[meteorite-list] NASA Considers Manned Asteroid Mission

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Thu, 15 May 2008 20:56:51 -0700 (MST)
Message-ID: <52869.71.226.60.25.1210910211.squirrel_at_timber.lpl.arizona.edu>

Hi Sterling and others:

Be careful how you set up your tent. If you assume similar densities (the
density of the asteroid is probably less), both gravity and escape
velocity go as 1/r (r=radius).

Therefore with a mean Earth radius of 6365 km (6,635,000 m) and the radius
of the asteroid of 20 m, the gravity of the asteroid is about:

20/6365000 or 1/320,000 of Earth

and the escape velocity would be about (11.2/320000 km/s)

0.035 m/s or 3.5 cm/s (think my math is correct; never quite sure at this
hour),

so look before you leap!

Larry

On Thu, May 15, 2008 6:05 pm, Sterling K. Webb wrote:
> A grand scientific mission!
> Curiously inconsistent news story, like most news
> stories. If the rock is a 40-meter diameter sphere, then its volume is
> about 33,500 cubic meters, but if its mass is 1.1 million metric tons,
> then its density is 32.8 times that of water, denser than any known
> element. (The mass appears to be "off" by about a factor of ten.) Maybe
> it's an asteroid from another universe? As for its worthiness as a target
> destination, a 40-meter diameter sphere has a total surface area of just
> over 5000 square meters, equal to a square 70.7 meters (or 232 feet) on a
> side. This is slightly more than one acre (which is 209 feet 4 inches
> square). There's about enough room to a) park the spacecraft,
> b) put up a big popup tent, c) have a barbeque and picnic table, and d)
> maybe, just maybe, a miniature golf course. A really small miniature golf
> course, but you know how astronauts love to play golf. Try not to leave any
> beercans behind.
>
>
> Sterling K. Webb
> --------------------------------------------------------------------------
> -
> ----- Original Message -----
> From: "Ron Baalke" <baalke at zagami.jpl.nasa.gov>
> To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
> Sent: Thursday, May 15, 2008 7:12 PM
> Subject: [meteorite-list] NASA Considers Manned Asteroid Mission
>
>
>
>
> http://www.guardian.co.uk/science/2008/may/07/starsgalaxiesandplanets.spa
> ceexploration?gusrc=rss&feed=science
>
> Closer encounter: Nasa plans landing on 40m-wide asteroid travelling
> at 28,000mph
>
> Ian Sample
> The Guardian
> May 7, 2008
>
>
> 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."
>
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Received on Thu 15 May 2008 11:56:51 PM PDT