[meteorite-list] NASA May Slam Captured Asteroid Into Moon (Eventually)

[Ron Baalke]

http://www.space.com/22993-nasa-slam-captured-asteroid-moon.html

NASA May Slam Captured Asteroid Into Moon (Eventually)
By Mike Wall
space.com
September 30, 2013

Decades from now, people on Earth may be gearing up for an unprecedented 
celestial spectacle - the intentional smashing of an asteroid into the 
moon.

NASA is currently planning out an ambitious mission to snag a near-Earth 
asteroid and park it in a stable orbit around the moon, where it could 
be visited repeatedly by astronauts for scientific and exploration purposes. 
But the asteroid-capture mission may not end when astronauts leave the 
space rock for the last time. Seeing it through could require disposing 
of the asteroid in a safe - and possibly very dramatic - manner, experts 
say.

"You can be comfortable that [the asteroid] will stay in this orbit for 
100 years or so," Paul Chodas, a scientist with the Near-Earth Object 
Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif., 
said earlier this month during a panel discussion at the American Institute 
of Aeronautics and Astronautics' Space 2013 conference in San Diego.

"But if that's not enough, I think that, once you're finished with it 
and you have no further need of it, send it in to impact the moon," Chodas 
added. "That makes sense to me."

A bold plan

NASA announced the asteroid-retrieval effort in April. The plan calls 
for a robotic spacecraft to rendezvous with a roughly 25-foot-wide (7.6 
meters), 500-ton space rock and drag it to a stable lunar orbit.

Alternatively, the probe could break a chunk off a larger asteroid; NASA 
is investigating both options. Either way, astronauts would then fly out 
to this transplanted rock using NASA's Orion capsule and Space Launch 
System mega-rocket (SLS), which are slated to fly crews together for the 
first time in 2021.

The mission represents one way to achieve a major goal laid out by President 
Barack Obama, who in 2010 directed the space agency to get astronauts 
to a near-Earth asteroid by 2025, then on to the vicinity of Mars by the 
mid-2030s.

Grabbing a space rock would also help develop asteroid-mining technology, 
reveal insights about the solar system's early days and give humanity 
critical experience working in deep space, NASA officials say.

"It provides a tremendous target to develop our capabilities and operation 
techniques for our crews in the future as we go beyond low-Earth orbit," 
NASA human exploration chief Bill Gerstenmaier said during the panel discussion 
at Space 2013.

Earlier this year, NASA asked the public and researchers in industry and 
academia to help them figure out how to pull off the asteroid-capture 
mission. The agency received more than 400 proposals in response, and 
it will discuss the top 100 or so during a workshop held Monday through 
Wednesday (Sept. 30 to Oct. 2) at the Lunar and Planetary Institute in 
Houston.

Multiple visits

The first manned visit to the captured asteroid could come in 2023 or 
so, Gerstenmaier said. The timeline will depend heavily on the ability 
of researchers to find and characterize prospective target asteroids. 
(Not just any rock will do - the chosen object must be the right size 
and have the proper orbit and spin rate.)

The asteroid's manmade lunar orbit should be stable for about a century, 
researchers say, so crews could continue flying out to the asteroid far 
into the future. Such visits may include both government-funded research 
and exploration flights as well as efforts undertaken by asteroid-mining 
firms or other commercial entities, NASA officials say.

"We think we have a lot of options," Steve Stich, deputy director of engineering 
at NASA's Johnson Space Center in Houston, said during the Space 2013 
panel. "We haven't really talked in detail about all those kinds of things 
that we can go do, but certainly we have enabled, by the way we have designed 
this mission, multiple visits to the asteroid."

Once those visits are done, NASA may decide to bring the asteroid down, 
slamming it intentionally into the lunar surface. The agency has never 
done this with a space rock before, but it does have considerable experience 
de-orbiting moon probes that have reached the end of their operational 
lives.

For example, the twin Grail spacecraft became part of the lunar landscape 
last December after wrapping up their mission to map the gravitational 
field of Earth's nearest neighbor.