A NASA spacecraft described as a "robot geologist" is scheduled to arrive on Mars next week.
Nearly seven months to the day, NASA's InSight lander is finally ready to reach its destination, and the toughest part of its journey is still ahead.
The robot's job is to study what's under the surface of the Red Planet, but according to CBS News, it must first survive a difficult landing.
Payloads system engineer Farah Alibay is part of the engineering team that designed InSight's instruments. She says data from the mission will reveal more about the Red Planet's core - that is, if it survives its seven-minute landing in one piece.
"We call it the seven minutes of terror because at that point there's nothing we can do," she told CBS News.
NASA scientists estimate the spacecraft will enter Mars' atmosphere at just over 19,300km per hour.
A supersonic parachute will deploy first to slow the spacecraft's descent, and then InSight will drop from its heat shield about 1.6km from the surface, freefalling until reverse thrusters put on the final breaks.
InSight will then deploy solar panels and get ready for work, using a robotic arm to place a seismometer and a heat probe on the Martian ground.
Those tools will track the planet's temperature and measure quakes - if they end up as planned on a flat surface.
"We have one shot and we have to do it well," says Ms Alibaby.
"If we end up being on a little rock or something then that could affect our science."
If it all goes well, scientists expect InSight to beam back critical information for at least the next two years, helping pave the way for a manned mission to Mars.