Here are the answers to the crossword puzzle:

Across
6. McAuliffe was the teacher killed in the Challenger explosion.
8. Venus is the second planet from the Sun.
9. Sally Ride is an astronaut.
10. Venus is the hottest planet.
11. Neil Armstrong was the first man on the moon.
Down
1. The Challenger blew up in 1986.
2. When the life of a star ends, a supernova sometimes happens.
3. SkyLab is a space station.
4. Galileo improved the telescope.
5. The Space Shuttle is the first reusable space craft.
7. The International Space Station will have over 100 modules.