3 ms·

Surely shipping stuff down is basically free.

• lmm 5y ago
  Putting stuff on a ballistic reentry is free, but will burn up a certain amount of your material and is very hard to do safely. Maybe China could bring one down in their big desert and not worry too much about whether it hits anyone who lives there, but many nations would balk at that, and it complicates the retrieval. Otherwise the atmosphere helps you somewhat, but you've still got to fit a heatshield and some way to decelerate. The mass limit for parachutes is pretty low, so we're probably talking about a lifting body and some proper engines - maybe air-breathing engines, which are going to be significantly cheaper (especially fuel-wise) than rocket engines but by no means free. Maybe thousands per kilogram is an overstatement, but the cost is significant and there's only so much you can do about it (short of building a space elevator).