[meteorite-list] Visit to a Small Planet

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Fri, 09 May 2008 11:01:35 -0400
Message-ID: <8op824tqe0on6qm9gim3okl1a9s2srli4p_at_4ax.com>

http://www.guardian.co.uk/science/2008/may/07/starsgalaxiesandplanets.spaceexploration

Closer encounter: Nasa plans landing on 40m-wide asteroid travelling at
28,000mph

It was once considered the most dangerous object in the universe, heading for
Earth with the explosive power of 84 Hiroshimas. Now an asteroid called
2000SG344, a lump of rock barely the size of a large yacht, is in the spotlight
again, this time as a contender for the next giant leap for mankind.

Nasa engineers have identified the 1.1m tonne asteroid, which in 2000 was given
a significant chance of slamming into Earth, as a potential landing site for
astronauts, ahead of the Bush administration's plans to venture deeper into the
solar system with a crewed voyage to Mars.

The mission - the first to what officials call a Near Earth Object (NEO) - is
being floated within the US space agency as a crucial stepping stone to future
space exploration.

A report seen by the Guardian notes that by sending astronauts on a three-month
journey to the hurtling asteroid, scientists believe they would learn more about
the psychological effects of long-term missions and the risks of working in deep
space, and it would allow astronauts to test kits to convert subsurface ice into
drinking water, breathable oxygen and even hydrogen to top up rocket fuel. All
of which would be invaluable before embarking on a two-year expedition to Mars.

Under the Bush administration, Nasa has been charged with sending astronauts
back to the moon, beginning in 2020 and culminating in a permanent lunar
outpost, itself a jumping off point for more distant Mars missions. With the
agency's ageing fleet of space shuttles due to be retired soon after 2010, the
agency has begun work on a replacement called Orion and a series of Ares rockets
that will blast them into orbit.

In a study due to be published next month, engineers at Nasa's Johnson Space
Centre in Houston and Ames Research Centre in California flesh out plans to use
Orion for a three to six month round-trip to the asteroid, with astronauts
spending a week or two on the rock's surface.

As well as giving space officials a taste of more complex missions, samples
taken from the rock could help scientists understand more about the birth of the
solar system and how best to defend against asteroids that veer into Earth's
path.

"An asteroid will one day be on a collision course with Earth. Doesn't it make
sense, after going to the moon, to start learning more about them? Our study
shows it makes perfect sense to do this soon after going back to the moon," said
Rob Landis, an engineer at Johnson Space Centre and co-author of the report,
which is due to be published in the journal Acta Astronautica.

More precise measurements of the orbit of 2000SG344 have allayed fears that it
could hit Earth sometime around the end of September 2030, but the asteroid is
still expected to come close in astronomical terms.

The report lays out plans for a crew of two to rendezvous with a speeding
asteroid that is due to pass close by Earth. After a seven-week outward journey,
the Orion capsule would swing around and close in on the rock.

Because gravity is close to zero on asteroids, the capsule would need to attach
itself, possibly by firing anchors into the surface. For the same reason,
astronauts would not be able to walk around on the surface as they did on the
moon. "On some of these asteroids, you could jump up and go into orbit, or maybe
even leave for good," said Landis.

A round trip to an asteroid could be done with less fuel than a moon mission,
but is technically very challenging. The asteroid is only 40 metres across and
spins as it hurtles through space at 28,000mph.

Landis thinks that a trip to an asteroid could capture imaginations even more
than a return to our nearest celestial neighbour. "When we head back to the
moon, I think we'll see many of the same scenes we saw in the 60s and 70s Apollo
programme. We've been to the moon, we got that T-shirt back in 1969. But
whenever we've sent robotic probes to look at asteroids, we've always been
surprised at what we've seen," he said.

Because asteroids were forged in the earliest days of the solar system,
analysing samples from them could shed light on the conditions that prevailed
when the Earth was formed.

"Near Earth objects are a potential collision hazard to Earth and it may one day
be necessary to deflect an asteroid from a collision course with Earth," said
Ian Crawford, a planetary scientist at Birkbeck College, London. "Having the
capability in your back pocket to deflect an asteroid might be a good insurance
policy for the future, and for that, you want to know what they are made of, how
to rendezvous with them, and whether you risk getting hit by debris if you fire
something at it."
Received on Fri 09 May 2008 11:01:35 AM PDT