A US science satellite set to launch to Mars in March has been grounded due to a leak in a key research instrument.
The spacecraft, known as InSight, was designed to help scientists learn more about the formation of rocky planets, including Earth.
The cancellation raises questions about the future of the research effort, as it will be another two years before Earth and Mars are favourably aligned for a launch.
NASA has not said if it will have funding for the program, which was capped at $US425 million ($A591 million).
The agency is expected to discuss the decision on a conference call scheduled for Tuesday afternoon.
After landing on Mars, the science satellite would have remained stationary, using three science instruments to detect quakes and other seismic activities.
It was also designed to measure how much heat is being released from the planet’s subsurface and monitor Mars’s wobble – or variations in its orbit – as it circles the sun.
A problem with the seismometer triggered cancellation of the launch, the agency said in a statement on Tuesday.
The instrument, which was provided by France’s CNES space agency, has a leak in the vacuum container that houses its primary sensors.
CNES repaired a faulty weld on the vacuum tank, but apparently the problem remained, according to NASA.
InSight had arrived last week at Vandenberg Air Force Base in California to begin launch preparations.