NASA Chooses Plucky Option B for Asteroid Redirect Mission
NASA Associate Administrator Robert Lightfoot announced today that NASA has selected "Option B" for implementing its Asteroid Redirect Mission (ARM). Option B involves plucking a boulder from the surface of a large asteroid and moving just the boulder to lunar orbit. The alternative, Option A, was to move an entire small asteroid.
The ARM project involves sending a robotic probe to an asteroid and moving all or part of it to lunar orbit where it can be visited by astronauts on an Orion spacecraft. Today's announcement was about the robotic portion of the mission and follows completion yesterday of a Mission Concept Review (MCR). ARM now transitions into "Phase A" planning where NASA will refine the concept. Lightfoot said the next major step will take place in July when officials meet to discuss how to acquire the solar electric propulsion (SEP) system -- in-house or through contractors -- needed for the robotic spacecraft.
Under the preliminary plan, NASA will choose which asteroid to visit in 2019, send the robotic probe in 2020, reach the asteroid and go into a halo orbit around it for 215-400 days to assess which boulders look most promising and then pluck one from the surface and move it to lunar orbit using SEP. In 2025, an astronaut crew aboard an Orion spacecraft will collect a sample and return it to Earth. Three asteroids are under serious consideration right now, but NASA is continuing to search for candidates and can wait until 2019 to make a final selection.
Today, NASA said asteroid 2008 EV-5 looks the most promising. It is a carbonaceous chondrite, the type of asteroid of most interest to scientists. No spacecraft has visited that asteroid yet, but its characteristics are well known. The other two asteroids either have been or will be visited by spacecraft before the ARM mission launches: Itokawa, visited by Japan's Hayabusa, and Bennu, the target for NASA's OSIRIS-REx scheduled for launch in 2016.
NASA repeatedly says that ARM will cost $1.25 billion, but that is only for the robotic portion of the mission, does not include launch costs, and it is not entirely clear what costs are included. NASA describes ARM funding in two categories: "leveraged" and "direct" funding. Leveraged funding is money that NASA asserts it would spend even if there was no ARM mission, while direct funding is unique to ARM. Of the $220 million NASA is requesting for ARM in FY2016, only $43 million is identified as direct funding; the rest is leveraged, including the sum for SEP. Lightfoot said he could not break down the $1.25 billion in those terms, but expects SEP to cost $300 million of the $1.25 billion so he seems to include that in the mission's cost estimate even though NASA counts it as leveraged funding. The situation should become more clear in the FY2017 budget submission next year.
Lightfoot was poised to reveal the Option A versus B choice in December, but when it came time for the press conference, said only that more time was needed. NASA has not publicly stated what came up at the last minute. Rumors are that Option B was the choice then, too. The December press conference was announced with 6 hours notice; today's notice was only 2 hours and the briefing was exactly at the same time as Dava Newman's nomination to be NASA Deputy Administrator was being considered by the Senate Commerce, Science, and Transportation Committee (it was approved by the committee).
Lightfoot said today that Option B has several factors in its favor: multiple targets to choose from because whatever asteroid is selected is expected to have many boulders, reducing mission risk; the spacecraft will orbit the asteroid for several months, allowing a demonstration of the gravitational effect a spacecraft can have on a large asteroid, which is relevant to planetary defense objectives (the ability to move an asteroid that threatens Earth); even though it will cost $100 million more than Option A, the technologies are more useful ("extensible") for human missions to Mars, NASA's long term goal; and there was more interest in Option B from domestic and international, traditional and non-traditional, entities responding to a NASA Request for Information (RFI) about ARM. The spacecraft bus in particular, he said, has "tremendous applicability" to various industries from communications satellites to space tugs.
ARM remains a very controversial project. It evolved from President Obama's April 2010 directive to NASA to send astronauts to an asteroid as the next step in U.S. human spaceflight instead of sending people back to the lunar surface as President George W. Bush planned. In 2013, the Obama Administration decided instead to bring an asteroid to the astronauts, but many question the value of such a mission in its own right or as a step towards eventual human missions to Mars.
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