NASA has built a spacecraft that will study the atmosphere of Mars like never before. A NASA spacecraft built to study the atmosphere of Mars like never before arrived at the Red Planet tonight on September 21, 2014. After 10 months in deep-space, NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft entered orbit around Mars and began a one-year mission studying the planet's upper atmosphere. The Mars arrival will cap a 442 million-mile (711 million kilometers) trek across the solar system. The $671 million MAVEN spacecraft has eight instruments to study the Martian atmosphere in detail. It is one of two missions that launched toward Mars last November and are making their arrival this month. The other probe is India's Mars Orbiter Mission, which launched just before MAVEN and will arrive at the Red Planet on Wednesday (Sept. 24).