Redirecting Asteroid Not Top Objective of Asteroid Redirect Mission, NASA Official Says
WASHINGTON — A NASA official on Jan. 7 offered one of the clearest reminders yet that the agency’s proposed Asteroid Redirect Mission (ARM) is more about technology development than actually sending a small asteroid to lunar orbit to be visited by astronauts next decade.
After a presentation in Phoenix to the NASA-chartered Small Bodies Assessment Group (SBAG), Lindley Johnson, head of the agency’s Near Earth Object Observations Program, said redirecting an asteroid to a distant retrograde orbit around the Moon is “not the top objective of the [ARM] mission,” which was trotted out in spring 2013 as a means to road test technology needed for a crewed Mars expedition and provide — in the form of the titular asteroid — a near-term destination for the Space Launch System rocket and Orion crew capsule NASA is building.
NASA’s notional ARM concept involves launching a $1.25 billion robotic spacecraft around 2020 to either capture a free-floating asteroid about 10 meters wide or pluck a somewhat smaller boulder from the surface of a much larger space rock. The probe would then take the specimen to a lunar storage orbit where it could be visited by astronauts aboard the Space Launch System and Orion.
Asteroid redirection has dominated public discussion of ARM, both in the press and in the halls of Congress, since NASA unveiled the proposed mission with great fanfare almost two years ago.
Yet now, according to Johnson, NASA might not even make redirection of a boulder or asteroid a requirement for mission success. Pressed by SBAG member Mark Sykes, director of the Planetary Science Institute in Tucson, Arizona, on whether a mission concept review scheduled for Feb. 26 would cement redirection as an ARM requirement, Johnson said no.
Redirecting an asteroid “is certainly something that the agency as a whole wants to do with the mission, but to a certain level, objectives are tradable,” Johnson said.
Sykes, a veteran planetary scientist, scoffed at that answer in a Jan. 7 Twitter post, asking rhetorically, “[T]hen what is the point?”
#sbag ARM: returning an asteroid/boulder an objective (not a requirement??) – objectives are tradeable… [then what is the point?]
— Mark V. Sykes (@psisykes) January 7, 2015
Johnson’s remarks at SBAG are the latest, but not first, attempt on NASA’s part to manage expectations about ARM. Even NASA Administrator Charles Bolden has advised the public to brace for the possibility that no asteroid will show up in lunar orbit for astronauts to poke and prod.
In March, Bolden told attendees of the American Astronautical Society’s Robert H. Goddard Memorial Symposium in Greenbelt, Maryland, he would be “happy” if the ARM is able to move an asteroid at all, “even if it’s an arcsecond that we can measure [and] we miss lunar orbit.”
Whether it can capture an asteroid or not, just getting the ARM spacecraft into orbit would provide NASA with a chance to test technologies that are not obvious fits for any of the other missions in the agency’s pipeline.
Prominent among these are large-scale, solar-electric propulsion systems, which if successful could be scaled up further and adapted for the interplanetary cargo-hauling spacecraft NASA says it needs to deliver hardware for a crewed Mars landing to the red planet in advance of the crew’s arrival.
The same day SBAG met in Phoenix, Johnson said, NASA officials were scheduled to convene at the agency’s Washington headquarters to settle the question of how the robotic ARM spacecraft will attempt to collect the asteroid the agency hopes to return to the Earth-Moon system.
NASA is weighing two options: Option A, assumed to be the cheaper of the two by about $100 million, involves capturing a free-floating asteroid roughly 10 meters across with a petal-like grappling system. Option B calls for flying out to a much larger asteroid, one about 100 meters wide, and collecting a boulder from its surface using a robotic arm tipped with tiny, finger-like appendages.
NASA was expected to announce its choice in a Dec. 17 press conference, but wound up punting until after the winter holidays. A decision is now expected in January, Johnson told SBAG.
Robert Lightfoot, NASA associate administrator and pointman on ARM, indicated a preference for Option B at the Dec. 17 press event. The boulder-plucking option, Lightfoot said, would mature more technology and operational techniques applicable to future human exploration missions, such as visits to Mars’ two small, asteroid-like moons, Phobos and Deimos.
Johnson, meanwhile, told SBAG members he did not know exactly when senior NASA managers would decide between Option A and Option B — only that they would do so before the mission concept review now scheduled for Feb. 26.
That decision “is out of my hands, and out of the ARM team’s hands, frankly,” Johnson said.
The robotic ARM spacecraft would launch on a United Launch Alliance Delta 4 Heavy, the Space Launch System — which is still under development at NASA, but scheduled for a maiden flight around 2018 — or SpaceX’s Falcon Heavy, which like the NASA rocket is still under development.