STS-131: Teamwork Overcomes Mission's Challenges
Even the best game plans sometimes need a little adjustment. That proved true during space shuttle Discovery's STS-131 mission to the International Space Station.
The mission began with a beautiful, on-time liftoff from Launch Pad 39A at NASA's Kennedy Space Center in Florida. The 6:21 a.m. EDT launch on April 5 went well, and the shuttle sustained no damage during its climb to space. However, Discovery's Ku-band antenna system, a vital link for radar and high-rate data communications from the shuttle to the ground, failed to work once in orbit. This caused Commander Alan Poindexter and his crew -to employ some "workarounds" throughout the mission.
The seven-member crew, consisting of Poindexter, Pilot James P. Dutton Jr., and Mission Specialists Rick Mastracchio, Clayton Anderson, Dorothy Metcalf-Lindenburger, Stephanie Wilson, and Japan’s Naoko Yamazaki, joined the six residents of the International Space Station two days after launch.
The merging of the two crews marked the first time four women were in space at the same time -- Discovery's three women astronauts and Expedition 23 Flight Engineer Tracy Caldwell Dyson. The Japan Aerospace Exploration Agency also marked the first time two of its astronauts were in space simultaneously when Yamazaki met up with station Flight Engineer Soichi Noguchi.
The station's downlink capability via its Ku-band system proved to be the solution to the shuttle's communication issues. The station was able to send information back to the Mission Control Center in Houston for the shuttle crew, including images from Discovery's final inspection that was done at the station instead of after undocking -- extending the mission one-day.
Discovery delivered supplies and equipment to the station, more than 17,000 pounds of it stowed inside the Italian-built multi-purpose logistics module Leonardo. The payload included new crew sleeping quarters, an ammonia tank, gyroscope and experiments. The module’s next and final journey to the station will be a one-way trip, when it attached and left on the station during the STS-133 mission.
The heart of the mission's work was accomplished during three trips outside the station by a team of veteran spacewalkers, Anderson and Mastracchio. While they encountered some difficulty during their work, the main goal of replacing a depleted ammonia tank with a new one, as well as other exterior work, was accomplished. The ammonia tank is part of the station's cooling system.
Small but troublesome technical issues throughout the mission, such as uncooperative bolts and a malfunctioning nitrogen tank assembly valve, kept the crew and mission managers on the ground working together in problem solving.
Inside the station, the astronauts from both shuttle and station transferred tons of cargo from Leonardo, which was temporarily docked to the station's Harmony node, and from Discovery's middeck. The 16 racks inside Leonard included four racks of experiments.
With the shuttle's inspection completed before undocking, Discovery was cleared to return to Earth, and the two crews parted company.
The mission was extended yet again, to 15 days, when unstable weather moved into Florida and the two landing attempts on April 19 were waved off. Better weather prevailed the following day, and Discovery arrived home on the second landing opportunity on April 20 at 9:08 a.m. EDT. Touching down on Runway 33 at Kennedy's Shuttle Landing Facility, Discovery and crew had traveled more than 6 million miles during 238 orbits of Earth.
After stepping off the shuttle following landing, Anderson, who participated in the mission's three spacewalks, may have summed up the mission best: "We had a lot of adversity, but we overcame it all with some great teamwork."
While perfect missions are preferable, those that involve a few changes in the game plan can sometimes yield valuable lessons about working in space.
Cheryl L. Mansfield
NASA's John F. Kennedy Space Center