The International Space Station: the habitable sattelite and research unit orbiting the Earth. Through international efforts, it received a lot of upgrades over the years.

New Horizons: the brave probe who traveled for nine years through space to reach Pluto and send us pictures of it. Thanks to this one, we now know Pluto has a heart shaped spot (and what its atmosphere and surface are like, how solar winds work, how the universe came to be etc etc.)

Curiosity: the Wall-e'esque rover studying the environment of Mars right now, so we may one day be able to explore it in person.