This button is a souvenir of the second human mission to service the Hubble Space Telescope (HST), conducted aboard the Space Shuttle Discovery via STS-82 in 1997. The HST was designed to be serviced in orbit so that repairs and upgrades could be made, expanding the capacities of the instrument and extending its life.
In particular, the button called attention to the collaboration between NASA, the European Space Agency, universities, and industry required to perform this human servicing mission to the astronomical instrument.