The Future of Space Travel: Practice Problem Solutions

1. To return people to the Moon, to stay, using the SLS rocket and Orion spacecraft.

2. Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen flew around the Moon and back in about ten days in April 2026, the first people beyond low Earth orbit since 1972.

3. They lower the cost of reaching space by reusing the most expensive parts instead of throwing them away.

4. Any three of: distance and travel time, radiation, landing heavy cargo in thin air, supplies and life support, the harsh environment.

5. They use very little fuel for long, steady thrust, so they are good for long trips; the thrust is tiny, so they accelerate slowly.

6. About 75,000 years.

7. Any two of: knowledge, practical benefits, safety from asteroids, inspiration, a sense of calling.