During the long cruise, InSight’s team of scientists, engineers, and other staff will practice operations, test out command sequences, and exercise a whole lot of patience.

The journey begins with a collective sigh of relief from the people InSight leaves behind on Earth. By the time a spacecraft reaches the launchpad, virtually every piece of it has been vigorously tested—dunked into cryogenic chambers, shaken violently from side to side, blasted with loud noises. It’s held together with heavy metal, but also some blood, sweat, and tears. When the spacecraft finally launches into space, a weight is lifted in more ways than one.

“You’re relieved. It’s done,” says Florence Tan, the deputy chief technologist at NASA’s Science Mission Directorate. Tan was the electrical lead engineer for Curiosity’s sample-analysis unit. She also worked on the Cassini mission that plunged into Saturn last year, and which took seven years to reach its destination. “You can’t do anything about it. You can’t bring something back.”

The flutes and bubbly will come out, but the celebration will be short. Within days of launch, the InSight team must conduct a check of the spacecraft’s hardware to make sure it survived the stresses of launch. They’ll make more checks like that, monitoring the health of the instruments and various systems.

Most of the cruise is one giant dress rehearsal. Staff undergo a barrage of operations-readiness tests. They practice the operations, data collection, and analysis that their spacecraft will experience once it’s on Mars. They simulate everything from the deployment of instruments to planning meetings. They test how and when to send commands, making sure a set from one team doesn’t interfere with another’s.

During Curiosity’s nine-month cruise, NASA plopped a replica rover in the New Mexico desert and had scientists and engineers back at the lab pretend it was the real thing. They’d study grainy photos of the landscape and plan where to take the rover, where to drill for soil samples.

“When we finally arrive, we’re not like deer caught in headlights,” Tan said.

NASA doesn’t make it easy, either. “The people who created the tests would throw a few glitches in to see how we would react if there was a problem,” said Paul Mahaffy, the principal investigator of Curiosity’s sample-analysis unit that Tan helped build.

And, all the while, they’re periodically checking in with the spacecraft to assess the health of instruments and various systems. It’s rare, but disaster can strike during the cruise phase. In 2002, a spacecraft dispatched to study two comets in the inner solar system broke apart just six weeks after launch. CONTOUR—COmet Nucleus TOUR—fired its engines to push itself out of Earth’s orbit and bring it closer to its targets, but ended up overheating and split into pieces. Tan, who helped build CONTOUR, says its untimely demise was a shock.