The Air Force expects to release a request for proposals for a new rocket engine to replace the Russian-made RD-180 by the end of 2015, according to the service's director of space acquisition programs. Maj. Gen. Roger Teague told reporters during a Feb. 6 media roundtable at the Pentagon that the Air Force continues to work to complete a series of trade studies aimed at reducing risk and maturing technology for the next-generation rocket engine development program. He would not...