The spacecraft, a satellite known as InSight, was designed to study the deep interior of Mars, information that will help scientists figure out how the planet, and other rocky planets such as Earth, formed and evolved.
The space agency said it was reviewing how much the repair would cost, but the project’s lead scientist last week estimated the price tag would be about $150 million above the $675 million already budgeted.
InSight missed its launch opportunity in March after scientists in December discovered that a pesky leak in its main science instrument had re-appeared.
That setback raised questions about whether NASA would cancel the mission. But agency managers said on Wednesday that the science goals were compelling and the plans for repairing the leak were sound.
The next time Earth and Mars will be properly aligned for InSight to launch is in May 2018. The spacecraft would arrive at Mars in November 2018 to begin a two-year mission.
The primary instrument is a seismometer with sensors that need to be suspended in near vacuum conditions so that they can make measurements as small as the diameter of a hydrogen atom.
The nine-inch (22-cm) spherical chamber holding the sensors has a tiny leak, so small that if a car tire leaked at that rate it could go three centuries without needing additional air, project scientist Bruce Banerdt of NASA’s Jet Propulsion Laboratory in Pasadena, California, said during a March 2 presentation to the Mars Exploration Program Analysis Group.
But even that leak rate is too high for the seismometer to work properly, so NASA grounded the mission for review.
Spacecraft builder Lockheed Martin said InSight would be stored in a facility near Denver while the seismometer instrument was repaired.