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Mars Sample Return
Explorer1
post Dec 5 2018, 04:17 PM
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A press release from a Canadian company that has been selected for a 'Fetch Rover' by Airbus to pickup the 2020 samples:
https://mdacorporation.com/news/pr/pr2018120401.html
QUOTE
Brampton, ON - MDA, a Maxar Technologies company (NYSE: MAXR) (TSX: MAXR), announced today that it was selected by Airbus to provide a conceptual design of a rover mobility system and sample acquisition system planned to explore Mars and acquire samples that will be returned to Earth. The rover, a small vehicle approximately 1 metre wide by 1.5 metres long, will be capable of withstanding the harsh atmosphere of Mars and its challenging terrain. The ‘Sample Fetch Rover’ is planned to be part of the mission concepts the European Space Agency (ESA) is exploring with NASA for an international Mars Sample Return campaign between 2020 and 2030. The new contract is one of a number of innovative programs MDA’s space systems is supporting.


Also some details on a European orbiter to pick up the samples in orbit and return them to Earth.
QUOTE
ESA’s Earth Return Orbiter will be the third launch in this campaign to Mars and it is timed to capture the basketball-size sample container orbiting Mars. The spacecraft will then return to Earth, where it will release the entry capsule, allowing extensive analyses of the samples in laboratories with varied scientific equipment too large to take to Mars.


Obviously just a press release, so take it with a grain of salt, but a NASA/ESA partnership seems like the best way to split the costs.

Still almost no details on the MAV as we have been discussing in the thread. Any idea who would build it?
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mcaplinger
post Dec 6 2018, 01:32 AM
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QUOTE (Explorer1 @ Dec 5 2018, 08:17 AM) *
a NASA/ESA partnership seems like the best way to split the costs.

FWIW, I'm unconvinced that international cooperation ever saves money if a full cost accounting is done.


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MahFL
post Dec 6 2018, 01:52 AM
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QUOTE (Explorer1 @ Dec 5 2018, 04:17 PM) *
...Obviously just a press release, so take it with a grain of salt, but a NASA/ESA partnership seems like the best way to split the costs.
...


I have never heard any talk of splitting costs from NASA HQ staff, eg the reason Insight has the instruments it has are because they were the best available to achieve the mission objectives, not to split any costs.
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Explorer1
post Dec 6 2018, 02:25 AM
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Well the whole point of the 2020 rover is lost if no one builds an ascent or Earth-return vehicle! If NASA doesn't get the funding for both of those in the 2020s, by definition it will be some other agency that needs to do it.
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vjkane
post Dec 6 2018, 02:19 PM
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QUOTE (Explorer1 @ Dec 5 2018, 08:17 AM) *
Obviously just a press release, so take it with a grain of salt, but a NASA/ESA partnership seems like the best way to split the costs.

NASA and ESA signed a statement of intent on April 26, 2018 to develop plans to jointly accomplish the sample return by splitting the development along clear system/subsystem lines. The SOI is based on direction in the FY19 budget submitted by NASA to plan for a sample return and on the 2016 direction by ESA's Ministerial Council to prepare for a joint sample mission. Both agencies have been doing technology development along the lines of the proposed split of responsibilities for a number of years. For example, the Canadians have been doing rover development for several years including building prototypes.

Here's the split of responsibilities from the SOI:

NASA: MSR lander including Mars ascent vehicle, sample capture and containment system for the return orbiter, Earth entry capsule

ESA: fetch rover, return orbiter, sample transfer arm for the MSR lander

Formal approval of this plan would come for NASA in the form a new start in a funding bill (and subsequent year funding); for ESA at the next Ministerial Council meeting (I'm not sure if this is in 2019 or 2020).

I've attached a copy of the SOI

Attached File(s)
Attached File  2018_04_26_NASA_ESA_SOI_Signed.pdf ( 753.79K ) Number of downloads: 925
 


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John Whitehead
post Jun 21 2019, 04:05 PM
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Here is an update for the Mars ascent vehicle (MAV).

A 2019 publication (URL below) from engineers at the Marshall Space Flight Center (NASA MSFC) compares conceptual designs for a single-stage hybrid propellant MAV and a two-stage solid propellant MAV. This study, done at the request of JPL, is a bit of a revelation, considering that the hybrid rocket alone was presented as the solution in 2018, at two science community meetings (MEPAG and the National Academy decadal midterm review, see my 2018Sep10 post). The MSFC paper says there will be a down-select at the end of 2019, followed by detailed design for one of the two options.

A two-stage solid propellant MAV was favored by NASA for most of the past 20 years, then was put on the back burner for roughly 5 years of research into hybrid propulsion, which is considered to be more tolerant of cold temperatures while waiting on Mars. The 2015 JPL study found that four different versions for a two-stage solid would all be heavier than two different options for liquid propulsion (hybrid best, then liquid, then solid). Notably, this latest MSFC paper dismisses liquid propulsion as less worthy of consideration, without explaining the discrepancy.

So not only is there is no easy answer, but selecting the least difficult option is also fraught with uncertainty. As I've written before, it is unfortunate that engineers have always been constrained by the notion of designing and building a MAV in the next several years (on and off for over 20 years now), rather than doing long-term experimental research to create new technology. Yes, the hybrid work is experimental, but it is mostly "propellant research" rather than "miniature launch vehicle research." The latter kind of effort needs to emphasize making components that weigh much less than the state of the art for small-scale space propulsion.

The 2019 MSFC paper shows top-level numbers for thrust and mass, from which it can be calculated that the solid propellant needs to burn at only about 60 percent of the typical rate for existing solid rocket motors of the same size. The lower thrust is needed for trajectory reasons, but the paper does not mention that the propellant burn rate needs to be much lower, or to what extent that would be a development challenge. While the nozzles need to be flexible for steering, the authors offer no comments for how much weight that would add.

The MAV mass is yet again heavier. The 2018 JPL publications show the hybrid MAV as 346 kg, and the 2019 MSFC paper shows 374 kg for both the hybrid and the solid, for the same 18-kg payload in all cases. Twenty years ago, the notional two-stage solid MAV was to be inside a thermal enclosure (the "igloo") for survival on Mars, while the 2019 study says little about the extra mass needed for "ground support equipment" on Mars. There needs to be a lot of building and testing to figure out how to make small rocket parts super-lightweight, but the engineering efforts have been limited to design studies and propellant research.

Here's the URL for the 2019 MSFC MAV publication.
https://ntrs.nasa.gov/archive/nasa/casi.ntr...20190002123.pdf

Also during the past year, the international MSR science team (iMOST) published a 186-page report that details the scientific reasons why it is more compelling than ever to have Mars samples in labs on Earth.

Long version from 2018 August:
https://mepag.jpl.nasa.gov/reports/iMOST_Fi...port_180814.pdf

Short summary from 2019 March, published in Meteoritics & Planetary Science:
https://onlinelibrary.wiley.com/doi/full/10.1111/maps.13232

Considering the science case, and the fact that a small MAV continues to be elusive, maybe the answer is for the MSR mission to be way bigger and heavier than anyone has thought. But budget-wise, that just pushes it farther into the future. See Mike Caplinger's post from 2018Oct28.
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stevesliva
post Jun 21 2019, 05:18 PM
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I was thinking this thread, and about sample return when reading that the 2020 rover just got its wheels installed. The 2020 rover is supposed to cache samples for return. So the time on the surface vs 20 years ago is likely shorter. That said, you're not avoiding nighttime entirely.
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John Whitehead
post Aug 31 2019, 06:03 PM
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Regarding the comment from Steve, the MAV will need to survive Mars surface temperatures for weeks to months, while a fetch rover (arriving on Mars with the MAV) would retrieve the sample containers left by the Mars 2020 rover in multiple locations. The duration is not especially different from 20 years ago, when the notion was that a science rover and a MAV would be sent together, and the MAV would similarly wait to receive its payload.

Ideally, the MAV will be there only during Mars summer. However, this can't always happen because a Mars year is 22.57 Earth months, while Mars arrival opportunities average every 25.62 months, the latter being the interval over which Earth "laps" Mars, going around the sun 2.135 times versus 1.135 for Mars.

The Mars 2020 rover is planned to depart Earth in 2020Jul-Aug, arriving at 19 degrees north latitude in early 2021, near the beginning of the spring season according to the following URL <http://www.planetary.org/explore/space-topics/mars/mars-calendar.html>. In subsequent years, each Mars arrival opportunity will be 3 Earth months later relative to Mars seasons (25.62 minus 22.57 is 3.05). In particular, the 2026 Earth departure will arrive near the fall equinox on Mars, and subsequent mission opportunities for years to come would require the MAV to survive winter on Mars. Presumably this is one reason for current hopes to have a MAV ready to launch from Earth in 2026.

Meanwhile, the latest NASA technical papers about MAV propulsion were presented in mid-August at the AIAA Propulsion & Energy Forum. At least one of them refers to the "igloo," the insulated container around the MAV, with heaters inside. Uncertainties include how much electricity will be available to run heaters, and whether the MAV plus igloo can be lightweight enough to deliver to Mars along with a fetch rover.
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JRehling
post Sep 2 2019, 01:54 AM
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Wouldn't a simple way around this, if 2026 is missed, be to launch on a non-minimal energy trajectory that arrives a few Mars months later? A trajectory that involves Earth/Venus gravity assist might even involve the same or less energy, spend more time in space, and thereby avoid a martian winter.
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John Whitehead
post Sep 2 2019, 02:21 PM
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Great thinking out of the box. Not having a working familiarity with alternative trajectory options, my guess is that they would come with their own timing constraints that may or may not work out. If more launch energy is needed, that would mean less mass going to Mars (or a bigger launch vehicle). A trajectory closer to the sun can change the thermal design requirements for the whole spacecraft and lead to unfortunate surprises (remember the Galileo high-gain antenna that didn't unfold, likely because it got too hot). These and other considerations would have to be traded against designing the MAV enclosure for Mars winter temperatures. Can someone point to solid info for how much colder it gets, i.e. night winter temps vs night summer temps (and-or average temps for winter vs summer) at only 19 degrees north latitude (the Mars 2020 location)?
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mcaplinger
post Sep 2 2019, 05:23 PM
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QUOTE (John Whitehead @ Sep 2 2019, 06:21 AM) *
(remember the Galileo high-gain antenna that didn't unfold, likely because it got too hot)... Can someone point to solid info for how much colder it gets, i.e. night winter temps vs night summer temps (and-or average temps for winter vs summer) at only 19 degrees north latitude (the Mars 2020 location)?

The Galileo antenna problem was caused by loss of lubricant from multiple truck shipments to and from JPL and KSC, not heating. From https://www.cpp.edu/~gkuri/classes/ece431/G...Workarounds.pdf

QUOTE
Extensive analysis has shown that, in any case, the problem existed at launch and went undetected; it was not related to sending the spacecraft on the VEEGA trajectory or the resulting delay in antenna deployment.


That said, it is true that there are thermal impacts from using Venus flybys. Another option that's been discussed is using solar electric propulsion for the sample return.

Based on the limits we had to test the instruments to, I expect temperatures at Jezero to be pretty similar to those at Gale -- lows about -70C min in the summer, -90C in the winter. That doesn't seem like a huge driver to me but it depends on the sensitivity of the MAV.


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JRehling
post Sep 3 2019, 01:24 AM
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I'd love to have a less speculative way to discuss trajectories, but there is some room for flexibility, aforementioned caveats withstanding.

One fact: Northern winter on Mars (or late fall) is during the time closer to aphelion, so some trajectories that reach Mars at other positions in its orbit have an "energy dividend" compared to Hohmann transfer trajectories that arrive at those times.

Another possibility without the thermal issues of a Venus gravity assist would be a Mars gravity assist. Put the craft into a solar orbit that is close to Mars' and ride along relatively nearby the planet until they intersect later for a second time. This would likely mean a relatively long cruise before arrival, but avoid all of the aforementioned issues – winter on the surface, thermal issues near Venus, and significantly higher delta v.
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John Whitehead
post Sep 3 2019, 05:30 PM
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Thanks Mike for the temperature info and the Galileo correction. Yes, solar electric propulsion could change the equation for interplanetary transfer (just to be clear that electric propulsion would not apply to a MAV).

Regarding a heliocentric orbit close to that of Mars (roughly circular), the delta-V would be significantly greater than the elliptical orbit from Earth to Mars, the extra amount being analogous to satellite apogee burns from GTO to GEO. There would be no need for any further gravity assist, other than that landing on Mars is "assisted by gravity." Solar electric propulsion for Earth-to-Mars would greatly change the arrival timing restrictions. Maybe it doesn't matter so much, considering minus 90 degC versus minus 70.

Regarding Venus gravity assist, looking around the Internet shows that flying by Venus is almost as difficult as going directly to Mars. Venus gravity assist is very useful for Jupiter and beyond, because it is so much harder to go directly that far out. Here is some delta-V info.
https://www.reddit.com/r/space/comments/1kt...e_solar_system/
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mcaplinger
post Sep 3 2019, 09:43 PM
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The most recent NASA/ESA-proposed mission ( http://www.planetary.org/blogs/guest-blogs...t-msr-plan.html ) would launch the sample into Mars orbit in spring 2029 (Earth spring) and leaves it in orbit for 6 months until the Earth return spacecraft grabs it and returns to Earth in spring 2032 using solar-electric propulsion.

You have to get into Mars orbit anyway, so to limit the MAV's time on the surface, just launch the sample and let it wait in orbit.

Of course I'm not holding my breath for any of this to happen.


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John Whitehead
post Sep 4 2019, 02:54 AM
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Thanks for that latest link Mike, directly relevant to our last several forum posts. The notion for a 2026 launch of a sample retrieval lander is that it would orbit the sun 1.5 times (elliptical I assume), on an unusually long journey to Mars, to arrive during the desired Mars season. The article says that the thing to avoid is dust storms, apparently more important than temperatures in selecting the best Mars season to land and pick up the samples from Mars 2020.

Amazingly, the article almost completely ignores the need to create a MAV. Under the heading, "Launching Mars 2020’s Samples into Space," there are multiple paragraphs about every other part of the retrieval mission. The only mention of the MAV is:

"Once all samples are retrieved, the rover will launch them into orbit using a deck-mounted rocket. This rocket’s design has not been finalized, but NASA is weighing a 2-stage solid rocket or a single-stage hybrid rocket as options."

It would be more accurate to say that after decades of wanting to do MSR, the MAV effort has barely begun. I love the part about "the rover" launching the samples, very revealing about the MAV being taken for granted.

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