article_snippet: Astronauts on a mission to and from Mars will be outside of Earth’s magnetic field, and thus the risk of harm is much higher than when in Earth orbit.
article_snippet: Owing to the orbits of Earth and Mars there are specific windows of opportunity when a mission can take place.
article_snippet: Our planets come as close to each other as 33.9 million miles (54.6 million km), but can be as distant as 250 million miles (400 million km).
article_snippet: For this reason spacecraft to Mars, such as the Curiosity rover, have to launch in certain windows when Our planets are aligned.