 At the time the treaty was drafted, the prospect of rescuing travelers in space was unlikely, due to the limited launch capabilities of even the most advanced space programs, but it has since become more plausible.For example, Mir and later the International Space Station have each maintained docked Russian Soyuz spacecraft to be used as an escape mechanism in the event of an in-orbit emergency; in certain scenarios this vessel might also be able to assist in a rescue.A significant shift in attitudes toward in-orbit rescues came as a result of the Space Shuttle Columbia disaster, after which NASA took steps to prepare the STS-3xx or "Launch on Need" missions to provide for rescue in certain scenarios.