WASHINGTON – NASA plans to delay the next phase of its Mars Sample Return campaign and split a lander mission into two separate spacecraft to reduce the overall risk of the program.
At a March 21 meeting of the National Academies’ Space Studies Board, Thomas Zurbuchen, NASA’s deputy administrator for science, announced that NASA and the European Space Agency had agreed to revise the schedule and design for upcoming missions, the rehearsals Perseverance Rover will return to Earth from the cache.
Initial plans called for the launch of both a NASA-led Sample Retrieval Lander and an ESA-led Earth Return Orbiter in 2026, ahead of the Mars Ascent Vehicle (MAV), which would launch them into orbit. The orbiter would collect the samples using a NASA-provided collection system and return them to Earth in 2031.
However, an independent review in November 2020 recommended that NASA delay those future missions to 2027 or 2028 to provide a more sensible development schedule. Another recommendation from the panel was that NASA investigate how to convert the single spacecraft Sample Retrieval Lander into two separate landers, one carrying the rover and the other carrying the MAV.
Zurbuchen told the Space Studies Board that NASA and ESA had agreed to split the Sample Retrieval Lander into two landers, which would now be launched in 2028. “The Phase A analysis has shown that the individual lander frankly breaks entry, descent and landing heritage. It’s actually high risk,” he said.
The single-lander approach would require a larger heat shield, estimated at 5.4 meters in diameter, which in turn would require a larger payload fairing for the rocket launching it. The design also had “untested” boarding, descent and landing capabilities and would require electric propulsion on the voyage leg to increase payload performance.
A dual-lander approach, he said, could use the same landing system used by Perseverance and, before that, by Curiosity. “It can be completed in the 20’s just the way we want it,” he said, avoiding the complexity of the larger design.
Both NASA and ESA agreed to adopt the approach, as well as a timeline that would delay the launches of the two landers until 2028. The Earth Return Orbiter would launch in 2027 and samples would return to Earth in 2033 according to this revised schedule.
Zurbuchen said a lander called SRL1, carrying the MAV and a robotic arm for sample transfer, would be built by the Jet Propulsion Laboratory because of “criticality and integration.” NASA had not yet decided who would build the second lander, SRL2, which will carry the fetch rover. The decision, he said, would come by June, when the mission reaches a programmatic milestone called Key Decision Point B.
He did not discuss the cost implications of the schedule or design changes. Just before the launch of the Mars 2020 mission with the Perseverance rover, NASA and ESA officials estimated that the entire Mars Sample Return campaign would cost at least $7 billion. NASA will not be making formal cost estimates for its future lander missions pending the later review of Key Decision Point C, although the agency’s proposed budget for fiscal year 2023, due to be released on March 28, may contain some additional details.
A complicating factor for the Mars Sample Return plans is the delay in ESA’s ExoMars rover mission, which was due to launch in September, until the agency ended its partnership with Roscosmos earlier this month following Russia’s invasion of Ukraine. ESA is now considering options for continuing the mission, which would delay its launch to at least 2026.
ESA officials said March 17 that those options could include a renewed partnership with NASA. Zurbuchen alluded to these comments in his remarks at the meeting, but did not address NASA’s role in ExoMars. “We have many discussions with our European colleagues, which may or may not influence some of the discussions here related to ExoMars,” he said. “It’s up to them to talk about it.”