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An illustration of the InSight Mars lander on the surface of Mars. InSight is scheduled for launch next month, but after it Mars 2020 is the only other mission on the books. (credit: NASA/JPL-Caltech)

So, what about Mars?

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The biggest visible change in civil space policy so far under the Trump Administration has been a renewed emphasis on the Moon. Space Policy Directive 1, signed in December, formally instructed NASA to send humans back to the Moon, and the 2019 budget proposal released in February included detailed about an “Exploration Campaign” with several lunar-themed elements, from buying rides on commercially-developed lunar landers to repurposing the Deep Space Gateway as the Lunar Orbital Platform-Gateway.

“We didn’t give up on Mars in this plan,” said Lightfoot. “I think what this budget did for us is it kind of filled in the blanks for that decade of the 2020s, and allowed us to still keep an eye on Mars.”

This shift has been, at the very least, mildly disconcerting for advocates of human Mars exploration. NASA’s “Journey to Mars” has been sidelined in favor of one that still sees the Red Planet as the “horizon goal” of human spaceflight but one without any definite schedule or specific programs.

At a “Return to the Moon” symposium held by the Universities Space Research Association and George Washington University’s Space Policy Institute March 28, NASA’s outgoing acting leader made the argument that Mars was still a focus for NASA’s human space flight program, even with new lunar initiatives.

“We didn’t give up on Mars in this plan,” said Robert Lightfoot, who will retire from NASA at the end of this month. Instead, he said the new plan provided details about the cislunar activities NASA had intended to carry out in the 2020s in preparation for Mars, but about which the agency had offered few details beyond the development of the Deep Space Gateway

“We always said that the decade of the 2020s was a little bit uncertain,” Lightfoot said. “I think what this budget did for us is it kind of filled in the blanks for that decade of the 2020s, and allowed us to still keep an eye on Mars.”

Those filled-in blanks include much more activity around, and on, the Moon, than previously envisioned, including potential cooperation with international and commercial partners. That will be supported by the gateway, but Lightfoot added it could also serve as a point of departure for future human Mars missions. However, the concept of a Deep Space Transport, which would be developed and tested at the gateway according to proposals published last year, is no longer being emphasized by the agency.

NASA internally is still studying Mars mission architectures for future human missions. “We continue, again, to consider Mars a horizon goal, and we’ll be looking for opportunities to prove technologies to inform this architecture to make Mars missions more affordable and sustainable,” said Nantel Suzuki of NASA Headquarters at a meeting of the Mars Exploration Program Analysis Group (MEPAG) April 5 in Crystal City, Virginia.

That includes participation in studies like “Architecting Mars” carried out a few months ago, said John Connolly of NASA at the MEPAG meeting. That study looked at options for Mars missions ranging from Apollo-like sorties to the development of a “science field station” visited by several crews to the long-term ambition of many space advocates, permanent settlement of Mars.

National space policy no longer includes language about humans to Mars in the 2030s, Suzuki said. “You can draw whatever conclusions you want from that. It’s probably not moving to the left in that case.”

That study, slated for release next month at the Humans To Mars Conference in Washington, examined the various technical and financial aspects of those differing architectures, he said. Despite their differences, they agreed on some aspects, from leveraging international and commercial partnerships to limiting time spent on Martian orbit or on the planet’s two small moons.

“If you’re going to the Martian surface, go to the Martian surface,” he said. “Don’t put a base in Mars orbit. Don’t go to Phobos and Deimos. If the Martian surface is what you want to explore, go there.”

Those approaches, though, have different timetables. A sortie mission, he said, could be flown as soon as the mid-2030s, while the research base architecture could be developed by the late 2030s. A permanent base, he said, might not be feasible until “well into the 2040s.”

For now, NASA has no firm timeline for any kind of human mission to Mars. “The national space policy had previously said the mid-2030s,” Suzuki said, a date wiped out by the new space policy directive. “You can draw whatever conclusions you want from that. It’s probably not moving to the left in that case.”

“We continue to push ahead,” he added, “but it’s hard to put dates on there.”

Planetary scientists who study Mars have their own long-term uncertainty about exploration of the planet. Today there’s a flotilla of robotic spacecraft orbiting the planet and operating on its surface. They will be joined late this year by NASA’s newest Mars mission, InSight, scheduled to launch May 5 and land on the planet November 26, the Monday after Thanksgiving.

After InSight is Mars 2020, the rover mission based on Curiosity that will cache samples for later return to Earth. And after Mars 2020 is… nothing, so far, beyond early development of a so-called “lean” sample return architecture that includes a lander to collect the samples and launch them into orbit, followed by an orbiter to grab that sample canister and return it to the Earth, or somewhere in cislunar space (such as the gateway.)

That architecture is still being developed, including studies of key technologies needed to enable sample return. The 2019 budget proposal includes $50 million for that work, a level that stays flat in future years, out to 2023.

MAVEN is also being asked to operate for the long haul. “We’re under direction to not exhaust our fuel until 2030,” said Jakosky.

No other Mars missions, orbiters or landers, are currently under consideration by NASA. Instead, the agency is looking to extend the lives of current missions, in particular orbiters like the Mars Reconnaissance Orbiter (MRO) and Mars Atmosphere and Volatile EvolutioN (MAVEN), in part to ensure they can also serve as communications relays for future sample return missions well into the 2020s.

MRO has been in orbit around Mars since 2006. “We’re now regarded as a milestone mission for the Mars program,” said Leslie Tamppari, deputy project scientist for MRO, at the MEPAG meeting April 4. “We’re requested to be alive through 2027 so that we can support the Mars program.”

She said that requires dealing with various issues as the spacecraft ages, such as lowering power loads on the spacecraft to better manage the spacecraft’s aging batteries. Controllers will likely shift the spacecraft’s orbit to shorten the duration of eclipses that drain the spacecraft’s batteries. One issue not likely to pose a near-term issue is propulsion: the spacecraft has more than ten years’ worth of fuel reserves at current levels of usage.

MAVEN is also being asked to operate for the long haul. “We’re under direction to not exhaust our fuel until 2030,” said Bruce Jakosky, principal investigator for the mission, at the MEPAG meeting. MAVEN has been in orbit since September 2014.

MAVEN has focused on its science mission, but will increasingly take up communications relays duties as well, he said. Right now MAVEN handles only one communications pass a week, split between the Curiosity and Opportunity rovers. That will change, he said, when InSight arrives at Mars, with about one pass a day planned during the lander’s commissioning phase.

After that commissioning is done, MAVEN will aerobrake into an orbit with a lower apoapsis, or high point, in its orbit, to be a more effective relay for Mars 2020. That should start in March of 2019, he said.

“We will see an increase in relay usage during what has been referred to as the ‘2020 era,’” he said, supporting Mars 2020 operations. That will involve two to three communications passes a day, which he said should still give MAVEN enough time to continue its science work. “If we go above three relay passes per day, it starts to get hard to envision how we would fit in MAVEN science. We understand that is not our choice.”

Any future Mars missions, including sample return missions, will not get special treatment at NASA. The budget proposal sees the Mars Exploration Program line start to taper off in the 2020s as currently planned missions are completed and launched. Those projections don’t reserve any funding as of yet for later missions.

“It’s absolutely essential that you realize that this is not an entitled program,” said Jim Green, director of NASA’s planetary science division, at the MEPAG meeting April 3. “What we have to be able to do is argue, and get into the budget, our next set of Mars missions as new starts. It’s not a given that the next major mission, or new start, will be Mars.”

“It’s absolutely essential that you realize that this is not an entitled program,” said Green. “It’s not a given that the next major mission, or new start, will be Mars.”

That could be done through existing programs, like the Discovery class of low-cost planetary science missions. “The Discovery program is an open competition. There are no exclusion of objects in the Discovery program,” he said. That contrasts with the larger New Frontiers program, which limits missions to one of a handful of potential destinations based on priorities established in the planetary science decadal survey. (InSight is part of the Discovery program, although its selection caused some grumbling among other planetary scientists.)

Jim Watzin, the director of NASA’s Mars Exploration Program, offered an upbeat assessment about the future despite the budget challenges and missions that he admitted were “a little long in the tooth” as their missions were extended. “I think we’ve got a really healthy program,” he said in a presentation following Green’s at the MEPAG meeting, citing everything from ongoing missions to what might follow a sample return mission. “We’re actually starting to think about what comes after sample return.”

One attendee, though, worried that an emphasis on the Moon could hurt Mars exploration, noting that despite calls that technology developed for lunar missions “feed forward” to Mars missions, the two are “different in almost every way you could imagine.”

“I think, overall, the plans are strengthening now,” Green responded, noting that Mars sample return development can support later human missions, whenever they might fly. “We’ll see them solidify more over the next several years.”