This graphic depicts the relative shapes and distances from Mars for five active orbiter missions plus the planet's two natural satellites. It illustrates the potential for intersections of the spacecraft orbits.
The number of active orbiter missions at Mars increased from three to five in 2014. With the increased traffic, NASA has augmented a process for anticipating orbit intersections and avoiding collisions.
NASA's Mars Odyssey and MRO (Mars Reconnaissance Orbiter) travel near-circular orbits. The European Space Agency's Mars Express, NASA's MAVEN (Mars Atmosphere and Volatile Evolution) and India's MOM (Mars Orbiter Mission), travel more elliptical orbits. Phobos and Deimos are the two natural moons of Mars.
NASA's Goddard Space Flight Center manages the MAVEN project for the NASA Science Mission Directorate, Washington. MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics. JPL, a division of the California Institute of Technology in Pasadena, manages NASA's Mars Exploration Program and the Odyssey and MRO projects for the Science Mission Directorate. Lockheed Martin Space Systems, Denver, built all three NASA Mars orbiters.
For more about NASA's Mars Exploration Program, visit: http://mars.jpl.nasa.gov.