It’s all well and good to debate how we might deflect an asteroid, but there is no substitute for actual in-space experience. Fortunately, we are starting to get some. On July 3, 2005, after a 267 million mile journey, NASA’s Deep Impact spacecraft launched an 820-pound copper projectile that delivered the equivalent of 4.7 tons of TNT while striking comet 9P/Tempel. NASA’s Osiris-Rex mission, scheduled to launch in 2016, will approach the near-Earth asteroid Bennu, in 2019, land on it, and return home with a sample. As a follow on, NASA is considering adding to its 2016 InSight Mars mission an experiment to slam an impactor dubbed ISIS into Bennu following the Osiris-Rex encounter, creating a crater tens of meters in diameter. The price tag of adding the experiment would be $100 million, a tough sell under the current federal budget environment. But the potential value of the mission is great, as among all the known asteroids, Bennu is viewed as having one of the highest probabilities of impacting with Earth in the next few centuries. Finally, NASA is also discussing with the European Space Agency potential collaboration on the Asteroid Impact and Deflection Assessment (AIDA) mission concept, with the idea of studying the binary asteroid system Didymos with two spacecraft and determining if a small interceptor called DART (Double Asteroid Redirection Test) can deflect the smaller member of the binary near-Earth asteroid  Didymos in October 2022, and measure the deflection to within 10 percent. And then there is NASA’s Asteroid Redirect proposal.
NASA’s Asteroid Redirect Proposal
Related to all this activity is the administration’s proposed mission to launch a new robotic spacecraft using solar electric propulsion in 2017 to capture a 7- to 10-meter diameter asteroid weighing up to 500 tons, haul it to a stable location near the moon, and send astronauts on the Orion Multi-Purpose Crew Vehicle to it in 2021 to investigate it and return samples to Earth. No candidate asteroid has been identified for the proposed mission, labeled Asteroid Redirect. NASA has requested $105 million in its FY 2014 budget to begin work on Asteroid Redirect. The funding request includes doubling the current $20 million allocated to locating near-Earth objects to $40 million, in hopes a candidate asteroid can be found, $45 million for accelerated work on the retrieval craft’s solar-electric thrusters, and $40 million to start studying the robotic asteroid retrieval craft. In addition, through its Grand Challenge issued June 18, NASA is soliciting ideas for asteroid detection and deflection from other government agencies, industry, academia and the public.
Asteroid Redirect, says Thomas Jones, “is really more about human exploration than planetary defense, but there will be some real concrete planetary defense results… You’ll certainly get an idea of how a small asteroid is put together, and that will lead to smarter questions being asked about potential impactors down the road.” Jones notes that a small sized boulder, the kind of which NASA envisions going to with an asteroid capture and retrieval mission, “would break up and never make it to the surface of the Earth. But you’d get the ability for these astronauts to probe the interior to find out how it’s put together. That kind of civil engineering information is bound to be useful in transferring to other asteroid studies. And the same kinds of experiments that are used on this small captured asteroid would then be applied to larger bodies in solar orbit which are more threatening to the Earth. It would be a great first step in helping to solve the planetary defense problem, and I think most important, the fact that you’ve moved a small asteroid into lunar orbit over the course of several years, is by definition an asteroid deflection mission, the same kind of thing you’d have to do to a larger asteroid someday. So it could lead to a great test of techniques on a small scale that you’d expand with your experience to larger scales.”
Despite its potential utility, not only for planetary protection purposes, but for advancing human exploration experience, Asteroid Redirect has been greeted on Capitol Hill with a resounding thud. The draft NASA Authorization Bill being considered in the House Science, Space and Technology Committee forbids any funding for the mission, with committee leaders claiming it would divert funds from other human exploration goals including the Moon and Mars. The Senate has yet to consider any language for the NASA Authorization Bill. Among the objections to Asteroid Redirect raised by House Science, Space and Technology Committee Chairman Lamar Smith (R-Texas) is that it would not attempt to catch one big enough to threaten humanity. But as Jones noted above, first you have to take small steps.
[Asteroid deflection] investments, Rusty Schweickart told Universe Today, “would be a ripple in NASA’s budget…1.5-2 percent at the most of NASA’s annual budget for 10 years, then dropping back to less than 0.5 percent. It does not displace anything else that NASA is doing. It would be a small budgetary issue, but the importance of it is huge. This saves lives, protects the global environment, and saves future generations.”
Responding to this potential setback, NASA Deputy Administrator Lori Garver told participants at the agency’s June 18 Asteroid Initiative Industry and Partner Day, “We are proceeding the way we have for so many missions, being able to initially outline a concept, but make it better. We don’t in this case just need to explain it better. We need to align it better…with those things that we know Congress is driving us to do … and that is detect those threatening asteroid populations. And if we can get a concept that aligns that better, that might be a way to proceed.” During this event, the agency released a request for information, due July 18, seeking ideas for the Asteroid Redirect Mission, and an alternative mission involving a robotic craft visiting a larger asteroid and separating a boulder-sized chunk for return to the Earth-Moon system.
Mitigation and the Big Picture
The experts I spoke to about potentially hazardous near-Earth objects emphasize that our first priority must be detection. As Lu says, “Deflection is important, but only if detection happens. In terms of where the effort should be, it should be on detection. You can’t deflect an asteroid you can’t find.” That said, a standard decision tree analysis might guide decision makers to the conclusion that we also need to continue to make prudent investments in developing and demonstrating non-nuclear asteroid mitigation techniques. Such investments, Rusty Schweickart told Universe Today, “would be a ripple in NASA’s budget…1.5-2 percent at the most of NASA’s annual budget for 10 years, then dropping back to less than 0.5 percent. It does not displace anything else that NASA is doing. It would be a small budgetary issue, but the importance of it is huge. This saves lives, protects the global environment, and saves future generations.”