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   Undertoad  Thursday Dec 12 01:05 PM

12/12/2002: Sunset on Io

Day two of Io. The notion that someday we might see the surface of Io set me to finding all of the photo sites NASA has on it, and seeing what we do know. This seems to be the best we have.

The sun is "setting" here from the left and so scientists could take a look at the ridges in the mountains there, and somehow determine that those mountains are COLLAPSING.

Also, there are no craters on Io because it's so volcanic. It's rebuilding its surface all the time.

The fact that it's black and white disguises the color, which almost made me not post it, feeling like it's not representative, feeling like I don't understand it well enough. Other photos of sections of Io are bright orange or yellow.

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Torrere  Thursday Dec 12 08:06 PM

Whoa. I wonder how they determined that the mountains are collapsing.

Griff  Thursday Dec 12 08:20 PM

As I understand it, Sir Edmund Hilary parked his Subaru Outback next to one and while he scaled the mountain the science guys scaled the mountain.

Degrees  Friday Dec 13 08:34 AM

Black and white is probably OK

I mean, these bodies are *so* far away from the sun, the actual quantity of photons landing on their surface has got to be pretty small. Although the color might be orange, the brightness level has got to be near black, if you or I got to travel into orbit around the thing and looked out the window of (whatever) spaceship.

I wonder what the exposure times are on those cameras?

Jacque Strapp  Friday Dec 13 09:45 AM

I think they get plenty of light

I don't think you'd have any problem seeing Io from a nearby spaceship, since if you have a decent telescope, you can look at Jupiter and its moons and see them fine from right here on the surface of the earth.

And  Friday Dec 13 12:31 PM

I'm no astronomer, but I'll wager they get the camera's iris as open as possible, and then do digital enhancements (hence the light fuzziness in blacker portions of the picture). Since spacecraft sent out there are usually in a lot of motion, exposure times couldn't be that long. However, there is the possibility of moving into geostationary orbits around bodies, but I imagine that would require more adjustments and efforts than they would be willing to make if they wanted to fly by several celestial objects. At best, it's probably that if they pass by a moon or whatnot, they do some trajectory-work and as the craft passes by, it temporarily matches the orbit and revolution of the body it photographs, allowing longer exposure times.

...But I'm just guessing.

kbarger  Friday Dec 13 05:17 PM

Re: Black and white is probably OK

Originally posted by Degrees

I wonder what the exposure times are on those cameras?
I'm not sure, but I think (it's been a long time since I read up on this stuff) that any "color" pictures we see from spacecraft are generally composites of three exposures made using red, green, and blue filters.

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