London: British-born astronaut Piers Sellers has died of pancreatic cancer, aged 61, Nasa has said.
Sellers, a climate scientist and former astronaut gained fame late in life for his eloquent commentary about the earth's fragility.
The British-born space scientist, who flew on three space shuttle missions between 2002 and 2010, died on Friday in Houston, Texas, the BBC reported.
Sellers shared his astronaut's perspective on climate change in Leonardo DiCaprio's documentary, Before the Flood, released earlier this year.
He told DiCaprio that seeing the earth's atmosphere as a "tiny little onion skin" from space helped him gain a fuller understanding of the planet's delicacy.
He also wrote a New York Times op-ed about grappling with the meaning of his life's work after learning he had terminal cancer, the Guardian said in its report.
In both the film and the op-ed, he was optimistic, arguing that he expected human ingenuity to rescue the planet from a dire future of runaway global warming.
Nasa Administrator Charles Bolden described Sellers as "a tremendous public servant who was dedicated to Nasa, the nation and the world".
Born in Crowborough, East Sussex, Sellers began working for the US space agency as a scientist in 1982 before joining its astronaut corps in 1996.
Nasa said Sellers was diagnosed with stage four pancreatic cancer in 2015.
He became a naturalised US citizen in 1991, making him eligible for the space programme.