Mars Sample Return Options

[hendric]

Competitions and contests like this have been used for centuries to drive innovation. As a recent example, look at self driving cars. Stagnated for years until the DARPA grand challenges, which started with off-road autonomy and progressed to urban environments and now we are close to commercially available full autonomy.

Mock Musk all you like, but he has successfully launched and recovered and relaunched fully reusable first stages. NASA can't claim that.

It does sound like NASA is sponsoring a model-rocket class competition (obviously not looking at full performance launchers)

https://www.nasa.gov/sites/default/files/at...s/mav_rules.pdf

I approve. These kids are going to be the engineers working on a future MAV.

[vjkane]

Development of technologies for the MAV is making good progress and the increasing maturity of the technologies is a key element of the discussions for a possible mid-2020s sample return mission.

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[John Whitehead]

Check out My Website https://mepag.jpl.nasa.gov/meeting/2018-02/...l_MEPAG_VM1.pdf

Thanks for the link, nice to see all that. We can only wish that the MAV design could be mature enough to show a detailed mass budget, without which the fancy CAD renderings are effectively an artist's concept. The distinction between art and engineering has been blurred by 3D CAD.

A bit more reality is offered by the latest professional publications from the JPL and Marshall folks who are doing the work on the hybrid MAV concept. Their 2017 AIAA paper showed that the version planned for high altitude terrestrial flight testing above Earth would use propulsion parts three times heavier than needed to launch off of Mars (without the kind of detailed mass breakdown needed for sanity checking). The MSFC paper from the 2018 AIAA propulsion conference describes thermal expansion and contraction issues in the fuel grain, with some cracking. The latter seems ironic, considering that the hybrid propellant combination was selected for low-temperature survival on Mars.

Here are questions that can be asked about the 2018Feb20 presentation by Chad Edwards (on the JPL website in the quote above).

1. On the page showing 2015 Case Studies, what are the error bars (uncertainty in calculations and assumptions) for the GLOMs (gross liftoff mass). The hybrid offers the least total mass, but how can that be certain for a technology at a low maturity?

2. The page for MAV Reference Design shows that the non-propulsion dry mass is only ten percent, astonishingly good for such a small propulsion system. What technical insights can be offered to explain what makes hybrid propulsion so much better than liquid or solid?

3. The page for Hybrid MAV Technical Maturity says that "standard flight tank engineering" will work, but spacecraft tanks are spherical for structural efficiency, or cylindrical with hemispherical ends. In contrast, the MAV oxidizer tank ends are relatively flat, which certainly has to be heavier (relative to the pressure-volume product).

[John Whitehead]

Competitions and contests like this have been used for centuries to drive innovation.

Wasn't there a NASA competition about 5 years ago for "lunar landing" propulsion? Several organizations built small rocket vehicles that could take off, ascend, hover, descend, and land again. In 2016, Dave Masten showed me around his shop in Mojave, from which I recall that his vehicles were used for testing landing algorithms for Mars and-or the moon. The key point is that the propulsive capability (delta V) is nowhere near what is needed for lunar landing, let alone Mars ascent.

For me, the lesson of the Google Lunar X-Prize is that "low budget" lunar landing is very unlikely. For lunar landing, propulsion needs to be at the best state-of-the-art ever used for spacecraft (also for other subsystems). Mars ascent is beyond the state of the art so far.

Maybe another way to say this is, if Mars ascent would be straightforward for "professionally built" spacecraft, then lunar landing should be within the reach of "amateur" spacecraft.

[djellison]

Wasn't there a NASA competition about 5 years ago for "lunar landing" propulsion?

Are you thinking of the Northrop Grumman Lunar Lander XCHALLENGE ? https://lunarlander.xprize.org/

The level 2 challenge of that was specifically designed to demonstrate a Delta V of that required to take off from the moon and enter lunar orbit. To that end - it is exactly what's needed for lunar landing.

No one suggested the NGLLC was about designing vehicles for Mars ascent.

For lunar landing, propulsion needs to be at the best state-of-the-art ever used for spacecraft (also for other subsystems).

There is nothing state of the art required to build a lunar lander. It was done autonomously over 50 years ago with Luna 9. The surveyor spacecraft didn't even have proper onboard computers. They used a solid rocket motor to do most of the landing burn, followed by vernier thrusters for the last 7km or so. It could maybe be considered best state-of-the-art ever used....in 1966.

There is no fundamentally new technology required for a MAV. It's simply a case of spending the money to do the engineering and make it work.

It's not - for want of a better phrase - rocket science.

[mcaplinger]

Competitions and contests like this have been used for centuries to drive innovation. As a recent example, look at self driving cars.

Well, that's an interesting case, but AFAIK what happened was that the competition created a cohort of people with an interest in the problem, who happened to be available when significant resources became available from industry. Correlation, certainly, but causation would be hard to prove. As Heinlein said, "When railroading time comes you can railroad—but not before."

I stand by my claim that competitions in general have not proven that useful in aerospace but have been quite oversold by people who stand to benefit directly from them (*cough*X-Prize Foundation*cough*). But it would be an interesting thing to study in detail ala https://en.wikipedia.org/wiki/Connections_(TV_series)

Mock Musk all you like...

I wasn't mocking Musk, only pointing out that it's difficult or impossible to have a balanced discussion on https://forum.nasaspaceflight.com/ on any Musk-related topic. How Musk's Mars ambitions play out is obviously yet to be known.

It does sound like NASA is sponsoring a model-rocket class competition... These kids are going to be the engineers working on a future MAV.

I've spent thousands of hours doing outreach and I'm all about inspiring the next generation, but I don't want to leave MSR for the next generation. We've had the tech for 20 years or more, if only we would choose to do it. While I have some significant concerns about whether the viewgraphs Van linked to represent the best approach, I suspect it would be workable with sufficient commitment.

[djellison]

We've had the tech for 20 years or more, if only we would choose to do it. While I have some significant concerns about whether the viewgraphs Van linked to represent the best approach, I suspect it would be workable with sufficient commitment.

This. The only thing lying between Mars 2020, and returning its samples to Earth - is the will to do so, expressed in an appropriate budget to get it done.

[John Whitehead]

Northrop Grumman Lunar Lander XCHALLENGE ? https://lunarlander.xprize.org/
... Delta V of that required to take off from the moon and enter lunar orbit...exactly what's needed for lunar landing.

Doug, thanks for this reminder in answer to my question. In 2009, Dave Masten's Xoie vehicle hovered above Earth for a bit longer than 180 seconds, which (multiplying by Earth g) is 1800 m/s deltaV, good for moon-to-orbit or vice versa. Arriving directly from Earth, as is typical for unmanned lunar landers, roughly 700 m/s more is needed. In round numbers, landing from lunar orbit needs the whole vehicle to be 45 percent propellant, landing directly from Earth needs at least 55 percent, and Mars to orbit needs 75 percent, much harder. The Xoie was low-tech in the sense that it did not have to survive a launch from Earth or the 3-day coast to the moon (e.g. boiloff losses for Masten's liquid oxygen, no solar panels on board). Did the prize criteria even include a payload requirement other than carrying guidance? All these differences are what I meant in referring to "low budget" and "amateur" versus "state of the art" and "professional," in Post #319.

There is nothing state of the art required to build a lunar lander. best state-of-the-art ever used....in 1966.

Professionally built space propulsion has hardly changed from 50 years ago. For example, MSL used Viking engines with minor modifications. This is what I meant by the state-of-the-art being good for lunar landing but not for a MAV (small enough to deliver to Mars).

There is no fundamentally new technology required for a MAV. It's simply a case of spending the money to do the engineering and make it work.
It's not - for want of a better phrase - rocket science.

It is fair to say, "only a matter of political will and money," but this blanket statement is wide open without qualifications. If the MAV has to be delivered using the same landing system as MSL and Mars 2020, then the mass is constrained, and if it has to launch from Earth in 2026, then schedule is constrained, etc., and we're back to reality.

Yes, there needs to be rocket engineering, not rocket science. But MAV funding is being spent on "rocket science" (propellant research), instead of engineering to improve the state of the art. There needs to be an engineering effort to make propulsion components less than half as heavy as typically used for satellites and spacecraft. Whether or not this counts as "new technology" is only semantics.

[John Whitehead]

People seem to be expecting some magic solution that will all of the sudden make MSR more affordable. I doubt that such a solution exists.

Mike, I've been meaning to respond to your comment above, which is exactly what has been happening for 20 years. In the absence of an actual quick fix, there always seems to be a new possibility on the horizon, which the community as a whole sometimes buys into completely at each step. We might go full circle and end up with Carl Guernsey's 1996-1998 design for a two-stage pressure-fed liquid biprop MAV. That would be large and heavy (likely too big for the existing sky crane lander), but the JPL spacecraft propulsion team would be able to make it work reliably.

In 1998 in Pasadena with Carl as a co-author, I presented a concept for a small single-stage pump-fed bipropellant MAV, so that a MAV and a science rover could both fit on the same mission. At about that time, perhaps inspired by my presentation to make it smaller, JPL latched onto a 3-stage, 20-kg "mini-MAV" promoted by a JPL engineer (not primarily a propulsion professional), a concept which was considered a breakthrough for about a year or two. The following year, I noted that pump-fed monoprop hydrazine was more mature, suggesting that could work. The multi-stage solid was studied by a NASA-industry team in 1999, with the expectation that the 2003 and 2005 launches to Mars would actually do MSR. The study team morphed the mini-MAV into a 100-kg two-stage solid rocket. Subsequently, it gradually grew to 300 kg over a series of studies, with Lockheed and ATK (now Northrop) on board. The solid MAV was considered most likely viable for more than a decade, in my opinion because small solid motors on the scale of interest are existing technology, and the "quick fix" perspective made it too tempting to pretend that steering control could be added without adding any weight. Also in the mix from another aerospace prime contractor was a MAV using gelled propellants (another example that a "new propellant" is perceived as a "rocket breakthrough.")

In 2005-2007, NASA funded me to test my miniature piston pump design, which had a lot of promise for mass reduction. At one point it was shown off at NASA HQ as the latest and greatest solution for a MAV. In retrospect, possibly the only reason I won funding is because I had an existing pump design that was ready to be built and tested, i.e. doing something creative and challenging would have been perceived as more risky. A year or so into my building and testing, I reached the point of actually having to solve a technical design problem in order to proceed. I still remember the JPL managers looking very disappointed when I showed up at a quarterly progress meeting to say that my most recent test had not gone perfectly. After I got past that problem, and had a pretty impressive final report, I remember the final presentation at JPL. After my talk, I was alone in a small kitchen adjacent to the conference room, when a senior JPL geologist (I think) walked in and whispered "thank you." I tried to get continued funding, but the cultural bias worked against me (and still does). Namely, making "smoke and fire" seems to count as rocket engineering (regardless of how heavy the parts are), but building a lightweight pump by itself does not sell very well.

Another one of the propulsion projects funded circa 2005 by the Mars program was a scheme to mix fuel and oxidizer together in one tank, to make a monopropellant system having a high exhaust velocity more typical of bipropellants. That team continued to receive funding from NASA (for a single-stage MAV) and other government organizations, for more than five years, at least past 2010. Ultimately there was an explosion, I think (never advertised of course).

Through the 1990's, a research group at MIT had been trying to build very tiny pump-fed rockets using silicon chip fabrication technology, advertising "turbine on a dime." Later some alumni of that effort started a small company and received NASA money for small turbopump-fed engines, ultimately collaborating with MAV people at JPL around 2012-2015. It is unfortunate that there can't be a more serious discussion about what works and what doesn't work and why, because pump-fed engines are the solution that large launch vehicles use to minimize the mass of propulsion components.

Roughly around 2010, a big change to MSR plans was to stop hoping for the possibility of a MAV small enough to send along on the same mission with a science rover, so at least acknowledging that the MAV has to be larger is probably a significant step in the right direction (assuming there will never be a serious effort toward a smaller MAV).

Also around 2010, the candle-wax fuel research received funding at Stanford University as another hopeful quick fix. Perhaps not coincidentally, the faculty advisor had previously been head of NASA Ames and had been the lead Mars person at NASA HQ for a time. People from that Stanford graduate school research are now at JPL, leading the hybrid propellant MAV effort. I suspect that some of the various projects were inspired by my publications advocating a single-stage MAV, in which I also explained why a solid rocket MAV would not be ideal.

The link provided by Van Kane (post #317) shows a document that was presented to Mars scientists at the February 2018 MEPAG meeting. The minutes of that meeting indicate that the hybrid MAV presentation was accepted at face value (no sanity-check questions as I suggested in post #318). See the middle of page 4 at the following link for the MEPAG reaction to Chad Edwards' MAV presentation.
https://mepag.jpl.nasa.gov/meeting/2018-02/...0Notes%20v3.pdf

Now after 20 years of wanting a "quick fix" MAV, will the community hunker down and get to work, or will a new "silver bullet" appear?

[vjkane]

The link provided by Van Kane (post #317) shows a document that was presented to Mars scientists at the February 2018 MEPAG meeting. The minutes of that meeting indicate that the hybrid MAV presentation was accepted at face value (no sanity-check questions as I suggested in post #318). See the middle of page 4 at the following link for the MEPAG reaction to Chad Edwards' MAV presentation.
https://mepag.jpl.nasa.gov/meeting/2018-02/...0Notes%20v3.pdf

Now after 20 years of wanting a "quick fix" MAV, will the community hunker down and get to work, or will a new "silver bullet" appear?

John, I don't have your knowledge of rocket science. I do hope that given the building momentum toward a mid-2020s sample return mission means that the current leading MAV candidates have received critical reviews from appropriate experts.

One comment on your post: I wouldn't expect a room full of planetary scientists to ask critical questions about MAV technology readiness or comment on a specific design. Conversely, I wouldn't expect a room full of rocket scientists to ask critical questions about the interpretation of a Curiosity SAM analysis.

There's a paper on one of the candidate MAV approaches, Low-temp MAV. It is behind a paywall, but if you private message me, I'll send you a copy. I'd be interested in your and mcaplinger's thoughts about whether this represents the community having hunkered down over the last decade or not.

[John Whitehead]

I do hope that ... current leading MAV candidates have received critical reviews from appropriate experts.

Van, thanks for the detailed reply. The irony is that I have been trying for over 20 years to meet those "appropriate experts," people who really focus on how heavy the MAV propulsion components are going to be, because that's what I groove on. I never found them, despite making friends long ago who worked on Cassini propulsion and later went on to build the MSL descent propulsion, and myself also having connected in the past with at least one of the people doing the MAV hybrid propellant research. All these folks do terrific work, but the missing piece needs to be put into the puzzle. I share your hope for smooth sailing toward MSR, but I'm left to conclude that I'm an "appropriate expert" (which my professional publication record shows), and that the system doesn't want "critical reviews" (to use your words).

I wouldn't expect a room full of planetary scientists to ask critical questions about MAV technology...

Yes, I do appreciate that people have to be specialists in one technical field or another, although there is a notion that the Mars science community, through MEPAG, is to some extent an oversight group, while no one has asked a committee of propulsion engineers to review geology work. A decade ago, I contacted two different MEPAG chairpersons a few years apart, offering to make a presentation at one of their meetings, and they replied, "not interested." My 2012 abstract, "A Perspective on Mars Ascent for Scientists" (mentioned in post #301) was an attempt to lure Mars scientists out of their comfort zone, to learn about rockets for the sake of their own high priority science goal.
https://www.lpi.usra.edu/meetings/marsconce...12/pdf/4290.pdf
Theoretically that could have gone viral among Mars geologists. Assuming that astronomers care about how telescopes work, then Mars geologists should want to know the basics of the MAV problem. Is it possible that there would be negative career implications for any Mars geologist who stands up to alert the community to my concern? Most likely, they simply assume that "appropriate experts" are on the job.

There's a paper on one of the candidate MAV approaches, Low-temp MAV.

Yes, I printed that paper in mid-July, finished reading it one week ago, then I mentioned it in Post #318, "The MSFC paper from the 2018 AIAA propulsion conference describes thermal expansion and contraction issues in the fuel grain, with some cracking." This particular publication only describes the challenges of making the hybrid fuel grains, with no big-picture information about the overall MAV propulsion design (but yes this does correspond directly to Chad Edward's presentation to MEPAG in February).

One more comment about Chad's presentation (see Post #317 and #318). Page 8 says that the notional 300-kg MAV mass has a 50 percent margin. I have to wonder what this margin number really means. Given that the rocket equation curves are so steep with respect to the mass of the components, this margin statement should be supported by two complete sets of mass-budget numbers, one with the margin and one without. For example, does the less-heavy version, without the mass margin, have the same propellant capacity and thrust as the one with margin (so it would be all the same component functionality at different weights)? This question brings us back to the start of my comments today, where are those "appropriate experts" hiding?

[vjkane]

This question brings us back to the start of my comments today, where are those "appropriate experts" hiding?

John, your comments are disquieting. As a total layman in this field, I'm left hoping that NASA has a backroom with appropriate experts somewhere. NASA and ESA certainly are fast tracking the program, and the MAV and orbital capture seem to be the two pieces of critical technology development.

Thanks for the detailed reply.

[hendric]

John, thanks for your patience. I went back and reread your original reports, and now I think I understand better the problem. I see now why you are concerned about the lack of tech demonstrators now.

[Gerald]

I'm not at all involved in the development of propulsion systems. But my very first idea about downscaling existing systems would be considering tanks mantled by slightly elastic kapton composit products. From that idea, it has been only a short googling to find a site reporting about an update of composite tanks for cryogens (of 2005). It appeared, that they have more trouble with upscaling than with downscaling.

For the propulsion system itself, I've learned about 3d printed replacements of traditionally manufactured systems a while ago. The article I've linked to is of more recently, and it says

The winning part – support bracket for the payload adapter of Europe’s Vega launcher – offers a 25% mass reduction compared to the standard equivalent.

Those developments may not be designed specifically for a MSR system. But there should exist ways to apply these findings to MSR, at least from my naive point of view in this respect.

[JRehling]

Before the dual failures of MCO and MPL in 1999, there was a timeline that slated MSR launch for 2005 and return in 2008.
https://trs.jpl.nasa.gov/bitstream/handle/2...amp;isAllowed=y

This discussion in 2018 certainly highlights how wildly optimistic that was even if the 1999 missions had succeeded (they've both been reflown, and moreover aren't really on the critical path to MSR) and not even considering the gap in scientific knowledge of Mars' water between now and then. It's eye opening to consider the disconnect that had anyone slating a mission to launch six years after those 1999 failures when the required technology is hardly less ephemeral now than it was then.