SpaceShipTwo Crash: Astronauts And Entrepreneurs Offer Condolences

Astronauts, officials and members of the private space community have offered their condolences to the families of two Virgin Galactic test pilots after a disastrous test flight on Friday.

One of the pilots was killed in the crash while the other is said to be in a critical condition.

On Twitter current and former astronauts, space officials and others offered their sympathy: