitter is being provided to the Arecibo telescope facility expressly for the purpose.  We expect it to be delivered to the telescope sometime around May 18th.  This transmitter will be used, in concert with the Ettus SDR and Labview to attempt to command and receive telemetry from the spacecraft.  If time permits we will have Dirk built at least one more transmitter for the folks at AMSAT-DL and for California, depending on several factors still in the air…

We have another transmitter that is under construction that would be sent to Morehead State University Space Science Center.  When I get permission I will release that company’s name.  We will get a shipping date for this transmitter this week.  This system will be a loaner from the company and will be used to command the spacecraft after it gets closer to the Earth.  More on this as it evolves.

So the answer to question 2 and 3 above is that everything is in progress!  We have had a lot of success, driven by a lot of volunteers that have shown up that we will properly acknowledge in our next post about our team.  It is amazing to behold and if things work as they seem to be, we will fly to Arecibo around the 17th-18th of this month to attempt to command ISEE-3.

Commanding the Spacecraft (Question 4)

There is one prequel to commanding ISEE-3/ICE that we want to do.  We are going to send a tone to the ranging transponder.  We know the transmitter is operational.  We want to see if the receiver for the ranging transponder is turned on, and if we can get a return of that audio tone.  If that happens, this means that we can range to the spacecraft before commanding it.  This may change our sequence of events dramatically as we really would like to do ranging to update the spacecraft’s trajectory. (meaning the question 5 may be answered first, before 4)

The next thing we will do is to attempt to command the spacecraft to turn on its engineering telemetry mode.  We can determine that this happens by watching the high resolution spectrum from the engineering telemetry transmitter.  We then feed that signal into the SDR demodulator to see if we can get bits out.  If we get bits out, we feed them to the Labview/Matlab application that will take the bits produced and route them to the appropriate screens.  This is the big test and we have two things that we have to debug at once.

The first thing to debut is the demodulator itself.  This is done by reading out the bits and see if they make sense in terms of packet size, format, and content.  If that works, then we have to debug the telemetry screens to makes sure that for each sensor in each subsystem  (power, propulsion, and attitude system) is in the range that it is supposed to be.  The difficult part will be debugging the Labview code, our calibrations, and the determining that the spacecraft is functioning properly.  This may take a bit of time!!  Which is something we don’t have by the way.  We have experts in Labview working with us and our internal team is handling the telemetry and command formatting so they are giving it their undivided attention.

When all of the above turns out ok we go to the next step.

Ranging (Question 5)

Ranging, without the Deep Space Network is an incredibly difficult affair.  We have some ideas on this but they are still under development.  Thus, it is pre mature to discuss.  At the end of the day, this is our most challenging question to answer.  However, we have a few ideas that we are mulling around and should have at least a direction toward an answer by the end of this week.

The ICEMAN Cometh (Question 6)

There is a program that was originally used by the command team for ISEE-3/ICE called ICEMAN.  This program was used to implement firing sequences for the spacecraft’s thrusters.  ISEE-3/ICE has three sets of thrusters, two sets of which we will use to modify the trajectory of the spacecraft to put it on a more optimal path into Earth orbit.  Figure 2 shows the spacecraft with its thrusters:

Figure 2: The ISEE-3 Spacecraft Details

Figure 2: The ISEE-3 Spacecraft Details

There are two sets of radial and axial thrusters in addition to the spin/despin thrusters.  The spacecraft is spinning about the centerline that points toward the north ecliptic pole. The spacecraft is spinning at 18.6 RPM which is a little slower than once every three seconds.  So what has to happen is that if you are going to thrust in, or against the direction of travel,  you have to fire the radial thrusters in pulses.  These pulses are timed by a sun sensor that is also mounted on the spacecraft.  It is actually a very clever design.  Since the thruster is not firing exactly in the direction of travel (since it is spinning), that has to be taken into account as well.

ICEMAN took care of all of these variables.  However, it is in fortran code that we, as of this date, don’t have.  So, what we are doing is going back to first principles and rebuilding the functionality of ICEMAN in Matlab (well Marco Colleluori, our grad student from San Jose State is doing this).  We do have some support from some of the former flight team and we may get a copy of the original code.  The reason that this is important is that we have found that the thrusters can only be fired a certain number of times before overheating and thus we have to take that into account.  We are working to get the code from some of the retirees or from NASA.  We will be able to take the output of ICEMAN and feed it into Systems Tool Kit (formerly Satellite Tool Kit) astrogator, where Mike Loucks will simulate the thruster firings from the ICEMAN output to verify.

After the telemetry system is up and running and we know the state of the propulsion system we may try a couple of test firings before we go for the long sequence.  At the time when we think we can actually do this, sometime in June, it will take thousands of firing pulses to get the orbit trajectory that we want accomplished so a couple of test firings first is prudent.  If that works then we load the entire sequence, and pray.  Our objective of course is to modify the trajectory such as to capture into Earth orbit, not the final orbit, but a transition orbit whereby we can then see what we have to do for the final maneuvers.  Figure 3 is our graph of panic, which tells us by what date this has to be done before the spacecraft no longer has sufficient fuel for the maneuver:

Figure 3: dV required for Earth Capture Course Correction

Figure 3: dV required for Earth Capture Course Correction

When the number on the left goes higher than about 150, it is game over.  Thus if at all possible we are going to try and get this done by early June.

Earth Orbit and Science Operations (Question 7)

Due to the press of time and lack of resources, we have not given much thought as of yet to the science instruments.  If we get the burn done in June we will have time to work the science instrument issue before the August 10 flyby maneuver.  We have a critical issue for the flyby which is to turn on all the spacecraft’s heaters for its propulsion system so that it does not freeze during a 25 minute eclipse period during the flyby.  The battery on the spacecraft has been dead since 1981 so there is no help there.  Fortunately, this spacecraft does not have a computer!  The memory on board is not really memory as we understand it today so it will retain and regain its pre eclipse state after it comes back out of eclipse and power is generated by its solar cells.

We are still discussing the final orbit of the spacecraft in Earth orbit and this will be the subject of a future post.  By the time we get back into Earth orbit we will have put together the commissioning plan for the experiments.  Several of the original principle investigators are either already working with us or have indicated an interest in doing so.  It is our strong desire for a mentor relationship here with students to teach them about solar physics, the solar cycle, and the Earth’s magnetic field.  This is an important field of science that impacts our lives every day.  We take a lot of the science for granted that NASA, ESA, and other space agencies do in this area, but without them and the missions that have come after ISEE-3, we would have more difficulty in executing a modern civilization.

Soon we will do a short write up on the scientific objectives of the project.

Wrap Up

As I think you the reader can see, there is a heck of a lot going on, and not much time to get it done.  Thus, we are going to focus on getting the job done with a minimum of distractions and all but the most essential paperwork.  In a very short time, with the volunteers that have come forth, the corporate support we have gained, and the amazing outpouring of financial support in the crowd funding (yes we need every penny of the $125k to do this!), it is starting to look like we have a good shot of pulling this off.  The critical dates are in the third week of this month the transmitter is delivered and when we travel to Arecibo where we will attempt the first command session.

Please continue to help us reach our financial goal for the project.  We now have a really cool patch, designed by our incredible artist, Mark Maxwell.  The same for the images that are in our mission prints goodies now.  From being a completely insanely impossible thing to do on this short of a schedule, it is now merely insane.  Onward Sancho!




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ISEE-3 Reboot Project Technical Update and Discussion

Today is April 30th, the 16th day after we started our Rockethub ( project to raise $125k to allow us to attempt to contact, evaluate, and command the International Sun-Earth Explorer-3 (ISEE-3) spacecraft to fire its engines in such a way as to return it to Earth orbit after a swingby of the Moon on August 10th, 2014.  If you want to know all of the details, please read my previous posting on this subject here.  Today I want to give a discussion related to some of the technical issues and hurdles that we face in bring this spacecraft back into a stable Earth orbit.  I am leaving out the experiments for the time being as we have to focus on the engineering required before we get to that part.

First the Good News

The good news is that the team that did the ISEE-3/ICE mission really planned ahead.  In 1986 a series of maneuvers were done in three stages that targeted a flyby of the Moon at an altitude of 63 kilometers over the lunar surface on August 10, 2014 at around 8:30 PM UTC.  The first series of firings, with a total delta v of 1.51 meters/sec were done on February 27, 1986 when the spacecraft was near perihelion (closest point to the sun), to target the general vicinity of the Earth.  The second series of firings were done on April 7th 1986 to do a plane change to place the spacecraft on an intersect path to the Moon of ~38 meters/second.  The third   firing sequence was used to target the desired perilune target plane aim point (to the nearest kilometer of course!) with a 0.4 meter/sec burn that gave the lunar flyby distance of 63 kilometers.  Figures 1,2 and 3 show the resulting trajectory for these maneuvers:

Figure 7: ICE Trajectory from April 1986 Through August 2014

Figure 1: ICE Trajectory from April 1986 Through August 2014

Figure 1 shows the ICE/ISEE-3 trajectory relative to a fixed inertial frame from April of 1986 through the August 10 2014 lunar flyby.

Figure2: ICE/ISEE3 Lunar Flyby, August 10, 2014

Figure2: ICE/ISEE3 Lunar Flyby, August 10, 2014

This graphic, from Mike Loucks at Space Exploration Engineering, shows the flyby at ~15 km.  This was from just plugging the 1986 ephemeris into the modern Satellite Tool Kit application and running it.  It is shown here just as a general representation of the flyby.

Figure 3: ICE/ISEE3R Trajectory Post Lunar Flyby (1986 estimate)

Figure 3: ICE/ISEE3R Trajectory Post Lunar Flyby (1986 estimate)

This graphic, from the 1987 ICE Handbook shows the trajectory if everything went perfect, with no further maneuvering required.  For those who look at this with an engineering eye, the dark lines in the middle is the orbit of the moon around the earth.  There are a lot of out of plane orbits here that require course corrections to fix.  The lines to the side of the orbits are tick marks for days.  This is where the bad starts in that no matter how brilliant these guys were, they could not completely foresee the influences on the spacecraft from 1986 through now.  Also, the orbit chosen does not really, after the last ranging contact in 1999 and 2008, match and the orbit that the spacecraft is actually in, will result in the spacecraft not being permanently captured in Earth orbit.  This is shown by a new plot by David Dunham, who did a lot of the previous work and is now on our team:

The Bad

The above was the good part.  The targeting of the ISEE-3/ICE for its various comet rendezvous and return trajectory to the Earth is a tour deforce in understanding orbital dynamics and Dr. Farquhar and his team did a magnificent job.  However, there was only so much that computers of that era could do, and even if they had been perfect, in 28 years one has to expect that some course changes have to happen to put the vehicle on target to be captured into Earth orbit.  To recap from my previous post, figure 4 and 5 show what will happen if we do nothing vs what we want to do:

Figure 11: The Fate of ICE/ISEE-3 If We Fail

Figure 4: The Fate of ICE/ISEE-3R Without Course Adjustment

This is obviously not desirable.  The desired (baseline for our project) orbit is shown in Figure 5:

Figure 12: ISEE-3R Flight Path Baseline If We are Successful

Figure 5: ISEE-3R Flight Path Baseline If We are Successful

So, the goal of our project is to achieve the orbit that is in figure 5.  However, the trajectory of the spacecraft must be adjusted and it must be adjusted soon.  The current orbit is a nearly circular (eccentricity ~0.054) with an inclination relative to the ecliptic plane (the plane of the Earth and Sun projected on a two dimensional plane) of 0.06 degrees.  The perihelion (closest point to the sun) is 0.926 AU (astronomical unit or the average distance between the Earth and Sun of 146.6 million km) or 135.75 million kilometers [81.75 million miles]).  The aphelion (farthest point from the sun) is 1.033AU or 151.44 million km [91.196 million miles].  The orbital period is about 354 days.  So now, after 30 years the alignment of the orbit of ICE/ISEE-3 at aphelion lines up with the Earth’s orbit.  Figure six shows the decreasing range of the spacecraft at this time relative to the Earth:

Figure 10: Range from the Earth of the ICE/ISEE-3 Spacecraft

Figure 6: Range from the Earth of the ICE/ISEE-3 Spacecraft

As of May 1, 2014 ICE/ISEE-3 will be at .16 AU or 23.46 million km [14.1 million miles).  This is important as the closer the spacecraft gets to the Earth, the more energy it takes to nudge the course in the right direction for the right altitude lunar flyby that will result in capture into Earth orbit.  This can be seen in the figure 7  plot of delta v versus time done by our team member David Dunham:

Figure 7: dV required for Earth Capture Course Correction

Figure 7: dV required for Earth Capture Course Correction

There is approximately 150 meters/sec of dV left on the spacecraft in its hydrazine fuel system.  As can readily been seen the amount of energy needed as the range gets closer increases rapidly.  Table 1, also by David and a researcher at the University of Arizona, shows the problem in tabular form:

Table 1: ICE/ISEE Course Correction dV needed by 2014 Dates

Table 1: ICE/ISEE Course Correction dV needed by 2014 Dates

As you can readily see, as the spacecraft gets closer, the more energy needed to turn the spacecraft into the right trajectory.  Since there is only about 150 m/s of dV left (uncertain to at least 5%), then sometime very soon after July 1st it is game over.  However, it is worse than that in that we would like to have fuel left over in case of further maneuvers.  This includes more lunar flybys to trim the orbit or to have enough fuel to operate in Earth orbit for a while at the L1 point.  Thus time is of the essence!!!

The Ugly

So, we have a very hard deadline looming.  The problem has been that the people at NASA and the retirees that wanted to do this were unrealistic about the chances of obtaining funding.  With NASA getting ready to shut down operational missions there was no way that a 36 year old spacecraft coming back to the Earth would have any priority.  On April 10th of this year NASA headquarters in a teleconference with senior leadership in the Science Mission Directorate confirmed this to us and the people that wanted to do this mission with NASA funding.  Thus, four days later our effort was born.

The problem is that all of this should have started months ago!  However, just as we learned in our project to recover the Lunar Orbiter and Nimbus I, II, and III tapes from the 1960’s, modern technology can do things now that would have cost millions for NASA to do even ten years ago.  There are several technical problems that have to be solved and we are going to focus on them today and where we are at in the process.

Talking to and Commanding the Spacecraft

First we have to know what language the ICE/ISEE-3 spacecraft speaks in order to understand the formats of the data for commanding and telemetry.  Fortunately, the spacecraft does not have a computer!!  It has a sequencer that looks pretty much like a printer looks like to a computer.  In the days before NASA put computers on spacecraft the overhead for the operations team was huge as each individual command had to be developed on the ground, sequenced, and then sent to the spacecraft.  An acknowledgement, in the form of telemetry indicated that the command had been accepted and executed. What we have to do is to recreate that entire system.

Since this particular problem has a very strong ITAR flavor (International Traffic in Arms Regulation), we are doing this part in house with some help of some volunteers that have come on board (we will be paying them through the critical part of this activities).  We have to first figure out what the command structure is like for the engineering systems on the spacecraft (we are not bothering with the experiments yet) and figure out how to do that using modern computers.  We are making a lot of progress there but we at this time have insufficient documentation.  We are working with NASA to develop a Space Act Agreement that will give us access to this documentation.  We have enough to develop the command screens and we have an approximation of the data that we need to send.  However, there are (as of today) some gaps that we have to fill.  We continue to get documents from former engineers that worked the ISEE-3 mission so we are confident that we will have what we need.

Our initial tasks for commanding the spacecraft are as follows:

1. Turn Engineering Telemetry Mode on.

This mode commands the spacecraft to transmit telemetry regarding the functions of the onboard systems, including the attitude determination and control system, the power system, and the propulsion system.  This will help us evaluate the health of the spacecraft.

2. Two Way Ranging

This command will place the ranging transponder in a mode that allows ground stations to measure the distance (range) to the spacecraft and back.  We have to use multiple stations and use triangulation to get a better fix on the position.  We will have a team that takes this range data and then turns that into an updated position in space of the spacecraft.  Then the flight dynamics guys (Dr. Farquhar and David Dunham), will update the required energy to put the spacecraft into a proper Earth orbit.  Then….

3. Engine Firing

Back in the day, NASA had a program called ICEMAN that worked with a couple of programs called GMAT and GMAS.  These were all old mainframe programs that took the data and the developed a firing solution for the thrusters on the spacecraft.  This is an area where we don’t have the programming information for the old way so we going back to first principles of the spacecraft and re-deriving what we need to fire the thrusters.  We are working with Space Exploration Engineers (that did the NASA LADEE mission trajectories) to help us verify and validate what we are doing so that we can close in on a firing solution that looks good.

So this is what we are going to do.  To get there we have to solve the problem of how to read the telemetry, properly format commands, send the commands, and verify that the commands were executed.  We are developing the screens and the process to do this now.  More as this develops.

Modulator/Demodulator Development

Another big problem to solve is to redevelop the demodulator and modulator for talking to the spacecraft.  If this was even ten years ago it would be very difficult and expensive to do.  However, with the continuing advance in software technology for embedded computer systems we can now develop a demodulator in software and run it on some hardware that interfaces to the transmitters and receivers on the spacecraft.

We are working diligently with Ettus Research  on the development of the modulator/demodulator.  This basically formats the digital data that comes from the command generation software (also under development) and turns it into a waveform that the S Band transmitter can transmit to the spacecraft and that can then be demodulated on the spacecraft and sent to the command sequencer.  Note that there is no computer on the spacecraft and thus the commands are directly executed.  There are a lot of details related to this that we are glossing over for now in the interest of brevity.

When we command the spacecraft into engineering telemetry mode, the spacecraft transmits a signal back.  The signal is received, also on S-Band and then down converted to a signal that can turn the analog waveforms into bits that can then be received by our telemetry system software (also under development).  We will report back more on this later but suffice to say that the folks at Ettus are the best in the business and we will have this part of the system functioning soon.

Telemetry System

Another huge issue is redeveloping a telemetry display system.  When ISEE-3/ICE was operational this was comprised of several computers with old style displays for command line or numerical telemetry.  Today we have off the shelf software that can take the bits output from the demodulator and turn them into graphical displays and switch positions. This is a gross simplification in that we have to be able to take the incoming data, verify that the parity is right, then slice and dice all of the bits at their right addresses to push them to the right displays.  We are working with some people at National Instruments as well as working to develop our own displays for certain functions.  Following are the three spacecraft subsystems that we are focused on for the critical thruster firing.

  • Propulsion System
  • Attitude Determination and Control System
  • Power System

These are the screens that will be redeveloped and then when we command the spacecraft into engineering telemetry mode we will be able to verify its last known state, evaluate the condition of the spacecraft, and test a few of the subsystems without hitting the propulsion system and turning it on.  We are obviously going to be very careful about that one!


Another and possibly our biggest issue is ranging.  What ranging is, is to send a signal to the spacecraft, have it returned, and measure the flight time to a very high order of accuracy (a few to tens of nanoseconds over a two and a half minute period).  We also really need to do this at multiple stations so that we can get differential flight times that can then be used to create a triangular baseline so that we can do a much better job at determining the spacecraft’s current position.  We know it to then tens to hundreds of kilometers level.  However, we need to know it much better than that in order to know exactly how much to fire the spacecraft thrusters for the lunar flyby at the right altitude.  NASA makes this look easy.  One time I read that the Voyager spacecraft’s position was accurate to a few kilometers out to Neptune!  This is an incredible feat of navigation that no one else in the world can do.  We are trying to replicate this at a much shorter range (about 23 million kilometers).  We know what to do, but we don’t have this one fully solved yet.


The above are the biggies right now but another aspect is to keep all the parties in the loop, get our team of mostly volunteers working together, and to coordinate all the things that have to be done.  Part of the problem is that to read and absorb the documents takes time, and then to write formal documentation in a manner that should be done also takes time, and time is the one thing that we don’t have!  This is probably the biggest challenge overall and we have been bringing a couple of new team members that are local on board to help and start to get a handle on everything.  We also have to scare up resources, in people, in hardware, in time.  All of this takes time, time that is a very precious resource right now.

There is also the paperwork that we have to do with NASA.  We are currently working out a Space Act Agreement with NASA that will allow us to collaborate with them on a no exchange of funds basis.  This will give us access to the documents that we need and other things that as soon as the Space Act Agreement is signed, we will tell you about.  We will be sharing data about the spacecraft, its performance, and the condition and operation of the experiments with them in return for some things from them.

Current Status

We have a lot of balls in the air right now, from ordering transmitters, to coordinating ground stations and engineers, to getting documents from NASA, getting the Space Act Agreement signed, to getting the team organized and working as a team.  All of this while the crowd funding effort is still going forward and without being able to access the money from it!!

More next Monday, but for all of the Crowd Funding supporters, we are working very diligently to meet our deadline for the firing of the thrusters and so far we don’t see anything that makes this impossible!  Just darn difficult!

I would like to thank the following companies people at this time for their support.


Arecibo Observatory.

Ettus Research

National Instruments

Ball Aerospace



Keith Cowing, Media, and all around gadfly of making things happen and my Co-lead on this project.

Tim Reyes, Flight Operations

Cameron Woodman, Flight Operations

Karl-Marx Wagner, Transmitters and communications

Patrick Barthelow, Transmitter and antenna support.

My Wife Nikki!

Mike Loucks, Space Exploration Engineering

Mark Maxwell, Space artist extraordinary!

Leonard Garcia, overall great guy doing this on his own time at NASA

Dr. Robert Farquhar, former ISEE-3 Mission Design lead

David Dunham, Flight Dynamics

I also want to thank my internal team of Austin Epps and Marco Colleluori who are working some of the very difficult problems with telemetry.

and many others!!





Posted in Space | 1 Comment

The International Sun-Earth Explorer (ISEE-3) Reboot Project, Bringing an Old Bird Back to the Earth, and Back to Life

Life isn’t fair. So many times in my life I start to do something and end up going in a completely different direction. I do a lot of advanced technology spacecraft and systems design for lunar, mars, and asteroid exploration. I love to think about, plan, and build systems that will help mankind extend its reach beyond the Earth.   I was very fortunate that when I left the computer industry in my late 20’s to return to college and get my degree I was able to have many wonderful mentors at the University of Alabama in Huntsville. Some of these were  German rocket scientists like Dr. Ernst Stuhlinger and many of the Americans who made up the team that built mankind’s first lunar exploration system. Also, when I was in my early 20’s in the early 1980’s I worked as a non-degreed engineer in the California computer industry. I had great mentors there as well, who taught me how to be a good engineer in the extremely competitive microcomputer industry of the era.

One of the companies in the microcomputer industry back then was Vector Graphic Inc. who, before the advent of the IBM PC, was one of the leaders and innovators in the industry.  My boss and the manager of engineering was Nick Esser, an incredible engineer and a great mentor.  I would often come bounding into his office with what I thought was a great idea.  He would immediately stop me and say, sounds good, now go research what has already been done in this area.  Well we did not have the online resources that we have today so in order to impress the boss, I would go and do a lot of in depth research, perusing IEEE proceedings, textbooks, ask people questions.  I would often determine that my bright idea was someone else’s before me and often they had usually done it better.  This taught me two things.  The first is that there are a LOT of smart people out there, many of them much smarter than I (when you are 22 this is a revelation).  The second was that in doing this research I would almost always come out smarter myself.  I took this incredible lesson with me to my college years and it has made a critical difference for me in how I think about technology and engineering in general. It is also the origin of the life is not fair comment.

How the Above Relates to the ISEE-3 Project

Many of you know about our Lunar Orbiter Image Recovery Project (LOIRP), and many of you who read this helped us out last year as we raised a critical $68k dollars that helped us get over the top to obtain more funding, which has allowed us to finish the tape captures (thanks!).   That project started when I was working in 1989 with Lunar Orbiter Lunar images derived from film, and found out after my research that the original tapes had much higher dynamic range.  This gave me the technical foundation to sell the project to NASA in 2008 after we found and obtained the tapes and tape machines.  Despite deep skepticism that the project was viable or worthwhile we were able to show the improvements to worldwide acclaim and thus gained the credibility that we could work with and improve old data sets.

Like most engineers and scientists I would rather work on new missions but it just kept bugging my engineering sensibility that these tapes were not being saved and also I knew that if our team did not take on this project, no one else would, and thus an incredibly valuable part of our history as well as incredibly valuable data for future science and exploration would be lost.  Now that the LOIRP project is coming to a successful conclusion, another instance of a violation of my engineering sensibility has taken place.  That violation is that a spacecraft, originally called the International Sun-Earth Explorer or ISEE-3 is coming back to Earth in August and if something is not done it will be lost forever.  Why should anyone care?  That my friends is the rest of the story and why I am going to ask you to liberate some of your hard earned cash to give to this project…

The ISEE Mission

The ISEE-3 vehicle was the third of three spacecraft, two from NASA and one from ESA. Figure 1 is the NASA graphic for the mission:

Figure 1: ISEE-1,2, and 3, launched 1978

Figure 1: ISEE-1,2, and 3, launched 1978

The three ISEE spacecraft are comprised of a mother/daughter (ISEE-1/2) configuration and a heliocentric spacecraft (ISEE-3). The ISEE-1 and -2 spacecraft, mated together, were launched on October 22, 1977, and the ISEE-3 was launched on August 12, 1978. The purpose of the ISEE Program was to increase knowledge of the magnetosphere, interplanetary space, and the interactions between them.

The original mission objectives were:

  •  Investigate solar-terrestrial relationships at the outermost boundaries of the earth’s magnetosphere.
  • Examine in detail the structure of the solar wind near the earth.
  • Examine the shock wave boundary between the solar wind and the earth.
  • Investigate motions of, and mechanisms operating in, the plasma sheets.

The ISEE-3, the one of interest today, had an extensive array of experiments, designed to probe solar emissions and to gauge the effect of these emissions on the Earth’s magnetosphere.   Figure 2 shows a graphic of the ISEE-3 spacecraft:

Figure 2: The ISEE-3 Spacecraft

Figure 2: The ISEE-3 Spacecraft

ISEE-3 s a spin stabilized spacecraft and was built by Fairchild Space in Maryland (now Orbital Sciences Corporation).  Look at the graphic above and you will see that the 3D radio mapping antenna in the radial axis is 92 meters across from tip to tip!  Figure 3 is the vehicle in testing and a graphic of it in space:

Figure 3: ISEE-3 In Testing and a Graphic of its 1985 Comet Flyby

Figure 3: ISEE-3 In Testing and a Graphic of its 1985 Comet Flyby

Table 1 shows the instruments for ISEE-3 and their operational status as of the last substantial contact in 1999:

Table 1: ISEE-3 Instruments, the Principal Investigators, and the Last Known State

Table 1: ISEE-3 Instruments, the Principal Investigators, and the Last Known State

In short, this is an incredibly capable spacecraft.  If that was it, it would be an interesting story.  However, this is just the beginning.

The ISEE-3 Extended Mission Turns into ICE

Most spacecraft in this era were not really meant for extended operations beyond a few years (Voyager 1 and 2 being the obvious exceptions).  The primary mission of the ISEE-3 spacecraft was three years.  The ISEE trio were designed to operate through solar cycle 21 maximum and all three operated brilliantly.  These were the first spacecraft dedicated to the study of heliophysics, a term coined in 1981 based upon the discoveries of the ISEE satellites.  A NASA Technical Reports Server ( search turns up dozens of scientific papers, almost all breaking new ground in the emerging discipline of solar/terrestrial physics.

The ISEE-1 and 2 spacecraft were in low earth orbit, but ISEE-3 was placed into the Earth/Sun Lagrange point L1, the first spacecraft to be sent to that location.  This location, about 1 million kilometers closer to the sun than the Earth, is still gravitationally bound to the Earth and thus is “upstream” of the planet and in front of the bow shock of the Earth’s magnetosphere.  This is the perfect vantage point for a maximally instrumented spacecraft to observe solar phenomenon before it reaches the interface between the solar wind and the magnetosphere.

Dr. Robert Farquhar, ISEE-3 Flight Dynamics Manager comes up with a scenario that will take ISEE-3 out of the Earth-Moon system and take it to an asteroid flyby with comet Gaicobini-Zinner and then later to comet Halley.  Figure 4 shows the flight trajectory for this extended mission:

Figure 4: ISEE-3/ICE Extended Mission to World’s first Comet Flybys

Figure 4: ISEE-3/ICE Extended Mission to World’s first Comet Flybys

In order to obtain the energy necessary to escape Earth orbit for the comet flybys, the ISEE-3 spacecraft did multiple flybys of the Earth and a final flyby of the Moon.  This is an extremely delicate dance of orbital dynamics, trading of gravitational energy  for kinetic energy, a strategy developed by Dr. Farquhar and executed by his team.  When ISEE-3 did its final lunar flyby it was renamed the International Cometary Explorer (ICE). The renamed ICE spacecraft left the Earth/Moon system in September of 1982 (about the time I started bugging my boss).  On September 11, 1985 ICE passed through the tail of comet Gaicobini-Zinner at a distance of less than 8,000 kilometers, a masterful feat of celestial navigation.  Figure 5: shows the encounter:

Figure 5: ISEE-3/ICE Passes the Tail of Comet Gaicobini-Zinner Sept 11, 1985

Figure 5: ISEE-3/ICE Passes the Tail of Comet Gaicobini-Zinner Sept 11, 1985

ICE used its full suite of instruments during this pass and had the first instrumental confirmation that a comet perturbs the solar wind and the  magnetic field.  Again, a search of the NASA Technical Reports Server finds dozens of papers about this flyby and the next one at comet Halley.  Figure 6 shows the Halley and Gaicobini-Zinner flyby:

Figure 6: Two Comet Flyby’s By ISEE-3/ICE Spacraft in Heliocentric Orbit

Figure 6: Two Comet Flyby’s By ISEE-3/ICE Spacraft in Heliocentric Orbit

The illustration in figure 6 is relative to a fixed Sun-Earth line, essentially an inertial point in space.  The flyby of Halley’s comet was from a further distance of about 21 million kilometers.  Even at this distance the sensitive instruments on ICE detected the influence of the comet on the surrounding solar wind and magnetic field.  After the flybys ICE was tasked to do complimentary studies of the interplanetary solar wind, magnetic fields, and coronal mass ejections in concert with the NASA/ESA Ulysses spacecraft, that had been slung into a solar polar orbit by a close flyby of Jupiter.

After these flybys of two comets and the solar mission by this veteran spacecraft, Bob Farquhar’s flight dynamic guys had one more trick up their sleeves, and it was a doozy.

ICE/ISEE-3 Returns to the Earth in 2014

Figure 7 shows the final tour-de-force genius of the ICE navigation team:

Figure 7: ICE Trajectory from April 1986 Through August 2014

Figure 7: ICE Trajectory from April 1986 Through August 2014


The above illustration shows the orbital trace of ICE/ISEE-3 from a fixed Sun-Earth line.  Each loop represents each time the ICE spacecraft passe by the Earth.  It is in a 355 day solar orbit so ICE “laps” Earth in those number of days.  The orbit of ICE is slightly eccentric orbit with an aphelion (furthest distance from the sun) of 1.03 AU, and a perihelion (closest to the sun) of 0.93 AU.  What this does is to set ICE up for an encounter with the Earth, a lunar flyby, on August 10th of this year.

The Return and the Dilemma

On March 2nd  2014 a group of amateur radio satellite operators at AMSAT-DL in Germany heard the ICE spacecraft carrier, that had been left on intentionally by NASA.  Figure 8 shows the signal trace:

Figure 8: ICE S-Band Transponder First Reception (Down Converted)

Figure 8: ICE S-Band Transponder First Reception (Down Converted)

ISEE-3 ICE spacecraft signal spectrum recorded on March 2, 2014 at 1822 UT using the 20m dish antenna of Bochum Observatory, Germany. Range 43M km, azimuth 230°, elevation 49°. Average of 2 spectra spanning 2.1 seconds.

This is the reception report from the radio telescope at Bochum Observatory.  This was followed by a reception report from the Search for Extraterrestrial Intelligence (SETI) Allen array on March 20th.  This was followed by a reception report by Arecibo, the largest radio telescope in the world on April 9th of this year. Another report comes from Morehead State University, who we are working with in figure 9:

Figure 9: Morehead State Reception of the ICE Telemetry Transmitter 3/10/14

Figure 9: Morehead State Reception of the ICE Telemetry Transmitter 3/10/14

The dilemma is this, after all this time, after all the travels, and all of the planning by the ICE flight dynamics team, the one thing that they could not have foreseen in 1987 is that NASA would no longer be able to hear or to pay for the recovery of ICE.  Linked here is an article by Emily Lakdalla of the Planetary Society.  She copied a post by NASA Goddard on the subject.  It is reposted here:

Communication involves speaking, listening and understanding what we hear. One of the main technical challenges the ISEE-3/ICE project has faced is determining whether we can speak, listen, and understand the spacecraft and whether the spacecraft can do the same for us. Several months of digging through old technical documents has led a group of NASA engineers to believe they will indeed be able to understand the stream of data coming from the spacecraft. NASA’s Deep Space Network (DSN) can listen to the spacecraft, a test in 2008 proved that it was possible to pick up the transmitter carrier signal, but can we speak to the spacecraft? Can we tell the spacecraft to turn back on its thrusters and science instruments after decades of silence and perform the intricate ballet needed to send it back to where it can again monitor the Sun? The answer to that question appears to be no.

The transmitters of the Deep Space Network, the hardware to send signals out to the fleet of NASA spacecraft in deep space, no longer includes the equipment needed to talk to ISEE-3. These old-fashioned transmitters were removed in 1999. Could new transmitters be built? Yes, but it would be at a price no one is willing to spend. And we need to use the DSN because no other network of antennas in the US has the sensitivity to detect and transmit signals to the spacecraft at such a distance.

This effort has always been risky with a low probability of success and a near-zero budget. It is thanks to a small and dedicated group of scientists and engineers that we were able to get as far as we have. Thank you all very much.

Thus, with an impossible schedule, and without a budget, was born the ISEE-3 Reboot Project.

The ISEE-3 Reboot Project Begins

I have known about the ISEE-3/ICE spacecraft since my college days at the University of Alabama in Huntsville where I worked for the Center for Space Plasma and Aeronomic Research (CSPAR).  I have known Dr. Farquhar personally and by reputation for many years.  His work in orbital dynamics should have gotten him a Nobel Prize for its originality and brilliance.  When I read the above about them not having the equipment to talk to the spacecraft, it got me thinking and researching.

Our team has already successfully built a demodulator and software to recover images and data from the 1960’s Lunar Orbiter.  We have also recovered and modernized the infrared images from the Nimbus I,II, and III spacecraft of the 1960’s.  I had a vague notion that the ISEE-3 was not that much more advanced, so yet again our team started diving into the data and found that there was no computer on the spacecraft, which made things easier.  The modulation scheme is simpler than modern cell phones, which use a modern technique of using software for the modem, directly digitizing the signal and then processing it.  It seemed logical that this could be used for the ISEE-3 spacecraft.

Last year, as most readers who are aware of the Lunar Orbiter LOIRP project know, we crowd funded some significant money last year, about $68k, which spawned more private funding, which allowed us to make enough progress to get further funding that allowed us to completely finish the tape digitization portion of that project (we are still processing the final products).  Keith Cowing of NASA Watch was instrumental in making that happen.  These types of crowd funding projects require someone who really knows the media and very few people know more than Keith about modern online media Keith is also our co-lead on the LOIRP project.  So we started talking about what we would do if we were to do this project.  Keith is starting up a non profit STEM education project called Space College and this seemed to be a great project that we would use to involve students, volunteers and others attempt to recover the spacecraft.

Keith, being a former NASA civil servant and a long time pain in the rear/friend of the agency, knows everyone.  So, after it was determined by NASA GSFC that they could not do this, and after a teleconference where NASA headquarters told NASA GSFC, their contractors, and us that there was no money for any recovery effort, we started another crowd funding effort on Rockethub.  Things have started moving since then, beginning with panic.  Why, because we only have a short amount of time to make this happen!  We are fortunate that in two weeks we have raised over $51k of our $125k goal, but that is not where the panic is.

A question that you might have is why do this, what is going to come from it if I give a bit of my hard earned money to support it?  The long term answer is that we want to put it back into Earth Orbit, turn the science instruments on, and have it be an open science data source, used for STEM education, amateur radio solar predictions, and for science about the sun.  It is also an incredible technical challenge for as far as we know, no private entity has ever commanded, communicated with, and returned to earth orbit a spacecraft!  It is also a testament to the foresight of Dr. Farquhar and his team that deserves recognition.  Here is a list of firsts for the ISEE-/ICE spacecraft:

  • First Mission to a Libration Point
  • First Mission to Use a Suite of Instruments across the electromagnetic spectrum to measure the dynamics of the magnetosphere between the Earth and sun during a solar maximum.
  • First Lunar Flyby for Gravity Assist to an Interplanetary Trajectory
  • First Comet Flyby (1985)
  • Second Comet Flyby (1986)
  • 36 Year Trajectory to Return to Earth (2014)

This is a truly historic spacecraft and to not try and save it to me is an engineering and science tragedy that offends my engineering sensibility. Here simply is the problem in Figure 10:

Figure 10: Range from the Earth of the ICE/ISEE-3 Spacecraft

Figure 10: Range from the Earth of the ICE/ISEE-3 Spacecraft

In looking at figure 10 you see as we get closer to the date of the perigee pass around the Earth, the distance continues to decrease.  The problem is that no matter how good those guys were in doing the maneuvers in the 1980’s, it is not perfect and will not result in a capture into Earth orbit.  Thus we have to fire the thrusters of the spacecraft by late June or there will not be enough fuel left to make the course correction to put it into a permanent earth orbit.  Thus, Isaac Newton is driving this bus and unless we change the course, the spacecraft will drift back into planetary space, not to return until 2029.

ISEE-3 Reboot Technical Issues and Our Process

There are several questions that must be answered in the ISEE-3 Reboot Project.

–      Is the Spacecraft Still Alive (verified yes)

–      Can We Talk to it? (Under Development)

–      Can the Propulsion System Be Activated (Working on it)

–      Can the Spacecraft Be Put Back Into A Stable Earth Orbit (Depends on the Previous Questions)

We have made a lot of organizational and technical progress toward answering these questions.  In summary, we have the folks at Morehead State University in Kentucky working with us on the project.  We have also gained the agreement from Arecibo that they will listen to the spacecraft more for us and that if we send them a transmitter that is easy to set up, that they will transmit our command signals to the spacecraft.  This is beyond valuable and means that we don’t really have to worry that much about link margin but can just blast a signal that way, especially as the range is decreasing every day.

Our plan for the recovery is this.

  1. Secure and send 200W transmitter to Arecibo.
  2. Arecibo sends simple audio tone to the spacecraft to ascertain whether or not the ranging function was left on.
  3. Develop a single manual command that can be fed into the HP synthesizer at Arecibo to turn the Engineering Telemetry function on.
  4. Ascertain the health of the spacecraft and debug the telemetry recording and display system.
  5. Figure out how to do the ranging, we  have a team working this right now.
  6. Update any trajectory (Dave Dunham/Farquhar).
  7. Install 700 Watt transmitter at Morehead State and test as the spacecraft gets closer.
  8. Command the burn either at Morehead or Arecibo.
  9. Pray
  10. Do ranging after the spacecraft is captured into Earth orbit for final orbital insertion burns (much easier to do with reduced range).
  11. Put into final orbit and re-commission the science experiments.

We have several groups of people working with us right now, almost everyone a volunteer at this point.  We still have a couple of really big problems (well maybe four or five) to solve, the ranging seeming to be the biggie.

We will have a lot more press releases and blog posts out over the next few days but I wanted to give everyone the highlights.  We are going to setup our mission operations center at a location that I can’t disclose until some paperwork is finally signed but it is in progress.  Really all we are going to do is to revive the command and telemetry consoles.  We are going to display in real time the propulsion system, the attitude determination and control system, as well as the power system.  We have several analyses done, documents scanned, data transferred from archived pdf’s to excel, and many other things.  We have an incredible bunch of people helping us but we need one thing more…


As I stated earlier, we are right now an almost completely volunteer project with the exception of a couple of my engineers at my small company who are working on critical aspects of the project.  We are raising $125k that we hope will get us to the point where we get the steps outlined above done.  If we can do this, we will have an open source, publically accessible satellite data stream of the first open source satellite above Low Earth Orbit.  Personally I am already learning boatloads about how to operate and control an interplanetary satellite.  I am still learning after all these years and the design of the ISEE-3 has some incredibly interesting features that I think are valuable to spacecraft design today that we may use.


If we don’t fire the thrusters by late June, figure 11 is what the orbit will look like:

Figure 11: The Fate of ICE/ISEE-3 If We Fail

Figure 11: The Fate of ICE/ISEE-3 If We Fail

I can tell you that, from being completely panicked that this was going to be darn near impossible, it is just going to be very darn hard.  It will be impossible without your financial help.  Here is the trajectory in figure 12 if we save the bird:

Figure 12: ISEE-3R Flight Path Baseline If We are Successful

Figure 12: ISEE-3R Flight Path Baseline If We are Successful

Help us be successful.  What I would like to ask of this community is that 300 people give $100 each to the project.  For those who cannot do that, please do what you can.  I can tell you though, that if the 300 give $100 the rest will come.  It is just how the momentum thing works in crowd funding.  I know that this is hard earned money and that this is a science mission.  However, it is also about bringing a team of people together to do what other people say is impossible.  Going back to my opening, I did a lot of research on this, and by standing on the shoulders of giants like Bob Farquhar, Dave Dunham, and the rest of the ISEE-3/ICE crew, we can do this.  NASA is providing moral support and documents and have indicated their positive support for our effort.  More to come soon, so again thanks and I look forward to giving everyone more reports soon!

Oh, by the way, here is the link to our crowd funding site:


Posted in Space | Tagged , , , , , | 1 Comment

The International Sun-Earth Explorer (ISEE-3) Reboot Project, Bringing an Old Bird Back to the Earth, and Back to Life


Hope you folks will help out!

Originally posted on Watts Up With That?:


ISEE3-ICE, launched in 1978

Citizen backed space science attempts to do the near impossible

Guest essay by Dennis Wingo

Life isn’t fair. So many times in my life I start to do something and end up going in a completely different direction. I do a lot of advanced technology spacecraft and systems design for lunar, mars, and asteroid exploration. I love to think about, plan, and build systems that will help mankind extend its reach beyond the Earth.

I was very fortunate that when I left the computer industry in my late 20’s to return to college and get my degree that I was able to have many wonderful mentors at the University of Alabama in Huntsville. Some of these were the German rocket scientists like Dr. Ernst Stuhlinger and many of the Americans who made up the team that built mankind’s first lunar exploration systems. When I was in…

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