The US space shuttle Endeavour comes back to Earth today for a landing in Florida that will close its 19-year operational career. The ship has spent the past two weeks at the International Space Station, where it delivered a $2bn particle physics experiment. Once on the ground, the orbiter will be decommissioned and prepared for public display in Los Angeles. This will leave just the Atlantis shuttle to make a final flight in July. Nasa is committed to ending its shuttle programme. The vehicles are too costly to maintain and operate, and the agency believes a more affordable approach to getting astronauts to the ISS can be achieved by contracting out their transport to private companies.