NASA has released an Asteroid Initiative Request for Information on the issue of asteroid retrieval. It’s an interesting document both in its audience — the agency is making a point about soliciting comments not only from academics, scientists and engineers but the general public — but also because of the issues it explores. Being sought are ideas on how best to capture an asteroid, land an astronaut on one, and change its orbit, not necessarily in that order. The Los Angeles Times quotes NASA associate director Robert Lightfoot on the public component of NASA’s initiative:
“Too often, by the time we present a mission to the public, it has already been baked, and there’s not much we can change. This is your chance to present your ideas to us before the mission is baked.”
If you’re interested in contributing, move quickly, for the deadline for responses is July 18, with a workshop to follow in September.
The creation of a Solar System-wide infrastructure will necessarily precede any interstellar probes, if only because the methods we are studying to make such a probe happen all involve large construction projects in interplanetary space and resource retrieval from places as far away as the gas giants. But making the early infrastructure viable could well be the result of asteroid activities through companies like Planetary Resources and Deep Space Industries, or whoever manages to sustain an economic model for exploiting these interesting objects.
Asteroids are compelling targets for mining everything from gold, iron, nickel and platinum to water that can be extracted to support human settlements. But the case for developing our asteroid capabilities is also wrapped up in planetary defense, and it’s interesting to see this section of the NASA RFI:
Asteroid Deflection Demonstration: NASA is interested in concepts for deflecting the trajectory of an asteroid using the robotic Asteroid Redirection Vehicle (ARV) that would be effective against objects large enough to do significant damage at the Earth’s surface should they impact (i.e. > 100 meters in size). These demonstrations could include but [are] not limited to: a. Use of the ARV to demonstrate a slow push trajectory modification on a larger asteroid. b. Use of the ARV to demonstrate a “gravity tractor” technique on an asteroid. c. Use of ARV instrumentation for investigations useful to planetary defense (e.g. sub-surface penetrating imaging) d. Use of deployables from the ARV to demonstrate techniques useful to planetary defense (e.g. deployment of a stand alone transponder for continued tracking of the asteroid over a longer period of time).
10,000 NEOs and Counting
All of this is wrapped up inside the larger agency effort to capture and de-spin an asteroid and redirect it into translunar space, as described in the document. Just after the release of the NASA Request for Information on June 18, we learned that the 10,000th near-Earth object, asteroid 2013 MZ5, was detected by the Pan-STARRS-1 telescope in Hawaii. Near-Earth objects (NEOs) can approach the Earth’s orbital distance within 45 million kilometers. Known NEOs are as large as 40 kilometers (1036 Ganymed) or as small as a meter in diameter. Asteroid 2013 MZ5 turns out to be about 300 meters across and is not in an orbit that is considered hazardous.
Image: Asteroid 2013 MZ5 as seen by the University of Hawaii’s PanSTARR-1 telescope. In this animated gif, the asteroid moves relative to a fixed background of stars. Asteroid 2013 MZ5 is in the right of the first image, towards the top, moving diagonally left/down. Credit: PS-1/UH.
I’ve been reading Don Yeomans’ book Near-Earth Objects: Finding Them Before They Find Us (Princeton University Press, 2012), an excellent overview of the field that I’ll be reviewing here in coming weeks. In this JPL news release Yeomans, manager of NASA’s Near-Earth Object Program Office at JPL, comments on the overall effort to track down NEOs:
“The first near-Earth object was discovered in 1898. Over the next hundred years, only about 500 had been found. But then, with the advent of NASA’s NEO Observations program in 1998, we’ve been racking them up ever since. And with new, more capable systems coming on line, we are learning even more about where the NEOs are currently in our solar system, and where they will be in the future.”
A glimpse of that future is provided by Lindley Johnson, who is part of NASA’s Near-Earth Object Observations Program. Johnson notes the significance of finding the 10,000th NEO but adds “…there are at least 10 times that many more to be found before we can be assured we will have found any and all that could impact and do significant harm to the citizens of Earth.” So we keep looking. NASA expects there are about 15,000 NEOs that are 140 meters in size and more than a million that reach 30 meters. The latter is a figure the agency cites as being the minimum size needed to cause ‘significant devastation’ in populated areas.
The news release has this to say about the NEOs we’ve already discovered:
Of the 10,000 discoveries, roughly 10 percent are larger than six-tenths of a mile (one kilometer) in size – roughly the size that could produce global consequences should one impact the Earth. However, the NASA NEOO program has found that none of these larger NEOs currently pose an impact threat and probably only a few dozen more of these large NEOs remain undiscovered.
The Near-Earth Object Observations Program is indeed, as Yeomans says, ‘racking them up.’ Working through the Catalina Sky Survey, the University of Hawaii’s Pan-STARRS survey and MIT’s LINEAR survey, NEOs are being discovered at a rate of about 1,000 per year. All observations flow to the Minor Planet Center in Cambridge MA in an effort that is clearly making progress on finding and cataloging objects. We now need to emphasize the effort to study the kind of deflection and trajectory-altering techniques NASA describes in the new RFI.