The European Space Agency mission, launched almost four years ago, revealed the universe's "coolest" secrets by observing the frigid side of planet, star and galaxy formation.

"Herschel gave us the opportunity to peer into the dark and cold regions of the universe that are invisible to other telescopes," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate at NASA headquarters in Washington. "This successful mission demonstrates how NASA and ESA can work together to tackle unsolved mysteries in astronomy."

Confirmation the helium is exhausted came today, at the beginning of the spacecraft's daily communication session with its ground station in Western Australia. A clear rise in temperatures was measured in all of Herschel's instruments.

Herschel launched aboard an Ariane 5 rocket from French Guiana in May 2009. NASA's Jet Propulsion Laboratory in Pasadena, Calif., built components for two of Herschel's three science instruments. NASA also supports the U.S. astronomical community through the agency's Herschel Science Center, located at the California Institute of Technology's Infrared Processing and Analysis Center in Pasadena.