[meteorite-list] NASA Considers Manned Asteroid Mission

[lebofsky at 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."

>

> ______________________________________________

> http://www.meteoritecentral.com

> Meteorite-list mailing list

> Meteorite-list at meteoritecentral.com

> http://six.pairlist.net/mailman/listinfo/meteorite-list

>

>

> ______________________________________________

> http://www.meteoritecentral.com

> Meteorite-list mailing list

> Meteorite-list at meteoritecentral.com

> http://six.pairlist.net/mailman/listinfo/meteorite-list

>

>