WASHINGTON — NASA has at last confirmed something that seemed implicit until it was not: That redirecting an asteroid sample to lunar orbit is indeed the goal of the agency’s proposed Asteroid Redirect Mission (ARM).
Asked here during a June 29 meeting of the NASA-chartered Small Bodies Assessment Group (SBAG) whether the agency considered asteroid redirection a success criteria for ARM, Michele Gates, program director for the Asteroid Redirect Mission at NASA headquarters, answered “yes.”
It was a complete change of tack from the answer Lindley Johnson, head of NASA’s Near Earth Object Observations Program, gave in January at SBAG’s last public meeting. At that time, Lindley framed asteroid redirection as a nice-to-have goal, noting that “at a certain level, objectives are tradable.”
At both meetings, it was Mark Sykes, director of the Planetary Science Institute in Tucson, Arizona, who dragged rather than coaxed answers about the mission’s Level One objectives — those essential to mission success — out of ARM’s managers in Washington.
“First ‘yes’ I’ve heard,” Sykes said June 29 during a question-and-answer session with Gates. Sykes vented on Twitter about ARM’s $1.25 billion development cost cap.
#sbag ARM is still $1.25B not including launch vehicle and mission operations (Phase E)!
— Mark V. Sykes (@psisykes) June 29, 2015
One aspect of ARM that NASA has been consistent about is the $1.25 billion cost cap, which only covers construction of the robotic redirect craft. Neither the price of a launch, either on a United Launch Alliance Delta 4 heavy or NASA’s yet-to-be-built Space Launch System, nor the cost of operating the spacecraft, which is being designed to last six years, is included in that estimate.
The next big milestone for ARM will be Aug. 4, Gates said, when NASA will hold an acquisition strategy meeting at headquarters here. Big procurement decisions, including on the spacecraft bus, will wait until after then, Gates said in an interview after her SBAG presentation.
After the acquisition strategy decision, ARM will work toward a February KDP-B review: a NASA program milestone that formally lays out a mission’s requirements and informs its final design.
The White House endorsed ARM in spring 2013 as a first step in what NASA has lately taken to calling the “Journey to Mars.” ARM will pluck a boulder-sized sample from a much larger asteroid as part of a demonstration of new technology NASA says it needs for crewed Mars missions. Among these technologies are lightweight, high-wattage solar arrays and a high-powered, solar electric propulsion system.
ARM’s asteroid would also provide a near-term destination for the Space Launch System rocket and Orion crew capsule NASA is building, at Congress’ insistence, as keystone hardware for sending astronauts to the Mars system in the 2030s.
Also at SBAG, Gates pegged some notional launch dates for ARM: 2020 for the robotic leg of the mission and 2025 for the crewed leg of the mission, which will carry two astronauts to the distant lunar retrograde orbit for a five-day rendezvous with the captured space boulder — which will remain locked in its capture craft as astronauts poke, prod and sample it.
A second Level One ARM objectives is a mandatory planetary protection exercise in which the ARM spacecraft, with boulder in tow, will perform a so-called gravity tractor maneuver intended to change the course of whatever larger asteroid the small spacecraft samples.
The gravity tractor maneuver notionally calls for placing the ARM robotic craft into a halo orbit about its target asteroid — which will be a body large enough to pose a threat to humans on Earth — such that the attractive force between the two masses nudges the asteroid slightly off course, Bo Naasz, systems engineering manager at the Goddard Space Flight Center’s Satellite Servicing Capabilities Office in Greenbelt, Maryland, told SBAG.
Such a maneuver could conceivably divert a city-killing asteroid on target for Earth safely away, said Naasz.
A third Level One objective is that ARM’s robotic redirect craft be able to be refueled in space. The Goddard office Naasz works for is hoping to build a robotic refueling craft up to the task. Sen. Barbara Mikulski (D-Md), the Senate Appropriations Committee’s ranking member, has proposed $150 million for the office in 2016 to do just that as part of the conceptual Restore-L mission in which the Goddard craft would refuel a government satellite later this decade.
Adding hard requirements for planetary protection and robotic refueling could help ARM’s case in Congress, where the mission has never received an outpouring of support.
Appropriations bills drafted in June did not set aside funding for ARM in particular, although a report appended to the NASA budget the House passed June 3 contained that chamber’s warmest words to date about the mission: that “it has been useful to the extent that it has motivated NASA to develop new rocket propulsion technology to be used in interstellar travel and methods to deflect near earth objects that threaten the Earth.”
As for the target ARM asteroid, NASA is considering four, as of June 29. The agency will pick the final target in 2019, Gates said. Currently, NASA’s top choices are:
• 2008 EV5, which for more than a year has been the reference asteroid NASA has used for planning purposes as it hashes out timelines for the robotic redirect portion of ARM.
• Bennu, the target of NASA’s Osiris-Rex asteroid sampling mission launching in 2016.
• Itokawa, the oblong, potato-shaped asteroid the Japan Aerospace Exploration Agency collected a sample from in 2010 with its odds-defying Hayabusa probe.
• 1999 JU3, the target of the Hayabusa 2 mission expected to return Japan’s second asteroid sample cache to Earth in 2020.