Mars sample return science continues amid budget uncertainty

THE WOODLANDS, Texas – Scientists' efforts to use a Mars rover to collect samples continue even as NASA completes a new assessment of when and how those samples will be returned to Earth.

The Perseverance rover, which landed on Mars in February 2021, filled 26 of 43 sample tubes, scientists involved in the mission said in presentations at the Lunar and Planetary Science Conference (LPSC) on March 12. The rover climbs along the remains of a river delta that once flowed into the Jezero crater.

Of those 26 tubes, 20 contain rock cores, said Meenakshi Wadhwa, a planetary scientist at Arizona State University who serves as chief scientist for the Mars Sample Return (MSR) at the Jet Propulsion Laboratory. Two contain regolith and another contains a sample of the atmosphere, while the other three are “witness tubes” that serve as controls to identify any terrestrial contamination in the other tubes.

Two of the remaining 17 tubes are also witness tubes, leaving 15 that can be filled with other samples. Scientists are planning the next stages of the rover's journey, she said, such as the rim of the crater, which promises what she called an “incredible variety” of rocks of different ages and exposed to different processes, “including materials of astrobiological potential.”

That work is ongoing as NASA enters the final stages of reviewing the entire MSR architecture, including the layout and design of the mission that will collect those sample tubes and return them to Earth. After an independent review board, or IRB, concluded that the agency's current approach could not meet cost and schedule goals, NASA hired the MSR IRB Response Team (MIRT) in October to evaluate alternative approaches.

“Much of the work has already been completed” by MIRT, Wadhwa said. MIRT is expected to complete its work by the end of the month, and NASA will announce its revised MSR plans and proposed budget as early as April.

This has put not only the MSR in limbo, but NASA's entire planetary science portfolio. NASA's fiscal year 2025 budget proposal, released March 11, left MSR funding undetermined or to be determined. At the same time, the agency must also develop an operational plan for fiscal year 2024 funding provided by an appropriations bill passed March 8 that directs NASA to spend at least $300 million and as much as $949.3 million on the MSR in 2024.

The TBD in the FY 2025 budget request for MSR reflects uncertainty about plans to carry out the program, said Lori Glaze, director of NASA's Planetary Science Division, during a March 11 LPSC town hall meeting. “We're trying to give the response team the time they need to complete their assessment and make a recommendation,” she explained.

Once that work is done, NASA will amend its budget request to seek specific funding for the 2025 MSR, but at the expense of allocations requested for other planetary programs in the original proposal. “I don't expect the top level of the planetary budget to go above $2.73 billion” in the original request, she said, which is already fully allocated to other programs. “We need to think about how to support the Mars Sample Return within a balanced planetary portfolio and within that $2.73 billion line.”

NASA faces similar challenges for determining MSR funding in 2024 within the limits set by the appropriations bill. “This will be the heart of a very difficult process,” she said.

While providing little information on what the new MSR architecture will be like, its cost and schedule, NASA officials at the conference reiterated the scientific value of the program.

“Returning a sample from Mars is one of the highest priorities in the last two decades of research. It's an agency priority,” said Lindsay Hays, acting lead scientist for MSR at NASA Headquarters, during a March 12 presentation. The samples, she said, can serve as a “Rosetta Stone” for decoding the early history of the terrestrial planets.

However, these officials acknowledged that the uncertainty surrounding the MSR is affecting scientific planning. This includes potential exploration beyond the crater rim by Perseverance to collect samples. “We're waiting to see what the MIRT results are,” Hays said. “MIRT will help us understand what our future architecture and future layout is.”

She added that “maximizing the number of samples and simple diversity is absolutely critical” to the mission, which Wadhwa also pointed out.

“Right now we're waiting on the outcome of MIRT in terms of what the timeline will look like,” said Wadhwa, who will determine what type of transit Perseverance will undertake to collect additional samples on and off the crater rim. “We have an incredible array of rocks waiting for us in those regions.”

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