HOUSTON — NASA and its prime French and German space agency partners have been cleared to begin assembly of the $541.8 million Mars Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport (InSight) mission spacecraft, following a successful critical design review (CDR).

The more than two-year mission is scheduled for launch from Vandenberg AFB, Calif., in March 2016.

The dual-instrument lander will be equipped to investigate processes by which rocky planets form and develop a layered crust, mantle and core.

Lockheed Martin Space Systems will assemble the spacecraft patterned after NASA’s Mars Phoenix lander, which touched down in 2007 to study the planet’s northern polar region.

InSight, which completed the CDR phase of its development on May 16, will be equipped with a robot arm and drill for deployments of surface and subsurface instruments provided by CNES, the French space agency, and DLR, the German space agency.

The French/German Seismic Experiment for Interior Structure (SEIS) will measure sound waves from Mars quakes and meteor impacts. The Swiss and the U.K. are contributing to SEIS development.

The German Heat Flow and Physical Properties Package will measure heat radiating from the Martian interior to the surface.

"We will incorporate many features from our Phoenix lander into InSight, but the differences between the missions require some modifications for the InSight spacecraft," said Stu Spath, Lockheed Martin’s InSight program manager. "For example, the InSight mission duration is 630 days longer than Phoenix, which means that the lander will have to endure a wider range of environmental conditions on the surface.’’