[meteorite-list] Inside NASA's Plan to Catch an Asteroid

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 10 Apr 2013 16:12:01 -0700 (PDT)
Message-ID: <201304102312.r3ANC1DN008548_at_zagami.jpl.nasa.gov>

http://www.space.com/20612-nasa-asteroid-capture-mission-explained.html

Inside NASA's Plan to Catch an Asteroid (Bruce Willis Not Required)
by Mike Wall
space.com
10 April 2013

President Barack Obama's 2014 federal budget request, which was released
Wednesday (April 10), gives NASA $105 million to jump-start a program that
would snag an asteroid and park it near the moon. Astronauts would then
visit the space rock using the agency's Space Launch System rocket and
Orion capsule, perhaps as early as 2021.

"This mission represents an unprecedented technological feat that will lead
to new scientific discoveries and technological capabilities and help protect
our home planet," NASA chief Charles Bolden said in a statement.

The space agency is still working out how exactly to pull off the mission,
which officials are calling the "Asteroid Initiative" or "Asteroid Retrieval
and Utilization Mission" at the moment. But a few things are already clear.

For starters, the probe that will chase down and capture the 25-foot (8 meters)
or so asteroid will be unmanned. And it will be powered by solar electric
propulsion, which generates thrust by accelerating charged particles called ions.

Ion thrusters have been used on other NASA probes, including Dawn, which
recently spent a year orbiting the huge asteroid Vesta before departing for the
dwarf planet Ceres. But engineers will need to develop an advanced version for the
Asteroid Initiative craft, since it will be towing a 500-ton space rock
over millions of miles.

"This mission accelerates our technology development activities in high-powered
solar electric propulsion," Michael Gazarik, NASA Associate Administrator for
Space Technology, said in a statement.

Still, it may take several years for the probe to meet up with the asteroid.
The spacecraft will then envelop the space rock with a bag of sorts, as
a new video animation of NASA's Asteroid Initiative mission depicts, and
de-spin the rock, likely using thrusters.

The asteroid will then be towed to a "stable orbit in the Earth-moon system where
astronauts can visit and explore it," NASA officials wrote in a mission description
Wednesday.

These visits will be made possible by Orion and the Space Launch System, which
are slated to begin flying crews together by 2021. The NASA animation
shows astronauts aboard Orion meeting up with the space rock, which the
retrieval probe is still holding onto.

In the video, the astronauts spacewalk their way over to the asteroid, accessing it
by unwrapping a small section of the bag. They grab some pieces using a hammer and
other tools, then come home with the samples in an ocean splashdown.

The overall asteroid-retrieval idea is similar to one proposed by researchers based
at Caltech's Keck Institute for Space Studies in Pasadena. In a feasibility study
published last year, the Keck team estimated the total cost of robotic capture and
return at $2.6 billion.

NASA hasn't released its own cost estimates yet, but agency officials think they can
get it done for less than that.

"The Keck study didn't take into account all the activities we already have
going on in our base, so we wouldn't need $2.6 billion in new money,"
NASA chief financial officer Elizabeth Robinson said during a press conference
Wednesday.

The Keck team also focused on grabbing a carbonaceous chondrite,
she added. These asteroids are compositionally diverse, full of complex
organic molecules, metals and volatile materials like water.

But carbonaceous chondrites also tend to be found farther away than other types of
near-Earth asteroids, Robinson said, making their retrieval more time-consuming and
expensive. At this point, NASA isn't so particular about the space rock
it hopes to target.

"For those two reasons, we think that the price is likely to come in - of
new money, new investment - at below that [$2.6 billion]," Robinson said.
Received on Wed 10 Apr 2013 07:12:01 PM PDT