The last flight of the Space Shuttle Endeavour has been delayed by technical problems with the new launch target being Monday at the earliest. President Obama was to have attended the Friday launch along with Congresswoman Gabrielle Giffords, wife of Endeavour commander Mark Kelly. She is recuperating from a gunshot wound to the head suffered during a shooting rampage in her home district in Arizona more than three months ago. The delay was caused by a problem with the power units that allow the orbiter to maneuver as it enters space and as it returns to earth.
About three and a half hours before its scheduled liftoff, NASA managers called off the Endeavour launch because of a malfunction in one of the spacecraft's auxiliary power units, called APUs for short. Endeavour has three power units and needs all three functioning in order to launch. Initially engineers thought they might be able to fix the problem in a couple of days. Speaking to VOA by telephone from the Kennedy Space Center, NASA spokesperson Mike Curie explained the engineers' decision to add one more day.
"They typically look at things as a one or two day slip and, in this case, as they looked at it further they determined that it was going to take longer to resolve so they went ahead and decided it was going to take at least 72 hours," said Curie.
Curie says two faulty heaters in the APU caused the problem. The NASA spokesperson says the heaters are needed to keep the fluid, hydrazine, from freezing when the orbiter is in space.
"When in space, the shuttle is controlled by the thrusters, the jets that maneuver it around, so the APUs are turned off," he said. "However the hydrazine is still in the lines and the shuttle is subject to temperatures that drop as low as 250 degrees below zero when it is on the dark side of the earth. The hydrazine would freeze without these heaters and if the hydrazine freezes, the APUs would not work correctly for landing."
If technical problems or weather should delay the launch Monday, Curie says there are a few other opportunities to launch before May 4. At that time, the shuttle would have to make way for a previously scheduled Atlas rocket launch from the same area, and managers would not be able to prepare it for launch again before May eighth.
The delay is a big disappointment to the more than 700,000 people who have gathered along the central Florida Atlantic coastline near the Kennedy Space Center to witness what would be the next-to-last launch of a US space shuttle and the last flight of Endeavour, which has flown 24 previous missions in its 19 years of service.
On this mission Endeavour is to carry six crew members on a two-week visit to the International Space Station to deliver a $2-million astrophysics experimental device called the Alpha Magnetic Spectrometer-2. It will be used to study cosmic rays and dark matter, which scientists hope will provide new information on the workings of the universe. The mission also includes four space walks, this will be the last time astronauts will step out of a space shuttle as no space walks are programmed for the final shuttle mission now set for late June.
Congresswoman Giffords has witnessed two previous launches in which her husband flew, but this occasion was particularly important since she is still recovering from a gunshot wound to the head. Doctors who have been working with her at a rehabilitation facility here in Houston approved her trip to Florida. She has doctors and therapists with her in Florida and plans to stay there at least until Monday's scheduled launch date.