A U.S. science satellite slated to launch to Mars in March has been grounded due to a leak in a key research instrument, NASA said on Tuesday, creating uncertainty about the future of a widely anticipated effort to study the interior of the planet.

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 $425 million US.

John Grunsfeld, head of NASA's science mission directorate, said the scientific goals of the mission are compelling and the repair plans are sound. (Win McNamee/Getty)

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' 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. 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.

InSight may launch in 2018

NASA managers and French designers of the instrument said Tuesday in a teleconference they must now decide whether the leak in the vacuum-sealed connector needs to be repaired, redesigned or the mission scrapped.

"We're close enough to launch but unfortunately we don't have enough time to try to identify the leak, fix it and recover and still make it to the launch pad in March," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate.

The next opportunity to launch the InSight lander is in May 2018 since the best chances of launching missions between Earth and Mars occur for just a few weeks every 26 months.

NASA managers said it could take several months of analysis and discussion before they decide how to proceed. A redesign of the part could make the 2018 opportunity unlikely since it could take up to five years.