WASHINGTON — On the eve of the release of the planetary science decadal survey likely to place a decreased emphasis on Mars, scientists and NASA officials are planning how to continue exploration of the planet with less expensive missions.
The National Academies is scheduled to release the latest decadal survey for planetary sciences April 19. The report will set priorities for planetary science and astrobiology missions for 2023 through 2032.
The previous planetary science decadal survey, released in 2011, recommended as its top priority for large, or flagship, missions a rover that could cache samples for later return to Earth. NASA ultimately implemented that recommendation as Mars 2020, with the Perseverance rover currently collecting those samples.
Agency officials, speaking at a conference on low-cost Mars mission options in Pasadena, California, in late March, acknowledged it’s unlikely another flagship-class Mars mission will be the top priority of the new decadal survey. Even if it was, the expense of the ongoing Mars Sample Return (MSR) campaign to return the samples Perseverance is caching makes it unlikely the agency could afford another large mission this decade.
“In the coming years, MSR is going to be the top priority for NASA relative to Mars and it seems unlikely that the next large-scale mission that the decadal recommends will have Mars as a target,” said Eric Ianson, director of the Mars Exploration Program at NASA Headquarters, in remarks that opened the meeting. “As such, there will not be the budget to develop a flagship-level mission on the order of Perseverance or MRO,” the Mars Reconnaissance Orbiter mission launched in 2005.
Another factor, he added, was NASA’s push to send humans to Mars as soon as the late 2030s. “Large science missions are probably not going to be the number-one priority,” he said.
Beyond MSR, the only other large Mars mission that NASA had announced was the International Mars Ice Mapper (I-MIM), an orbiter equipped with a radar to look for subsurface ice deposits of interest to both scientists and human exploration planners. The mission would include contributions from Canada, Italy and Japan, with NASA primarily responsible for mission management.
However, just before the conference, NASA’s fiscal year 2023 budget proposal zeroed out funding for I-MIM. “Due to the need to fund higher priorities, including to cover cost growth expected from the Mars Sample Return mission, the budget terminates NASA financial support for the Mars Ice Mapper,” the agency’s budget document stated.
At the conference, Rick Davis, NASA program executive for I-MIM, pressed ahead with a presentation about the mission, including how it could incorporate solar electric propulsion and also deploy a communications relay in Mars orbit to support other missions.
“We have some programs that are overrunning and they’re very high priority programs. That’s the driver for the budget submit,” he said when asked about the budget proposal, adding it would be up to Congress to restore funding for the program.
“The prime driver was overall stress on the budget for multiple projects,” Ianson said. “It’s not unprecedented for the budget to propose a cut to a mission and then Congress puts it back in.”
He sounded skeptical, though, that I-MIM could be revived in that way. “It depends on what kind of advocacy there is,” he said, noting successful efforts to restore funding for astrophysics and Earth science missions. “It’s not as clear to me that a strong advocacy for Ice Mapper exists in Congress.”
At the conference, many were pinning their hopes on smaller missions, both orbiters and landers, that could address key scientific issues. Recent studies, one by the Mars Architecture Strategy Working Group (MASWG) and another by a committee organized by Caltech’s Keck Institute for Space Studies, concluded that low-cost Mars missions were both feasible and useful.
Bruce Jakosky of the University of Colorado, who chaired the MASWG study, said at the conference that there was potential for missions with a total lifecycle cost of between $100 million and $300 million. “We think missions in this range have the potential to do outstanding science,” he said.
There are a couple recent examples, he noted, of such missions. Hope, the Mars orbiter by the United Arab Emirates launches in 2020, has an estimated cost of $200 million. NASA is also funding a smallsat mission to Mars called ESCAPADE with a cost cap of $55 million, scheduled to launch in 2024.
Rob Lillis of the University of California Berkeley, principal investigator for ESCAPADE, cautioned at the conference that his mission might not be applicable to other concepts for low-cost Mars missions. The mission, to study the interaction of the solar wind with the Martian atmosphere, can use low-cost instruments that do not require high data rates. The mission also won a commitment from Rocket Lab, which is supplying the Photon buses for the twin ESCAPADE spacecraft, to stick to the cost cap for the mission.
“$55 million is too low for most realistic missions,” he said. “It’s not the right cost cap for Mars missions in general.”
Jakosky agreed. “The MASWG committee thought that opportunities would really begin to open up to do important science at around $100 million,” he said. Within a projected cost range of $100–300 million, “we have a wide range of capabilities and a wide range of boxes that we can fit in.”