The following is a statement from NASA Administrator Charles Bolden on Piers Sellers, who passed away Friday in Houston of pancreatic cancer.

“The entire NASA family mourns the passing of scientist and astronaut Piers Sellers.

“Piers was dedicated to all facets of exploration. His curiosity and drive to uncover new knowledge was generously shared with audiences around the world, both from space and in wide travels to reach as many people as possible with an essential understanding of our fragile planet.

“Piers devoted his life to saving the planet. As a climate scientist, his work in computer modeling of the climate system, satellite remote sensing studies and field work using aircraft, satellites and ground teams broke new ground in our understanding of Earth’s systems. 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. 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.

“Piers was an eternal optimist whose positive energy inspired all those who had the good fortune to know him. His laughter, humor, and lighthearted spirit are as much a part of his legacy as his work.

“In his three journeys to orbit as a NASA astronaut, he demonstrated robotics, performed research and helped build the International Space Station. These journeys and his ongoing dedication to scientific inquiry inspired a new generation to take up his challenge to become better caretakers of Earth and extend humanity’s reach in space. It was my great honor to present Piers with the Distinguished Service Medal in June 2016 in recognition of his service to our agency and the world.

“In a New York Times opinion piece in 2016, he said, ‘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. From this God’s-eye-view, I saw how fragile and infinitely precious the Earth is. I’m hopeful for its future.’

“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. 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."