SLS and Lunar Return in 2024: “With Faith and Ambition”

Round 3

I was nine years old in July of 1969 when Neil Armstrong and Buzz Aldrin walked on the Moon.  I watched every time an Apollo mission was broadcast, every surface EVA that I could find.  I grew up less than 100 miles from the Marshall Spaceflight Center and eventually moved to Huntsville in 1987 after a career in the computer industry to learn about space.

I was a student at the University of Alabama in Huntsville in July of 1989 when President George H. W. Bush inaugurated what was then called the Human Exploration Initiative (HEI) (later it morphed into SEI) to return to the Moon and on to Mars.  I was there in 2004 when President George W. Bush inaugurated the Vision for Space Exploration (VSE) to return to the Moon and on to Mars. Bottom line, I have heard it all before. This past week Vice President Pence had these words to say in Huntsville, halfway between UAH and MSFC.

And let me be clear: The first woman and the next man on the Moon will both be American astronauts, launched by American rockets, from American soil.  

But to accomplish this, we must redouble our efforts here in Huntsville and throughout this program.  We must accelerate the SLS program to meet this objective.  But know this: The President has directed NASA and Administrator Jim Bridenstine to accomplish this goal by any means necessary.

In order to succeed, as the Administrator will discuss today, we must focus on the mission over the means.  You must consider every available option and platform to meet our goals, including industry, government, and the entire American space enterprise.

Our administration is committed to this goal.  And this President, this administration, and the American people are committed to achieving that goal at the Marshall Space Flight Center.  

But the truth is, we’re committed to Marshall, the incredible history that you have here.  But to be clear, we’re not committed to any one contractor.  If our current contractors can’t meet this objective, then we’ll find ones that will.  If American industry can provide critical commercial services without government development, then we’ll buy them.  And if commercial rockets are the only way to get American astronauts to the Moon in the next five years, then commercial rockets it will be.

Urgency must be our watchword.  Failure to achieve our goal to return an American astronaut to the Moon in the next five years is not an option.

You know what?  I believe him.  I believe him because it is our time.  It is our responsibility.  It is our future that is at stake.  I like to say in my twitter tagline that “We live in the 21st century, time to act like it!”  This is truth.  Things are different now.  We have key ingredients in our nation today that we simply did not have the last two times we tried, this, which is the desire, the passion to do this thing, and a strong commercial space enterprise that simply did not exist then.

Americans of all stripes are more concerned about our country and future than at any time since at least the 1970’s.  We have deep concerns over the environment, as we did then.  We have deep concerns about our political system now, as we did then.  We have a malaise in our human exploration space program today, as we did then. We have almost four billion more humans alive today than in 1970 and the stress that causes to our home-world.  However, we also have made amazing advances that will transform this return to the Moon from the camping trips of the Apollo age, to a sustained an permanent step toward the economic development of the solar system.

What we have now in a technology base that is literally 50 years beyond that time.  This makes a difference, a big difference in what we can do in space.  We have technology billionaires who put their lives, their fortunes, and their sacred honor toward making this happen.  We have an experience base in human spaceflight with the ISS that has taught us how to make humans and machines work longer in that environment, far longer than on Skylab.

The question is how and the question, why and the question is what are we going to do when we get there.  These are the good questions because at the end of the day, we must ask the questions and we must have good answers that make sense, or like the previous times since Apollo, we will fail.

This really demands a book level presentation but today I would like to address just a couple of points.

What to Do on the Moon

We go to Mars to take our civilization there.  We go to the Moon, to help save our civilization here. (Tagline from my book: Moonrush)

It is a fundamental principle of engineering project management to know what you want the product to be before you start designing it.  However, there is a catch 22 situation with NASA’s plan’s since the end of the Apollo program.  Whenever the full plan is presented, it is immediately attacked as being too expensive, out of step, or the equivalent of taking food from the mouth’s of babies.  It is my information, provided by those deep inside the machine, that NASA has been very reluctant to provide cost information because of such attacks.  However, the other side of the problem is that if you don’t have a vision (sense of purpose) for what you are going to do on the surface, that also provides openings for attacks for lack of purpose, waste of money, etc…yada yada….  This is shown following.

This is Eric Berger of Ars Technica’s tweet on congressional testimony today by NASA administrator Jim Bridenstine from democratic congressperson

Screen Shot 2019-04-02 at 9.48.42 AM

Here are the things that we know from the last few days of talks by Bridenstine and the Vice President.

  1. Lunar South Pole
  2. In Situ Resource Utilization (ISRU)

So, we can infer That…

  1. Start out at a single location (south pole)
  2. We are actually going to go after In Situ Resources…

This is awesome!  This allows an architecture to start being developed.   Vice President Pence had something to say in this area as well.


To continue to build a world-class workforce, NASA needs the authority to recruit, train, and motivate the world’s best and brightest scientists, engineers, and managers, and to remove any barriers standing in their way.  And that includes building new and renewed partnerships with America’s pioneering space companies and entrepreneurs.

And in this century, we’re going back to the Moon with new ambitions, not just to travel there, not just to develop technologies there, but also to mine oxygen from lunar rocks that will refuel our ships; to use nuclear power to extract water from the permanently shadowed craters of the South Pole; and to fly on a new generation of spacecraft that will enable us to reach Mars not in years but in months.

To develop these new technologies, NASA must adopt an all-hands-on-deck approach to procurement, contracts, and its partnerships.  If a commercial company can deliver a rocket, a lunar lander, or any other capability faster and at a lower cost to the taxpayer than the status quo, then NASA needs to have the authority and the courage to change course quickly and decisively to achieve that goal.  


So, not only is ISRU involved, but ISRU beyond just trying to go for water ice.  This is good as the water ice is apt to be a difficult problem to solve.   Bringing in other stakeholders is great as well and commercial interests.  I am currently reading a book about how the United States created the merchant marine and I think that could be a model to follow.

I am not going to belabor what we are going to do on the surface here.  For those who are interested, here are links to previous articles on the subject…




The lunar outpost should be much more than just NASA as it is the beginning of the economic development of the solar system and at the end of the day, private enterprise must carry most of the load, helped out and incentivized by our government as a facet of national policy.  This is something that many of us who were in ProSpace have been advocating for over 25 years.  Here is a link to the Zero G Zero Tax legislation that has been introduced at various times in the past, but should be revisited in order to help lower the risk of private investment toward the Moon and increase the amount of money invested in this new frontier.


Science provides insight, wonder, and knowledge, but economics (and probably national security) is the reason that we are going there.  As in any new realm of technical endeavor in the 500 year history of exploration and capitalism, new economic vistas that require investment have benefitted from long term support from government.  Government helps retire the initial financial risk (First steamship, intercontinental railroad, merchant marine, aviation), and the resulting economic output repays the government in long term tax revenue and additional investment by the private sector.

Late today on CNBC a leak of a potential program called the Advanced Cislunar and Surface Capabilities (ACSC) program, who’s budget would increase from $363m dollars in FY 2020 to $2.4 billion by FY 2024 seems to fit the bill for this on the government side.  I do feel that the Zero G Zero tax bill (or a renamed Lunar Industrial Operations Tax Credit (SITC) would remove the final argument against a full fledged economic development push toward the Moon.


“Any thing we don’t need to do, we are not going to do.” (Jim Bridenstine)

Everything is on the table” (Jim Bridenstine)

“You must consider every available option and platform to meet our goals” (Mike Pence)

The problem is how in the heck are we going to get to the Moon by 2024?  Those familiar with the SLS program have known how incredibly behind schedule it has been and continues to be.  There is also the issue of the “Gateway”.   Then we have to get to the lunar surface with humans as well.

Jim Bridenstine said the above at the NASA Town Hall meeting on Monday April 1, 2019. In this town hall (link here).  In that talk at about 42 minutes, Bridenstine made what to me was a curious statement.

“SLS, even with the Exploration Upper Stage, cannot get into Low Lunar Orbit”

Disclaimer: In writing this no one is paying me, nor has anyone promised anything for what follows.

In September of 2016 Skycorp (my company) was given a contract by United Launch Alliance to build a certain part of their Integrated Vehicle Fluids System (IVF).  In a 2013 presentation to the National Academies (link here), ULA presented about the development of the IVF system and its applications to the Exploration Upper Stage (EUS). The figure here from that presentation indicates its value toward enhancing the capabilities of the ULA ACES upper stage for the Vulcan and its benefits for the EUS stage.

Screen Shot 2019-04-02 at 6.12.59 PM
United Launch Alliance Integrated Vehicles Fluid System (ULA-IVF)

This is from a 2018 presentation to the National Space Society (link here) showing the IVF system on a stage that looks suspiciously like the EUS.

Screen Shot 2019-04-02 at 6.37.50 PM
ACES IVF Progress 2018
Screen Shot 2019-04-02 at 6.42.21 PM
The Business End of the IVF and ACES

Myself and some of my friends who do this kind of things for a living were stunned by what Jim Bridenstine said.  The short version is that in playing with the numbers, with validated information from NASA that is available, the Orion, with its service module, using the EUS implementing the IVF system, can get into a low lunar orbit.  Read on to see how.


When the NASA Constellation program was begun in 2005 the architecture was considerably different than the current NASA plans, which are today an outgrowth of another cancelled mission architecture called the Asteroid Redirect Mission (that is how we got the Gateway).  When Constellation was started, there were to be two launch vehicles to do a lunar mission, the Ares 1, which would loft the Crew Exploration Vehicle (later renamed Orion), and then the Ares 5, which was the heavy lifter that placed the Altair lunar lander into orbit.  In orbit (formally known as the Earth Orbit Rendezvous (EOR) the two would meet and the upper stage of the Ares 5 would do the trans lunar injection orbit burn.  This is shown below.

Screen Shot 2019-04-02 at 6.28.35 PM
Ares-5-Altair-CEV (Orion) in Low Earth Orbit

This is important to the current discussion because after the Ares 5 upper stage placed the Altair-CEV on a lunar trajectory, it was going to be up to the Altair to do the Lunar Orbit Insertion (LOI) burn.  Here is the Constellation program fact sheet link here.  Thus the Orion was not required to have enough propulsion to enter Low Lunar Orbit (LLO) on its own.  This carried over to the ARM mission because in that architecture, there was no requirement to enter LLO.  Thus, the Orion with its European provided Service Propulsion Module actually has less propulsion capability than the Apollo Command/Service Module combination.  Following is a comparison between the two (Courtesy of Wikipedia).

Apollo Command Service Module Vs Orion

So, as can be seen, the Apollo CSM weighs more than the Orion and also most importantly has more propulsion capability than Orion (1800 meters/second for Orion and 2800 meters/second for Apollo.  After the demise of the Constellation program (during a 5 year period of no real budgets for federal agencies), the original Constellation requirements were retained.  Since the European Space Agency (ESA) designed and built the Orion Service Propulsion System, it is highly unlikely that we can get it changed before 2024, as well as the fact that today the SLS with the ICPS does not have the capability no matter what to get the Orion, much less a heavier version into low lunar orbit.

At the end of the day, this is the only real engineering reason that the Gateway still exists as when you have only the ICPS upper stage it is not possible to get the Orion into any reasonable lunar orbit, and even with the EUS as it is it cannot get into low lunar orbit with Orion….



Myself as well as some of my expert friends in trajectories started playing around with the numbers for SLS plus the EUS that would incorporate the ULA IVF system to allow the stage to remain alive long enough to perform the lunar insertion orbit burn that Altair was originally going to do.  It turns out this works!  The following simulation was provided to improve on my very rough calculations with real numbers for the EUS and the Orion and it Service Propulsion System.  Note also that this simulation does not even fill up the EUS tanks.  If they were filled, then even more interesting things are possible.

 For Orion and the Service module, the following numbers are used:
2019 numbers
CM (Orion) 10329.2 kg 22772 lb
Service Module  (SM) Dry 6992.6 kg 15416 lb
SM Prop 8602.4 kg 18965 lb
SM Wet 15595.0 kg 34381 lb
Total EUS Inert 14106.7 kg 31100 lb
Usable EUS Prop 61337.6 kg 135226 lb
Stage Adapter 4377.2 kg 9650 lb
Payload Attach Fitting 907.2 kg 2000 lb

For the EUS fuel load, the numbers are:

Total EUS Prop 117900.6 kg 259926 lb
Total EUS Assist Prop Used 56563.0 kg 124700 lb
Total EUS LEO Usable Prop 61337.6 kg 135226 lb
We start off with 117000 kg of fuel in the EUS. The “Assist” is what gets the EUS/Orion stack to a 245 km, circular orbit at 28.5 deg after the SLS core shuts down.  The core plus the assist, leaves us in a circular LEO. Once we get to LEO, we have 61337.6 kg of fuel left to get us to the Moon.
If  8000 kg is added to the load, this is the result:
Orion + SM + Prop 25924.2 kg 57153.0 lb
Orion + SM + Prop + Adapters + EUS Dry 45315.3 kg 99903 lb

Excess Payload 8000.0 kg 17637 lb
LEO Dry Mass 53315.3 kg 117540 lb
LEO Fuel Load 61337.6 kg 252766 lb


LEO Wet Mass 114652.8 kg 270403 lb

According to  numbers from 2016, from the SLS program office, the SLS can put 115485 kg to this particular LEO (130 nm circular). So the LEO wet Mass is well below what we can take (thus the original idea that SLS/EUS stack can take Orion + 10 MT to the DRO/NRHO). Note also that from this page:

The EUS should be able to actually take 129,000 kg  of fuel. Note that we are only taking 117900 kg above, so we can easily put our “excess Payload” of 8000 kg right into the fuel tank and be fine. (EUS is not like a centaur, and can be partially filled). In our case, however, the SLS folks have assumed we don’t want to take fuel so they’ve offloaded as much as they can to accommodate other things (like hab modules). But we can re-add the 8000 kg back to the fuel load and move ahead.

The mission begins with an injection to TLI out of the 245 km orbit to a 3 day transfer (compatible with a free return, if desired) to a 400 km circular orbit at 90 degrees at the Moon. Obviously a 5 day transfer would use less fuel. The free return is a good idea, so it is left in at this time. You’d likely launch to the free return, and then correct away from it towards the polar orbit.

The EUS stage is modeled as 4 RL10 engines with the following parameters:



Duration:                        594.537 sec                                                                                                                 Fuel Used:                       57904.811 kg                                                                                          

DeltaV Magnitude:        3186.364 m/sec

This leaves us with:

Dry Mass:  45315.3 kg                                                                                                                    Fuel Mass:  11432.8 kg                                                                                                                    Total Mass:  56748.1 kg


Duration:                        103.794 sec                                                                                                                   Fuel Used:                       10108.976 kg                                                                                          

DeltaV Magnitude:         888.838 m/sec

Which leaves us with:

Dry Mass:  45315.3 kg                                                                                                                    Fuel Mass:  1323.81 kg                                                                                                                    Total Mass:  46639.1 kg

So this tells us that by simply fueling the EUS tanks with another 8000 kg, i.e. no mods at all to the tanks, we can brake the entire Orion/SM stack into a 400 km, lunar circular orbit.

Just fill the tanks up a bit. Same exact EUS design plus the IVF (and we have plenty of mass to work with) and we’re good. EUS can do it. Add the IVF and it works. Of course making the EUS refuelable would make this even more compelling.

This analysis was performed by mission analysis experts that have flown multiple lunar missions (2 to Lunar polar orbit), and have accounted for all of the relevant force models and geometry using software that was used to fly these missions. There is no inclination maneuver necessary to get to a Lunar Polar orbit from a 28.5 degrees inclination orbit at Earth. The Lunar orbit is at 23 degrees +/- 5 degrees from the Equator. 28.5 is always greater than 23+5. There are a few pathological cases where you might have trouble getting to the Moon at its maximum latitude, but in those cases you could just launch to a 30 deg inclination, take the small hit and avoid the maneuver. Or, you could just launch a day later.



This definitively shows that the EUS, with no structural modifications, can get the Orion into a 400 km lunar polar orbit.  The ULA IVF system is the only required modification.  This was part of an optional plan by MSFC several years ago but one of the parent companies of ULA shot it down for their own reasons.  I was there at MSFC for some of these discussions and thus this is not just speculation on my part.  This is also confirmed by the ULA presentation at the National Academies in 2013.

This would provide a major justification for proceeding rapidly with the EUS for EM-2 or a test flight in between and before a lunar landing.  The architecture would be that the Orion be placed into a 400 km lunar polar orbit where it would be met by a lunar lander provided by a commercial vendor and launch before Orion’s arrival.  This will work and will get us to the surface by 2024.  However, a lot more has to happen as well.  In order for that to happen, something has to be sacrificed.

With Orion able to get into a 400 km LLO there is no reason or purpose for the Gateway or the transfer stage.  Thus that money can be redirected to developing surface operations or the lunar lander.  What is not mandatory is not necessary said administrator Bridenstine, and thus, at this time, with the addition of the IVF on the EUS the Gateway is now obsolete.  This does not mean that one is not needed in the longer term but this reverses the order of implementation and frees Orion from that critical path element.

Lunar Surface Stay

To end this, a note should be taken of the limitations of the SLS architecture.  It is unlikely that a production rate of more than two per year will ever happen.  Bridenstine said as much during his congressional testimony on 4/2/19.  Thus, what makes the most sense is that the architecture shift a bit more toward commercial in this respect.

We want to pre-emplace materials, supplies, and hardware on the surface of the Moon at the south pole before the crew gets there.  This makes a lot of sense.  This is not the Apollo era and nothing says that we are on the Moon to stay than for the first crew to spend six months on the lunar surface.  There are things that will need to be done in order to facilitate that, but it makes a lot of sense.  The first crew will be technical experts trained in the engineering and operations needed to set up the outpost.  They can have all of their supplies pre-emplaced and more supplies can be delivered (all by various commercial vehicles) during their stay.

This is not going to be the Apollo program.  That was a series of expeditionary camping trips that succeeded gloriously.  Now we are going to start the economic development of the solar system, beginning in 2024.

I will be posting more on this in the next weeks on exactly how this can play out, but I would submit that we need the first landers on the surface no later than 2021 to perform a reconnaissance of the area and begin the preparations for the crew.  If we truly want to do this, this is a way to make the SLS work, eliminate the need for the Gateway (thus freeing up funds for surface operations and lander development), and begin the path toward full reusability.  This is because…..

EUS-IVF as a Fuel Depot

After the EUS delivers Orion to its lunar orbit, it still has plenty of resources to put itself into a higher storage orbit as the first element of an in lunar orbit propellant depot.  This is the genius of the IVF system.  It eliminates the things that are all life limiting to existing stages and sets the stage for the future.  One of the things that we want to play with next is that if you were to completely refuel an IVF enabled EUS how much payload could you throw to Mars?  It is a very big number, in the tens of thousands of kg.  If we do this, and have missions every six months, there will be a lot of these stages, and a lot of very interesting possibilities start to open up for the next phase of NASA’s adventure….



The title of this post had “with faith and ambition”.  That is a quote from President Kennedy’s speech on going to the Moon.  I heard him say that in the recent movie “Apollo 11”.  there are no finer words to describe what we want to do.

36 thoughts on “SLS and Lunar Return in 2024: “With Faith and Ambition”

  1. Thanks for putting in the work of details. The big change is there are now others talking about the moon besides you and Paul Spudis. With his passing there was a void but now we have others talking about the moon. And just recently others have mentioned a lander. I’m still skeptical because I’ve not seen any contracts awarded or someone building something like we see for Orion, SLS, Dragon2, FH, etc.

    Setting a goal for humans on the moon in five years doesn’t seem realistic. As you mentioned it is much easier to do such than it was 50 years ago. However I don’t see a Democratic congress providing funds for a Republican executive office.

    There has been extensive chatter in the space forums but go outside these groups issues have nothing to do with space. People in general are concerned with other matters. Though NASAWatch has becoming quite lively, it is the same 20 to 30 people posting comments.

    And my on-going complaint is never never talk about Mars regarding lunar missions. First show lunar capabilities that is sustainable otherwise people will work on a lunar exit strategy before even begin building a lunar lander.

    1. We live in a different world than the previous times we have tried this. Before we did not have Falcon Heavies, New Glenn’s, Falcon 9’s and a newsspace ecosystem. Its not just about NASA anymore. NASA, in my opinion, will be best served by teaming with the investment and commercial world to make this a national return to the Moon.

  2. Dennis, this is a very interesting analysis. Especially good catch of the 8,000 kg unused fuel capacity in the baseline numbers. I hope that the decision making machinery would be flexible enough to fast track the EUS development to implement this plan. I also hope that they would follow your recommendation to begin lunar development with the first landing (well, actually before).

    If you don’t mind me picking a nit regarding your title and post-script, I think the JFK quote you heard may have been this: “… even though I realize that this is in some measure an act of faith and vision, for we do not now know what benefits await us.” (A word search didn’t turn up the word “ambition” in the text.)

    Either way, the theme captures the significance of what we want to accomplish.

    1. Joe, works for me. The word vision means “sense of purpose”. Our sense of purpose this time is much different than before, and is of far greater import to our country and the world.

    1. Jim, thanks for that, I was listening to it in the theatre for the Apollo 11 movie. Is this the same clip as used in the movie? Damn the naysayers. If you don’t want to help, get the hell out of the way.

      1. Hi Dennis, yes I assume this is the same clip used in “Apollo 11”. That film is truly remarkable (I’ve seen it multiple times), I was 10 years old at the time and this movie really captures the essence and significance of those times. By the way I was born and raised in Tuscaloosa, AL, so we weren’t too far apart growing up.

        I have been excited ever since Pence’s speech in Huntsville, interestingly I was down at JSC the week before hanging out with some astronaut buddies and the rumors of this were swirling around big time. Like you said this is “Our Time” now we must all make it so!

        1. Cool! I assume that you go to the right football church, having grown up in Tuscaloosa. Yep, lots of stuff going on. So far so good on the response from those inside the beast…

          1. Keep posting on what you hear from the belly of the beast!
            While at JSC I also heard some word that President Trump may be there on July 20th…stay tuned folks.
            Back to the Moon in 5 and Roll Tide!

  3. Dennis — I *want* this to happen; don’t get me wrong. Yes, I know that the lander is in Boca Chica. But I didn’t see that addressed in your essay. I may have missed it.

    Many many years ago, for my Master’s thesis, I showed that one *could* get to LLO with available or so to be available commercial vehicles. It was…well, a kludge. It *would* have worked, but no one in their right mind would have done things that way. It was an existence proof. Years later now, and there are more and better *commercial* answers available. I’m 63, in good health, and expect now to live to see (a) a human lunar landing again, and (2) establishment of a lunar settlement.

    The Cold Rush is beginning. (That’s *my* coinage…! )

  4. Dennis most NASA observers say there is very little chance the Boeing EUS will be ready
    by a 2024 launch timetable, with many saying the EUS will even be cancelled.

    However, several rockets will be coming online with cryogenic upper stages by 2021 that might be used instead, some smaller, some larger than the EUS:

    Ariane 6
    Vulcain Centaur
    New Glenn

    Perhaps an analysis of a SLS powered lunar landing mission using one of these upper stages?

    Bob Clark

      1. I said “upper stage”, but actually for the Ariane 6 and H-3 cases I was thinking of their first stages.

        For ULA’s Vulcan Centaur upper stage at ca. 70 ton propellant load, I did a rough calculation it would allow a SLS/Orion lunar flight as long as you used an Apollo-sized ca. 15 ton lander, i.e., nothing like the 45 ton Altair or 60 ton monstrosity Lockheed now proposes.

        Bob Clark

        1. I don’t quite get where you are going with this. First stage? I agree with your premise if you are saying that one of the launch vehicles, either a Falcon Heavy or New Glenn could put a LM class lander into lunar orbit to rendezvous with an Orion launched with an IVF enabled EUS-SLS.

          The 45 ton Altair and the Lockmart 60 ton landersarus (Zubrin’s name) is a non starter for 2024 or 3034.

            1. Neither of those have enough fuel load to get the Orion into lunar orbit, even with IVF. The two engine Centaur comes closer than anything. The EUS should not take long to build, we just need to give the contract to someone other than Boeing.

              1. You’re still thinking of the upper stages. The EUS was planned to have a propellant load of 130 tons. But the Ariane 6 core stage is to have a fuel load of 140 tons. And the H-3 first stage is to have a fuel load of 200 tons.

                I also like the two or four engine Centaur planned for the upper stage of the Vulcan. It is to have a propellant load of 70 tons.

                Robert Clark

              2. So, I don’t really get where you are going with this. How are you going to get the first stage into orbit and to the Moon? Help me understand your thinking here.

  5. The EUS is all but cancelled. The reason is it is too expensive to develop that large stage from scratch. I’m saying use a stage already developed and paid for for other rockets and adapting it to the SLS rather than buying for a brand new EUS.

    It’s the same thing they did for the interim upper stage for the Block 1 SLS in using the already existing Delta IV Heavy’s upper stage and the same thing they did for the Orion Service Module, in adapting the ESA’s ATV for the purpose.

    You would use this stage for whatever the EUS was planned for, whether it is to be the final stage to LEO or to be used as an escape stage to the Moon.

    Bob Clark

    1. The ICPS cost just as much to modify and human rate as the EUS was going to cost to design and build. The problem today is the contractor, not the stage. Boeing has failed the nation in this regard and this must be recompiled.

  6. There is no discussion of a lander here. Suppose we give the EUS its full prop load of 129 tons, how much additional payload could we get to lunar polar orbit you mention?

    Bob Clark

      1. Yes. But the whole point is to get to the lunar *surface*. So we need to know how much extra payload capability this plan would have. Then we can make estimates of the size of a lunar lander we can use.

        Bob Clark

    1. Not much, certainly not enough for a lander and if we want to be on the Moon by 2024, forget SLS block 2. It is entirely ok to send a lander ahead of the Orion and meet up in lunar orbit.

  7. Were you able to ask Jim Bridenstine questions about this program during his recent visit to Ames?

    Thanks again for compiling all this tech stuff to a single website (I still have yet to digest the numbers).

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s