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Mars Sample Return
John Whitehead
post Jul 30 2021, 09:09 PM
Post #406


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Regarding the selection of a contractor to build the whole MAV (versus only the solid rocket motors, see Post #402 and #403 above), a new announcement from MSFC today says that a Request For Proposals is planned for August 16, with bids due September 16 (bottom of page 2 in the following attachment).
MSFCmavPlan2021Jul30fromSAMgov.pdf

An earlier related RFI (Request For Information) dated 2021Jun11, referred to the 525-kg MAV design (page 4, third paragraph).
MSFCmavRFI2021Jun11SAMgovSaveAsPDF.pdf

Another document with the RFI, also dated June 11, refers to the 400-kg MAV design having the unguided spinning upper stage (page J-6 of the DRAFT Performance Work Statement for the Mars Ascent Vehicle Integrated System, MAVIS).
MSFCmav2021Jun11-T-Draft+PWS_MAVIS.pdf

The above three PDF documents are attached here. So as of June 11, both MAV designs were under consideration. Page 2 of the June 11 RFI said that MSFC wanted to hear from small businesses, Historically Black Colleges and Universities (HBCU), and Minority Serving Institutions (MSI) that would have capabilities to contribute to the MAV project.

In response to questions during the MEPAG meeting on June 21, the MSR Program Director at NASA HQ said that he expected MSFC to have a MAV contract in place in FY22, which would be sometime in October or later, consistent with the attached procurement documents.
Attached File(s)
Attached File  MSFCmavPlan2021Jul30fromSAMgov.pdf ( 217.35K ) Number of downloads: 420
Attached File  MSFCmav2021Jun11_T_Draft_PWS_MAVIS.pdf ( 1.41MB ) Number of downloads: 426
Attached File  MSFCmavRFI2021Jun11SAMgovSaveAsPDF.pdf ( 259.91K ) Number of downloads: 566
 
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John Whitehead
post Aug 20 2021, 09:04 PM
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The formal request for proposals to help MSFC build the whole MAV was released on August 16, revealing new information about the MAV plan. Here are some key points from the RFP documents, with my comments.

1. The main RFP document (459-page PDF) shows that MSFC has selected the two-stage solid propellant MAV design that has the risky spinning unguided upper stage (page J-1-4). This "lightweight" MAV was 320 kg in mid-2020, then 380 (Planetary Decadal Survey Mars Panel meeting 2021Jan5), then 400 (Decadal Steering meeting Feb11), and now it is 450 kg. The MAV keeps getting heavier, and the design is still only "conceptual" (page J-1-3), so it is very possible that this MAV will end up too heavy to send to Mars, even without the fetch rover. While the Sample Retrieval Lander (SRL) will deliver the fetch rover, the MAV is hoped to fit (with its Mars ground support equipment) on the newer Mars Lander Vehicle (MLV, page J-1-2).

2. It is now certain that 2026 was too optimistic for departure from Earth, as the MAV RFP says 2028. Of the many supporting documents, at least one (MAV-001, page 10 of 115) says "Earliest launch window is 2028," indicating it could be later.

3. Flight testing over Earth is planned only for the spinning upper stage, starting at 100,000 feet altitude, which the RFP refers to as simulating the Mars atmosphere at second stage ignition (page J-1-6). This seems to be a typo of sorts, because 100,000 feet over Earth has atmospheric density like the Mars surface, while second stage ignition would occur above the Mars atmosphere.

4. The supporting document (MAV-001 page 31 of 115) acknowledges that the first stage thrust vector steering is new technology (presumably meaning for this particular size and the need to be unusually lightweight), "not space flight proven." It says that "early risk reduction testing" is needed, but there is no specific mention of flight testing the first stage, let alone the whole MAV.

5. If the whole MAV is not flight tested, that would risk the most expensive planetary mission on a brand-new launch vehicle (for Mars departure). For departure from Earth, launch vehicle development generally takes longer than expected, some designs do not work out at all, and important missions are usually not risked on the first flight. Presumably the MSR schedule will slip into the 2030s for Earth departure, after reality is acknowledged and at least one whole MAV is then flight-tested over Earth. The current MAV schedule has been squeezed unrealistically for two reasons. The 2026 and 2028 dates for Earth departure came from hopes for Mars surface operations during warm weather there (permitting solar power instead of RTG power). The other reason is that the MAV challenge has been underestimated and postponed for decades, as noted years ago in this forum and explained in my white papers submitted last October to the Planetary Decadal Survey (see Post #389). Hopefully MAV development will proceed whether or not MSR continues steadily as a formal flight program with Phase A, Phase B, etc.

6. The org chart for the MAV project could be messy. The RFP states, "The Contractor and the Government will work together in a collaborative environment, using the Government provided conceptual design as a starting point." MSFC will retain responsibility for procuring the solid rocket motors, guidance navigation and control including flight software, and flight testing, leaving the contractor to be responsible for the rest. Apparently, the contractor is not going to be held responsible for making a complete working MAV. Hopefully the collaboration will work out, benefitting from the combined expertise of MSFC and the contractor.

7. Some good news is that the MSR campaign is expecting more money than was anticipated in mid-2020, indicating a strong commitment to proceed.

8. Proposals are due on September 16, and the cover letter (attached here) says they expect to have a contract in place by February 2022. The MAV RFP can be found at the following U.S. Government website.
https://sam.gov/opp/30aaa0f8713f40ba898050d17b95f690/view

The 459-page PDF is the one having the following filename.
MAVIS RFP 80MSFC21R0001.pdf

The MAV-001 supporting document is inside the following Zip folder on the website.
J-4A Applicable Documents.zip

Attached File(s)
Attached File  Signed_RFP_Letter_MAVIS.pdf ( 257.94K ) Number of downloads: 344
 
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Explorer1
post Dec 13 2021, 10:41 PM
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Hardware is being tested! The jumping rocket looks as out there as the Sky Crane did (but in the opposite direction!)
https://www.youtube.com/watch?v=SAPaWLQbU_s

At 0:55 we are shown a rendering of what the entire lander would look like on the surface, including the MAV.

Also apparently no parachutes for the Earth return capsule? Just lithobraking, Genesis style? Or are they deliberately over-engineering to not rely on chutes to keep the capsule intact for landing?
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Paolo
post Dec 14 2021, 05:06 AM
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QUOTE (Explorer1 @ Dec 13 2021, 11:41 PM) *
Also apparently no parachutes for the Earth return capsule? Just lithobraking, Genesis style? Or are they deliberately over-engineering to not rely on chutes to keep the capsule intact for landing?


the 2003 Mars Surveyor sample return was to have used no parachutes exactly for that reason. I think the reasoning still stands
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John Whitehead
post Dec 14 2021, 09:41 PM
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Nice to see things are busy-busy at JPL. Do I correctly assume that tossing the MAV in the air was deemed to save weight on the lander, compared to a mechanism that would tilt the MAV upwards?

Perhaps the MAV is so heavy relative to the whole lander mass, that merely tilting it would tip the lander over. If so, a tilt-up mechanism would need to lift the MAV in addition to rotating it, so that the tail end could swing into position above the center of the lander.

Is the MAV now known for certain to be too heavy to be delivered on the same lander as the fetch rover?

Gotta love the statement in the first ten seconds of the video, "If there's a question that we don't know the answer to, we will test it."

Here is one exception, can the MAV be smaller, as was envisioned 20 years ago? There has been no testing to find out how small a MAV can be. Building and testing miniature launch vehicles seems totally consistent with "dare mighty things," quoted here from time 2:34 in the video.
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Explorer1
post Dec 15 2021, 01:56 AM
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And of course, any lifting mechanism has to withstand a not-insignificant period on the planet's surface, with all that entails in terms of dust, radiation, and day-night cycles. A mechanically simple hop into the air (and given Martian gravity, a much longer opportunity to ignite than even in the video), versus a potentially complex tilting manouevre might very well be a good trade off. And in this business, trade-offs are everything....
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John Whitehead
post Dec 19 2021, 09:00 PM
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Here is a JPL news release that includes the video from Post #408, with more info. The lander is expected to be 2400 kg, the mock MAV being tossed was 400 kg, and future tests will toss heavier ones, as they develop the Vertically Ejected Controlled Tip-off Release (VECTOR) system (and as the MAV gets heavier).
https://www.jpl.nasa.gov/news/nasa-begins-t...-back-from-mars

The MAV will be inside a thermal enclosure ("igloo"), with heaters to keep it warmer than the parts of the lander exposed to Mars temperatures. MAV RFP documents (see Post #407) show that the VECTOR mechanism is holding the MAV from inside the igloo, which has a MAV Bay Door that opens. Presumably some or all of the VECTOR mechanism will be shielded from the Mars environment, by virtue of being inside the igloo. There are certainly some challenges to designing good insulation around the MAV, while having a door at one end to load samples, plus the full-length door at the top to let the MAV out. The rendering noted in Post #408 shows the igloo without the bay door.

In the VECTOR video, the mock MAV has a large opening on the side, rows of holes along the length, and big blocks sticking out the side, presumably for expedient testing, while the actual MAV will need to be smooth for aerodynamics while the lifting blocks (hard points) will be very small. We might ask whether the VECTOR imposes structural requirements on the MAV that are above and beyond Mars arrival loads, and how close to vertical the MAV will be when it starts steering itself (to avoid wasting time and propellant).

One thing newly noticed in recent months is that in June 2020, MSFC issued an add-on to the MAV solid rocket motor contract, for "risk reduction," which presumably means that meeting all requirements is not as easy as initially hoped.

On 2021Nov15, a NASA HQ presentation to the Planetary Science Advisory Committee (PAC) did not include a timeline update, consistent with MSR enjoying a long-term funding commitment without schedule pressure. Up until almost a year ago, MSR was expected to finish "Phase A" (working through major engineering unknowns) and begin Phase B in October 2021. There has been a half-year slip so far, according to NASA HQ in response to a question during the meeting (Phase B expected to start in April 2022). An answer to another question was that the possibility remains open to send the MAV and the fetch rover on the same lander ("trade is in the process of being closed up"). A short video clip of a VECTOR test was shown, while the one mention of MAV progress in the formal presentation was that MSFC is working on getting the industry contract started to build the whole MAV.

Here is an addendum to the "Small World" comment in Post #403. The Chair of the MSR Independent Review Board (and founder of the piece of Northrop-Grumman that seems likely to win the MAV contract) was recently named the Chair of the Board of Trustees at Caltech, which oversees JPL.

The following news article says China plans a MSR mission, and they are quoted as saying that launching off of Mars needs technology more like Earth launch than lunar departure.
https://spacenews.com/china-is-planning-a-c...return-mission/

Attached to this post are four slides from the PAC meeting on 2021Nov15, including VECTOR info. Out-of-date artwork shows the whole igloo tilted up with the MAV blasting out (doesn't the launch need to be close to vertical?).

Attached File(s)
Attached File  MSRfourPACslides2021Nov15.pdf ( 492.78K ) Number of downloads: 209
 
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djellison
post Dec 19 2021, 11:41 PM
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QUOTE (John Whitehead @ Dec 19 2021, 01:00 PM) *
(doesn't the launch need to be close to vertical?).


Almost every single cad rendering or artists impression in the last few years has shown an ~45deg launch angle.

With the reduction in gravity and drag losses on Mars, plus the comparatively short burn duration - you don't want to be launching vertical.

You would be wasting a huge amount of energy on a sharp gravity turn shortly after launch.
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John Whitehead
post Dec 20 2021, 03:01 AM
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QUOTE (djellison @ Dec 20 2021, 12:41 AM) *
You would be wasting a huge amount of energy on a sharp gravity turn shortly after launch.
Doug, did you mean to say "sharp pitchover maneuver shortly after launch"?

I thought that "gravity turn" refers to the natural trajectory that happens when thrust is aligned with the velocity vector, so that gravity gradually bends the trajectory over to horizontal, the advantage of which is zero angle of attack for less drag.

If launched at 45 degrees, active steering might be needed to keep it near 45 degrees, versus the natural path reaching a peak altitude too soon.

Maybe for Mars ascent it is better to do some active steering, so we can look forward to learning more about that.
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rlorenz
post Dec 20 2021, 03:54 AM
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No doubt the engineers have thought this through, but I fear this VECTOR thing is going to at least superficially look as crazy as the skycrane once did, so I hope the trade study / design rationale is presented well.

Cold launch is pretty common now for a variety of missile systems, but usually at zero angle of attack (e.g. ballistic missile systems being tossed vertically upwards, in an upwards orientation, then doing a snap pitch-over prior to main engine ignition). Tossing the MAV upwards in a partly sideways orientation is going to look pretty crazy, although presumably this is driven by lander aeroshell packaging constraints which don't apply e.g. to truck-launched missiles. And presumably the thin martian atmosphere means the aerodynamic forces and torques during the toss are small.

I concur with John's definition of gravity turn. Strictly there is no such thing as a gravity turn for a vertical launch in a vertical orientation, gravity slows you down but it doesnt turn you over.

MAV's an interesting problem. Having recently participated in the NIAC Titan Sample Return study, I think there's a need for a good tutorial article on ascent trajectory considerations in different gravity / atmosphere environments.....
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djellison
post Dec 20 2021, 05:50 AM
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QUOTE (John Whitehead @ Dec 19 2021, 07:01 PM) *
Doug, did you mean to say "sharp pitchover maneuver shortly after launch"?


Yes
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John Whitehead
post Jan 4 2022, 03:54 AM
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Thanks to Doug and others for sharing my curiosity about the MAV launch angle. One thing I noticed is that the JPL video from Post #408 seems to show the MAV ascending vertically at time 1:15, and a nearly vertical launch with a curved trajectory at 1:40.

I ran some simulations, which suggest that the launch angle is not of utmost importance, and it probably won't be known precisely until the MAV becomes a complete known entity (thrust-to-mass ratio and aerodynamic characteristics). An uncertain launch angle seems consistent with the wide range of artist concepts.

The attached table shows that a gravity turn trajectory could easily crash starting with a 45-degree launch, but if the 45-degree angle is actively held for longer, then it will reach orbit with essentially the same trajectory as a steeper launch with less hold time. If the thrust is much higher, then 45 degrees can work with a very short hold time (but more aero drag). MarsLaunchTable2022Jan3.pdf

The general trend is that closer to vertical works better for less thrust and-or less active hold time for the initial angle. The "medium" thrust used for most of the lines in the table is greater than several NASA documents showed during calendar year 2021 (7.5 kN), but way less than the legacy STAR 20 rocket motor (see Post #401).

The top two lines in the table show that a purely vertical launch will result in a gravity turn trajectory, due to planet rotation. While the MAV would go very high and somewhat "downrange," the planet surface moves farther, so the impact would be west of the launch site.

Regarding the VECTOR toss-up of the MAV, presumably tests at a later date will include the flight IMU (maybe already a flight-like IMU), to verify that the MAV will accurately and reliably know its orientation. The VECTOR rotation rate of the MAV might impose requirements on the IMU that it would not otherwise experience in flight. If the IMU needs to measure a higher rotation rate, that might cost something in navigation accuracy.

If the launch angle is far from vertical, then the landing needs rotational control to point the MAV nearly east. If that is the plan, it might be consistent with samples being loaded in the morning, when there is good sunlight on that end of MAV.

Lots of tradeoffs!
Attached File(s)
Attached File  MarsLaunchTable2022Jan3.pdf ( 130.1K ) Number of downloads: 190
 
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John Whitehead
post Feb 2 2022, 05:31 PM
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Today, 2022Feb2, is the "anticipated contract award date" for a company to help NASA MSFC create and design and build and test a Mars ascent vehicle, according to the 2021Aug16 letter from MSFC, the attachment to Post #407 above.
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djellison
post Feb 7 2022, 10:16 PM
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https://www.nasa.gov/press-release/nasa-sel...mples-from-mars

QUOTE
NASA has awarded a contract to Lockheed Martin Space of Littleton, Colorado, to build the Mars Ascent Vehicle (MAV), a small, lightweight rocket to launch rock, sediment, and atmospheric samples from the surface of the Red Planet. The award brings NASA a step closer to the first robotic round-trip to bring samples safely to Earth through the Mars Sample Return Program.
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nprev
post Feb 8 2022, 05:27 AM
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What a long-awaited milestone!!! After all these decades it's finally gonna be real. smile.gif


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A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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