half a second before the Space Shuttle main engines (SSMEs) were to have started. Had they been started, they would have had to be replaced, which would have taken a month, pushing it into the scheduled maintenance window. There was no fuel leak; the sensor was faulty. The launch was rescheduled for two days later. It then had to be postponed a further day due to bad weather. On the third launch attempt, there was a seven-minute delay due to a communications problem, but Columbia lifted off at last on 23 July. One of the main engine controllers failed during takeoff, and one of the main engines cut out prematurely. As a result, the orbit reached was lower than intended but the situation could have been much worse; the engine problem was caused by a pin that had come loose and struck the nozzle, rupturing three liquid hydrogen coolant tubes. Had the controller not been faulty, it might have pumped more liquid oxygen and caused the engine to explode. After the flight, faults were found not just in Columbia, but in Discovery and as well, and the whole Space Shuttle fleet was grounded until December. Columbia eventually reached the proper orbit and the Chandra X-ray Observatory was successfully deployed. For the remainder of the mission, the crew used the Southwest Ultraviolet Imaging System (SWUIS) to take ultraviolet images of the Earth, the Moon, Mercury, Venus and Jupiter. Collins used the Shuttle Amateur Radio Experiment (SAREX) to talk to children on amateur radio stations with her call sign KD5EDS. On 27 July, Collins brought Columbia in for a night landing, the twelfth of the Space Shuttle program. The flight had lasted 4 days, 22 hours and 50 minutes. She was awarded the Distinguished Flying Cross for this mission. After a flight astronauts usually carried out a publicity tour. Collins appeared with Coleman on The Tonight Show with Jay Leno on 16 August. She opened the New York Stock Exchange on 7 January 2000, and appeared on the Oprah Winfrey show on 25 April 2000. She had a miscarriage in November 1999, but a son, Luke, was born in November 2000. STS-114 After the STS-84 mission, Collins had become the head of the Vehicle Systems Branch of the Astronaut Office, which she had renamed the Spacecraft Systems Branch, as the scope of its work now included the International Space Station (ISS) as