Milestones
| Year | Event |
|---|---|
| 1957 | Sputnik, the first satellite |
| 1961 | Yuri Gagarin, first person in space |
| 1969 | Apollo 11: first people on the Moon |
| 2000 | People begin living aboard the ISS continuously |
| 2020s | Artemis program aims to return people to the Moon |
Twelve astronauts walked on the Moon from 1969 to 1972.
Mars by the numbers
~7 monthsone-way trip
34–250 millionmiles from Earth, depending on orbits
38%of Earth's gravity
-80°Ftypical temperature
A round trip could take two to three years, waiting for the planets to line up.
The big challenges
Radiation
Space and Mars lack Earth's protective magnetic field
Low gravity
Bones and muscles weaken without exercise
Life support
Air, water and food for years
Distance
No quick rescue; messages take minutes
Sources: NASA
Remember
Getting to Mars is an engineering problem we can solve; living there safely is the harder one.
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Answer key
- When did people first land on the Moon?1969Apollo 11 landed in July 1969.
- How many people have walked on the Moon?12Twelve, from 1969 to 1972.
- About how long is a one-way trip to Mars?About 7 monthsAbout seven months with current rockets.
- How strong is gravity on Mars compared with Earth?About 38%About 38 percent of Earth's.
- Which is a major danger for Mars travelers?RadiationRadiation exposure is a key health risk.