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| Most rockets sit on a launch pad until they blast off. But one special little rocket needs no launch pad at all. This rocket, called Pegasus, recently put NASA's new GALEX space telescope into Earth orbit.
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| Pegasus rockets are very small and can carry only a small spacecraft that weighs less than 450 kilograms (1000 pounds). GALEX weighs only 280 kilograms (about 617 pounds). |
 Pegasus works by hitching a ride (with the spacecraft inside) under the belly of an L-1011 jumbo jet named Stargazer. Stargazer takes the Pegasus up to about 12 kilometers (40,000 feet). This is about as high as this plane can fly. Then, the plane lets go of Pegasus. For a few seconds Pegasus falls freely, waiting for the plane to get out of the way. Then Pegasus fires its first stage engine and heads for space, ferrying the spacecraft the rest of the way to Earth orbit.It is much less expensive to launch a small spacecraft using Pegasus than using a larger rocket that pushes off from the ground. |
 Pegasus has a delta-shaped (triangle-shaped) wing. The wing helps lift the rocket higher in Earth's atmosphere. But unlike a plane, the rocket keeps going higher even after the air becomes too thin for the wing to help. Once separated from the Stargazer, it took Pegasus only about 10 more minutes to boost GALEX all the way to orbit. This is fast! |
| (See why an airplane can't just fly into space and why we need rockets). |
GALEX is a space telescope that studies galaxies. It will help scientists understand how galaxies are born and change. GALEX is looking at almost the entire sky, gathering information on galaxies that are so far away it has taken over 10 billion years for their light to reach us. So GALEX actually sees back in time! It sees how the universe looked when it was only one-fifth as old as it is now. 
