WASHINGTON — NASA will hold a press call Tuesday afternoon (Dec. 22) to discuss its decision to suspend a March launch campaign for the Mars InSight lander, which was shipped to its launch site this month despite a problem with one of its instruments.

The holdup with the instrument, the French-built Seismic Experiment for Interior Structure (SEIS), means InSight will miss its Mars launch window and be stuck on the ground for about another two years, NASA said in a press release that hit the wire Tuesday afternoon on the heels of a brief heads-up emailed to journalists that morning.

“After thorough examination, NASA managers have decided to suspend the March 2016 launch of the Interior Exploration using Seismic Investigations Geodesy and Heat Transport (InSight) mission,” NASA said in its Tuesday morning notice. “The decision follows unsuccessful attempts to repair an air leak on a key component of the mission’s science payload.”

SEIS, provided by the French Space Agency (CNES), suffered “a leak in the vacuum container carrying its main sensors,” NASA confirmed Dec. 3. The instrument is still in France undergoing repairs at at Paris-based Sodern.

The leak was caused by a defective weld on the instrument’s vacuum tank, CNES President Jean-Yves Le Gall told SpaceNews Dec. 8. At the time, Le Gall said CNES had performed a new weld that should have fixed the problem.

Even as NASA was preparing to brief reporters Dec. 22, Le Gall told SpaceNews that CNES had not given up on fixing the SEIS instrument in time to launch this year.

CNES President Le Gall: We’re not giving up resolving NASA Mars InSight lander instrument leak; we have till 5 January to nail it down. — Peter B. de Selding (@pbdes) December 22, 2015

CNES’s Le Gall (2): We’re not 100% sure that the leak Mars InSight SEIS instrument leak isn’t leak-measure issue rather than actual leak. — Peter B. de Selding (@pbdes) December 22, 2015

CNES’s Le Gall (3): We took 3 InSight SEIS leak measures, all w/ identical results. That’s odd if it’s a real leak; could be false positive. — Peter B. de Selding (@pbdes) December 22, 2015

However, one official familiar with the instrument, said CNES and NASA on Dec. 22 decided that too many questions remained about the integrity of the SEIS sphere and that the 2016 launch would be cancelled.

InSight, which was built by Lockheed Martin Space Systems in Denver, arrived at its launch site at Vandenberg Air Force Base in California Dec. 16. SEIS was to follow in January and be integrated with the lander at Vandenberg. Now, with the instrument delivery delayed, “the spacecraft will be returned from Vandenberg to Lockheed’s facility in Denver,” NASA wrote in its press release.

NASA selected InSight as the 12th in its Discovery line of cost-capped Planetary Science missions in 2012. The lander, based heavily off the Mars Phoenix craft that touched down on the red planet in 2008, beat out a comet-hopping probe and a vessel designed to sail the hydrocarbon seas of Saturn’s moon Titan to win NASA funding.

InSight’s cost, excluding launch, was capped at $425 million. The mission was set to launch aboard an Atlas 5 in what would have been the first interplanetary launch from Vandenberg. Such missions ordinarily launch from Cape Canaveral Air Force Station in Florida.

Peter B. de Selding contributed to this story from Paris.