1 A spokesman says that Russia believes a prototype spacecraft powered by solar sails has been lost because of a malfunction during its launch.
2 NASA has launched its Contour spacecraft, one of a series of missions designed to investigate comets.
3 They hope to show that solar sails could replace traditional rockets and propel spacecraft to the stars.
4 Spacecraft propulsion is any method used to change the velocity of spacecraft and artificial satellites.
5 Almost thirty years ago, NASA's Mariner Ten spacecraft took the most recent pictures we have of Mercury, revealing a rocky surface - wrinkled like an old apple.
6 A spacecraft orbiting Mars has detected large quantities of water-ice just below the surface of the planet.
7 Cosmos 1 was designed to test whether it's possible to power a spacecraft by harnessing sunlight.
8 The tiny rocket is attached to the spacecraft and is designed to propel it toward Mars.
9 The force of friction affects the speed at which spacecraft can re-enter the earth's atmosphere.
10 The spacecraft lost contact with mission control.
11 Mission control ordered the spacecraft to return to earth.
12 A radio signal was sent to the spacecraft.
13 They scanned the sky for the spacecraft.