https://www.newscientist.com/article/mg23831802-100-cosmic-cooperation-is-just-what-space-exploration-needs/

But space exploration is more than the sum of its parts, and by collating what we learn about different space rocks we are piecing together a bigger picture. When NASA’s New Horizons probe arrived at Pluto in 2015, the dwarf planet’s make-up stumped researchers – until a comparison with findings by the ESA Rosetta spacecraft, which visited comet 67P in 2014, revealed it is perhaps made of a billion such comets, smashed and squeezed together to make a world (see “Pluto is not a planet – it’s a billion comets squished together”).

ESA and NASA now plan to work together on a mission to gather what could be the most valuable rock of all: a pristine piece of Mars (see “We need to grab some rocks from Mars – let’s just get on with it”). Subjected to a full battery of tests on Earth, such a rock could help unlock one of the deepest mysteries: whether life ever spawned elsewhere.