When used as a rocket booster, it is filled with 66 Ibs. of water heated electrically to 504° F. The water cannot boil because it is confined, but its pressure rises to 50 atmospheres (735 Ibs.

Cryogenic propellants have been viewed as unfeasible for spacecraft because they easily boil off, officials said ... can work with another company's orbital transfer vehicle to refuel rockets. "To ...