NASA's InSight Mars lander. (NASA/JPL-Caltech/Lockheed Martin)

NASA will delay its next scheduled Mars mission, the launch of a lander called InSight. The decision comes after attempts to fix a leaking instrument on the robot before the scheduled March launch. The next launch window won't come for another two years, leaving the future of the project unclear.

The offending instrument is the Seismic Experiment for Interior Structure (SEIS), provided by CNES, France's space agency. A faulty weld left the instrument, one of the lander's two primary scientific tools, with a persistent air leak.

At a news conference on Tuesday afternoon, NASA and CNES representatives explained that the SEIS instrument is incredibly sensitive, and it must operate inside a perfect vacuum. This is because Mars doesn't have seismic activity comparable to Earth's. Any motion that the SEIS might detect would be minute, and the instrument is designed to detect ground motions as small as the width of an atom. Without a perfect vacuum environment, the results can't be trusted.

"Unfortunately since last August we’ve been fighting a series of very small leaks," John M. Grunsfeld, associate administrator for the Science Mission Directorate at NASA, said during the news conference. The engineering team worked to fix leak after leak, but tests mimicking the coldest of Martian conditions revealed that air was still making its way into the chamber.

"As late as yesterday we thought we were still on track," Grunsfeld said. But on Tuesday the team had to make the call, and there simply wasn't enough time left to identify and fix the problem.

"The decision was made by the leak," Grunsfeld said. At the current leak rate, the instrument would not have worked at all on the surface of Mars.

NASA's InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) lander deploying its instruments. (NASA)

Grunsfeld and his NASA colleagues emphasized the strength of their partnership with CNES. "We got very very close, and this just reflects the difficulty when you challenge the technology, when you challenge scientists and engineers to do something that’s never been done before," Grunsfeld said.

The team is optimistic that the 2018 window might see InSight through. In fact, that launch window might be a little wider, because the planetary alignment between Earth and Mars will be even more ideal than it is in 2016. But because InSight is a cost-capped mission, the team will have to assess the cost of fixing the lander and maintaining the mission for another two years and seek funding approval. For now, NASA has limited the mission to $425 million.

If InSight makes it to Mars as planned, the lander will drill into the surface to monitor seismic activity. The hope is that these kind of measurements will help scientists learn more about how Mars (and other rocky planets, such as Earth) formed.

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