A NASA mission to Mars that was originally scheduled to launch this month — then was canceled when a flaw was discovered in a pivotal piece of equipment — is back on the calendar. If all goes well, it will launch in 2018.

The InSight mission — or "Interior Exploration using Seismic Investigations, Geodesy and Heat Transport" mission — has been in the works since 2012. It will send a lander to the Red Planet to measure Mars' seismic activity and interior temperature, among other things.

Data on marsquakes and the planet's interior heat will help researchers better understand Mars' "deep interior," NASA says. That, in turn, could help expand scientists' understanding of the formation of all rocky planets, including Earth.

The original launch was planned for March 2016. But in December, the mission had to be suspended because a flaw in the lander's French-built seismometer couldn't be fixed in time.

The instrument needs to work inside a vacuum "to provide the exquisite sensitivity needed for measuring ground movements as small as half the radius of a hydrogen atom," NASA says — and the container needed to maintain that vacuum was leaking.

At the time, it wasn't clear if the mission would be postponed or called off altogether. But on Wednesday, NASA announced that it would resume work on the project.

No matter how quickly the vacuum issue is resolved, March 5, 2018, is the earliest the mission could launch. That window of opportunity depends on the alignment of the orbits of Earth and Mars.

The InSight mission is a part of NASA's Discovery Program, in which scientists compete for approval of relatively low-cost planetary missions. (The total cost of InSight was to be capped at $675 million, Science Magazine reported last December. At that time, NASA had already spent $525 million, and the space agency is currently assessing the cost added by the two-year delay.)

When InSight was picked, it beat out two other finalists — one that would have sent a probe to a comet to hop across its surface and study multiple locations, and another that would have sent a boat to Titan, one of the moons of Saturn, to travel across its hydrocarbon oceans.

NASA is currently in the process of selecting the next Discovery Program mission — or missions — from a set of five finalists, including projects studying Venus and a probe to land on a metallic asteroid.

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