Getting to Mars is no easy feat, and roughly a third of the missions launched have failed.

No surprises then that there’s a lot of anxiety tied up with the landing of NASA’s InSight on the red planet later today.

The InSight mission is being led by NASA’s Jet Propulsion Laboratory in Pasadena, California. InSight lifted off in May, and the lander was accompanied by two small, Mars-bound satellites that are collectively called Mars Cube One.

There are a number of reasons why this landing won’t be easy. For one thing, the atmosphere on Mars is about 1% as thick as Earth’s, which provides enough friction to burn up a spacecraft, reports Business Insider.

This, among other things, makes the landing notoriously difficult with a high failure rate. Here’s WGN with what’s going to happen when the lander tries to touch down:

The landing capsule has to batter its way through the atmosphere. It will fly through the Martian air at an initial speed of 12,300 mph, and it must hit the atmosphere at an angle of precisely 12 degrees. Any shallower, and the probe will bounce off into deep space.

Any steeper, and the probe will burn itself up in a spectacular and fiery death. The probe will first touch the atmosphere six minutes and 45 seconds before landing. During this phase, it will experience acceleration 12 times that of the Earth’s gravity. Were the probe a 150-pound human, during the flaming descent, it would weigh nearly a ton.

About 3½ minutes after the probe hits the atmosphere, a parachute will deploy, slowing down the probe even more. Fifteen seconds later, explosives will blow the heat shield off, exposing the actual InSight probe hidden inside. Ten seconds after the heat shield falls away, the probe will extend its legs, much like an airplane extends its wheels before touching down.

The probe will fall for an additional two minutes attached to the parachute and protected by its conical shell. About 45 seconds before InSight lands, it will drop out of the shell and fall toward the surface. As soon as it leaves the shell, its landing rockets will ignite.

It takes between seven and eight minutes for a radio signal to travel from Mars to Earth, which means that the complete landing process will take place before we receive any word from it.

It will take roughly seven minutes for the probe to make contact, letting NASA know that the landing was successful, and radio silence means a failed mission. For the scientists and engineers who designed InSight, this is called “seven minutes of terror”;

If all goes well, the lander will drill into Mars and collect data until November 2020.

You can tune in at 9PM tonight to watch the landing here:

[sources:wgn&businessinsider]