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science.org SCIENCE“You just have to have the right tools to
find them.”
If Webb does find the early universe
swarming with black holes, astronomers
will be forced to reckon with their speedy
assembly. Did giant population III stars
collapse into black holes, providing “seeds”
that merged into supermassive ones? Or did
black holes form directly from collapsing
clouds of gas after the big bang? “It’s hotly
debated,” Maiolino says.
Besides probing the hectic birth of stars,
galaxies, and black holes, Webb will study
why the frenzy died down. “Forming stars
and galaxies is a party that is over,” says
Jane Rigby of NASA’s Goddard Space Flight
Center, who is Webb’s project scientist
for operations. Astronomers believe some
process—supernovae explosions, blasts from
AGNs, or stellar winds produced by giant
stars—could have blown clouds of gas out of
galaxies, starving star formation of its fuel.
One of Webb’s four instruments, the Near
Infrared Spectrograph (NIRSpec), should be
able to see these outflows and trace them to
their source. The NIRSpec has an innovative
mask with nearly 250,000 slitlike micro-
shutters, each about the width of a human
hair, that operators can open to let light
through at specific locations. By analyzing
light from each slit separately, the NIRSpec
can dissect the spectrum of light from mul-
tiple points on the sky. It could, for instance,
measure redshifts and calculate distances
for 100 different distant galaxies, all at once.
But it can also focus in on multiple slices of a
single galaxy, such as one undergoing a slow-
down in star formation. “It will get gorgeous
spectra of each distinct region of a galaxy,”
Rigby says, allowing observers to identify
gas clouds and assess their temperatures
and movement—along with what seems to
be blowing them out. “We’ve never had that
power before,” Rigby says.AFTER 10 YEARS of concept studies and false
starts, in 1999 NASA formally greenlighted
what was then called the Next Generation
Space Telescope. But by then, a new goal
had emerged: understanding exoplanets,
first discovered in the 1990s.
In the early years, exoplanet discoveries
were few—“stamp collecting,” says Natalie
Batalha of UCSC. But NASA’s Kepler mis-
sion, launched in 2009, stared at a patch
of sky for years on end, continually moni-
toring 150,000 stars for the telltale dips in
brightness that betray the passage, or tran-
sit, of an orbiting planet across the star’s
face. Kepler found thousands of planets,
showing exoplanets were not a galactic rar-
ity, but the norm.
Webb isn’t aiming to discover lots of new
planets; its time is too precious to sit and
wait for brightness dips to occur. What it
will do is get to know exoplanets better—first
by witnessing their formation, something
that researchers had previously only theo-
rized about. The Atacama Large Millimeter/
submillimeter Array (ALMA), a set of ra-
dio telescopes in Chile, has in recent years
zoomed in on protoplanetary disks, the swirls
of dust and gas around young stars that co-
alesce into planets. ALMA’s images show clear
gaps in the disks, suggesting protoplanets are
vacuuming up material as they orbit. But
ALMA can only see the faint radio emissions
from cold dust and gas in the outer parts of
the disks—not the planets themselves.
At shorter infrared wavelengths, Webb
will see newborn planets, which glow in the
infrared. It will be able to dissect the chemi-
cal makeup of the planet-forming material
and how it varies across the disk. “It’s im-
portant to know the environment in which
the planet is formed,” says Isabelle Baraffe,
a theorist at Exeter. “It helps to constrain
the models.”
Webb will also dive into planetary atmo-
spheres. Astronomers using Hubble and an
infrared telescope far smaller than Webb,
the Spitzer Space Telescope, pioneered the
key technique, called transit spectroscopy.
During a transit, the planet’s atmosphere
absorbs a small amount of the starlight,
resulting in tiny changes in the star’s spec-
trum. By watching transits, Hubble sensed
water vapor in a few exoplanet atmo-
spheres, and Spitzer found methane and
carbon monoxide. Webb, sensitive to a large
swath of the infrared, should find all those
gases and more, including ammonia, acety-
lene, and hydrogen cyanide. “Webb will
blow the door wide open,” says Nikole Lewis
of Cornell University.
The absorption signatures are strongest
when the starlight passes through a thick
atmosphere, so Hubble and Spitzer focused
on big, puffy planets that orbit close to theirTelescope name strikes discordant note for many
N
ASA Administrator Sean O’Keefe was trying to humanize what was then known as
the Next Generation Space Telescope, when in 2002 he decided to name it after his
1960s predecessor, James Webb. Even at the time the decision raised some eye-
brows, because NASA science missions are more typically named after scientists,
not bureaucrats. O’Keefe justified his decision by citing Webb’s prominent role in the
Apollo program and his acknowledged record of championing space science. Now, how-
ever, deeper questions have emerged about whether Webb deserves the honor—a debate
that is tarnishing the telescope’s name just as NASA is trying to celebrate its launch.
Webb, who died in 1992, had a leadership role at the U.S. Department of State in
the 1950s during the “lavender scare,” a systematic effort—encouraged by promi-
nent members of Congress—that removed hundreds of gay and lesbian people from
civil service because of their sexuality. Webb was involved in Senate discussions
that initiated the policies, according to historian David Johnson of the University of
Southern Florida in his 2004 book The Lavender Scare: The Cold War Persecution of
Gays and Lesbians in the Federal Government. More recently, astronomer Adrian Lucy
of Columbia University found documents in the U.S. National Archives showing Webb
was involved in meetings in which the discriminatory policies were discussed and
homophobic material was passed on to senators. In 1963, after Webb became NASA
administrator, an agency employee was fired on suspicion of being gay.
Earlier this year, four astronomers launched a petition calling for the instrument to be
renamed. In their letter to NASA, they wrote: “Webb’s legacy of leadership is complicated
at best, and at worst, complicit with persecution.” The petition drew more than 1200
signatures and included many scientists who will be using the telescope.
In June, NASA began an investigation. The agency’s official historian, Brian Odom, and
an external expert reviewed archival evidence about Webb’s policies and actions. Their
findings and conclusions have not been revealed publicly, and in September NASA re-
leased only a terse statement from Administrator Bill Nelson: “We have found no evidence
at this time that warrants changing the name of the James Webb Space Telescope.”
The agency considers the case closed. “It’s hard to go back and look at the histori-
cal record and see what someone’s opinions were, and if NASA has investigated this,
we shouldn’t second guess that,” says Fiona Harrison, an astronomer at the Califor-
nia Institute of Technology who co-chaired a recent astronomy decadal survey. “But
I like the idea of honoring scientists.” Should a future NASA administrator decide to
reverse the decision, there is precedent: In 2018, NASA renamed Swift, a gamma ray
telescope—14 years old and going strong—after Neil Gehrels, its principal investiga-
tor, who had died the previous year. —D.C.810 12 NOVEMBER 2021 • VOL 374 ISSUE 6569