After seven months of traveling to Mars, Europe and Russia's two ExoMars spacecraft are scheduled to separate from one another this morning — a crucial move just three days before they reach the Red Planet. The two vehicles have been connected to one another since they launched from Earth in March, but now it’s time for both probes to get started on their primary missions. One will look for signs of life in Mars’ atmosphere, while the other just needs to land on the Martian surface in one piece.

Schiaparelli just needs to land on the Martian surface in one piece

It's all part of the first phase of the ExoMars mission, a joint project between the European Space Agency and the Russian Federal Space Agency to figure out of there is — or ever was — life on the surface or Mars. This current phase consists of two spacecraft: an orbiter, called the Trace Gas Orbiter, and a lander, called Schiaparelli. The orbiter’s job is, unsurprisingly, to orbit Mars and study the components of the planet's atmosphere. After separation today, the TGO will slightly change its course later this evening, putting itself on track for entering Mars’ orbit on Wednesday.

Schiaperelli will also have a big job to do on Wednesday, but it will be a much more harrowing experience. The lander needs to demonstrate that it can, in fact, land on Mars — which isn’t an easy task. Mars has a less dense atmosphere than Earth, so it provides less cushion for slowing down incoming spacecraft. But the cone-shaped Schiaperelli is equipped with a series of parachutes, thrusters, and a heat shield to help it land safely on the planet’s surface. All of these features will work in tandem to slow down the falling lander from about 13,000 miles per hour.

An rendering of the Trace Gas Orbiter (on the left) separating from the Schiaperelli lander (on the right). (ESA)

Today’s separation is meant to prepare Schiaperelli for that fateful descent. At around 10:42AM ET, mechanisms on the orbiter will push away the lander and give it a spin. This rotation will help keep the lander stable over the next three days as it continues on toward Mars. Schiaperelli will also enter hibernation mode about 15 minutes after separation to conserve energy prior to landing.

A lot of focus is being placed on making sure Schiaperelli’s landing goes smoothly, since it's really the lander's only job. Once it makes it to the surface, the vehicle will send back data about how the entry, descent, and landing went — and then in a couple days, its onboard battery will likely run out of power. That’s because Schiaperelli’s mission is considered a demonstration mission, showing that ESA and Russia's way of landing on Mars works. That’ll be important for the second phase of the ExoMars mission, where the two agencies will try to land a 680-pound rover on the surface of Mars. The second phase was originally scheduled to land in 2018, but technical delays have pushed the mission back to a 2020 launch. Schiaperelli’s landing will let the ExoMars team know if they are capable of landing such a heavy payload on the Martian surface.

ESA is providing live updates leading up to today’s separation, and there will be a short livestream starting at 10:30AM ET to confirm the event. If for some reason separation doesn’t occur today, ESA has the option of trying again tomorrow.