NASA’s Choice for Asteroid Redirect Mission May Not Sway Skeptics
WASHINGTON — Picking an option for the robotic portion of its Asteroid Redirect Mission (ARM) allows NASA to proceed with development, but does not appear to have won over those skeptical of the mission’s overall utility.
NASA announced March 25 that it selected what it calls Option B for the robotic element of ARM, where a spacecraft retrieves a boulder up to four meters across from the surface of a larger asteroid and returns it to a distant retrograde orbit around the moon to be visited by astronauts. That decision came during a mission concept review for ARM at NASA Headquarters March 24.
NASA Associate Administrator Robert Lightfoot said the decision to go with Option B was in part because more of its technologies could be used in later human space exploration missions. Those systems include mechanisms for landing on the asteroid and grappling a boulder on its surface.
“Those are the kinds of things we know we need when we go to another planetary body,” he said in a March 25 teleconference with reporters. “That was really important for me.”
Another factor, Lightfoot said, was mission success. Asteroids that are several hundred meters across — the current class of destinations that NASA is considering — should have many boulders on their surfaces, based on spacecraft observations of several such objects. “I’m going to have multiple targets when I get there,” he said. “That’s what it boils down to.”
The original concept for ARM, which became known as Option A, involved redirecting an entire asteroid up to ten meters across into lunar orbit. Lightfoot said that it has been difficult for astronomers to discover near Earth asteroids in that size, and also challenging to determine if they are suitable targets for the mission.
“Nature is telling us what targets we have,” Lightfoot said at a March 26 symposium here on asteroid research held by the Universities Space Research Association and George Washington University’s Space Policy Institute. “For Option A, there’s not a lot of candidates.”
NASA originally planned to make its choice in December, but announced then that it needed more time to study the two options. At that time, though, NASA appeared to be leaning towards Option B. Lightfoot said in December that the agency was weighing whether the additional technologies in Option B were worth its additional cost, about $100 million more than Option A.
Lightfoot said March 25 that Option B still costs about $100 million more than Option A. However, he added that Option B was still able, at least in this early planning phase, to fit with a cost cap of $1.25 billion, excluding launch vehicle, for the robotic part of ARM.
He later suggested NASA may be able to defray some of its costs of ARM through international partnerships. “There’s the cost of the mission and then there’s the price of the mission,” he said at the symposium. “If folks can come in as partners, it offsets the overall price that I have to pay from an agency perspective.”
Lightfoot said NASA has had discussions with several potential international partners, but declined to identify them beyond “typical partners” for NASA, or describe the capabilities they could provide. Those potential partners, he added, had “a lot more interest” in Option B than Option A.
“It’s our international partners participating with us on the International Space Station and some of our science missions,” he said. “They’ve offered to bring those kinds of talents to what we need to go do.”
NASA has yet to select a target for ARM, but is currently using for planning purposes a near Earth asteroid named 2008 EV5. That asteroid, about 400 meters across, has been previously proposed as a target for robotic asteroid sample returns, including a concept called MarcoPolo-R that was a finalist for the European Space Agency’s Cosmic Vision M3 mission in 2014, losing to an exoplanet science mission.
The notional schedule for ARM calls for launching the robotic mission in December 2020, arriving at the target asteroid about two years later. Lightfoot said the decision on the target asteroid could be deferred to as late as 2019, allowing NASA’s near Earth object search program additional time to find alternative targets. The robotic spacecraft would then leave the asteroid, returning the boulder to lunar orbit by late 2025.
ARM has received a lukewarm reaction, at best, in policy and scientific circles since NASA announced plans to pursue the mission nearly two years ago, with many people questioning its relevance to NASA’s long-term ambitions to send humans to Mars. The decision to go with Option B did not immediately appear to change many minds.
“I don’t understand what a boulder does for us in terms of helping us get to Mars,” said Richard Binzel, a professor of planetary science at the Massachusetts Institute of Technology, at the March 26 symposium.
Binzel argued that NASA’s budget for its overall asteroid initiative — about $200 million in its 2016 budget request — could be better spent developing a space-based survey telescope to search for near Earth asteroids, including ones in orbits accessible for future human missions without the need to redirect it into lunar orbit.
“If we knew the hundred or thousand more accessible objects, it would be like a gateway to space resource utilization,” he said.
Former NASA astronaut Tom Jones countered that ARM was essential to preserving NASA’s human spaceflight capabilities in the 2020s by providing a destination beyond the ISS.
“If you’re not doing something in the mid-2020s, you have stretched out the advance of NASA astronauts into deep space by such a long period, what I fear is that people will lose interest,” he warned. “You’ll wind up shutting things down.”
Binzel, though, said that NASA could carry out human missions in cislunar space, developing technologies needed for later missions to Mars, without flying ARM. For example, he suggested NASA could use solar eclectic propulsion, a key technology it plans to use for ARM, to deliver a cargo module to lunar orbit that astronauts later dock with. “The extensibility to Mars is where ARM fails,” he said.
With ARM having completed its mission concept review, it now moves into a planning phase known as Phase A in NASA program management parlance. “It’s really a refinement phase,” Lightfootsaid March 25. That work will include development of better estimates of the cost and schedule for the mission.
Phase A work also includes an acquisition strategy meeting in July to decide how to procure key elements of the mission. “That’s the next big milestone coming up,” Lightfoot said. He added that there appeared to be more commercial interest, in the form of supplying spacecraft components and technologies, in Option B.
Lightfoot emphasized that ARM was intended as one step in the agency’s long-term plans to send humans to Mars. “It’s bringing together the best of NASA’s human exploration, science portfolio, and technology portfolio,” he said. “It really gives an opportunity to demonstrate the capabilities we’re going to need for future human missions beyond low Earth orbit and ultimately to Mars.”
That claim, though, will likely continue to be challenged by skeptics of NASA’s plans. “What does picking up a boulder off the surface of an asteroid have to do with placing an astronaut on the surface of Mars?” Binzel asked. “If you’re dumbfounded, you’re not the only one. There’s plenty of controversy out there.”