The little Philae lander (100kg, 21kg of which is instruments) left the Rosetta mothership and plunked itself down safely on Comet 67P/Churyumov-Garasimenko. Or pulled itself down: the lander fired mini-harpoons into the surface and winched its way to contact. The mission was launched ten and a half years ago. Flight controllers had tense moments as they waited out the 28-minute signal delay from the distant comet. NASA was a partner in areas including maintaining deep-space communications.
(Artist concept - credit ESA)