An astronaut examines an asteroid pieced into orbit around the moon in this NASA illustration. Target date for the rendezvous: 2025.

If you pay attention to news about space exploration, you may have seen some skeptical stories about NASAs proposed Asteroid Redirect Mission. (And even if you dont follow such things, you might well have been dismayed by headlines announcing a less ambitious asteroid mission that is unlikely to get funded.) This is not another one of them.

I think the asteroid mission is a cool idea, and an important one. I think it will advance the cause of space exploration in several meaningful ways. And it is exactly the kind of medium-scale, focused mission that could revitalize the whole idea of sending humans on grand adventures beyond Earth orbitif only it can make its way past the naysayers, political opponents, and misguided scientific skeptics who threaten to derail it before it even gets started.

A little background first. The Asteroid Redirect Missioneveryone calls it ARM, because NASA loves to reduce everything to an acronymgrew out of a 2011 study by the Keck Institute for Space Science. The concept was both clever and expedient. NASA is developing a huge rocket, called the Space Launch System (yep: SLS), designed to carry humans on new deep-space voyages, but so far it has nowhere to go. It is a rocket without a destination.

In theory, SLS is supposed to take humans to Mars, but the government has provided no funding for the necessary technical infrastructure, much less for the actual cost of such a lengthy, dangerous, and complicated mission. The Obama administration suggested a human voyage to an asteroid as an intermediate step, but even that would be an expensive, multi-month voyageone that is, again, notably lacking any financial support. Where, then, to go?

The Asteroid Redirect Mission answers that question in a novel way. Instead of taking humans to an asteroid, it would do most of the work robotically (and at much lower cost) by bringing the asteroid most of the way to us. In the original plan, ARM would send a collector spacecraft to a small asteroid, no more than 5 meters [15 feet] wide, and tow it to a local orbit around the moon. Then the SLS rocket would ferry a crew to the asteroid, where they would analyze it, collect samples, and bring them back to Earth.

NASAs revised concept, announced earlier this week, still follows the same outline, but with one notable difference. Instead of grabbing and towing a tiny, solitary asteroid, the ARM spacecraft will now cozy up to a much larger object, pluck a large boulder off its surface, and bring that back to lunar orbit. The rest of the plan would unfold as before. The scientific return would probably be much the same as well. Many small asteroids are probably broken-off bits of larger ones, so a surface boulder on a larger asteroid might turn out to be pretty much the same type of object as the original target.

Looking like a vending-machine claw, the Asteroid Redirect Vehicle snatches a large rock off the surface of an asteroid. This part of the mission is scheduled for 2022. (Credit: NASA)

There are a bunch of reasons to like the Asteroid Redirect Mission:

It will advance our understanding of the solar system. Asteroids are time capsules that record a highly revealing early stage in the formation of the planets. Unmanned space probes have examined a number of asteroids up close, but the only sample-return mission (Japans Hayabusa) largely failed to deliver. Japan is trying again with Hayabusa 2, and NASA is preparing its own asteroid sampler, called OSIRIS-REx. But ARM would collect a sample on a vastly larger scale than has ever been attempted before. Just getting to know the target asteroid (potentially a carbon-rich, 400-meter-wide object called 2008 EV5) will be a great learning experience. And if the boulder proves geologically and chemically interesting, we can return to it again and again.

Here is the original post:

In Praise of NASA's Ambitious Asteroid Grab