WASHINGTON — As NASA continues to weigh two options for the robotic portion of its Asteroid Redirect Mission (ARM), the agency’s advisers say they are still unconvinced about the general ARM concept and its relevance to the long-term goal of sending humans to Mars.
At a recent meeting of the NASA Advisory Council at the Stennis Space Center in Mississippi, agency officials said they had not yet made a selection between two approaches for moving a small asteroid, or a boulder off a larger asteroid, into lunar orbit.
NASA had planned to make a decision in December on the two choices, known simply as Option A and Option B. In Option A, a spacecraft would shift the orbit of a small asteroid, up to ten meters across, into a distant retrograde orbit around the moon. In Option B, a spacecraft would grab a boulder a few meters across from the surface of a larger asteroid and move that into lunar orbit. In both options, a crewed Orion spacecraft would then visit the asteroid.
However, on Dec. 17, NASA Associate Administrator Robert Lightfoot announced that the agency needed more time to evaluate the options. Those additional studies, he said at the time, would take two to three weeks.
Michele Gates, ARM program director at NASA Headquarters, told a meeting of the NASA Advisory Council’s human exploration and operations committee Jan. 13 that NASA would make a decision between the two options in the near future. “We’re expecting a decision in mid-January on the robotic mission capture option,” she said.
NASA Administrator Charles Bolden made similar comment to the full council Jan. 14. “We hope to be able to announce something soon,” he said. NASA had yet to announce a choice between the two options as of Jan. 23.
Council members, though, were less concerned about the two options than about the relevance of ARM in general. As at their previous meeting in July 2014, members of the council raised concerns about the cost and utility of ARM versus alternatives, such as a mission to a near Earth asteroid in its “native” orbit.
Members also noted comments by NASA officials that suggest ARM could still be considered a success even if the robotic mission does not redirect an asteroid. On Jan. 7, Lindley Johnson, head of NASA’s Near Earth Object Observations Program, said at a meeting of the Small Bodies Assessment Group that returning an asteroid to cislunar space was a “tradable” objective for ARM.
“What we’re hearing, and it’s a logical position to take, is that if the mission doesn’t redirect an asteroid, it can still be a success,” said Steve Squyres, a Cornell University planetary scientist who is chairman of the council, during a discussion about ARM Jan. 14.
However, he and other council members wondered if ARM was the best way to develop and test technologies needed for later human missions to Mars. “If you’re going to spend $1.25 billion plus launch vehicle costs to do something,” he said, referring to the estimated cost of the robotic portion of ARM, “and you get the most important things by not going after the rock, don’t go after the rock.”
Bolden showed some frustration with the council’s pessimism about ARM. “Give me a break,” he said after Sqyures’ comments, adding that he was “miffed” by the criticism of the mission. He argued that ARM gives NASA the ability to show it can move an asteroid while testing solar electric propulsion, which the agency considers a key technology for future exploration. “Why not do it?”
“We’re trying to do a lot of different things and satisfy a lot of people who want us to do a lot of different things, and we thought we found a way that would get a lot of these previously disconnected things put together,” Bolden said of ARM.
Bolden, though, didn’t appear to be convincing to members of the council. Another member of the council, retired aerospace executive Thomas Young, argued against trying to justify ARM by saying the mission is on the path to Mars. “Proving that we can redirect an asteroid has nothing to do with going to Mars,” he said.