6 Things To Know About The ExoMars Mission

The European Space Agency is putting a spacecraft in orbit around Mars and landing a module on the planet's surface.

On Wednesday, if all goes to plan, a joint European and Russian Mars mission called ExoMars will reach two important milestones. Here is what you need to know.

ESA/ATG medialab / Via exploration.esa.int

1. A lander called Schiaparelli will touch down on the surface of Mars.

ESA / Via esa.int

It was launched along with an orbiter in March this year and has just reached the red planet. Schiaparelli separated from the orbiter a few days ago, and will do its entry, descent, and landing on Wednesday. It's due to enter the atmosphere at 3.42pm UK time and land at 3.49pm.

You can watch a video showing how it'll reach the planet here.

2. Around the same time, a spacecraft called the Trace Gas Orbiter (TGO) will enter orbit around Mars.

ESA / Via exploration.esa.int

At about 2pm UK time, the spacecraft will turn and then fire its engine for just over two hours (134 minutes, to be precise) to slow it down long enough that it can be captured by Mars's gravity.

Instructions for the manoeuvre have already been uploaded to the spacecraft, so all the scientists can do now is wait.

3. Schiaparelli is basically a test of how to land successfully on Mars.

ESA/ATG medialab / Via exploration.esa.int

To explore other planets in detail, first you have to land on them – intact, and in the right place. The European Space Agency (ESA) calls successfully pulling off the entry, descent, and landing procedures one of the "greatest challenges in space exploration", and it's using Schiaparelli as a test case.

A bunch of new technology will be used during the landing, including a parachute and liquid propulsion braking system, to slow the module down from its speed of 21,000km per hour to zero. Sensors will be monitoring the whole process and reporting back to Earth. If all goes well, the same technologies will be used in future European Mars missions.

The lander will also do a tiny bit of work while its on the planet, but its scientific mission will only last for a few days, running off excess battery power from the landing. The lander will be investigating what's going on in the atmosphere of the planet and measuring its electrical field.

Schiaparelli will land on the Meridiani Planum, a site of interest to scientists because of the layer of iron oxide they've spotted there. On Earth, iron oxide tends to mean water is present.

4. The orbiter is going to be looking for signs of life.

Thales Alenia Space/Imag[IN] / Via exploration.esa.int

While the Schiaparelli lander's mission might seem more dramatic, it's TGO that'll be looking for biological activity. It's going to be analysing trace gases, i.e. gases that are present but only in very small amounts, in the planet's atmosphere from orbit.

Previous missions have suggested that there might be a tiny bit of methane in there, and, if there is, it could be a sign of biological activity. The Martian atmosphere is constantly bombarded with UV radiation and that, over hundreds of years, would destroy methane – which means any that exists must have been produced recently. TGO will be finding out if that methane exists, and if so, where it exists, to help scientists figure out where it's coming from.

5. ExoMars is a joint mission by ESA and Roscosmos, the Russian space agency, and it's had a bumpy past.

ESA/ATG medialab / Via esa.int

Planning for ExoMars began in 2001, but the mission has changed significantly since then. In 2009, NASA signed up and agreed to work with ESA on launching two rovers to Mars using its Skycrane system, which successfully put the Curiosity rover on the planet. But in 2012 NASA pulled out of ExoMars, citing budget constraints.

The mission's future was then up in the air for a short while, until Roscosmos stepped in and agreed to work with ESA on the mission, providing two launch vehicles and various other bits and pieces.

6. The next stage of the mission is a rover that will launch in 2020.

Thales Alenia Space-Italy / Via exploration.esa.int

This week's events are really just the start of the mission, and will set the stage for a rover to launch to the planet in 2020. The plan is that the rover will arrive at Mars in 2021, using technology developed and used in the Schiaparelli lander. From then on, the TGO orbiter will act as a communications relay, sending commands to the rover on the planet, and the data it collects back to Earth.

The rover will drill to depths of 2 metres and collect samples that will then be analysed on its onboard lab. It'll help ExoMars live up to the "Exo" part of its name by focusing its studies on exobiology, the science of life beyond Earth.

If you want to follow along as the TGO orbiter gets into orbit and the Schiaparelli lander lands, watch ESA's livestream here.