[meteorite-list] NASA Considers Manned Asteroid Mission

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Fri, 16 May 2008 06:05:08 -0700 (MST)
Message-ID: <53267.71.226.60.25.1210943108.squirrel_at_timber.lpl.arizona.edu>

Hi Sterling:

Do not mean to rock your boat, but how do you fire the piton? "For every
action there is an equal and opposite reaction" (read that somewhere).
Firing the piton would send you off into space, even if you were in
"orbit" around the object.

Larry

On Fri, May 16, 2008 12:57 am, Sterling K. Webb wrote:
> Hi, Larry, List,
>
>
> My theory is that if you sleep on your back,
> the exhaust velocity of your snoring is great enough to keep you pinned to
> The Rock, safe
> and sound. But... if you thrash around in that loose micro-gee environment,
> you might end up floating face-down and then the reaction thrust of your
> breathing would keep you at the peak of the tent! At least, you couldn't
> snore yourself right off The Rock (no atmosphere).
>
> Somewhere (I wish I could remember), I saw a
> drawing of a post-and-cable network covering all of a very small world, a
> network to which space workers would attach their tethers with a clasp
> shaped like the greek letter omega that would allow them to move freely
> over the entire surface without any risk of "jumping off" or accidentally
> achieving escape velocity. But the materials would be heavy; the network
> would need to be constructed on arrival; there would have to be some
> compelling reason to bother. Is 2000 SG344 littered with gold nuggets?
> Diamonds as big as cabbages?
>
>
> I suspect astronauts would be tethered to the (soundly)
> anchored spacecraft by 125+ meters of light cable on a self-winding take-up
> reel. They could walk (or crawl or bounce) completely around the "world"
> as far as their own home base.
>
> A useful tool would be a piton gun with a cable reel-up
> to pull you down to the surface anywhere you fired it. The problem would be
> "sticking" to this tiny world at all!
> I am bulky enough that I never fear getting unstuck from
> this world but on 2000 SG344 (I calculate) I would weigh less than 1/3rd of
> a gram! (About as much as the active ingredient in an aspirin tablet.)
>
> You could wait for the gravity to pull you down. I tried
> to calculate how long it would take you to fall ten meters in this
> gee-field, but you're right -- it's too late for this much math. The
> gravitational acceleration is 0.000030625 meters per second per second! My
> advice? Take a book (or two) along to kill time while you "plummet" to the
> ground.
>
>
> Sterling K. Webb
> -------------------------------------------------------------------
> PS: Keep an eye out for a Little Prince...
> -------------------------------------------------------------------
> ----- Original Message -----
> From: <lebofsky at lpl.arizona.edu>
> To: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
> Cc: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
> Sent: Thursday, May 15, 2008 10:56 PM
> Subject: Re: [meteorite-list] NASA Considers Manned Asteroid Mission
>
>
>
> 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.s
>> pa 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 Fri 16 May 2008 09:05:08 AM PDT