On April 29, 1985, the European Space Agency’s Spacelab launched on the space shuttle Challenger on mission STS-51B.
This was the second time the Spacelab went to space and the first time it flew in a fully operational configuration.
Spacelab pallets had flown to space on three previous shuttle missions, but this was the first time that the entire laboratory was used to conduct research in microgravity.
Spacelab provided a platform for five fields of research: astronomy, atmospheric physics, materials science, life science and fluid dynamics.
Source: https://www.space.com/39251-on-this-day-in-space.html
