Falling Around Earth: teacher key

Astronauts and Space Travel, grade 9 edition, written for 9th grade. Astronauts on the space station float because they are in free fall, not because gravity has switched off. The book also covers Sputnik, the first flights of 1961, how rockets work, life on the station and the distance to Mars.

Read the book. Print this page for the key.

Questions and answers

1. Why do astronauts on the space station float?
   • Gravity has switched off there
   • They are in free fall together with the station (answer)
   • The station is too heavy to fall
2. How long did Yuri Gagarin's single orbit take?
   • 15 minutes
   • 92 minutes
   • 108 minutes (answer)
3. One circuit of Earth by the station takes about 92 minutes. How does Gagarin's orbit compare?
   • It took about 16 minutes longer (answer)
   • It took about 16 minutes less
   • It took exactly the same time
4. Which is farther from Earth: the space station or Mars?
   • The station
   • They are the same distance
   • Mars (answer)
5. What is the loss of bone and muscle in space called?
   • Orbit
   • Atrophy (answer)
   • Exhaust

Words

• orbit: path around
• suborbital: short of orbit
• exhaust: hot gas
• atrophy: wasting away