Live coverage: Cygnus rendezvous and arrival journal and webcast

The United Launch Alliance Atlas 5 rocket that will hurl the four MMS satellites into a highly elliptical Earth orbit on March 12 has completed its basic build up at Cape Canaveral’s Complex 41 Vertical Integration Facility.

The Cargo Dragon spacecraft, tail number C209, will carry 6,659 lbs. (3,021 kg.) of science and supplies to the orbiting outpost. Liftoff from pad 39A at NASA’s Kennedy Space Center happened Monday, April 21, at 4:15 a.m. EDT (0815 UTC).

The Pentagon has awarded at least $162 million in contracts to Aerojet Rocketdyne and United Launch Alliance for development of the AR1 and BE-4 rocket engines, candidates to power the first stage of a next-generation rocket and replace the Russian-made engine currently flying on the Atlas 5 launcher.