Tech2 4/21/2017
Nasa is working with private American companies to prime spacecraft for use as escape pods, to return to Earth quickly in case of a crisis. There has been no emergency situations on the International Space Station (ISS) so far, but the US space agency is preparing for any possible eventuality. Nasa astronauts are thoroughly tested to ensure their good health over the duration of a mission, but in the case of a medical emergency, there needs to be a vehicle for rapid evacuation.
Currently, the Russian Soyuz spacecraft does double duty as an escape vehicle. Every astronaut on board has a seat reserved, which limits the number of crew working at the ISS at any point of time. Nasa is working closely with Boeing and SpaceX for getting their spacecraft ready to use as lifeboats for the ISS. The CST-100 Starliner from Boeing and the Crew Dragon from SpaceX are being thoroughly tested on the ground. The critical functionality for use as a lifeboat is that all the systems required for a safe flight back should be up and running in short notice. The air circulation fans, the thrusters and the life support systems have to engage within minutes.
More:
http://tech.firstpost.com/news-analysis/nasa-wants-to-use-spacecraft-from-boeing-and-spacex-as-lifeboats-for-the-international-space-station-372821.html
