HOUSTON, Dec. 24 (UPI) -- British-born NASA astronaut Piers Sellers died of pancreatic cancer at the age of 61 in Houston on Friday, officials said.
NASA released a statement mourning Sellers, a climate scientist who flew to the International Space Station in 2002, 2006 and 2010 and performed six spacewalks during his time in the space program.
"Today we lost a tremendous public servant who was dedicated to NASA, the nation and the world. He was a strident defender and eloquent spokesperson for our home planet, Earth," NASA Administrator Charles Bolden said. "Spacewalker and scientist, free thinker and friend to our planet, and all who seek new knowledge, to say he will be missed would be a gross understatement."
Fellow astronauts, including Tim Peake of the European Space Agency, paid respects to Sellers.
"Saddened to hear the loss of British born astronaut Piers Sellers - a true inspiration," Peak said on Twitter. "Thoughts are with his family."
Sellers was born in Crowborough, East Sussex on April 11, 1955 and began working for NASA as a scientist in 1982 before becoming a member of the astronaut corps in 1996, according to the BBC.
During his three trips to orbit he demonstrated robotics, performed research and helped build the International Space Station.
He was diagnosed with stage four pancreatic cancer in 2015, and wrote an op-ed about the diagnosis in the New York Times.
"As an astronaut, I spacewalked 220 miles above the Earth. Floating alongside the International Space Station, I watched hurricanes cartwheel across oceans, the Amazon snake its way to the sea through a brilliant green carpet of forest, and gigantic nighttime thunderstorms flash and flare for hundreds of miles along the Equator," Sellers wrote. "From this God's-eye-view, I saw how fragile and infinitely precious the Earth is. I'm hopeful for its future."
Sellers also appeared in Leonardo DiCaprio's documentary, Before the Flood, to discuss climate change.
"His legacy will be one not only of urgency that the climate is warming but also of hope that we can yet improve humanity's stewardship of this planet," Bolden said. "His cancer diagnosis became a catalyst for him to work even harder on efforts to save the planet from global warming for the benefit of future generations."