lunar lifeboat

noun1

1. •
   In the US Apollo moon program, a lunar module repurposed as a makeshift shelter for an astronaut crew returning to earth after a mishap necessitating cancellation of a moon landing; the emergency procedure of using the lunar module in this manner.

   • As the "lunar lifeboat" neared the Earth, the hard problem loomed of how to separate the vehicles before they entered the atmosphere. — 1970