Asteroid Expert Richard Binzel: ARM is "Emperor With No Clothes"

NASA’s plan to send humans to retrieve asteroid samples in the next decade is not driven by science, acknowledged many participants at NASA’s 11th Small Bodies Assessment Group (SBAG) meeting this week in Washington.  There was no consensus, however, about the mission’s utility toward sustainable human exploration of space.

Richard Binzel, asteroid expert and planetary science professor at MIT, made the controversy the focus of his presentation, telling the gathering that NASA’s Asteroid Redirect Mission (ARM) is “the emperor with no clothes, or at best with very thin cloth” as to how it applies to a pathway to sending humans to Mars.

Unlike the Apollo lunar missions that brought back the first lunar rock samples, which were “transformative science,” it is “irrational” to risk human lives to grab an asteroid sample, Binzel said.

NASA is using ARM to test technical capabilities required for human exploration of Mars in the mid-2030s, though the agency’s fact sheet on ARM also states the mission would allow “important scientific investigations and develop capabilities for deep space exploration and potentially for planetary defense.”

ARM is divided into three mission phases: select an asteroid; robotically capture and redirect it (the entire asteroid or just one of its boulders, each 10 meters or less in diameter) to stable lunar orbit using advanced solar electric propulsion; then use the future Space Launch System (SLS) and Orion capsule to transport astronauts to collect samples by 2025.

Binzel criticized the retrieval part of the mission in particular and cited the abundant population of “accessible” asteroids in their native orbits.  He asserted that a 10-meter object traverses cis-lunar space (between Earth and the Moon) weekly. “We don’t have to go to them, they’re coming to us.”

“The asteroid becomes exciting and interesting only because it’s a stunt,” Binzel said, a “one-and-done stunt that will irreparably damage small body exploration.”  Planetary scientists use the term “small bodies” to refer to asteroids, comets, interplanetary dust, small satellites, and Trans-Neptunian Objects.

He advocated that “thorough surveys” of accessible asteroids be conducted first while an “extended human capability” is being developed in order to achieve a sustainable path of small body and Mars exploration.    According to one of his slides (which are posted on the SBAG website), “99.9 % of accessible 10 meter asteroids remain undiscovered.”

Representatives from various NASA centers and others in the audience agreed on the need for a thorough survey to look for asteroids.  They did not agree with everything Binzel said, however.  One objection was Binzel’s mixing of  “two different things such as” Apollo and ARM. Another participant expressed skepticism about finding enough asteroid targets that would be accessible.

“Fundamentally we don’t have enough money available to do the things we need…So we have something like ARM,” one attendee responded to Binzel.  “You’re absolutely right, [ARM] would not be something a scientist would design,” but “science needs to be involved simply to make it safer and to make it better.”

Binzel noted the National Research Council’s (NRC’s) recent “Pathways to Exploration” report was critical of ARM.  An audience member pointed out that while that was true, the NRC did not recommend any specific pathway to Mars.

The House-passed 2014 NASA Authorization Act, which has yet to pass the Senate, would require SBAG, along with the NASA Advisory Council (NAC), to assess “how the proposed mission is in the strategic interests of the United States in space exploration.”  SBAG reports to NAC’s Planetary Science Subcommittee (PSS), which in turn reports to NAC’s Science Committee.  SBAG cannot formally give advice to NASA, but it informs PSS and the Science Committee, which do give advice.

“Our credibility is at stake,” Binzel told the SBAG audience. “Either say you love it or you hate it, but don’t be neutral.”

Binzel’s presentation was on Wednesday (July 30).  The ARM debate continued Thursday, the last day of the 3-day forum, though to a lesser degree.

SBAG received briefings from a number of NASA officials on the agency’s overall human space exploration plan, the “Evolvable Mars Campaign.”  ARM is one of several steps in that campaign that eventually leads to humans landing on Mars.   On Thursday, NASA’s Patrick Troutman presented the role that the moons of Mars — Phobos and Deimos — could play as possible destinations.  An audience member asked Troutman why not have a trip to one of those moons as a precursor to landing on Mars instead of ARM?

“There are things pulling against that with respect to near-term activities and there’s also a feeling that maybe the next president comes in and perhaps Mars is not the target,” said Troutman, a member of NASA’s Human Spaceflight Architecture Team at Langley Research Center.

Phobos and Deimos are worth exploring because they are close enough to Mars to provide access to the planet’s surface, are rich in science, and would utilize the same crew transportation systems that would be needed for a Mars landing mission, yet require less investment in surface assets, Troutman said.

“I got the impression that there was not necessarily a consensus view,” said SBAG chair Nancy Chabot, in her closing remarks.  Chabot is a planetary scientist at Johns Hopkins University’s Applied Physics Lab.