Sellers , who was Deputy Director of the Sciences and Exploration Directorate and Acting Director of the Earth Sciences Division at NASA 's Goddard Space Flight Center, was known for his advocacy for the climate change policies.
Hollywood star and environmental activist Leonardo DiCaprio featured Sellers in his documentary "Before the Flood" on the impacts of global warming that was released two months ago.
Eloquently speaking about the fragile earth's climate and his own cancer diagnosis in the opinion section of the New York Times in January 2016, Sellers urged of the reality of climate change and called for measures to stem it.
President-elect Donald Trump has suggested climate change is a hoax and raised the possibility of withdrawing U.S. support for a new global accord to reduce greenhouse gas emissions which most scientists believe are driving up sea-levels and more droughts and violent storms.
As astronaut , Sellers made three space shuttle missions to the International Space Station between 2002 and 2010, before NASA retired its shuttle fleet in 2011 after completing the U.S. portion of the $100 billion International Space Station, a permanently staffed research complex orbiting 250 miles (400 km) above Earth.