Q&A with Mark Sirangelo, leader of Sierra Nevada Space Systems

Boeing Co. and SpaceX, selected by NASA last month to carry astronauts to the International Space Station, can resume development of their human-rated spacecraft after officials ordered a work stoppage prompted by a protest by Sierra Nevada Corp., the company left out of the contracts.

Leveraging progress made to build a human-rated space plane for NASA’s commercial crew program, Sierra Nevada Corp. said this week it has offered a cargo-carrying version of the Dream Chaser spacecraft to resupply the International Space Station beginning in 2018.

A Falcon 9 booster fresh from SpaceX’s factory briefly fired its nine Merlin main engines Tuesday on a Cape Canaveral launch pad, passing a key test before liftoff Dec. 4 with a Dragon supply ship heading for the International Space Station.