Engineers for NASA's MarCO (Mars Cube One) technology demonstration inspect one of the two MarCO CubeSats. Cody Colley, MarCO integration and test deputy, left, and Andy Klesh, MarCO chief engineer, are on the team at NASA's Jet Propulsion Laboratory, Pasadena, California, preparing twin MarCO CubeSats.

The briefcase-size MarCO twins were designed to ride along with NASA's next Mars lander, InSight. Its planned March 2016 launch was suspended.

InSight -- an acronym for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport -- will study the interior of Mars to improve understanding of the processes that formed and shaped rocky planets, including Earth.

The MarCO and InSight projects are managed for NASA's Science Mission Directorate, Washington, by JPL, a division of the California Institute of Technology, Pasadena.