Mars Sample Return Options

[mcaplinger]

A two-stage solid rocket to be supplied by Northrop-Grumman has been selected for the MAV.

That seems like the right answer to me. The hybrid was a science project and liquids are just too complicated.

https://spaceflightnow.com/2020/04/20/nasa-...es-off-of-mars/

To anticipate a couple of objections John Whitehead will probably have:

1) the TVC for each stage is not shown. Interesting omission.

2) the launch concept is to "eject vertically from the lander in a horizontal position with the first stage motor ignited within a short interval at a predetermined time following the vertical ejection. In order to navigate the MAV safely away from the lander, this could require sudden, high nozzle vector rates on a motor that has been stored at -40C for up to a year." I guess they decided that simply raising the MAV to vertical prior to launch was more complicated than this maneuver. Well, maybe.

[John Whitehead]

Mike, thanks for the link to that long article about MSR and MAV. After carefully reading the article, here are my comments.

Regarding solid rockets being "known," that was said more than 20 years ago, and multiple times since, while the opportunity has been repeatedly missed to build and test prototype MAV stages to get ahead of the schedule crunch. Back then, and now, the fact that a solid rocket motor is not a "stage" tends to be unappreciated by those who say the technology is "known." Key challenges are downplayed, namely the naturally excessive thrust (short burn times) of small solid motors, and the general difficulty of making all the parts lightweight enough. Excessive thrust requires the steering components to be heavier and more responsive than otherwise.

The liquid hydrazine steering on the upper stage is risky, because it might run out. The total propulsive impulse needed there has to be very well understood, because the mass budget cannot tolerate plenty of extra hydrazine. Multiple Earth launch vehicles have failed because they ran out of a fixed supply of hydraulic fluid for steering.

Regarding the 2026 mission schedule, rocket engineering was in the driver's seat for planning the Apollo missions to the moon. The famous Kennedy speech of May 1961 came after JFK asked what could be done, and a rocket engineer (Von Braun) answered in late April of 1961. For MSR, mission planning has forged ahead while MAV engineers stand by the side of the road with their thumbs out, ever hopeful that they will be able to catch up to expectations. At least now it is finally in the budget to begin to do some serious work, but if the 2026 schedule goes by the wayside, will they cut the MAV budget and continue to fund future mission studies, as has always happened in the past?

Seemingly, people don't know that being up against physical limits (such that the components end up too heavy) is a different kind of difficulty from complexity (but hats off to those who are so good at organizing and managing complexity for huge projects). Earlier this year, I reviewed the requirements for the new job opening at NASA HQ, the MSR Program Director. The main criterion was experience leading a major spaceflight program with international collaboration. Considering how that kind of leadership work is typically done, the person hired will probably have the bias that the MAV is a mere subsystem that can simply be bought, like space propulsion typically is. If the person hired has a good understanding of miniature launch vehicles, I may have to eat that hat after tipping it.

Also misunderstood at the tops of org charts is the fact that rocket engineering is a different activity from propellant research. The latter activity is more public and visible, e.g. done in universities, so that's what people think rocket engineering is. Most of the work toward the conceptual hydrid MAV was essentially propellant research. The effort fell short in that domain, never approaching the problem of making flight hardware sufficiently lightweight.

The MAV study done at JPL circa 2015 concluded that the hybrid technology would make the smallest MAV, followed by pump-fed liquid, then pressure-fed liquid, and finally by solid, heavier. Therefore it is interesting to see no further mention of a potential liquid propellant MAV. It is easy to conclude that comparison studies are useless if the technology options do not exist. In this case, the "technology" is not heritage for propellant use in space, but rather it has to be complete working miniature rocket stages that have a sufficiently high ratio of propellant mass to component mass.

I'll continue to look forward to serious MAV progress, however long it takes.

[mcaplinger]

On the two-stage solid MAV design, see https://ntrs.nasa.gov/archive/nasa/casi.ntr...20190030430.pdf and https://ntrs.nasa.gov/archive/nasa/casi.ntr...20190002124.pdf

The first stage burns for 55 seconds with a boost-sustain thrust profile.

[John Whitehead]

Thanks, Mike. Your first link is paper number AIAA 2019-4149, presented in August 2019 at the AIAA Propulsion and Energy Forum. The second link is a paper presented at the (March) 2019 IEEE Aerospace Conference. In summer 2019, I printed them, read them carefully, and wrote many notes in the margins about questions left unanswered.

At first glance, all the graphs, tables, and details shout out, "serious engineering is happening," which presumably impresses decision-makers. Not having time today to look over the details again, here are some of the notes I wrote last year.

AIAA 2019-4149, "A Design for a Two-Stage Solid Mars Ascent Vehicle."
This paper is mostly about solid motor trades, not MAV design, e.g. RCS propellant (liquid steering) not discussed.
No big-picture discussion of why it is hard to build a MAV (making the mass budget close).
No mass budget info, no Isp or deltaV (page 10 has Isp for a long nozzle not used).
Nozzle steering and TVC are left for future work.
Some of the writing was unclear, e.g. at the bottom of page 6 I wrote, "What part of Stage 2 counts as 'second stage mass'?"
On page 7 next to Figure 8 I wrote, "No scale on graph." Their graph says the stage mass fractions are "evolving."
At the bottom of page 9 I wrote, "Complete mass info remains hidden."
A the bottom of page 15 I wrote, "Figure 16 says TVC details are unknown, but the whole thing hinges on whether TVC can be lightweight."
Next to Figure 17, I wrote, "The graph only says their design points have typical shapes, re length versus diameter. So what, already shown in Figure 16. Moot comparison, how about propellant mass fractions?"
The final paragraph says that the mass came out 6 kg below the 400 kg limit, and my note says "error bar uncertainty?"
Overall, I was disappointed enough to mark up the title to, "A Study of Solid Rocket Motor Design Trades for a Notional Two-Stage Mars Ascent Vehicle."

2019 IEEE Aerocon paper, "Mars Ascent Vehicle Propulsion System Solid Motor Technology Plans."
TVC mass is a big open question, but not listed as one of the challenges.
The total mass could be anything (i.e. too heavy), yet it is stated that a design will converge.
Above the intro I wrote, "Can't say the reason for 3 Earth launches, i.e. MAV too big to include on a science mission."
Above Figure 3 I wrote, "No mention of why it is hard to do, or that 40 years of concepts is not much progress."
Above Table 1 I wrote, "Arbitrary rating for rocket motor case materials, where is strength at temperature?"
Above pages 5 and 6 I wrote, "A bunch of math, no physical insight, and not enough info to see big picture or check calculations."
At the bottom of page 5 I wrote, "So how heavy are flex nozzles, and how heavy are TVC actuators and their power supplies?"
Next to Table 4 I wrote, "These differences are minutia compared to the uncertainties between the math and actually building MAV stages."
Above the top of the right column on page 9 I wrote, "TVC actuator mass seems totally unknown."
Overall I was disappointed that the graph axes did not show numbers or units of measure (Fig 4, 5, and others).

Certainly, the engineers are doing the best they can with the limited budget so far, namely more math than hardware. Let's hope that much more progress is being made (or will soon be made) regarding the unanswered questions in the professional publications.

Regarding the boost-sustain thrust profile, this addresses the trajectory concerns I published in 1997 and 2004-2005. it would be nice to see a discussion of how the thrust profile affects propellant mass fraction and-or motor shape (length vs diameter), considering that proven space motors have high propellant fractions, while missile motors with special thrust profiles may not be so good.

[mcaplinger]

Certainly, the engineers are doing the best they can with the limited budget so far, namely more math than hardware. Let's hope that much more progress is being made (or will soon be made)...

If you read the NGIS sole-source procurement (link below) it's for 10 copies of the first and second stage motors and associated TVC. The 10 copies are for 3 demonstration tests, 3 qualification tests, 1 flight test, 1 flight, 1 spare and 1 inert engineering unit.

It doesn't get much realer than that, and there is limited scope for iterative development on the timeline. I can only presume that NGIS (ATK) knows what they're doing; if anyone does, they do.

I share your reservations about the published papers (which are largely high-level parametric "spherical cow" stuff), but in my experience, descriptions of how something will really work rarely get published in advance in the open literature. At least it seems like they are going to cut metal and fly, not just write Powerpoints, and that's always a good sign.

https://beta.sam.gov/opp/349cbd728ab24d7693...true&page=1

[stevesliva]

I can only presume that NGIS (ATK) knows what they're doing; if anyone does, they do.

Granted I can't keep track of all the consolidation, but given the number of SLBMs, SAMs, AAMs, etc that use solid rocket motors, there's probably a few others in the defense industry.

[mcaplinger]

Granted I can't keep track of all the consolidation, but given the number of SLBMs, SAMs, AAMs, etc that use solid rocket motors, there's probably a few others in the defense industry.

Within the US, only Aerojet Rocketdyne AFAIK. And I didn't say there wasn't anyone else, only that ATK clearly has a lot of experience and NASA decided was the only suitable manufacturer (hence the sole source contract.)

[Brian Swift]

They also have a nice rocket garden worth checking out if one happens to be near Promontory UT.DSC08644 by bswift, on Flickr

[John Whitehead]

If you read the NGIS sole-source procurement (link below) it's for 10 copies of the first and second stage motors and associated TVC...
It doesn't get much realer than that...

Yes, I read this news in early April, a welcome step toward "real work" on a MAV. Here is the question that I think no one can answer for sure. Will it turn out to be a "design and build" engineering effort, or a "trial-and-error" research and development effort? Both count as "real work" in my book. If it turns out to be "only R&D," the effort needs to continue until there is a mission-capable MAV, regardless of the overall schedule for MSR.

Regarding the nice image from Utah posted by Brian Swift, my understanding is that the small rocket motors are made in Elkton, Maryland. At least that is where Thiokol historically made the STAR series of solid rocket motors for space applications.

[Quetzalcoatl]

Bonjour à tous,

Delayed launch again !?!

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

[Explorer1]

Some good details about the MAV's future development in this report (pages 5, 6 and 7 in the summary).

[Quetzalcoatl]

yes, that’s a positive aspect.

[mcaplinger]

Some good details about the MAV's future development in this report (pages 5, 6 and 7 in the summary).

Frankly, I find the concern about thermal cycling of the MAV solid motors, and the suggestion to add an RTG to the lander to heat the MAV to reduce thermal cycling, to be a massive step backward from the seeming progress of letting the contract to buy the SRMs discussed upthread.

This is the kind of "adding epicycles" that signals that a program is in trouble IMHO.

[John Whitehead]

Delayed launch again !?!

The MSR Independent Review Board's (IRB) recommendation for 2028 (instead of 2026 for the MSR launch from Earth) is not a delay, it is simply a recognition that the technology is not ready. NASA experts wrote in 2009 that work on the Mars ascent vehicle (MAV) needs to start 8 years before Earth launch, with MAV flight testing 5 years before Earth launch. See page 4 (PDF p5) at the following link from 2009. No doubt the IRB did their own careful analysis of the situation, but they could have simply added, 8 + 2020 = 2028.
https://mepag.jpl.nasa.gov/reports/decadal/SamadAHayati.pdf

This 2009 document was a new find for me this year, and it is noteworthy that the long-ago advice from inside NASA was not followed. The lead author is the Mars Technology Manager at JPL (since 2000). One of the co-authors (Stephenson) was NASA's lead person for MAV circa 2000. Another co-author (Dankanich) was the MAV lead for several years around 2010, and recently has been the Chief Technologist at MSFC. One would imagine that these folks know their stuff. Their page 4 also says that in 2002 the best solution for a MAV was determined to be solid rocket motors, but after paper studies no real work was done and the TRL remained very low.

Before and after 2009, many people hoped for an easier path to a MAV, so various other ideas were considered from 2010 to 2014. From about 2015 to 2019, millions of dollars were spent at JPL, MSFC, and subcontractors to test hybrid propulsion (liquid oxidizer burning a wax fuel grain). The main selling points of the hybrid propulsion were that wax could handle low temperatures on Mars, and this hydrocarbon fuel (versus hydrazine fuel or solid propellant) would have more chemical energy (high Isp, high exhaust velocity), but a lot of challenges had to be overcome (see my post number 339 in this forum). As of early 2020, the official plan has been to build a two-stage solid propellant MAV, which ideally would have been tried sometime during the past 20 years, but now is just starting.

suggestion to add an RTG to the lander to heat the MAV to reduce thermal cycling, to be a massive step backward

Mike, the problem is that the 2026 and 2028 launch opportunities let the MAV be at Jezero Crater during the warm season, consistent with high hopes for supporting the MAV with a solar powered sample return lander (SRL). Any further delay (2030-ish) would change the whole project, e.g. less mass can be landed on Mars and it will be colder, hence RTG heat is sensible long-term planning.

To me, a more shocking revelation in the IRB report is that the MAV might be so massive that the sample fetch rover (SFR) would have to be sent on a separate lander. The irony of course is that 20 years ago the notion was a large science rover carrying a small MAV, then in 2010 that changed to a big MAV with a small fetch rover to pick sample tubes off the ground already cached by an earlier big science rover (Perseverance). Now, if the fetch rover has its own lander, people will want it to carry science instruments, and it could morph into another big science rover and MSR could go by the wayside if there is still no MAV.

Considering imaging instruments (did not want to insult anyone with merely "cameras") would anyone send them to Mars without repeated testing? Are there some problems on the lab bench that result in design improvements? Do problems on the lab bench always make the news? A concern for MAV development is that "bench testing" may include explosions that are not only expensive, but also widely noticed. SpaceX has shown us how trial-and-error engineering (with explosions) works to push launch vehicles beyond the state of the art. SpaceX methods may differ from the NASA Systems Engineering Handbook (297 pages) which seems founded on the principle that mission development is mostly a predictable process. Systems engineering "by the book" works very well when the technology is known.
https://www.nasa.gov/sites/default/files/at..._handbook_0.pdf

A lot has happened for MSR during 2020, so here is a summary of events in order.

Before the start of 2020, the two-stage solid MAV was selected instead of the hybrid MAV concept.

In April, plans were announced for NASA to buy solid rocket motors for the MAV (see post number 376 in this forum). Considering that the overall size of the MAV remains unknown, a contract for particular motors might become part of an evolutionary process, versus leading directly to a final MAV design (post 384).

On April 15, MSR plans were presented to MEPAG (Mars Exploration Program Analysis Group). A presentation from NASA HQ said we are ready to do MSR, noting that $20 million was spent on MAV technology from 2016 to 2019. The statement may have been a misunderstanding, if most of that money was spent on the hybrid propellant research versus the solid rocket MAV.
https://mepag.jpl.nasa.gov/meeting/2020-04/...5,2020_post.pdf
A presentation from JPL added more details for MSR, but the talk was arranged to first cover what will happen in Mars orbit after the MAV gets there, then the talk covered Mars surface operations ending with the MAV launch. The MAV flight was not explained.
https://mepag.jpl.nasa.gov/meeting/2020-04/...erview%20V3.pdf
Video links to the above presentations can be found at the following link (scroll to 2020Apr15 meeting). https://mepag.jpl.nasa.gov/meetings.cfm

In May, the JPL Director presented a Zoom webinar lecture titled, "The Mars 2020 Mission and Robotic Exploration at JPL," and of course MSR was discussed. One question from the audience was, "Why didn't we start building and testing MAVs ten or more years ago?" (of course we all wish we had done so). The question was rewritten to, "Why is now the right time for MSR?" and a statement was made to the effect that MSR technology is finally coming together.

In June, a new manager for MSR was hired at NASA HQ (Jeff Gramling, formerly at Goddard).
https://blogs.nasa.gov/drthomasz/2020/05/29...ogram-director/

In summer 2020, submissions were due for the Decadal Survey for Planetary Science (a two-year project for the National Academy of Science, Engineering, and Medicine to help NASA plan the next ten years of solar system exploration).
https://www.nationalacademies.org/our-work/...urvey-2023-2032

In August, Jeff Gramling presented the HQ plan for MSR to the Planetary Science Advisory Committee (PAC). It is difficult to see how MAV flight testing would fit into the timeline for launching in 2026. https://science.nasa.gov/science-pink/s3fs-...2017Aug2020.pdf
If the link changes, the following is one place to start. https://science.nasa.gov/researchers/nac/sc...-committees/pac

In September, I was reading a paper from MSFC about the navigation challenge of getting from Mars to orbit, and realized that even if the MAV rocket design was already perfected, flight testing would still be needed to work out the bugs for navigation. Flight through the Mars atmosphere is complicated. If a smaller IMU is used to make room for more payload, will it be accurate enough?
https://ntrs.nasa.gov/api/citations/2020000...20200002335.pdf

At the end of September was the first Steering Committee meeting for the Decadal Survey. The meeting included a presentation by a Harvard professor about implicit bias, which made me think about the expectation that space mission propulsion is typically straightforward.
https://www.nationalacademies.org/event/09-...group-meeting-1

In October, the final versions of my MAV submissions to the Decadal Survey were posted on the MEPAG website (hosted at JPL).
https://mepag.jpl.nasa.gov/reports/decadal2...AV2020Oct11.pdf
https://mepag.jpl.nasa.gov/reports/decadal2...AV2020Oct11.pdf
https://mepag.jpl.nasa.gov/reports/decadal2...AV2020Oct11.pdf

On October 16, NASA HQ presented a spending plan to the Decadal Steering Committee. MSR will have a rapidly growing budget through 2025, while the budget for other Mars science will shrink (HQ is really serious about MSR). Another presentation on October 16 stated that "NASA is making substantial progress on technology development that will be required for MSR."

On November 2, the Decadal Survey Mars Panel started having public Zoom meetings. Jeff Gramling presented MSR plans. Another HQ presentation (Ianson) showed Mars org chart changes in the Science Mission Directorate (SMD). MSR is reporting directly to the top of SMD, while the shrinking Mars Exploration Program (MEP) continues within the Planetary Science Division (PSD), part of SMD. The same presentation said that we are ready for MSR because past work has included "significant investments in key technologies" including the MAV.
https://www.nationalacademies.org/event/11-...rs-meeting-no-1
https://www.nationalacademies.org/our-work/...2-panel-on-mars

On November 10, the IRB report was made public. See below for MAV details with specific page references.
https://www.nasa.gov/sites/default/files/at...eport_small.pdf
If the link changes, the following is one place to start. https://www.nasa.gov/news/reports/index.html

On November 17, the IRB Chair made a presentation to the Decadal Survey Mars Panel, including the recommendation for 2028. In the embedded video of the meeting at the following link, the half-hour IRB report starts 5 minutes into the meeting. Hours later at time 3:09:30, there is a question about the increasing uncertain MAV mass. HQ explains the uncertainty in terms of margin that will be reduced as the design matures. Depending on how unknown the design is, it seems uncertain whether the term "margin" is really applicable. https://www.nationalacademies.org/event/11-...rs-meeting-no-2

At the end of November, Jeff Gramling of NASA HQ presented a MSR update to the Planetary Science Advisory Committee. His presentation charts re-affirmed the 2026 launch date, so HQ might not adopt the 2028 date from the IRB.
https://science.nasa.gov/science-pink/s3fs-...edule-FINAL.pdf

MSR IRB Report details and my final comments:

Page 38 of the IRB report (PDF p47) reveals that NASA has been studying a "two lander" concept, for the possibility that the MAV will be so big and heavy that the sample fetch rover (SFR) would have to be delivered on a separate Mars lander.

Page 42 (PDF p51) is specific to the MAV, and says that the MAV might be anywhere between 320 kg and 520 kg. This page also says, "Experience has shown that the smaller a launch vehicle, the more sensitive its dry mass to design uncertainty." This statement is exactly what I have been saying and writing for more than 20 years now, and is consistent with the need for trial-and-error component engineering to make all the MAV parts sufficiently lightweight.

If we want to talk about a "delay," we should ask why MAV development cannot be done before planning the MSR mission timeline. The crux of the problem might be that actually trying to build a MAV cannot be funded without formal approval of the MSR mission, "Phase A" per the NASA Systems Engineering Handbook.

One thing I've been saying for decades, that the review board did not say, is that a serious long-term technology development effort would ideally be done to figure out how small a MAV can be, before planning the MSR mission. In the absence of trying to build and test a prototype MAV, the expected mass has generally kept increasing over time. In my opinion, heroic efforts will be needed from the MAV team (and other parts of MSR) to meet the 2026 date.

[Explorer1]

Phase A has just been approved: https://www.nasa.gov/press-release/nasa-mov...amples-to-earth

Looks like the MAV and fetch rover are still on one launch:

In the next steps of the MSR campaign, NASA and ESA will provide respective components for a Sample Retrieval Lander mission and an Earth Return Orbiter mission, with launches planned in the latter half of this decade. The Sample Retrieval Lander mission will deliver a Sample Fetch Rover and Mars Ascent Vehicle to the surface of Mars. The rover will retrieve the samples and transport them to the lander. The Perseverance rover also provides a potential capability for delivery of collection tubes to the lander. A robotic arm on the lander will transfer the samples into a container embedded in the nose of the Mars Ascent Vehicle.