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Here’s Why NASA Had to Postpone a 2016 Mission to Mars

A leak in a key instrument on board the InSight lander means the team will have to wait for the next launch window in 2018

The back shell of NASA’s InSight spacecraft being lowered onto the lander, last July, in preparation for the mission. (NASA/JPL-Caltech/Lockheed Martin)
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The Mars rover Curiosity won’t be getting company as soon as planned. Yesterday NASA announced that it has suspended the InSight lander mission, which had been slated to launch in March 2016, after a French-built seismological instrument sprang a leak.

The Seismic Experiment for Interior Structure (SEIS) involved a suite of three instruments designed to listen for quakes rippling through Mars and gather data about the planet’s core, mantle and crust. The sensitive instruments are supposed to be housed in a vacuum-sealed metal sphere so they can better pick up faint signals deep inside the planet, Peter B. de Selding writes for SpaceNews

Earlier in December, the French space agency CNES announced that the sphere was leaking, but that they expected to have it fixed ahead of the launch date.

However, attempts to repair the faulty weld responsible for the leak were unsuccessful. When investigators tested the new weld with the kind of extreme cold that the instrument would encounter on Mars, the leak let in two-tenths of a millibar of pressure. For the instrument to work, that number needed to be less than one tenth of a millibar, reports Eric Hand for Science.

Without a proper vacuum seal, the instrument won’t be able to make the measurements experts need, which are “displacements on the size scale of atoms,” writes Phil Plait for Slate. And since SEIS was one of two main scientific probes on board InSight, NASA made the call to postpone its launch.

“We’re all just pretty disappointed right now. Devastated would be a better word,” Lisa Pratt, the chair of a Mars advisory committee for NASA and a biogeochemist at Indiana University, tells Science. “Everyone has been waiting to get a seismic instrument on Mars after Viking.” The two Viking landers that made the trip in 1976 did carry seismometers, but one failed and the other couldn’t make all its measurements because of movements created by Martian wind.

The next opportunity to launch InSight will be in 2018, when the alignment of Mars and Earth are favorable for the trip. Plait writes that this is “plenty of time to fix the problem,” but there is still a chance that the mission could be canceled altogether. “InSight is a cost-cap mission; there’s a hard upper limit of $675M for the mission including launch, and $525M has already been spent,” he writes.

Curiosity endured its own two-year postponement before launch, and that mission’s successes have now “vastly outweighed any disappointment about that delay,” Jim Green, director of NASA’s Planetary Sciences Division, says in a press statementDiscovering the leak before launch is also far more preferable to discovering it once the rover is on the surface of Mars, points out John Grunsfield, the associate administrator for the NASA science mission directorate, in a story by Alexandra Witze for Nature

In the meantime, Mars exploration fans can look forward to another launch on the horizon: The European Space Agency still plans to send its ExoMars Trace Gas Orbiter to the red planet in March, so stay tuned.

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