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.
1. A lander called Schiaparelli will touch down on the surface of Mars.
2. Around the same time, a spacecraft called the Trace Gas Orbiter (TGO) will enter orbit around Mars.
3. Schiaparelli is basically a test of how to land successfully on Mars.
4. The orbiter is going to be looking for signs of life.
5. ExoMars is a joint mission by ESA and Roscosmos, the Russian space agency, and it's had a bumpy past.
6. The next stage of the mission is a rover that will launch in 2020.
If you want to follow along as the TGO orbiter gets into orbit and the Schiaparelli lander lands, watch ESA's livestream here.
Kelly Oakes is science editor for BuzzFeed and is based in London.
Contact Kelly Oakes at email@example.com.
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