Profiles in Science | The Planet Hunter
Geoffrey Marcy of the University of California, Berkeley, has discovered scores of alien worlds, so-called exoplanets circling distant stars.
BERKELEY, CALIF. — Last summer a homely room in the
basement of a math building on the University of California campus here was
ground zero in the epic quest to end cosmic loneliness.
An area rug with geometric shapes and yellow rings
suggestive of planetary orbits covered the floor. A photograph of the Milky Way
rising over the Hawaiian volcano Mauna Kea hung on one wall. A Naugahyde couch
ran along one side of the room. Opposite it was a small refrigerator with a
stash of Grape-Nuts and soy milk.
The nearest bathroom was two sets of
password-protected security doors away.
This is the lair of Geoffrey W. Marcy, holder of the Watson
and Marilyn Alberts Chair in the Search for Extraterrestrial Intelligence and, outside a certain robot spacecraft named Kepler,
the most prolific American discoverer of alien worlds, so-called exoplanets
circling stars beyond the sun.
An August evening found Dr. Marcy, a gray-goateed,
twinkly-eyed presence with an aggressively empathetic air, crouched as usual in
a corner in an old wooden desk chair. In front of him were computer screens and
a video display connecting him to Mauna Kea, home of the twin Keck telescopes, at 40 feet in diameter the two largest in the world.
Photo
CreditIllustration by Sean McCabe; Photograph by Brian
L. Frank for The New York Times
He clicked an icon on one of his screens. Three
thousand miles west and 14,000 feet up, a glass container about the shape and
size of a tuna can slid into place in the beam of the Keck I telescope,
interposing a calibrating layer of iodine gas between it and the stars.
That was farther away, he noted, than the Hubble
Space Telescope.
Queued up for observation from Mauna Kea that night
were a few dozen of the most promising objects yet found by NASA’s vaunted
planet-huntingKepler spacecraft.
“These are earths,” Dr. Marcy said, gesturing to the
screens. “All my life I’ve pointed telescopes at stars not knowing if planets
were there or not. Now we know.”
He paused.
Humanity, he said, had arrived at a special but
bittersweet moment.
For thousands of years, people had looked up at the
night sky wondering whether they were alone in these starry depths, whether
there was any place like Earth out
there, and how they would ever know. Only 20 years ago, the notion of other
worlds and other life was dismissed as science fiction in respectable academic
circles. Now astronomers have evidence that there are more planets than stars
out there, a billion chances for Darwin, a billion potential real estate deals,
a billion sci-fi dreams come true — a signature shift in cosmic perspective, in
which Dr. Marcy played a leading role.
He and his colleagues were on the verge of being able
to say how common Earthlike worlds were in the galaxy.
Dr. Marcy was being mentioned as a contender for the Nobel Prize.
But Kepler had broken down after
four years of planet-hunting glory, and plans had collapsed for a grand, much-promoted
space mission known as theTerrestrial Planet Finder, which could produce images of distant planets, sniff
their atmospheres and perhaps map their geography to determine whether they
were habitable or inhabited.
The field, he feared, was approaching a lull.
“What are we going to do when we’ve squeezed the last
drop from Kepler?” Dr. Marcy asked. “A side of me is already grieving.”
Cosmic Dreams
Photo
Dr. Marcy, wearing his heart on his car bumper. The
astronomer has not shied away from earthbound causes, either.CreditRamin
Rahimian for The New York Times
The road to the math building basement had been bumpy
and long, and Dr. Marcy had the emotional bruises to show for it. He was born
59 years ago in St. Clair Shores, Mich., and had what he called a “plain
vanilla” upbringing in the San Fernando Valley, imbued with a love of sports
and space. Carl Sagan, the Cornell astronomer, best-selling author and host of
the PBS series “Cosmos,” was his hero.
He attended U.C.L.A. and then the University of
California, Santa Cruz, where he earned a Ph.D. using spectroscopic
measurements to study magnetic fields in stars.
But the starry road almost ended shortly after that.
Dr. Marcy won a prestigious postdoctoral fellowship to continue his magnetic
research at the Mount Wilson Observatory in Pasadena, Calif., where he would be using the
same telescope with which Edwin
Hubble had
discovered the expansion of the universe in 1929.
But Dr. Marcy’s measurements didn’t work and his
previous results came under fire from other astronomers. “I
got really hammered in Pasadena,” he recalled.
He was devastated. He felt stupid and ill judged. “I
was so obviously a fraud,” he recalled thinking. He consulted a psychiatrist.
He wondered if he was suicidal. Then he wondered how
he would know.
A turning point, he said, came while he was in the
shower one morning in 1983, contemplating the end of his astronomy career. He
decided that if he was going down in flames, he would go down doing something
he believed in. He vowed to spend the rest of his career hunting for life in
the universe. That meant searching for planets around other stars.
“You need planets,” he said. “That stands at the
nexus. The logical platform for life is a planet.”
By the time he got out of the shower, his fingers were
all wrinkled.
“I’ve never forgotten how miserable I was in that
shower,” Dr. Marcy said.
A Fire in the Belly
When his fellowship was up in 1983, Dr. Marcy took a
job teaching at San Francisco State University, far from the research limelight
— it had no Ph.D. program. In his spare time, between teaching and fixing the
telescope on the roof of the science building, he assembled a team of students
to work on how to find planets around other stars — if they were out there.
One of his students was Mario Savio,
formerly the firebrand leader of the Free Speech Movement in Berkeley in the
’60s. In his office, Dr. Marcy keeps a picture of Mr. Savio, who went on to
teach physics at Sonoma State and died in 1996, at 53. He was brilliant, Dr.
Marcy recalled, but “he hated writing computer code.”
A big break
came when a graduate student, R. Paul Butler, who had just received an
undergraduate chemistry degree, showed up in his office in the fall of 1986.
A recipe for
finding planets had been laid out by the eminent astronomer Otto Struve in 1952. He pointed out that a planet would give
its home star a small gravitational kick, inducing a wobble into the star’s
motion as seen from Earth. In principle this could be detected by slight shifts
in the wavelengths of light from the star, like theDoppler shift that causes the pitch of an ambulance siren to
change as it goes past. But it required a spectrograph that could detect the
shifts of one part in 10 million to see something like Jupiter.
Dr. Marcy’s
new graduate student had “fire in his belly,” he recalled, and he put him to
work finding a way to make a spectrograph sensitive enough to do the job. At
Mount Wilson, Dr. Marcy already knew, solar astronomers calibrated their
spectrographs by passing sunlight through iodine, which absorbs light at
particular wavelengths, producing dark lines like the gaps in a picket fence that
can serve as reference points.
After
considering other ideas, he and Mr. Butler settled on iodine to calibrate their
own machine. Mr. Butler built a cell to hold iodine, and in 1987 they installed
it on the Shane three-meter telescope at the university’s Lick Observatory, outside San Jose, and began
looking at stars.
It took them
eight years to refine their techniques to find a planet. Wavelength shifts
could be easily blurred, for example, by changes in the atmosphere from night
to night or even moment to moment. The same effects that make stars twinkle
could make their planets indistinguishable.
“We were we
struggling without any road map,” said Dr. Butler, who earned a Ph.D. from the
University of Maryland in the process and is now at the Carnegie Institution for Science in
Washington. “Nobody knew who we were. The few people who knew what we were
trying to do also knew that our quest was quixotic at best, and more likely
just flat out laughable.”
Natalie
Batalha, then a student at Berkeley and now a leader on the
Kepler project, agreed.
Dr. Marcy, she
said, “was a San Francisco State professor, hanging around Berkeley working on
a program nobody had confidence that it would come to anything.”
‘Like Being on
Columbus’s Ship’
Just when they
were getting good at searching, Dr. Marcy and Dr. Butler were scooped.
In the fall of
1995, using the same wobble technique, a team led by Michel Mayor and Didier
Queloz, of the University of Geneva, found a planetroughly half the mass of Jupiter,
circling the star 51 Pegasi, about 50
light-years away, in only four days — way inside of where Mercury orbits our
sun. That was a major surprise. Jupiter takes 12 years to orbit the sun, and
astronomers had presumed that other planetary systems would be structured like
our own.
Dr. Marcy and
Dr. Butler dashed up to Lick Observatory and confirmed the new planet. They
came down the mountain elated.
“It felt like
being on Columbus’s ship,” Dr. Marcy said.
A Milky Way
section which Kepler has scanned for planets.CreditCarter Roberts
Their own time
came a few weeks later.
Early on the
morning of Dec. 30, Dr. Marcy and his wife, Susan Kegley, were getting the
house ready for a New Year’s Eve party, when Dr. Butler called, summoning him
to the office. “All he said was ‘Geoff, get over here,’ ” Dr. Marcy
recalled later.
On a graph
when he got there was the up-and-down velocity cycle of a giant planet orbiting the star 70 Virginis, about 60
light-years from here.
With the next
two years they found 10 more planets, generating headlines but also bruising
controversy, as if Dr. Marcy had never gotten out of that shower. Some
prominent astronomers argued that the Marcy-Butler team was confusing starspots
or double stars for planets. The systems they were discovering were too unlike
our solar system to be taken seriously.
“For three or
four years, nobody believed us,” Dr. Marcy said.
At one point
he was invited to give a talk at a prominent meeting in Houston, home of the Lunar and Planetary Institute.
But when he got there he was ushered into a small room where half a dozen
scientists interrogated him.
“It sent me
into a tailspin,” Dr. Marcy said. “I was back to feeling stupid.”
Finally, in
November 1999, Dr. Marcy’s group and another team, led by David Charbonneau of
the Harvard-Smithsonian Center for Astrophysics,
more or less simultaneously detected the shadow of a planet crossing,
or “transiting,” in front of a star that already had been seen to wobble. The
combination of wobble and blink was impossible to explain as anything other
than a planet.
Sweet
vindication at last? Perhaps, but Dr. Marcy still is quick to point out that
the objections to his work were never retracted.
One of the
critics, David Black, an astronomer at the Lunar and Planetary Institute in
Houston, says there is no apologizing in science.
“It was never
personal, as he seems to think it was for some reason that I have never been
able to figure out,” Dr. Black said. “I think Geoff deserves all of the credit
and praise he has gotten for his work.”
Strained
Relationships
By the end of
the decade Dr. Marcy and Dr. Butler, joined by Dr. Marcy’s old mentor Steven
Vogt of the University of California, Santa Cruz, and Debra Fischer,
now at Yale, found themselves in intense competition with Dr. Mayor’s team,
often referred to as “the Swiss.” The two groups leapfrogged each other, adding
to the planet count.
The
constellation Cygnus, which Kepler has scanned for planets.CreditPalomar
Observatory, DSS; Davide De Martin, Sky Factory; Michael Benson
Dr. Marcy and
Dr. Butler were awarded the first Bioastronomy Medal of Honor by the International Astronomical Union,
beginning an avalanche of medals and awards. Dr. Marcy was elected to the National Academy of Sciences and
was on David Letterman’s show.
“We’re getting
closer to answering the golden question of whether there is life out there,” he
said in 2004. “We’re trying to find our own roots, chemically and biologically,
in the stars.”
By the end of
2005, he and Dr. Butler had found 107 planets. They were the Batman and Robin
of astronomy. But as the partnership grew, strains developed, with Dr. Butler
feeling increasingly marginalized as reporters flocked to the eloquent and
emotionally available Dr. Marcy.
Dr. Butler was
more brusque. When asked for a sound bite he was more likely to grumble that he
was looking forward to more data. “Some people want to be an astronomer, “ he
said in an interview a few years ago. “Other people just want to play one on
TV.”
Matters grew
tenser in 2005, when Dr. Marcy and Dr. Mayor were awardeda $1 million prize given annually by the late
Hong Kong film mogul and philanthropist Run Run Shaw.
Dr. Marcy
didn’t tell the rest of his team about the prize until he returned from Hong
Kong.
“I was afraid
it would cause the divorce it, in fact, caused,” he said later.
In 2007 Dr.
Vogt resigned from the team, saying he had lost confidence in Dr. Marcy’s
leadership. Dr. Butler soon followed. The real heroes in the exoplanet story,
he wrote in an email, are the astronomers who build the instruments. “In both
my career and Geoff Marcy’s career, the single most important person is Steve
Vogt.”
Interviewed
recently, a clearly uncomfortable Dr. Marcy said he had been saddened but not
surprised, comparing the rift to the breakup of the Beatles. “I would never
have left Paul and Steve,” he said. “They are family, period,”
He is
unapologetic about his own fame. “The news media likes me,” he said and added:
“I’ve been lucky. Professional astronomers know I’ve been in the basement.” Dr.
Marcy gave the bulk of his award to Cal-Santa Cruz and San Francisco State.
Dr. Batalha,
of the Kepler project, said the rivalries of the early days of the exoplanet
hunt had taken their toll. “It was a very intense competition,” she said. “It
didn’t have to be. Everybody was racing to be first.”
The divorce
had major consequences for the Automated Planet Finder, a
robot telescope that Dr. Vogt and Dr. Marcy had been planning to build at Lick
Observatory but was delayed for years. “In divorce, the kids are the
telescopes,” she said.
Dr. Marcy
eventually agreed to split the time on the telescope with the team of Dr. Vogt
and Dr. Butler. They drew straws to divide the 1,700 stars on their target list
and 12 years of data.
Dr. Marcy,
left, and a research partner, Dr. Paul Butler, at Lick Observatory in 1997. Dr.
Butler eventually resigned from Dr. Marcy’s team.CreditSusan Spann
“At the end of
the day you try to be honorable,” Dr. Vogt said. It began operating this year.
The Age of
Kepler
Then came
Kepler.
The NASA
spacecraft was launched in 2009 into an Earth-trailing
orbit around the sun. Its mission was to stare at one patch of stars for four
years looking for the periodic dimming that might signify planets passing in
front of their suns.
The grand goal
was to find Earthlike planets. The fraction of stars with such planets is known
as eta-Earth; it is a key factor in the so-called Drake Equation, used to calculate the number of
intelligent civilizations in the galaxy.
If we ever
have the ability to step out of our cosmic cocoon, the answer could help us
decide whether there will be anywhere to go, and how far away the nearest
habitable planet might be.
Or as William
Borucki, who spent 20 years persuading NASA to take on the
Kepler project, said, “We provide the data mankind needs to move out into
space.”
Kepler shook
the sky as if it were a tree. More than 1,000 possible planets fell out in the
first year.
Dr. Marcy had
been a member of Kepler’s science team from the beginning, in 2001. But it was
only in 2007, he said, that he finally had time to start going to the meetings.
“It changed my life by bringing Earth-size planets into view,” he said.
“Geoff is a
good guy,” said Dr. Batalha, Kepler’s deputy science director. She described
him as a gracious team member, generous with credit and going out of his way to
make younger astronomers feel valued.
When the
Kepler astronomers realized in 2012 that they would need more time than planned
for their survey, Dr. Marcy put on his “lucky underwear,” as he put it, and
went to NASA headquarters to argue for more time. “This is for my students,” he
said at the time.
When Kepler’s
pointing system failed a year later, cutting short its planet quest, Dr. Marcy
was theatrically despondent. Borrowing from a W. H Auden poem, he wrote:
Stop all the
clocks, cut off the Internet,
“All my
life I’ve pointed telescopes at star not knowing if planets were there or not,”
Dr. Geoffrey W. Marcy said. “Now we know.”CreditEuropean Southern Observatory
Prevent the
dog from barking with a juicy bone,
Let jet airplanes
circle at night overhead,
Skywriting
over Cygnus: Kepler is dead.
‘Chicken
Geoff’
Dr. Marcy
lives high in the Berkeley hills with Dr. Kegley, “wife, chemist, goddess,” as
he puts it on his website — an environmental chemist and chief executive of the
consulting firm Pesticide Research Institute. Their backyard is home to
beehives decorated with astronomical symbols, and a flock of chickens, leading
the son of one of his graduate students to call him “Chicken Geoff.”
Social
consciousness is part of his identity. At Santa Cruz he ran around plastering
“Men Against Rape” stickers over nude pinups in the engineering and optics
shops.
At Berkeley he
regularly hits the tennis courts with the women’s team. “They give me lessons,”
he said. Perhaps reflecting his own years of self-doubt, his website also has a
section on depression and suicide awareness. “Now I know I wasn’t alone,” he
said of those dark days in Pasadena. “It’s a common phenomenon.”
Once an
outsider with no future, Dr. Marcy now has his pick of collaborators and
students. “My undergraduates are even smarter than my graduate students,” he
said recently. He has also embraced the freedom to be outspoken.
At a meeting
at M.I.T. in 2011, he startled his colleagues with a bitter tirade about their
collective failure to win approval for the Terrestrial Planet Finder and
challenged President Obama to make a Kennedyesque declaration that we would
send a probe to Alpha
Centauri. That mission would revive the agency and maybe the
nation, which he says has been squandering its technological leadership in the
world.
“Every young
person is wondering, ‘What will my generation do that my parents didn’t
do?’ ” Dr. Marcy said.
His former
student Andrew W. Howard,
now at the University of Hawaii, said Dr. Marcy had the ability to see the big
picture and what to do next.
“He tries to
zero in on the right answer,” he said. “He’s not concentrated on little
details.”
This tendency
was in play last fall when Erik Petigura, another of Dr. Marcy’s graduate students, announced,
based on his own analysis of Kepler data, that about a fifth of the 100 billion
sunlike stars in the galaxy had potentially habitable Earth-size planets. In
effect he had beaten the Kepler team to the first estimate of the all-important eta-Earth.
The craft’s
breakdown prompted a W.H. Auden-inspired poem by Dr. Marcy.CreditRamin Rahimian
for The New York Times
Under Dr.
Marcy’s direction, Mr. Petigura had spent the previous two years building and
testing his own version of the computer pipeline by which Kepler data was
analyzed. “Learning the occurrence of Earthlike planets can be done only once,”
Dr. Marcy told him. “Erik, you’re the one; you can sleep later.”
The
announcement overshadowed a major exoplanet meeting at NASA’sAmes Research Center,
even as astronomers agreed that it was only the first of what would be many
tries at getting eta-Earth right. Mr. Petigura’s analysis was full of
assumptions and extrapolations that would be tested and retested in the coming
years, astronomers said.
As Dr.
Batalha, among others, pointed out, “we don’t yet have any planet candidates
that are exact analogues of the Earth in terms of size, orbit or star type.”
Dr. Marcy
nevertheless pronounced himself “tingly,” saying it was the most important work
he had been involved in. The National Academy of Sciences recently named their paper as
the best on the physical sciences published last year in The Proceedings of the
National Academy of Sciences, giving it the Cozzarelli
Prize.
The Stars of
Summer
One thing
Kepler couldn’t do without outside help was to say what these putative planets
were like. By recording those blinks, it could measure the sizes of planets,
but not their masses and densities. Thus there was no way to know whether these
worlds were bags of gas or rocks like Earth.
That was where
Dr. Marcy came in, along with the Keck telescope array and its ability to
measure wobbles and masses.
“We’re pouring
all our effort into planets roughly the size of Earth,” Dr. Marcy said, “not
just discovering but measuring the properties of Earth-size planets.
“The Greeks
would have enjoyed this,” he added. “They would understand. This is not quantum
field theory.”
He was
particularly interested in learning at what size a planet went from being a
rock with water on it, and possibly habitable like Earth, to being gas, like Neptune. The question
was of more than academic interest, since most of the Kepler planets are
between Earth and Neptune in size. The data seemed to suggest, he said, that
the break-even point between rocky and gaseous was about one and a half times
the size of Earth. Kepler has shown that there are plenty of such worlds out
there.
But without
the Terrestrial Planet Finder or something like it, the search for Earth 2.0
could go only so far. You could find a planet with the mass and orbit of Earth,
he explained, but “how do we know it’s not an ocean world like Kevin Costner, or dry as a
bone?”
Once upon a
time, astronomy was a romantic and physically grueling endeavor. Astronomers
kissed their spouses and children goodbye and decamped for distant mountains,
where they donned electrically heated flight suits to survive a frigid,
nightlong telescope vigil.
On this night
Dr. Marcy set up the telescope and its spectrometer with that tuna can of iodine,
then headed home for a meal of wild salmon and tomatoes and figs from his
backyard. Thus fortified, he returned to watch as Keck sent data from Hawaii to
Berkeley.
In his
California backyard, Dr. Marcy is known by a more informal name.CreditRamin
Rahimian for The New York Times
Over the next
few hours, a rogue’s gallery of stars, all of them home to suspected planets,
swam into view, one after another. “They are my children,” he said.
One screen
showed a star’s spectrum — a picket fence of dark and light, depending on which
wavelengths of light were there.
Another screen showed previous measurements of that star’s
velocity cycle as determined by earlier observations. Some looked like perfect
sine waves, the signature of a star being jerked rhythmically back and forth by
a planet; others were noisy clumps of points in which one could imagine
regularity. Dr. Marcy provided color commentary as if he were checking up on
old friends.
“This is a star pulling on a star,” he said as one came up.
He pointed to a small wiggle on another curve that suggested
a second planet where there was already one. “This is
frankly publishable now,” he said.
Another star, an old friend known as 16 Cygni B came up with
a saw-toothed pattern of motion, the signature of an egg-shaped orbit. He
recalled that he and Dr. Butler had been in his office at 4 a.m. when they
first saw it — the fourth or fifth planet they had discovered — “and it’s still
interesting.”
“Look at this beauty,” Dr. Marcy exclaimed. “This is Isaac
Newton screaming with joy from his grave.” He continued with a chuckle: “This
is my life. When we saw this, we were so excited. People didn’t realize planets
could be in elliptical orbits.”
The thought brought him back to the days of being criticized.
“It feels like a black and white movie to me, really a horror
film,” he said. “I was really distressed with myself.
“Kepler taught us that planets are common. We didn’t know
that.”
If Mr. Petigura’s analysis was right, he said, the nearest
Earthlike planets could be as close as 10 or 12 light-years away, within reach
of a moderate-size telescope. “If you do T.P.F., you will not come up empty.”
he said, referring to a Terrestrial Planet Finder. “You’ll have a handful of
them. So we have our homework.”
By then the sky was getting cloudy in Hawaii. “Bad news, but
this is astronomy,” Dr. Marcy said with a sigh as he went to look for bright
stars that would punch through the clouds.
“One thing about having a big telescope,” he explained: “We
can collect a lot of light through clouds.”
It was midnight when he moved on to the next star, one with
five planets.
“This is a great thing,” he said. “I love this.” For him the
night and the universe were young.
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