Jim Green

Chapter 1 · Late 1960s A Telescope in a Small Iowa Town

Jim Green was born and raised in Burlington, a small town in Iowa on the bank of the Mississippi. In the interviews he gave to NASA, he traces his vocation back to high school, and to an instrument many amateur astronomers would envy.

The Keys to the Observatory

His high school chemistry teacher had been given the keys to a small observatory housing a donated telescope. It was no ordinary telescope: a refractor, that is, a lens telescope, of twelve inches, about thirty centimeters, made by the Alvan Clark firm in the 1930s, “1936 or so,” he believes. Alvan, he notes, has since gone out of business.

For two years the instrument was at the high school student’s beck and call. He built instruments for it himself. He studied the stars and the planets. Some of his pictures ended up in Sky & Telescope, the leading American magazine for amateur astronomers. For two summers he photographed the Sun every day, for three months each time.

A Decision Made

By the end of high school, he relates, he knew exactly what he wanted to do: get into college and earn a degree in astronomy. He did not yet know that these amateur photographs of the Sun would open the door to the office of one of the most famous scientists of the space age.

He would later say that he was not always great in school: there were ups and downs, and the lesson he draws for young people is that you have to stay the course.

Sources: NASA, Gravity Assist podcast, season 2, episode 1, “Explorer 1 with Jim Green,” March 1, 2018, transcript (Burlington, the chemistry teacher, the twelve-inch Alvan Clark refractor from the 1930s, two years, instruments, pictures in Sky & Telescope, the Sun over two summers, the decision, the ups and downs). The sources consulted do not give his date of birth; we therefore do not state it.

Chapter 2 · 1970s “You’re My Only Student”

At the University of Iowa, in Iowa City, Jim Green took the introductory astronomy course in his first year, with about four hundred other students. On the first day, the only seats left were in the front row. That suited him: he wears glasses and does not see well at a distance. The professor was James Van Allen.

The Man of Explorer 1

Van Allen was then one of the most famous scientists in the United States. On January 31, 1958, four months after the Soviet Sputnik, the first American satellite, Explorer 1, had carried his experiment into space: a Geiger counter meant to measure cosmic rays. The measurements from Explorer 1, then Explorer 3, revealed a surprise: a ring of very high-energy particles, trapped by Earth’s magnetic field above the atmosphere. In May 1958 Van Allen announced the results. These regions have since been called the Van Allen radiation belts. For nearly all scientists, Jim Green recalls, it was a huge surprise.

Room 701

Jim Green got an A in the first semester. In the second, he signed up for a small two-credit course, “readings in astronomy,” taught according to the catalog by the professor’s “staff.” At the appointed time he opened the door of room 701 in Van Allen Hall and found what looked like a warehouse: printouts on every table, magnetic tapes, cluttered bookcases. He thought he must have messed up and checked his course catalog in the doorway. From behind a bookcase, a voice called out: “Jim, this is the place and you’re my only student.”

So instead of a graduate student, he had Van Allen to himself for a whole semester. When the professor learned that the student had photographed the Sun every day with his high school refractor, during a period of maximum solar activity, he suggested turning it into research. “Research? What’s research?” Jim Green answered. Van Allen suggested measuring how fast the Sun spins by following its sunspots from day to day. The student thus repeated a measurement made some seventy years earlier and wrote a real science paper, with abstract, introduction and discussion. Van Allen was the referee. By the end of the semester, he says, he knew what research was all about. This is what he calls, in the vocabulary of his podcast, his “gravity assist”: the encounter that changed his trajectory.

Three Degrees and Jupiter

Jim Green did all his studies at the University of Iowa: bachelor’s, master’s, then a doctorate in space physics, earned in 1979. It was, he says, a fabulous time for the space program. He was involved in major missions and experiments. He worked in particular on data from the Voyager 1 and 2 probes, and a great deal on Jupiter. His research would focus on the magnetospheres of Earth and Jupiter, the magnetic bubbles that surround planets and trap charged particles.

Sources: NASA, Gravity Assist podcast, season 2, episode 1, March 1, 2018 (the introductory course, four hundred students, the front row, Van Allen, the A, the readings course, room 701, Van Allen’s words, the Sun’s rotation, the paper, Explorer 1 on January 31, 1958, Explorer 3, the May 1958 announcement, the surprise); NASA Headquarters Oral History Project, interview of J. L. Green by J. Ross-Nazzal, April 11, 2017 (three degrees at Iowa, Voyager and Jupiter, “fabulous time”); NASA, “Chief Scientist History” (1979 doctorate, papers on the magnetospheres of Earth and Jupiter).

Chapter 3 · 1980 – 1985 Huntsville, Rocket City

In 1980, doctorate in hand, Jim Green joined the Magnetospheric Physics Branch of NASA’s Marshall Space Flight Center in Huntsville, Alabama. This is where Wernher von Braun and his team had built the rockets of the early space age. He would never leave NASA again.

A Network for Scientists

At Marshall he continued his research and worked on several missions, even more than at the university. He also developed and managed a computer network, the Space Physics Analysis Network, which gave scientists all over the world rapid access to data, to other scientists and to NASA’s computing resources. It was the beginning of a specialty that would mark his whole career: the management of scientific data.

He also remembers a supervisor who one day walked into his office and asked him: “Don’t you know when to give up?” He was trying to do something very simple in his eyes, but that had never been done at the center, and that, for that very reason, nobody wanted to do. He draws a rule from it: you have to take the attitude of never giving up on some things.

A Diver in the Tank

The Marshall center has a large water tank, the Neutral Buoyancy Simulator, where engineers and astronauts learn to work as if weightless. Jim Green became a safety diver there. He would make more than one hundred fifty dives before leaving Marshall in 1985. He would recall that he “pushed around engineers and astronauts in the water” while they learned to work in space, and that the experience gave him an enormous appreciation for human spaceflight.

The Mystery of the Letters UE

In Huntsville he once invited his former professor, James Van Allen, to give a talk, then held a reception at his house. Tray of hors d’oeuvres in hand, he went from group to group and stopped next to Van Allen, who was talking with his next-door neighbor, Jack Waite, an engineer who had worked with von Braun. Waite asked Van Allen if he knew what the two big letters “UE,” painted on the Explorer 1 rocket, meant. Van Allen admitted he had never known.

Waite explained: the word Huntsville has nine unique letters. U is the second, E the ninth. “UE” was a code for the number 29. Why not simply paint 29 on the rocket? Because the press would have asked what happened to the other twenty-eight. And the answer, Waite added, was that they had all blown up. Jim Green remembers exchanging a look with Van Allen and thinking that, thank God, UE had not blown up.

Sources: NASA, “Chief Scientist History” (joined Marshall in 1980 in the Magnetospheric Physics Branch, the Space Physics Analysis Network, more than 150 dives until 1985); NASA oral history interview, April 11, 2017 (missions at Marshall, diver in the tank, appreciation for human spaceflight); interview of June 7, 2017 (the supervisor and his question); Gravity Assist podcast, March 1, 2018 (Van Allen’s talk, the reception, Jack Waite, the UE code). The explanation of the UE code is the one Jack Waite gave that evening, as Jim Green reports it; we have not checked it elsewhere. The mention of von Braun in Huntsville comes from the same podcast.

Chapter 4 · 1985 – 2006 Keeper of the Data

In 1985 Jim Green left Huntsville for the Goddard Space Flight Center in Greenbelt, Maryland, near Washington. He would stay more than twenty years. There he continued his career as a researcher, but he also discovered management.

NASA’s Memory

From 1985 to 1992 he headed the National Space Science Data Center, NASA’s largest space science data archive. That is where, mission after mission, the measurements sent back by the probes are kept. In 1992 he took over a larger division, the Space Science Data Operations Office, with three branches, including the center he had headed. In 2005 he became Chief of the Science Proposal Support Office.

Missions Around the Earth

He remained a researcher. He was a co-investigator and the Deputy Project Scientist on the IMAGE mission, a satellite that imaged Earth’s magnetosphere. From 1992 to 2000 he was also Deputy Project Scientist for Mission Operations and Data Analysis for the WIND and POLAR satellites. Many years later he would tell the astonishing story of IMAGE: the satellite, orbiting in the radiation belts, stopped calling home one day, probably clobbered by those particles, then came back to life thirteen years later.

His work dealt with the magnetospheres of Earth and Jupiter. He would author more than one hundred ten articles in refereed scientific journals, and more than fifty technical articles on data systems and computer networks. In the scientific world, he notes, one hundred peer-reviewed papers is considered a good career.

The Whole World

Starting in 1986, Stan Shawhan, head of the Magnetospheric Physics Branch at NASA Headquarters, drew him into many international activities. In the 1980s and 1990s, four space agencies worked together on joint missions, and Jim Green took part. He built personal connections with scientists and administrators from space agencies around the world. These relationships, he would say, would prove essential later, when he ran NASA’s planetary science.

His work was recognized. He received the Arthur S. Flemming Award, which honors outstanding federal employees, in 1988 according to NASA and Wikipedia, in 1998 according to another NASA article. In 1996 Japan awarded him the Kotani Prize for his international science data management activities.

The Wish to Give Back

Toward the late 1980s, he relates, he began to think that one day he wanted to give back to the scientific community. For a space scientist, the best service possible, in his view, is to come to NASA Headquarters in Washington and work in the science program, helping others succeed.

Sources: NASA, “Chief Scientist History” (NSSDC from 1985 to 1992, Space Science Data Operations Office in 1992, Science Proposal Support Office in 2005, IMAGE, WIND and POLAR from 1992 to 2000, more than 110 and more than 50 articles, Flemming Award in 1988, Kotani Prize in 1996); NASA oral history interview, April 11, 2017 (more than twenty years at Goddard, three branches, a hundred papers, Stan Shawhan from 1986, international connections, the wish to serve); interview of June 7, 2017 (four agencies and joint missions); Gravity Assist podcast, March 1, 2018 (loss and return of IMAGE after thirteen years); T. Talbert, “NASA’s Jim Green: A Decade of Planetary Discovery,” NASA, August 15, 2016 (Flemming Award in 1998); English-language Wikipedia, “James L. Green” (Flemming Award in 1988; tertiary source).

Chapter 5 · 2006 – 2012 Running Planetary Science

In 2006 the director of NASA’s Planetary Science Division left, and the deputy position was vacant as well. The Science Mission Directorate, then headed by Mary Cleave with Colleen Hartman as her deputy, urgently needed someone to step in.

“Call Jim Green”

Colleen Hartman called the Goddard Center Director, Ed Weiler, and read him a list of names. At the end, Jim Green relates, Weiler told her to call Jim Green, who was on the list, and tell him to get down to Headquarters and help out. Hartman called Green and gave him a week to think about it. He answered that he did not need to think about it: Ed had just told him what to do. He asked only for a few days to prepare a transition plan. In August 2006 he arrived at NASA Headquarters in Washington as acting director. He enjoyed the job at once; he applied for it and got it officially.

Two Goals

On arrival he set himself two goals. The first: fix research. In 2005 the planetary science budget had been $1.4 billion; in 2006 it had fallen to $1.1 billion, a cut of nearly $300 million. He wanted to put money back into research, which funds scientists at universities, in industry and at NASA centers. The second: start a mission to Europa, the icy moon of Jupiter he had studied through the Voyager data. He naively believed, he would say, that he could get it going quickly. It would take him ten years.

A Job That Wears You Down

He would stay in the post until April 2018: nearly twelve years, making him the longest-serving planetary science director in NASA’s history. The average tenure, he noted in 2017, is about 2.8 years. Why? Because this job, he says, “chews you up and spits you out.” He is the top advocate for planetary science in the federal government, and a whole community of researchers depends on his ability to protect the budget.

He also explains how a large mission gets decided. About every ten years, the National Academy of Sciences brings together the best specialists to set the priority science questions and the missions that might answer them: the “decadal survey.” NASA follows it. But to start a very large mission, you must convince your own boss, then the NASA Administrator, then two White House offices, the science policy office and the budget office, then both houses of Congress. It takes only one of them to stop it all.

Twelve Hours a Day

He arrives at the office around six in the morning. Before the meetings start, around eight, he spends two hours reviewing what is being published in every field: astrobiology, planetary geology, Mars, Venus. He works about twelve hours a day, and says that this is the fun part of the job.

Sources: NASA oral history interview, April 11, 2017 (the director’s departure, M. Cleave and C. Hartman, the call to Ed Weiler, Green’s answer, August 2006, application, 2005 and 2006 budgets, research and Europa, ten years, naivety, longest-serving director, average of 2.8 years, “It chews you up and spits you out,” the decadal survey and the approval steps, twelve hours a day from six o’clock); NASA, “Chief Scientist History” (director from August 2006 to April 2018); T. Talbert, NASA, August 15, 2016 (longest-serving director in NASA history).

Chapter 6 · 2008 Phoenix, the Ice of the Martian Far North

The first Mars landing Jim Green experienced as director was that of Phoenix, a stationary lander designed to study the soil and ice near the north pole of Mars.

In the Antenna Room

Phoenix left Earth on August 4, 2007. On May 25, 2008, after ten months of travel, it touched down in the north polar region, on terrain poor in boulders and rich in ice, using small thrusters that shut off when the sensors in its footpads detected the ground. That day Jim Green was at JPL in Pasadena, but not in the main control room. He had settled into the adjacent room, that of the Deep Space Network, NASA’s network of large antennas, where signals from space arrive first. There he had, he relates, a console that displayed a lot more information, right where the signals were coming in.

Ninety Days Are Not Enough

Phoenix’s nominal mission was ninety days. As Jim Green remembers it, the lander lasted close to one hundred fifteen days, before the polar winter covered it in snow and broke off its solar panels. NASA’s catalog states that its last signal was received on November 2, 2008, more than five months after landing.

What he remembers most is the state of the team. Running a mission for ninety days, he says, exhausts people: they are pushed to their limits, they had high aspirations, and they could not get everything done, however well organized they were. There is never enough time. He was still talking about it nine years later, in his 2017 interview.

Water Under the Surface

Phoenix was part of a long investigation. For Jim Green, one of the best discoveries of the Mars Odyssey orbiter, in service around Mars since the early 2000s, was the indication of a subsurface layer of water, detected remotely by its neutron detector. That discovery, he says, gave a reason to get down to the surface. It is in this logic, as we see it, that Phoenix belongs, set down on ice-rich ground.

Sources: NASA NSSDCA, “Phoenix Mars Lander” entry (launch on August 4, 2007, ten months of travel, landing on May 25, 2008, powered descent, ice-rich polar site, last signal on November 2, 2008); NASA oral history interview, June 7, 2017 (the Deep Space Network room, the console, ninety days, “close to 115 or so,” the snow and the panels, the team’s exhaustion); interview of April 11, 2017 (Mars Odyssey, the neutron detector and subsurface water). The lifetime Jim Green gives does not match the date of the last signal; we give both.

Chapter 7 · 2009 – 2012 “If Curiosity Crashes, It’s Going to Be Me”

Curiosity is a one-ton rover. NASA had never landed anything that heavy on Mars, and the method planned was new. For Jim Green, its landing would remain one of the high points of his career.

Twenty-Six Months of Reprieve

The rover was supposed to leave in 2009. Technical difficulties made that date impossible. Since one can leave for Mars only about every twenty-six months, the departure was pushed back two years. That delay, Jim Green says, turned out to be the right thing to do: it gave time to work out the problems. Curiosity was launched on November 26, 2011.

The “Bad Day Plan”

For each landing, NASA prepares a contingency plan: what to say, how to run the press conferences, which procedures to trigger if the craft crashes. For Curiosity, this “bad day plan” was half an inch thick. Jim Green was supposed to read it on the plane. He admits he was so confident he was almost cocky; during the landing he stayed calm.

He also wanted the public to live the event. With Kristen Erickson, whom he had brought into his team, he organized events at NASA centers and museums across the country, and even on the jumbotron in Times Square, in New York, where people could follow the JPL operations room live. His boss, Ed Weiler, asked him to scale back these preparations. Jim Green answered that if Curiosity crashed, he knew exactly what would happen: somebody would get fired, it would be him, and he was good with that.

Engineering as the Hook

Before a thousand researchers gathered for the meeting of the “Division of Planetary Science,” he presented the upcoming landing and asked them to study the material prepared for them, so they could answer the journalists in their own cities. A top scientist, not a Mars specialist, stood up and objected that it was all about engineering. Jim Green answered that he was missing the point: spectacular engineering brings everybody together; once you have a captive audience, you can talk to them about the science. The engineering, he said, is the hook.

On August 6, 2012, at 05:32 Universal Time, Curiosity touched down in Gale Crater, chosen for its potential as a former habitat for life. Everything went perfectly.

What Curiosity Found

Within the first eight months of its mission, Curiosity met its main objective: finding evidence of a past environment well suited to support microbial life. Jim Green would sum up its results with simple images. The rover sits in an area that was full of water for tens of millions of years at least; by drilling into the sediments laid down by that water, it showed that the water was not salty: 3.5 billion years ago, he says, you could have drunk it. The soil also contains nitrates, a great fertilizer, and all the necessary elements: carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus. You could, in his view, grow crops in it.

Curiosity runs on plutonium: the heat of its decay produces electricity. It can therefore work at night, or in the middle of a dust storm, without depending on the Sun.

Sources: NASA oral history interview, June 7, 2017 (one-ton rover, new method, the 2009 delay and twenty-six months, the “bad day plan,” his confidence, K. Erickson, Times Square, Ed Weiler and the words “it’s going to be me,” the thousand scientists, “the engineering is the hook”); interview of April 11, 2017 (drinkable water, nitrates and elements, plutonium and night work); NASA NSSDCA, “Mars Science Laboratory” entry (launch on November 26, 2011, landing on August 6, 2012 at 05:32 UT, Gale Crater); T. Talbert, NASA, August 15, 2016 (objective met within the first eight months).

Chapter 8 · 2008 – 2017 Follow the Water

“Follow the water”: during the years Jim Green ran planetary science, this was the motto of Mars exploration. He made it his own, because the question that drives him most is that of life elsewhere.

A Lost Ocean

Mission after mission pieced together the history of water on Mars. The Spirit and Opportunity rovers, then Curiosity, found on the ground minerals that form only in the presence of water, such as hematite. In 2017 Jim Green summed up what we think we know: Mars once had an enormous amount of water; about thirty percent of its northern hemisphere was an ocean, in places more than a mile deep. That ocean may have lasted more than a hundred million years, maybe five hundred million, at the very time life was starting on Earth.

Then Mars lost its magnetic field. Without that shield, the solar wind, the stream of particles flowing out from the Sun, began stripping its atmosphere, the oceans evaporated, and the planet became today’s cold desert. Much of the water, however, remains trapped in the polar caps and under the surface. In March 2017 NASA announced that the MAVEN probe had made it possible to estimate that most of the gas ever present in the Martian atmosphere had been lost to space; about 65 percent of the argon, for instance.

Streaks on the Slopes

On September 28, 2015, NASA announced that the Mars Reconnaissance Orbiter had provided “the strongest evidence yet” that liquid water, very salty, flows intermittently on present-day Mars. These were dark streaks that appear on slopes in the warm season and fade in winter; hydrated salts had been detected in them. Jim Green was one of the agency’s spokespeople for the announcement.

Science also advances by correcting itself. On November 20, 2017, a new study, presented by JPL, interpreted these streaks instead as flows of dry sand and dust, on slopes steep enough for that, and concluded that these sites would be too dry for microbes to thrive. NASA then added a note to its 2015 release to flag this update.

Planets That Echo Each Other

For Jim Green, the history of Mars sheds light on that of Earth. What happened on Venus, he says, can happen on Earth; so can what happened on Mars. Planets evolve, and each shows a possible stage. He draws a striking conclusion from this, in his 2017 interview: “When we end up looking like Venus, we’d better be on Mars, or this species won’t survive.” Planetary science, he adds, is one of the sciences that matter for the survival of the human race.

Sources: NASA oral history interview, April 11, 2017 (Spirit, Opportunity, Curiosity and hematite, the ocean over thirty percent of the northern hemisphere, more than a mile deep, one hundred to five hundred million years, loss of the magnetic field, water in the polar caps, Venus and Mars, the quotation on Venus and Mars); interview of June 7, 2017 (“what’s happened on Mars could happen on Earth”); NASA, release 15-195 of September 28, 2015; JPL, “Recurring Martian Streaks: Flowing Sand, Not Water?,” November 20, 2017; NASA, release 17-033 of March 30, 2017 (MAVEN, 65 percent of the argon); English-language Wikipedia, “James L. Green” (spokesperson for the 2015 announcement; tertiary source). The motto “follow the water” is quoted in the 2015 release.

Chapter 9 · 2010s Adviser on “The Martian”

In 2015 The Martian came out, Ridley Scott’s film based on Andy Weir’s novel, with Matt Damon as astronaut Mark Watney, stranded on Mars. If you look closely at the credits, you will find Jim Green’s name. He has told in detail how he ended up there.

A Serial Novel

Andy Weir, he explains, loved science fiction and wanted to write it. His first book did not do well; he became a programmer. But he kept writing and posted The Martian chapter by chapter on his website, free, taking his readers’ comments into account. He drew his research from everything NASA was putting online about Mars. When he finished, about three thousand people were following the serial. To let them read it on an e-reader, he put it on sale on Amazon at the minimum price of 99 cents. The book became the site’s top science fiction seller. An agent contacted him, a publisher brought it out, and Fox studios bought an option on it.

A Phone Call

Ridley Scott wanted a realistic film. So he called NASA. At Headquarters, all film industry requests go through the Office of Communications, and in particular through Bert Ulrich. One day Ulrich came running to look for Jim Green and caught him coming out of the cafeteria: could he talk to Ridley Scott at two o’clock? “The Ridley Scott?” Green asked. He talked with the director and his team for close to an hour. The next day he received the script. Over the weekend he bought and read the novel. On Monday he told Bert Ulrich that it was the most realistic Mars movie ever, and that NASA had to get behind it. The Office of Communications made him the head contact for the film team. He went from twelve to fourteen hours of work a day.

Tours and Questions

He organized tours of NASA centers. At the Johnson Space Center in Houston, the team saw the Mars habitat NASA was developing and the International Space Station control rooms; at JPL, the probes’ control rooms. Jim Green began with a forty-five-minute overview of the real planet Mars compared with the novel, then proposed changes to the script. He quickly understood that the script was already locked; three or four of his suggestions were nonetheless taken, and he is proud of that. For months he received twenty or thirty questions each week, which he answered himself or passed on to specialists: ion engines, radioisotope power for probes…

He would have liked Mark Watney to flip his rover on the way to Schiaparelli crater, and above all for the film to deal with Mars sample return, a subject dear to him. Time ran out. Much of what is in The Martian, he says, is nonetheless true: Andy Weir used the research NASA was publishing. The Martian soil analyzed by Curiosity contains what is needed to grow crops.

Science Fiction and Science Fact

After the film came out, he gave around the world, from Beijing to Tokyo and from England to Canada, a talk titled “The Martian: Science Fiction and Science Fact,” comparing what we really know about Mars with how the film portrayed it. It was, he says, his first film as an adviser; if there was ever one to be on, it was this one.

Sources: NASA oral history interview, April 11, 2017 (Andy Weir’s story, three thousand readers, 99 cents, Amazon, the agent, Fox, Ridley Scott’s call, Bert Ulrich, the cafeteria, forty-five minutes to an hour, the script and the book, “the most realistic Mars movie ever,” fourteen hours, the JSC and JPL tours, the suggestions taken, the questions, the flipped rover, sample return, Martian soil, the talk “The Martian: Science Fiction and Science Fact,” the first film); T. Talbert, NASA, August 15, 2016 (his name in the credits); English-language Wikipedia, “James L. Green” (2015 involvement; tertiary source).

Chapter 10 · 2015 – 2018 Where Should the First Humans Land?

Around the time he was working on The Martian, Jim Green realized something: the satellites NASA had placed around Mars could provide imaging and mineral maps precise enough to prepare a landing of astronauts. He decided to put planetary science at the service of human spaceflight.

A Coffee Table on Mars

The main tool is the Mars Reconnaissance Orbiter, which arrived at Mars on March 10, 2006. Its camera, he says, could see a living-room coffee table sitting on Mars. But in eleven years it had imaged only about 3.5 percent of the surface at that resolution: Mars is a big place, and the orbiter has other tasks, notably relaying the data of rovers and landers back to Earth. The farther you are from Earth, the lower the data rate. If humans are ever to land, they will need very high-resolution imaging of their site, and nobody yet knows which site it will be. And the orbiter will not last forever.

“Learning to Be a Martian”

At a panel discussion he hit it off with astronaut Mike Fincke, who invited him to come and speak to the astronauts at the Johnson Space Center. Jim Green wrote a talk called “Learning to be a Martian: Science and Exploration on Mars.” The room was packed. In the afternoon, a public discussion set him in friendly disagreement with an astronaut: the astronaut thought any flat place would do; Jim Green answered no way, the site would have to be chosen carefully, because astronauts would need to use the resources of the Martian soil. He also met the center director, former astronaut Ellen Ochoa, and asked her to detail an astronaut to NASA Headquarters to work with his team on finding a landing site. He also asked her if she had read The Martian; she had not, and he urged her to. An astronaut was soon detailed to work with him.

Exploration Zones

With the human exploration directorate, his team defined an “exploration zone”: a region about two hundred kilometers across, where you land in one place, live in another, do science at several locations and extract resources: water from an underground aquifer or buried ice, dust to be turned into habitat panels with 3D printing, perhaps heat from the interior. The zone must also contain fascinating science sites, such as the shoreline of the ancient ocean, where life might have started. A workshop brought scientists and engineers together; it produced some forty candidate sites, forty-five according to the June 2017 interview, forty-eight according to the April one.

Unlike what the film shows, he insists, NASA does not intend to go from site to site: it will choose a single site and return to it for decades, because habitats and power will have to be installed there. He hopes that once the site is chosen, it can be turned into a virtual reality model, so that today’s children, who may be the ones who go, can walk around in it.

The Moons of Mars

He also supported the Japanese MMX mission, which is to bring back a sample from Phobos, one of the two moons of Mars; NASA provides an instrument. Knowing where Phobos and Deimos come from, captured asteroids or pieces of Mars, interests scientists; knowing Phobos also interests human spaceflight, because the first astronauts might stop there before going down to Mars, or operate robots on the surface from there. Human exploration, he likes to say, is not Star Trek: before sending people, you have to know everything about their destination.

Sources: NASA oral history interview, June 7, 2017 (the realization, MRO and the coffee table, 3.5 percent in eleven years, relay, data rate, Mike Fincke, “Learning to be a Martian,” the disagreement, Ellen Ochoa and the detailed astronaut, exploration zone of two hundred kilometers, resources, shoreline, forty-five sites, a single site for decades, virtual reality, MMX and Phobos); interview of April 11, 2017 (forty-eight sites, 3D printing with dust, the moons of Mars and human spaceflight, “Human exploration is not Star Trek”); NASA NSSDCA, “Mars Reconnaissance Orbiter” entry (arrival on March 10, 2006). The exact dates of the talk and the workshop are not given in the sources consulted.

Chapter 11 · 2012 – 2021 Mars 2020: Bringing Back Pieces of Mars

Among the missions he championed, Jim Green names two great battles: the mission to Europa, and Mars 2020, the rover that would become Perseverance. The second bears directly on Mars.

A Mission Deemed Too Expensive

The decadal survey ranked the beginning of Mars sample return as a top priority. But the way it laid that out was, according to Jim Green, “completely unexecutable.” Another way had to be found. Mars 2020 came at the worst moment: the planetary science budget was falling year after year. In a single fiscal year, in the early 2010s, the division lost well over $200 million according to his April 2017 interview, about $370 million according to the June one. No one in the Obama administration wanted to move Mars 2020 forward; it was deemed way too expensive. The White House budget office also feared the snowball effect: if you core rock on Mars, you will have to pay for the missions to bring the samples back.

In the same period, NASA had to back out of agreements made with the European Space Agency for the 2016 ExoMars mission. Jim Green deeply regrets it: the decision was forced on him, he says, and NASA was not a very good partner. Europe agreed to let NASA keep a small piece of the mission.

Reusing Curiosity

Curiosity’s success changed the picture. Mars 2020 would reuse Curiosity’s chassis and its “crazy” sky crane, the entry, descent and landing system that had already proven itself. The rover could be built with existing spare parts, for far less than an entirely new craft. It would core rock, store the cores in cases for an eventual return to Earth, and its instruments would even examine the walls of the drilled holes to read the rock’s layers.

The stakes, he explains, are climate. Mars looked like Earth when life started here; then its climate changed very quickly. We do not know whether the shift from a water world to today’s desert took ten million years or a hundred million. Bringing back rocks from that era would tell us, and perhaps reveal traces of microbial life.

Jezero

Mars 2020 left on July 30, 2020. On February 18, 2021, at 20:55 Universal Time, the Perseverance rover touched down in Jezero Crater, on the edge of the Isidis basin. Jim Green was then NASA’s chief scientist. With Perseverance traveled a small helicopter, Ingenuity, which made its first flight on April 19, 2021: thirty-nine seconds, thirty of them hovering at three meters.

Sources: NASA oral history interview, April 11, 2017 (the decadal sample return “completely unexecutable,” the loss of “well over $200 million,” ExoMars 2016 and the forced decision); interview of June 7, 2017 (Mars 2020 and Europa, the falling budget, about $370 million, the Obama administration, the budget office’s fears, reuse of Curiosity, the sky crane, the cases, examining the holes, climate, ten or a hundred million years); NASA NSSDCA, “Mars 2020” entry (launch on July 30, 2020, landing on February 18, 2021 at 20:55 UT, Jezero, Ingenuity and its first flight on April 19, 2021); NASA, “Chief Scientist History” (chief scientist from 2018 to 2021).

Chapter 12 · 2017 A Magnetic Shield for Mars

In late February and early March 2017, the Planetary Science Division held an unusual workshop at NASA Headquarters: “Planetary Science Vision 2050.” The aim was not to set priorities, but to imagine what solar system exploration might look like by the end of the 2040s. Jim Green presented there, with seven co-authors, an idea that would get people talking.

The Diagnosis

Their abstract starts from the present state of Mars: an arid, cold world with a very thin atmosphere, holding much frozen water at the surface and underground. That atmosphere prevents liquid water from staying on the surface and makes landings difficult, because it is not thick enough to brake a craft. In the past, Mars may have had an ocean covering perhaps thirty percent of its northern hemisphere. When it lost its protective magnetosphere, three or more billion years ago, the solar wind was able to ravage its atmosphere directly. The Mars Express and MAVEN probes have measured that Mars is still losing atmosphere; this loss is partly balanced by gases escaping from the planet’s interior, so that the surface pressure is about six millibars, less than a hundredth of Earth’s.

The Idea

The authors proposed to study, through simulation, what would happen if Mars were protected from the solar wind. Their idea: place a powerful magnet at Mars’s L1 Lagrange point, a point of balance between Mars and the Sun where an object keeps the same position relative to both. This magnet would create an artificial magnetosphere whose “tail” would envelop the whole planet and shelter it. The authors admit that this may sound “fanciful,” but cite recent research on miniature magnetospheres to protect astronauts and spacecraft, and the idea that inflatable structures might one day generate a field of one or two tesla.

The Hoped-For Result

Sheltered, the Martian atmosphere could thicken and warm up to a new equilibrium. According to their abstract, an average rise of about 4 °C would be enough to melt the veneer of frozen carbon dioxide over the northern polar cap. That greenhouse gas, released, would begin melting the water in the cap, where nearly one seventh of the ancient Martian ocean is thought to be trapped. A thicker atmosphere would allow heavier craft to land, shield against radiation, ease oxygen extraction and allow “open air” greenhouses. If this could be achieved in a lifetime, they write, the colonization of Mars would not be far away.

This is a proposal for a study, not a NASA project. But it shows how Jim Green thinks about Mars: as a planet that was habitable, that lost that quality for physical reasons we are beginning to understand, and about which we can at least ask whether it might regain it.

Sources: J. L. Green, J. Hollingsworth, D. Brain, V. Airapetian, A. Glocer, A. Pulkkinen, C. Dong and R. Bamford, “A Future Mars Environment for Science and Exploration,” Planetary Science Vision 2050 Workshop, 2017, LPI Contribution No. 1989, abstract 8250 (all the scientific content of the chapter, the word “fanciful” and the sentence on colonization); Planetary Science Vision 2050 Workshop website (purpose of the workshop, dates: February 27–28 and March 1, 2017 in the text, February 28–March 1 in the dates box). The explanation of the Lagrange point and the pressure comparison are the author’s clarifications; the last paragraph is the author’s reflection.

Chapter 13 · 2018 – 2022 Chief Scientist

In 2018, after nearly twelve years at the head of planetary science, Jim Green changed roles. NASA’s acting administrator, Robert Lightfoot, named him the agency’s chief scientist, effective May 1, 2018.

The Agency’s Adviser

The chief scientist advises NASA’s leadership on all its science programs. In this role Jim Green followed a line of researchers that includes, among others, astronaut Shannon Lucid and Ellen Stofan. He held the post during Perseverance’s landing on Mars, in February 2021.

Telling the Science

Since Curiosity’s landing, he has considered that making discoveries known is part of his job. The public, he explained in 2017, is one of the top stakeholders: it pays for everything through its taxes. He hosts a NASA podcast, Gravity Assist, in which he asks scientists about their careers and the person or event that changed their trajectory. In 2015 he gave a TED talk on the places in the solar system most likely to harbor life.

A Question Left Open

In 2016, marking ten years at the head of the division, he said he did not plan to retire until we answer the question: are we alone in the universe? Confirming the existence of microbial life, past or present, on Mars, Europa or Enceladus would be, in his words, “mind-blowing”; not finding it would be remarkable as well. He had told his whole community that he planned to be director of planetary science on the day life was found elsewhere.

He retired on January 1, 2022, after more than forty years at NASA, without the question being settled. The samples collected by Perseverance are still waiting, as this book is written, for the mission that will bring them back to Earth.

An Asteroid and Balloons

In 2017 an asteroid was named after him: (25913) Jamesgreen. A Civil War Trust member, he is also interested in the observation balloons of the American Civil War: he has written and spoken on the subject and advised on building a replica of a balloon of the period, which lifted off on July 4, 2012 in Mumford, New York.

Sources: English-language Wikipedia, “James L. Green” (appointment by R. Lightfoot effective May 1, 2018, retirement on January 1, 2022, more than forty years, 2015 TED talk, asteroid 25913 Jamesgreen in 2017, Civil War balloons, replica and flight of July 4, 2012; tertiary source); NASA, “Chief Scientist History” (list of chief scientists, including S. Lucid and E. Stofan; J. L. Green from 2018 to 2021); NASA oral history interview, June 7, 2017 (the public paying through its taxes); interview of April 11, 2017 (director on the day life is found); T. Talbert, NASA, August 15, 2016 (“My current plan is not to retire until we answer the question, ‘Are we alone in the universe?’,” “mind-blowing”); Gravity Assist podcast, 2018 (the podcast’s premise). The chief scientist’s role is summarized from his successor’s entry on the same NASA page. The sentence on Perseverance’s samples is the author’s, as of October 2026.