The top photo shows the plane during assembly in 1977, the lower during an early test flight. The first prototype first flew in November of 1978. On April 3, 1980 the aircraft crashed during stall testing in the Mojave desert and was destroyed. Two crewmembers parachuted to safety, the pilot's parachute failed to deploy and he was killed. More here.
The third prototype had a much longer life, acting as a testbed for many modifications and tests as the Challenger matured. It was finally retired in 2005 and is now at the Canadian Air and Space Museum in Ottawa.
The comprehensive story of the program and aircraft here.