|Preparing for a Return to Flight|
For well over 20 years, the Space Shuttle has been a vital part of American spaceflight. It has played many roles in the exploration and development of space. The Shuttle has been the spaceflight equivalent of a van, carrying large numbers of people into space.
Image to left: The Space Shuttle blasts off from the launch pad to begin another mission. Credit: NASA
It has served as a science laboratory, where experiments can be conducted in microgravity. It has been like a delivery truck, placing satellites in orbit. The Shuttle has done the job of a construction vehicle, carrying components into space for the International Space Station (ISS). It's worked as a space taxi, transporting crews back and forth from the ISS. It has been a mobile home, providing accommodations for astronauts during their flights. The Shuttle is a rocket when it launches and a glider when it lands. Can you think of any other vehicle capable of doing so many different things?
But, the era of the Space Shuttle is drawing to a close. With the completion of the International Space Station in 2010, the Space Shuttle fleet will be retired, almost 30 years after the Shuttles began flying. New American spacecraft will be developed that will carry astronauts to the Moon and out through the solar system. But, that does not mean that NASA is ready to start giving up on the Shuttle yet. To complete the ISS, the Shuttle has many more important missions still to fly. NASA is currently working to make the Space Shuttle better than ever so that it can fulfill those missions. After the loss of the Space Shuttle Columbia and its crew in 2003, NASA engineers have been working to make the Shuttle safer. They are not only fixing the problems related to the loss of Columbia, but they are working to make sure that other problems do not occur. When the Space Shuttle returns to flight for the STS-114 mission, it will be one of the safest Shuttle flights ever.
Image to right: The Space Shuttle's External Tank falls away from the Orbiter during launch. Credit: NASA
Among the changes being made is work to reduce the shedding of debris during launch. A major factor in the Columbia accident was foam that came off of the External Tank (ET) and hit the wing of the Orbiter. The ET stores liquid hydrogen and liquid oxygen, which must be stored at extremely low temperatures. On earlier rockets, this caused ice to form on the outside of the booster. The ice then fell off the rocket during launch. For the Space Shuttle, however, engineers had to find a way to prevent this from happening so that falling ice would not damage the Orbiter. The foam was placed on the ET to serve as insulation to prevent ice from forming. Now, NASA has replaced the bipod ramp foam that was shed on the STS-107 mission with a heating system that performs the same task. Other efforts are also being made to prevent debris damage on future Shuttle flights. For example, NASA is redesigning the bolt catchers that are used for the pyrotechnic bolts used in separating the Solid Rocket Boosters from the External Tank.
NASA is also working to develop ways to inspect and repair the Shuttle's thermal protection system while in orbit. Prior Shuttle flights did not have a way to repair the black heat shield tiles that protect the Orbiter during re-entry if something went wrong. Now, engineers are working to find ways to patch holes in the heat shielding. In addition to creating such a patch, scientists and astronauts are working together to develop the tools and techniques necessary to perform any needed repair work. While performing work on spacewalks, astronauts rely on handholds and footholds to keep them in place. The bottom of the Orbiter, however, is a relatively smooth surface with no place to hold onto. To make things more complicated, bumping into the tiles while performing repairs could cause even more damage. In addition to developing repair procedures, NASA is also working on ways to inspect the Orbiter for damage while it is in space. A long camera boom was developed that can be held by the Shuttle's robotic arm to look at the bottom of the Orbiter. Procedures are also being created for the crew of the ISS to look for damage to the Shuttle when it arrives for docking. The Shuttle will approach the ISS, and then turn around doing a somersault, so that all of it can be seen from the windows of the ISS. Plans are even being developed for flying a rescue mission with another Shuttle if it ever became necessary.
Image to left: Astronauts practice tile repair techniques in case repairs are needed during a flight. Credit: NASA
Some of the changes being prepared for the return to flight do not even involve the Shuttle itself. NASA is working to develop better ways to capture the details of Shuttle launches. Following the STS-107 launch, there was uncertainty about exactly where and how the foam had struck the Orbiter. This led to poor understanding of the potential consequences of the impact. NASA is working to make sure that much better detail will be available in film footage of future launches. Better cameras at the launch site will be trained on the Shuttle during takeoff. The agency is researching ways to film the launch from aircraft, as well. In addition, cameras will be placed on the Shuttle itself to provide another perspective on the launch. To improve visibility, when the Shuttle returns to flight, launches will be held during the daytime, rather than at night.
Over two years have passed since the last time the Space Shuttle flew. But, that does not mean that nothing has been happening during that time. Engineers, ground crews, mission controllers and astronauts have all been extremely busy and will stay that way until the crew of STS-114 is safely back on the ground. The Space Shuttle has an important job ahead, and NASA is working to make sure it finishes its tasks successfully and safely.