Slate The lander was set to launch in March 2016 for a September 2016 touchdown. by Phil Plait via Bad Astronomy
'Its mission is to study the interior geology of Mars; the name is short for Interior Exploration using Seismic Investigations Geodesy and Heat Transport.
'The main instrument on the lander, the Seismic Experiment for Interior Structure, is a seismometer designed to study the ground movements of Mars to extraordinary accuracy, literally displacements on the size scale of atoms.
'SEIS, built by the French Centre National d'Études Spatiales, needs a very rigorous vacuum seal around its three sensors. During a vacuum test last week, though, a leak was found. Leaks had been found earlier in the year and repaired, but this new leak is too close to the launch date to be sure it can be fixed.
'Given that, NASA admins made the hard call: The mission has been suspended for now. During a press conference, Bruce Banerdt, the principal investigator, said they don’t think there’s a fundamental design flaw with the instrument, just a stubborn part or parts. It’s possible this can be repaired, and the instrument thoroughly checked again. For now, InSight will be shipped to Lockheed to undergo examination.'