1. Substance that drives rocket propulsion

2. Returning to Earth's atmosphere from space

3. Device to slow descent by increasing air resistance

4. Person trained for space travel

5. Measurement and transmission of data

6. Circular or elliptical path around a celestial body

7. Astronaut from Russia

8. Change in velocity

9. Relating to the sun

10. Radio detection and ranging system

11. Height above a reference point

12. Device to control the thrust of an engine

13. Force that propels a rocket forward

14. Leaving a gravitational field

15. Distinct section of a rocket

16. Rate of motion