NASA has decided to proceed with the InSight mission to Mars, with launch now targeted for May 2018.

The spacecraft missed its launch opportunity this month due to a small leak in its primary science instrument, a seismometer that is designed to study the deep interior of Mars.

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NASA grounded the mission for review in late December after a vacuum chamber housing the seismometer’s sensors failed a leak test.

“The quest to understand the interior of Mars has been a longstanding goal of planetary scientists,” John Grunsfeld, NASA’s associate administrator for science, said in a statement. “We’re excited to be back on the path for a launch.”

The agency said it was reviewing how much the repair and launch delay would cost, but the project scientist estimates it will be about $150 million.

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NASA said it should know the final tab in August after it selects a new launch vehicle. The Atlas 5 rocket that was being prepared to fly Insight was re-assigned to another spacecraft.

InSight will be put into storage near Denver while the seismometer’s vacuum chamber is re-designed, said spacecraft builder Lockheed-Martin.