[stcredzero]

Summary: If you allow making a man-shaped space capsule with retro rockets, heat shield, and parachute, then it's possible. If you call that cheating, then it's not.

Incidentally, the "unobtanium" comment is quite clueless. People have proposed making ablative heat shields out of wood, for heaven's sake. If you allow a "suit" to get bulky enough, an ablative heat shield in one is well within the realm of existing materials science.

[andyjohnson0]

The ablative heat shield used by the Spirit and Opportunity rovers was a blend of cork wood and silica spheres [1].

Also, the reentry vehicles for the Chinese FSW reconnaissance satellites used heat shields made from Oak.

[1] http://marsrover.nasa.gov/mission/spacecraft_edl_aeroshell.h...

[sehugg]

I think the real problem is stability, i.e. how do you keep aerodynamic forces from spinning the (unguided) capsule too fast during reentry? If you look at video of Baumgarter's free-fall he is spinning very fast -- a couple RPM I'd estimate -- when he begins his deceleration after the near-vacuum free fall.

Orbital reentry would last for minutes and at much higher velocities. The centrifugal forces generated by unchecked rotation could cause blackout or even death. You'd also need to figure out what happens if your heat shield is not heated evenly due to rotation.

Guided reentry is a solution, but then we're talking RCS thrusters, fuel tanks, guidance equipment -- maybe something you can strap onto a spacesuit, but approaching a spaceship. And then you need one for each astronaut, increasing weight and complexity.

[icebraining]

Incidentally, the "unobtanium" comment is quite clueless. (...) If you allow a "suit" to get bulky enough

I think that's what the comment is saying. He said it would be unobtanium or a lot, by which I assumed he meant the bulk.