WASHINGTON — With time running out to start work on a 2022 Mars orbiter, a NASA official said July 10 the agency plans to have a “coherent Mars architecture” for future robotic Mars missions ready for presentation an at August committee meeting.

Michael Meyer, lead scientist for the Mars Exploration Program at NASA Headquarters, said that architecture is on track to be presented at a meeting in late August of a National Academies committee reviewing progress NASA has made implementing the planetary science decadal survey published in 2011.

“It is in August when the committee meets that they’ll hear a coherent Mars architecture for what we hope to do for sample return and potentially other missions associated with that,” Meyer said at a teleconference meeting of the Mars Exploration Program Analysis Group (MEPAG). He added that he and others were working to ensure “agency endorsement” of that plan prior to the presentation.

Such an architecture, he noted, has been requested by Congress. “We’re on the hook to present something because this is actually something that Congress has asked for in their appropriations,” he said.

Meyer didn’t disclose details about what would be in that architecture, beyond its emphasis on sample return. The Mars 2020 rover mission will be the first step in a multi-mission sample return process, collecting samples that future missions will collect and return to Earth.

However, there are no missions to Mars under development by NASA beyond Mars 2020. That has caused increasing concern within the Mars science community, worried about both progress on sample return and on developing a new orbiter that they argue is needed to replace the telecommunications and imaging capability currently provided by the Mars Reconnaissance Orbiter (MRO).

NASA’s fiscal year 2018 budget request, released in May, provided only $2.9 million for “Future Mars Missions” that could include planning for an orbiter or other follow-on missions to the 2020 rover. That amount increases in the five-year budget projections to $178.9 million by fiscal year 2022, but MEPAG meeting attendees believed that was insufficient to launch an orbiter mission of any kind in 2022.

“Although there have been additions to the planetary science budget that have been impressive, they’ve been devoted elsewhere,” said Jeff Johnson, a planetary geologist at the Applied Physics Laboratory who is chair of MEPAG. “Without substantial augmentation to that Mars mission line by Congress, there’s little chance of actually launching a Mars spacecraft in 2022.”

Appropriations committees in the House and Senate have yet to reveal their plans for funding future Mars missions. The full House Appropriations Committee is scheduled to mark up its fiscal year 2018 appropriations bill July 13, which may provide more details about its interest in future Mars missions. The Senate Appropriations Committee has yet to take up a companion appropriations bill for NASA.

A new orbiter is seen as crucial for supporting ongoing missions by ensuring continued communications links to spacecraft on the surface, and to provide the high-resolution imaging currently done by MRO that will be needed to support future robotic and human landers. “Our main concern is that the Mars Exploration Program is getting old and nearing exhaustion,” Johnson said.

Concerns about a lack of planning for a 2022 orbiter extend to Mars robotic exploration in general for the upcoming decade, which the new architecture under development by NASA may not fully address. At the meeting, some noted a lack of engagement by NASA with the research community on scientific priorities for future Mars missions.

Those problems are hidden to some degree given the ongoing results from current missions, some operating at Mars for more than a decade. “The problem here is that things look good because we have so many missions there from past investments,” said Casey Dreier, director of space policy for The Planetary Society, at the MEPAG meeting.

That organization recently published a white paper warning that a lack of investment now in future Mars missions could jeopardize the progress NASA has made in studying Mars and establishing an infrastructure that supports future exploration. “It’s much harder to point out that we’re not making the investments now to set up the program we want for the next decade,” Dreier said.

It’s possible, scientists said at the MEPAG meeting, that follow-on missions to Mars 2020 could return samples to Earth by the late 2020s or, more likely, the early 2030s. This is particularly the case if a Mars orbiter launched in 2022 is equipped with a solar electric propulsion system that would allow it to maneuver in Mars orbit, collect a cache of samples launched from the surface and then return to Earth. That concept has been studied, but NASA has made no decision about including that capability on any future orbiter.

“We’re so close to this payoff, in a sense, of sample return, that it would be a shame to step back right now,” Dreier said.