Chris Hadfield @Cmdr_Hadfield
Reentry heat is wicked - I've survived it 3 times. Learning a lot about the difference between simulation and reality today @SpaceX. Congratulations on both soft splashdowns - pushing the envelope right to the edge. Excellent!
@elonmusk
Thanks Chris!
A fully and immediately reusable orbital heat shield, which (as you know) has never been made before, is the single toughest problem remaining.
Being able to iterate with many ideas on many ships is key to solving this.