Since 1962, Cornell has been involved in unmanned missions to Mars. In the 21st century, Cornell had a hand in the Mars Exploration Rover Mission. Cornell's Steve Squyres, Principal Investigator for the Athena Science Payload, led the selection of the landing zones and requested data collection features for the Spirit and Opportunity rovers. Jet Propulsion Laboratory engineers took those requests and designed the rovers to meet them. The rovers, both of which have operated long past their original life expectancies, are responsible for the discoveries that were awarded 2004 Breakthrough of the Year honors by "Science". Control of the Mars rovers has shifted between NASA's Jet Propulsion Laboratory at Caltech and Cornell's Space Sciences Building. Further, Cornell researchers discovered the rings around the planet Uranus. Also, Cornell built and operated the world's largest and most sensitive radiotelescope in Arecibo, Puerto Rico.