Spacecraft specialists at Lockheed Martin Space Systems, Denver, are preparing to attach the cruise stage of NASA's InSight spacecraft to the top of the spacecraft's back shell in this April 29, 2015, photo.

The cruise stage will serve multiple functions during the flight from Earth to Mars. It has its own solar arrays, thrusters and radio antennas. It will be jettisoned shortly before the spacecraft enters the Martian atmosphere.

InSight, for Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport, is scheduled for launch in March 2016 and landing in September 2016. It will study the deep interior of Mars to advance understanding of the early history of all rocky planets, including Earth.

The InSight Project is managed by NASA's Jet Propulsion Laboratory, Pasadena, California, for the NASA Science Mission Directorate, Washington. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.