WASHINGTON — NASA says it still expects to make a recommendation on a new architecture for the Mars Sample Return (MSR) program by the end of the year despite a change in leadership of a key review committee.

At a Nov. 6 meeting of the Mars Exploration Program Analysis Group (MEPAG), Jeff Gramling, MSR program director at NASA Headquarters, said a committee called the MSR Strategy Review Team, or MSR-SR, is scheduled to provide a recommendation on a “go-forward architecture” for MSR in December. That recommendation will go to Nicola Fox, NASA associate administrator for science, and then to NASA Administrator Bill Nelson for final approval.

That was the same timeline that Gramling provided at an Oct. 21 meeting of a National Academies committee. That took place days after NASA announced the formation of the MSR-SR, chartered with reviewing a dozen studies by industry and NASA on ways to reduce the cost and speed up the timeline for returning samples from Mars. Current estimates project MSR to cost up to $11 billion and return samples as late as 2040.

At that time, the eight-person MSR-SR was chaired by Jim Bridenstine, the former NASA administrator. However, in Gramling’s presentation to the MEPAG, Bridenstine was no longer listed as chair or member of the team, which is now led by Maria Zuber, a planetary science professor at the Massachusetts Institute of Technology who has worked on previous Mars missions.

A NASA spokesperson referred SpaceNews to the original press release, which NASA updated Oct. 24 with the change in membership in the committee. NASA did not publicize the revised release, which also did not explain Bridenstine’s absence.

“Jim Bridenstine, who was previously announced as the chair of the review team, made the decision to withdraw from his position,” NASA told SpaceNews. “Upon further reflection, Bridenstine was unable to fully dedicate the time necessary to complete this important work for the agency.”

That change does not appear to alter the schedule of the committee’s work or its overall goal of recommending a new approach to MSR that could combine elements of several of the studies. “That go-forward architecture doesn’t necessarily have to be any of the studies as proposed,” Gramling said. “They’re free to evaluate the benefits represented in the whole span of the studies and put together the architecture they think gives us the best chance of returning samples to Earth before 2040 and/or putting together an architecture that will cost less than $11 billion.”

If that schedule holds, Gramling said the next step would likely be an acquisition strategy meeting in the spring of 2025.

Range of options

Several of the companies and organizations that did perform MSR studies briefed the results of their work at the MEPAG meeting.

One study was by the Jet Propulsion Laboratory, which revised the overall MSR architecture. Matt Wallace, director of the planetary science directorate at JPL, said that the revised approach would return samples to cislunar space in 2035 and reduce the projected $11 billion cost in half, bringing it back to the level recommended by the latest planetary science decadal survey.

“We took advantage of some features and factors and conditions that really did not exist three or four years ago,” he said, ranging from the health of the Perseverance rover itself, which gives them confidence the rover will be able to deliver the samples to a future lander, as well as making use of capabilities from the Artemis lunar exploration effort to take samples in the final leg from cislunar space back to Earth.

A key element of the JPL architecture is reducing the size of the Sample Retrieval Lander and its Mars Ascent Vehicle (MAV) rocket, which would launch the samples into Mars orbit. Current designs call for the lander to weigh up to 3,450 kilograms, but the revised JPL design shrinks that to no more than 1,350 kilograms, enough to enable the use of the proven “sky crane” landing system demonstrated on the Perseverance and Curiosity rover missions.

Two other studies presented at the meeting focused on reducing the size of the MAV. One study, by the Applied Physics Laboratory (APL) in cooperation with NASA’s Wallops Flight Facility, proposed a rocket called the Mars Integrated Launch System that leveraged their past work on missiles and sounding rockets. Doug Eng of APL said that the system could return a full set of 30 samples with a significantly smaller mass and size, enabling smaller landers like the one JPL proposed.

Another study by L3Harris examined dozens of different designs for the MAV, recommending a single-stage rocket using a storable bipropellant pressure-fed propulsion system. “You get a lightweight and compact MAV,” said Britton Reynolds of L3Harris. “It leverages the sky crane landing architecture.”

Ben Reed, chief innovation officer of Quantum Space, said his company’s study focused on the “anchor leg” of MSR, using a version of his company’s Ranger spacecraft to transport samples returned to cislunar space back to Earth. That approach could reduce the complexity and mass of the Earth Return Orbiter, the spacecraft being developed by ESA to bring samples from Mars orbit back to Earth, he said, and be ready as soon as 2033.

“We’re very happy that we have a range of options that are being looked at,” NASA’s Gramling said, without discussing details of those studies beyond the presentations made at the meeting. “We think we’re going to be able to come forward with a plan.”