There are two missions to Mars in 2021. An American and a European one. The ESA one has specifically been sent to search for signs that life once existed on Mars but I think they are going to be in competition with each other to find something which should be pretty exciting.
More promising than those, in my opinion, is the launch of the James Webb Telescope also next year. I think this is our best hope for finding life because I think it has the potential to do spectroscopy of exoplanet atmospheres. And that’s where we might start discovering some crazy stuff.
NASA have also announced they intend to send a crew to Mars by the end of 2024 including the first woman. I’m dubious about that timeline but they plan to use the Orion spacecraft so lots of the technology exists. But how will they get down and back from the moon’s surface? That one will be really interesting to watch.
But more interesting than all of these (but also potentially the most disappointing) is the Dragonfly mission to Titan in 2026. Titan is a truly fascinating place with its methane rain, lakes and rivers.