[X] My Assistant

[Guest_BruceMoomaw_*]

Has anyone noticed what an attractive living place Ceres starts to look like? Brimming over with easily accessible water and organic compounds; nice low gravity, making landings and takeoffs easier; far enough from the Sun that the intensity of solar radiation outbursts is considerably weakened (and water ice makes a good shield against that in any case)... maybe it's time to consider buying real estate there.

[David]

Brimming over with easily accessible water and organic compounds; nice low gravity, making landings and takeoffs easier; far enough from the Sun that the intensity of solar radiation outbursts is considerably weakened

I'm sold! Where do I pick up my tickets??!

[dvandorn]

I've been saying for a while that the asteroids are the logical next place for humans to visit. They're pieces of the ancient accretion phase of the solar system and hence scientifically interesting, and they also offer literally tons of resources that make them far more exploitable than smelly, rusty, salty old Mars down there at the bottom of that gravity well.

Does anyone have the stat for the surface gravity of Ceres? If it's enough that you could firmly root heavy machinery without extreme measures, I think we may have a winner there...

-the other Doug

[alan]

wikipedia lists it as 0.27 m/s^2

[David]

Divide Earth weights by 36 and you'll have approximately the correct number. An M-1 tank (by way of example) would weigh 1750 kg (about 4000 pounds) on Ceres. So no, you couldn't imitate Superman and lift a tank one-handed... but maybe a gang of Cereans drunk on Vestan ale could tip one over after a night of carousing.

[SigurRosFan]

Thanks Bruce!

Thus, the ice crust is roughly 50 kilometers thick.

[helvick]

Divide Earth weights by 36 and you'll have approximately the correct number.  An M-1 tank (by way of example) would weigh 1750 kg (about 4000 pounds) on Ceres.  So no, you couldn't imitate Superman and lift a tank one-handed... but maybe a gang of Cereans drunk on Vestan ale could tip one over after a night of carousing. 

Er - I feel I'm being awfully picky but kg != weight. Pounds are a measure of weight (ie a force) so yes it would be about 4000 pounds on Ceres but its mass would still be ~60,000 kg.

[Ames]

Er - I feel I'm being awfully picky but kg != weight. Pounds are a measure of weight (ie a force) so yes it would be about 4000 pounds on Ceres but its mass would still be ~60,000 kg.

Pedantic...

~600,000N - Newtons if we are talking mass

[Guest_BruceMoomaw_*]

The full "Nature" paper is now available at http://oposite.stsci.edu/pubinfo/pr/2005/27/pdf.pdf . (That double "pdf" at the end is no mistake.)

It turns out I made a dumb mistake by assuming that the "25% ice" figure was a reference to Ceres' volume, rather than its mass. Since ice is much lower density than rock, if that figure is for ice then the water-ice mantle on Ceres would have a bigger volume and thus be thicker than I had calculated. Sure enough:

"Assuming the densest core materials and the nominal mean density of 2,077 kgm23, ice mantles are 110–124km thick and constitute 24–26% of the body mass. The lighter core material requires a mantle thickness of 66 km and a 16% ice mass."

[Marz]

Thanks for the link and info, Bruce!

From reading, it almost sounds like Ceres is in its own class of 'roid, since it's the only one truly "relaxed". It's interesting that they expect the denser materials to have sunk to the core, and yet Ceres still maintains a spectral class of "C". Is there perhaps a layer of dusty "regolith" that is leftover from ice-sublimation that maybe lends it this spectral class, despite the fact that it is likely a "differentiated CM-chondrite"?

I had never even considered 'roids as the first stepping stone for a permanent human science base, but Ceres might make excellent sense. A 9 hour rotation period is a little funky, but maybe Ceresians would enjoy a nice after-lunch siesta every 18h "day" (if it's acceptable to call 2-full rotations a "day").

Perhaps most exciting in terms of human exploration potential is from the Nature letter: "Even the minimum mantle thickness is greater than the likely
excavation depths of craters a few hundred km across." So even if the crust is a nasty jumble of pebbles n' dust, a large crater would provide easy access to the water-rich mantle. A nice RTG rover could maybe scratch the bottom of the crater rim and begin melting a hole through the dirty-ice and begin excavating a nice cavern. Spray the walls with ice to make it air-tight, insulate with foam, pressurize and presto! Instant-igloo!

Before I rush out in my covered wagon to stake my claim in the land-rush:

1. is solar-power economically viable from Ceres? How much panels would be needed to crank out the equivelent of the ISS? (ISS = 110kW using 2,500 square metres of solar-panels).

2. is the low gravity a problem for long-term residents? would a gravity-centerfuge be required to keep folks healthy enough for return to earth?

3. is nitrogen available anywhere near the belt?

4. what would be the raison d'etree for a Ceres Base? Watching 'roids? Fuel-depot for outer-solar-system missions?

5. how hard would it be to move nearby small 'roids into orbit for material's processing?

Exciting stuff to dream about!

[tedstryk]

Er - I feel I'm being awfully picky but kg != weight. Pounds are a measure of weight (ie a force) so yes it would be about 4000 pounds on Ceres but its mass would still be ~60,000 kg.

Not only are pounds and kilograms measures for the same thing (the newton correction is right), but the original point is using the right measure for what it is supposed to show - how hard something would be to support on Ceres under its gravity. So there is nothing to be picky about here....

[ljk4-1]

I had never even considered 'roids as the first stepping stone for a permanent human science base, but Ceres might make excellent sense.  A 9 hour rotation period is a little funky, but maybe Ceresians would enjoy a nice after-lunch siesta every 18h "day" (if it's acceptable to call 2-full rotations a "day"). 

Future generations who spend their whole lives on worlds like Ceres will probably have no issues with a 9-hour day whatsoever, having never been on Earth. Of course the colonies may be set up inside these rocks, so daylight can be an entirely artificial and controlled affair.

And we are assuming that future space colonists will be humans and not AI machines, who likely would have no concerns about day-night awake-sleep cycles.

[helvick]

1. is solar-power economically viable from Ceres?  How much panels would be needed to crank out the equivelent of the ISS?  (ISS = 110kW using 2,500 square metres of solar-panels).

Ceres is at ~ 2.77 AU on average, solar panels in orbit around Ceres would produce about 18% of the power of an equivalent array in Earth orbit. On the surface that would be reduced by a further 50 to 75% depending on whether they were Sun tracking or not.

The numbers you quote for ISS are interesting - the Solar constant in Earth orbit (the amount of radiation incident per m^2) is 1.37 kW. Most Solar panels in orbit are >16% efficient on average (the MER type are very good at ~26%) which means that the ISS panels are only generating 40% of their capacity even after accounting for a 12 hour night cycle. I assume this is due to layout and mechanical difficulties keeping them perfectly normal to the sun.

[ljk4-1]

Asteroid or miniplanet? Cornell astronomer finds Ceres appears to have shape and interior similar to terrestrial planets

http://www.news.cornell.edu/stories/Sept05/Ceres.to.html

Sept. 15, 2005

By Thomas Oberst
cunews@cornell.edu


ITHACA, N.Y. -- When is a space rock more than just a space rock?

Ceres 1 was already holding the title of the solar system's largest asteroid. Now new observations show the space rock may be more worthy of the appellation "miniplanet."

On Sept. 7 NASA released photographs of Ceres that show the rock is a smooth ellipsoid, or oblong sphere, with an average diameter of approximately 590 miles -- about the size of Texas. A scientific paper on the findings, by a group led by Peter C. Thomas, senior research associate at Cornell University's Center for Radiophysics and Space Research, appeared in the Sept. 9 issue of the journal Nature.

Co-author Joel Parker, an astronomer at the Southwest Research Institute in Boulder, Colo., used the Hubble Space Telescope's Advanced Camera for Surveys to snap 267 images of Ceres on Dec. 28, 2003, during a nine-hour period -- one Ceres "day."

[tfisher]

I had never even considered 'roids as the first stepping stone for a permanent human science base, but Ceres might make excellent sense.  A 9 hour rotation period is a little funky, but maybe Ceresians would enjoy a nice after-lunch siesta every 18h "day" (if it's acceptable to call 2-full rotations a "day"). 

I would think it would be more natural to push 3 hours longer to a 27 hour day rather than compress by 6 hours to an 18 hour day. So maybe it would be like:

[ dark ][light ][ dark ][light ][ dark ][ light]
---- )( morning )(nap)( - evening - )( sleeptime

This gives you around 9 hours of sleeptime each 'night' with another 2-3 hour midday
nap. That leaves 15-16 hours of uptime split into a morning and evening period.

There have been studies putting people into such an environment: here, for instance, is a report from a 28-hour day study. The circadian rhythm doesn't stretch so far -- it ends up cycling around 24 hours 11 minutes -- but apparantly people function without major problems on such a cycle.