Piers Sellers: A Legacy of Science

Piers Sellers floating above on the aft flight deck of the Space Shuttle Atlantis in 2002. (Credits: NASA)

By Patrick Lynch
NASA’s Goddard Space
Flight Center

Piers Sellers, who passed away on Dec. 23 more than a year after learning he had pancreatic cancer, leaves behind a dynamic legacy at NASA.

As an astronaut he helped build the International Space Station. As a manager he helped lead hundreds of scientists. And as a public figure he was an inspiration to many for his optimistic take on humanity’s ability to confront Earth’s changing climate.

But his most lasting contributions will be in the field where he began his career: science.

Sellers arrived at NASA’s Goddard Space Flight Center in 1982 from his native Great Britain and dove into pioneering research on the use of satellites and computer models to study photosynthesis on a global scale. An ecologist by training, Sellers focused on the challenges of understanding and simulating the complex interactions between Earth’s atmosphere and biosphere – the collection of the planet’s plant life.

In the mid-1980s, Sellers led the work that created the first realistic computer model of how the biosphere interacts with Earth’s climate. He would go on to mine deeply this line of research, breaking new ground and helping build the foundation for what the science community now understands.

“It took years and years, but at the end of it we came up with a complete theoretical understanding of how it goes from a single leaf, with its little chloroplasts doing photosynthesis, to what that looks like from space, and then how to integrate the whole thing to find out the photosynthetic power of the planet,” Sellers said in a 2016 interview.

While Sellers could dazzle a crowd with stories of seeing Earth from space as an astronaut, he lit up equally talking about the excitement of scientific breakthrough.

“It was enormous fun,” he said. “It was the most fun I ever had. It was a huge scientific adventure.”

Sellers’ five most impactful scientific journal articles – collectively outlining his Simple Biosphere Model (SiB), updates to it (SiB-2), and insights into how forest canopies conduct photosynthesis – have been cited in a combined 7,697 scientific papers. The work has had enormous impact on the current understanding not only of how the planet works, but also of how Earth will respond to rising carbon dioxide concentrations in the atmosphere.

“Piers did seminal work,” said Colleen Hartman, head of Goddard’s Sciences and Exploration Directorate. “It completely changed the paradigm of how to use satellite data and made it so much more useful for applications in the real world and for understanding our changing climate. Purely on the science, he would be an icon.”

Compton Tucker, longtime close friend and scientific collaborator, said Sellers’ work unified different strands of research in the still nascent field of remote sensing from space.

“What was really crucial was that Piers brought the theory to what we were measuring,” Tucker said. “What his studies of photosynthesis showed was that it didn’t matter if you working on one leaf, or were working on tens, or hundreds, or thousands of kilometers. The same relationship held and scaled regardless of what scale you were working at. This was a major revelation.”

In the late 1980s, Sellers led two groundbreaking field research campaigns. The FIFE campaign in the Kansas grasslands and BOREAS campaign across the Canadian boreal forests combined ground, aircraft and satellite measurements and provided important new insights into forest and land ecosystems interactions with the climate.

The scale of the campaigns was beyond anything NASA Earth science had ever put together. Sellers organized the intricate details of people’s work on the ground, research flights by a fleet of aircraft, and the timing of satellite overpasses. Sellers, who learned to fly gliders growing up in Britain and remained an avid pilot throughout life, even piloted some of the research flights. The two campaigns alone generated nearly 900 scientific papers.

In the 1990s, Sellers served as the first project scientist for the Terra mission, the first satellite in NASA’s Earth Observing System and a flagship of the agency’s Earth-observing fleet.

As a young boy in England, Sellers watched the Apollo landings in awe.

“I thought NASA was the holy mountain,” he said during a 2016 ceremony in which Administrator Charles Bolden awarded Sellers the space agency’s Distinguished Service Medal. “As soon as I could, I came over here to see if I could climb that mountain.”

After 14 years as a NASA scientist, Sellers changed course in 1996 when he joined the NASA astronaut corps. In three space shuttle missions, STS-112, 121 and 132, he completed spacewalks, helped build the International Space Station, and gained a perspective on Earth that would infuse his talks to the public for the rest of his life.

And then after 14 years as an astronaut, Sellers returned to Goddard, this time as a leader within the Sciences and Exploration Directorate and Earth Sciences Division. He took to management with the same energy that he had applied to being a scientist and an astronaut, Hartman said, and in doing so inspired those around him.

“It’s not hyperbole to say every life he touched was moved for the better,” Hartman said. “His inclusiveness, kindness of heart, wit and intellect came through every day at Goddard. You can say Piers Sellers loved a lot of things, but high, high, high on that list would be science at Goddard. What mattered was he lived it each and every day, and he embraced management in a way that he never had before.”

Goddard center director Chris Scolese remarked on Sellers’ ability to energize those around him. “We remember Piers as an exceptional scientist and leader, but most importantly as an inspiring human being,” Scolese said. “He could make you think anything was possible, was always up for the adventure, and would remind you along the way how lucky we are to do the work we do here at Goddard.”

After learning of his cancer diagnosis, Sellers took on a much higher public profile when a January 2016 op-ed he wrote in The New York Times resonated deeply with people around the world. The piece described how his diagnosis affected his approach to our changing climate. It captured both the depth of his thinking on the topic and his pragmatic optimism.

“There is no convincing, demonstrated reason to believe that our evolving future will be worse than our present, assuming careful management of the challenges and risks,” Sellers wrote. “History is replete with examples of us humans getting out of tight spots. The winners tended to be realistic, pragmatic and flexible; the losers were often in denial of the threat.”

Sellers wrote that he considered all the ways he could spend his final months on Earth, but then reflected on his career and made his choice.

“Very quickly, I found out that I had no desire to jostle with wealthy tourists on Mount Everest, or fight for some yardage on a beautiful and exclusive beach, or all those other things one toys with on a boring January afternoon,” he wrote. “Instead, I concluded that all I really wanted to do was spend more time with the people I know and love, and get back to my office as quickly as possible.”

In the final year of his life, Sellers gave dozens of interviews about his grounded yet hopeful perspective, culminating in an appearance in the documentary, “Before the Flood,” released this fall. The message resonated, Hartman said, because of its authenticity.

“There was no artifice. He was exactly what he said he was. When you’re in the public arena, that’s so rare,” Hartman said. “Here is this incredibly accomplished NASA scientist. He never diverted into hyperbole, he never exaggerated for effect. He said what the science was showing and what conclusions could be drawn from that at this stage in a way that people could understand. He understood it so deeply that it was like falling off a log for him. And I think the public recognized that.”

Sellers’ enthusiasm for NASA’s role in understanding our home planet was apparent until the end. In an interview at Goddard earlier this year, he summed up his thoughts on working at NASA.

“We’re very fortunate working in the field that we do,” he said. “It’s incredibly fascinating and exacting and interesting, just the things we do day to day. And the bond among scientists in the group, the whole (Goddard Earth Sciences Division), all 1,500 people, is very strong, from the most junior post-doc up to management. And, you know, most of my friends are at work. Every day I work with my friends. I love it.”

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  • rzogheb

    I saw his interview in “before the flood” documentary and had to find out more about this amazing man. He will truly be missed.