1. Four billion years ago, Mars may have looked like Earth.
2. But where did Mars's water and atmosphere go?
3. Earth's powerful magnetic field protects us from the solar wind.
4. On Mars there is NO north-south magnetic field to deflect solar energy. Scientists suspect the Martian atmosphere was stripped away by the solar wind.
TAG: MAVEN is traveling at 65,000 miles an hour, taking 10 months before arriving at Mars in September 2014.