From - Sky & Telescope
By - David Dickinson
Edited by - Amal Udawatta
NASA / ESA / JPL-Caltech / GSFC / MSFC
Retrieving samples from Mars for study on Earth is crucial to our ability to understand the geological history of the Red Planet, including whether life ever existed on Mars. Perseverance has already collected 25 samples of both surface material and Martian atmosphere in Star Wars lightsaber-like tubes. But the architecture and timeline for a mission that would return these samples to Earth has been a budgetary bone of contention for years.
Now, NASA Administrator Bill Nelson and NASA’s Science Mission Directorate leader Nicky Fox have laid out a new path for the beleaguered Mars Sample Return proposal.
Perseverance's Treasure
NASA’s Perseverance rover (nicknamed “Percy”) landed in Jerzero Crater on February 18, 2021. Since then, 32.57 kilometers (20.24 miles ) of travel have now brought the rover to the crater's rim. In addition to the 25 samples the rover has collected, it has also gathered three of five "witness" tubes, which act as controls. Perseverance deposited 15 of them on the Martian surface for later collection; the remainder of samples are still on the rover awaiting deposit.
Perseverance has brought 43 tubes to Mars; the goal for Earth return is 30 filled tubes.
NASA / JPL-Caltech / MSSS
The initial plans for a sample return called for a collaboration between NASA and the European Space Agency (ESA) and multiple vehicles, including a NASA-led Sample Return Vehicle that would head to the Red Planet sometime in the 2028 pre-opposition launch window. That mission was to land near Perseverance, perhaps dispatching scout quadcopters similar to Ingenuity. Later, those tubes would be loaded onto a Mars Ascent Vehicle, currently contracted to Lockheed Martin. That vehicle would then rendezvous around Mars with ESA's Earth Return Orbiter, for Earth return in the mid- to late 2030s.
NASA / JPL-Caltech
But costs for this complex mission have frustrated efforts to get it off the ground. The 2023 decadal survey greenlighted a budget of $5–7 billion for the mission. This budget also received a go-ahead from an initial independent review board. But a second independent review cited a higher budget — $8-11 billion. Alternatively, the budget could remain the same, but the timeline would push back to the 2040 timeframe. The proposal faltered, with NASA calling for proposals from industry and all NASA centers to restructure the mission.
Last September, the agency accepted 11 studies from the NASA community and industry, a Mars Sample Return Strategic Review team was charged with assessing the studies and then recommending a primary architecture for the campaign, including associated cost and schedule estimates. Now, on the eve of the upcoming change of administration, Nelson, Fox, and others have outlined two potential options for the first step.
Two Landing Options
Option 1 relies on tested technology: The sky crane system for NASA's lander helped both Curiosity and Perseverance land a large mass on Mars. Option 2 would see NASA reaching out to commercial companies for a new landing system. Although no specific project was specified, SpaceX, Blue Origin, and Rocket Lab were mentioned as potential partners.
Regardless which option gets the go-ahead, the lander platform will be powered not by solar panels but by a radioisotope power source, like what currently powers Curiosity and Perseverance. This decision was made to ensure sufficient power. Both options would also carry a Mars Ascent Vehicle with it. The revised plans call for a smaller and simplified vehicle, which in turn allows for a lighter and less complex lander. The main difference between the two options is therefore the landing system.
NASA
“Pursuing two potential paths forward will ensure that NASA is able to bring these samples back from Mars with significant cost and schedule saving compared to the previous plan,” Nelson said in a recent press release. “These samples have the potential to change the way we understand Mars, our universe, and — ultimately — ourselves.”
Nelson said the first option would cost $6.6–7.7 billion, while the second option is slightly cheaper at $5.8–7.1 billion. Nelson also noted that the incoming administration and Congress would have to be onboard with the proposals almost immediately in FY 2025, to the tune of $300 million in preliminary funding, in order to move ahead.
A final decision on which option NASA will choose could come in 2026. Both options would still rely on a return vehicle provided by the ESA, which would now launch in 2030. A return via cis-lunar space was also considered, though NASA prefers a simpler, direct trajectory to Earth. The samples would then be on Earth for study in the 2035-2040 timeframe.
Of course, with such a long timeline, it’s entirely possible that China could beat the U.S. to the punch. China has already demonstrated the capability to perform sample-returns from the Moon with its Chang’e mission series, and the country landed a rover on Mars in 2021. China also plans on launching an asteroid sample-return mission Tianwen 2 this year. It’s entirely conceivable that China could roll lessons learned into a Mars sample-return mission of their own.
Nelson noted, however, that the quick “snatch and grab" missions that Chang'e has previously carried out aren’t in the same league as NASA's Mars Sample Return mission, for which sample selection has been carefully thought out to maximize scientific value.
For now, the proposal continues to be at the whims of funding and a new administration. In the meantime, the sample tubes will be there, waiting for a mission to bring them back to Earth for study.
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