Re: How would human dna be stored for 1000 years in an orbiting satellite?

Dear Brian,

Designing an orbital time capsule sounds like a reasonable thing to do. In fact there are groups already doing this -- see keo.org, for example. You would want to have it in a pretty high orbit, to minimize the drag exerted by the Earth's atmosphere and also to reduce the chances tha your capsule would get hit by manmade space junk. There's not all that much you can do about getting hit by micrometeorites, except to have some sort of shielding on the capsule.

Shielding will also be necessary if you want the DNA samples to come back in good condition. The radiation environment in space is much harsher than that on Earth (we are protected by the Earth's atmosphere and magnetosphere), and the DNA will be damaged if it isn't shielded. It could be that the amount of shielding required to protect the DNA for 1000 years makes the capsule too impractical to launch; it depends on how much damage you are willing to accept. It should be easy (and fun) to find out more about this with a Web search.

I don't know of any satellites that have been brought down to Earth by remote control -- unlike spaceships, satellites are not generally designed to withstand the heat and stress of re-entry. (This is a good thing in general, since it means that when satellites re-enter, they don't damage people or objects on the ground!) However, spy satellites drop film back down in canisters, so I don't see why your time capsule couldn't use a similar technique.

Pauline