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Mars Sample Return
John Whitehead
post Dec 18 2020, 04:50 PM
Post #391


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Terrific news that real money will flow to MSR, and here is another quote from the same article.
QUOTE
Phase A... the program will mature critical technologies and make critical design decisions
These two steps will include figuring out how big the MAV really needs to be, and how much payload it really can carry (with or without the fetch rover on the same lander). During the December 16 meeting of the Steering Group for the Planetary Decadal Survey, there was a fine explanation from retired Pegasus launch vehicle developer Antonio Elias, of the MSR Independent Review Board. He said launch vehicle development typically starts with a payload mass goal, then they figure out how big the vehicle needs to be. Conversely, he noted that Pegasus started with a vehicle size (so it could be carried by the airplane), and the engineering challenge was to get the most payload that they could. He said the MAV is the first launch vehicle development to start out with fixed constraints on both ends (required payload mass to Mars orbit, and a total mass limit for delivery to Mars). This is going to be a cool project!

A video of this week's meeting might end up at the following link (not there at the moment, but some other recent meeting videos have been posted).
https://www.nationalacademies.org/event/12-...-2032-meeting-7
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mcaplinger
post Dec 18 2020, 05:36 PM
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QUOTE (John Whitehead @ Dec 18 2020, 08:50 AM) *
These two steps will include figuring out how big the MAV really needs to be, and how much payload it really can carry...

As noted upthread, back in April 2020 NASA showed every indication that they were ready to buy the flight rocket motors from NGIS ( https://beta.sam.gov/opp/349cbd728ab24d7693...true&page=1 )
One presumes that this never happened, reason unknown.

I've seen progress. It doesn't look like this.


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John Whitehead
post Dec 22 2020, 01:51 AM
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QUOTE (mcaplinger @ Dec 18 2020, 06:36 PM) *
One presumes that this never happened, reason unknown.
See Post number 389 above, second paragraph under the heading "summary of events" in 2020, namely that it is hard to nail down how big the MAV is going to be. So the choices are:
1. Buy the motors, build prototype MAVs and do some test flights (expensive testing with evolutionary progress toward a final design like SpaceX does), or
2. Continue trying to converge toward a final design on paper (less costly like ULA is doing for the Vulcan launch vehicle, but harder to do for the MAV in the absence of sufficient experience building miniature launch vehicles).
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Steve G
post Feb 9 2021, 02:14 PM
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Is the sample return mission going to be NASA's next planned Mars mission? I see nothing on the books for any approved, or even a firm proposal, past Perseverance for a NASA Mars mission. When can we expect approval for the next mission?
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mcaplinger
post Feb 9 2021, 04:33 PM
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QUOTE (Steve G @ Feb 9 2021, 06:14 AM) *
Is the sample return mission going to be NASA's next planned Mars mission?

Currently yes, though not yet committed to AFAIK (it's been "approved for phase A" but I'm not convinced it's fully funded at that level in the FY2021 budget, maybe somebody who's waded through the budget knows more.)

MEPAG docs are the best source of information. https://mepag.jpl.nasa.gov/meetings.cfm

https://mepag.jpl.nasa.gov/meeting/2021-01/...1_2021%20V5.pdf

https://mepag.jpl.nasa.gov/meeting/2021-01/...2021%20v1.1.pdf


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mcaplinger
post Feb 12 2021, 12:42 AM
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QUOTE (mcaplinger @ Feb 9 2021, 08:33 AM) *
it's been "approved for phase A" but I'm not convinced it's fully funded at that level in the FY2021 budget, maybe somebody who's waded through the budget knows more.

http://spaceref.com/news/viewsr.html?pid=54522 says
QUOTE
Exceeding NASA’s request, Congress is providing $264 million for the Mars Sample Return mission, with direction to have it ready for the launch window that opens in 2026.



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John Whitehead
post Feb 12 2021, 06:01 AM
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After the MSR presentation to MEPAG on 2021Jan27 (middle link in Post number 395 above), one of the questions was whether the MSR schedule and budget includes iterative building and testing to converge on a final MAV design, considering that uncertainty remains after years of past trade studies. The NASA HQ reply was that analysis should be sufficient, and testing will only be needed to validate the design. This statement seems to lean toward option 2 in Post 393.

The Q&A described here starts at time 2:14:30 in the following video of the meeting.
https://mepag.jpl.nasa.gov/meeting/2021-01/...l%20Meeting.mp4
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Explorer1
post Feb 27 2021, 04:26 AM
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Some good details about the fetch rover and MAV in this PBS documentary (around 40 min in): https://www.youtube.com/watch?v=fhtw7Dpntb4
Worth watching on its own, too!
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John Whitehead
post Feb 27 2021, 06:37 AM
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Thanks for that link. Yes there are good details about the fetch rover, especially that prototype testing is ongoing. But there are no details about the MAV, only that it is a "pint size rocket" (not true) and the statement from ESA that the MAV is the hardest part of the whole mission, "super ambitious" (true). Then the animation shows the entire MAV reaching Mars orbit, without dropping the first stage (huh?). One has to wonder why the crack team of miniature launch vehicle engineers was not featured in this NOVA show, testing their prototype rockets and explaining the challenges they are working on.
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mcaplinger
post Mar 4 2021, 09:31 PM
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https://www.nasa.gov/press-release/nasa-awa...r-sample-return

QUOTE
The cost-plus, fixed-fee contract has a potential mission services value of $60.2 million and a maximum potential value of $84.5 million. Work on MAPS begins immediately with a 14-month base period, followed by two option periods that may be exercised at NASA’s discretion...
Marshall is responsible for the MSR Program’s MAV element, which is a two-stage vehicle that will be a critical element in supporting MSR to retrieve and return the samples that the Mars 2020 Perseverance rover will collect for return to Earth. The Martian environment will be a significant factor in the design, development, manufacturing, testing, and qualification of two different solid rocket motors with multiple deliveries of each. Through the MAPS contract, Northrop Grumman will provide the propulsion systems for the MAV, as well as other supporting equipment and logistics services.



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John Whitehead
post Yesterday, 06:37 PM
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QUOTE (mcaplinger @ Mar 4 2021, 09:31 PM https://www.nasa.gov/press-release/nasa-awards-mars-ascent-propulsion-system-contract-for-sample-return) *
14-month base period, followed by two option periods that may be exercised at NASA’s discretion
This contract for MAV solid rocket motors (SRMs) is a major step forward--finally real money for a MAV! A mere 14 months seems too short for flight deliverables, so this base period with options suggests a development project, versus having a final design that is straightforward to build. Ideally such an effort would have started ten years ago, to allow more time to work through uncertainties. Regarding the overall timing for MSR, it is encouraging that recent decades have seen huge improvements in at least two key technologies, inertial navigation instruments small enough for a MAV, and electric propulsion (for the Earth Return Orbiter, ERO).

Attached to this post is a MAV chart from a public presentation to the National Academies Planetary Decadal Steering Committee on February 11, with key points in my added sidebar and detailed comments below. DecadalMAV2021Feb11.pdf

In size, shape, and mass, the first stage SRM is very much like the 300-kg STAR 20 SRM that has decades of flight heritage and a terrific propellant fraction, about 90 percent. The challenges are to make a nozzle that can swivel without adding undue mass, and to reduce the thrust to about one-third of the STAR 20 (1700 lb versus over 5000 lb). Solid propellant burns at its own rate for a given formulation, so it is not necessarily easy to make it burn three times slower. Assuming that 1700 lb works out, there will be plenty of thrust to flight-test the MAV in Earth gravity.

While STAR motors for space applications are mostly spherical in shape, the second stage SRM is shown here as a short cylinder, not ideal structurally for internal pressure. Presumably there will be some development work to make the case sufficiently lightweight.

History shows that it is a major challenge to make all the MAV parts sufficiently lightweight, relative to the propellant and the payload. One year ago in March 2020 (IEEE Aerospace Conference), the two-stage solid MAV design had the same total mass (400 kg) and payload (16 kg). In the fall, the report from the MSR Independent Review Board revealed that the design had grown to over 500 kg, but switching to an unguided upper stage would reduce it to 320 kg. Stage 2 would be made lighter by leaving the liquid steering propulsion and inertial navigation instruments on Stage 1, so that Stage 2 becomes a point-and-shoot. According to a presentation to the Decadal Survey Mars Panel on 2021Jan5, the 320-kg MAV was up to 380 kg. As of Feb11 it was back to 400 kg, just like the design from one year ago, despite the risky unguided upper stage that was expected to reduce the MAV mass.

The take-away is that the year-old design must have had unrealistic assumptions for making the parts lightweight, and there might still be some extra optimism. One risk for the spinning upper stage is that it won't be put on a spin-balancing machine after the Mars geology samples are installed, so will it stay pointed in the right direction after spin-up and during the burn? After the de-spin motors fire, what is the allowable amount of residual rotation (tumbling) for the stage to eject the orbiting sample to the ERO?

After Perseverance landed on 2021Feb18, the public video feed included a feature about the Mars helicopter, Ingenuity. They showed a team of enthusiastic creative engineers doing trial-and-error flight testing, and it was specifically pointed out that the helicopter design is all about having high electrical power while being super lightweight. Hopefully we will one day see a similar news feature that documents the efforts of a successful MAV team to make all the parts super lightweight relative to the propellant and payload.
Attached File(s)
Attached File  DecadalMAV2021Feb11.pdf ( 152.71K ) Number of downloads: 19
 
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