Title: Forging a New Solar System.   
Subject(s): KUIPER, Gerard; ASTRONOMERS
Source: Astronomy, Mar99, Vol. 27 Issue 3, p40, 6p, 3c, 2bw
Author(s): Stern, S. Alan
Abstract: Profiles Gerard Peter Kuiper, known as the Dutch-American
father of planetary astronomy. His achievements in the field;
Educational background; Family life.
AN: 1587301
ISSN: 0091-6358
Note: Tucson-Pima Public Library subscribes to this magazine.
Database: MasterFILE Elite

FORGING A NEW SOLAR SYSTEM

Few people have entire regions of the solar system named after them,
but then few people contributed as much to planetary astronomy as
Gerard Kuiper.

"GPK" That's what he was called by his colleagues and students. Gerard
Peter Kuiper was the Dutch-American father of modern planetary
astronomy, turning a moribund science into a thriving marketplace of
ideas little more than a half-century ago.

Gerrit Peter Kuiper was one of four children, born in Harencarspel,
the Netherlands, on December 7, 1905. Like many astronomers, Gerrit
(later "Gerard") Kuiper had his love for the science sparked early. In
Kuiper's case, it was a reading of Descartes that fired his interest
in astronomy. When he graduated from his gymnasium (high school) in
Haarlem, the Netherlands, Kuiper chose to study physics and chemistry
at the University of Leiden.

Leiden is a small town, just south of Amsterdam and barely 20 miles
from the North Sea. Its university, however, looms large -- having
trained and harbored exemplary scientists for centuries, including
Antoni van Leeuwenhoek (the naturalist and pioneer in microscopy). In
Kuiper's day, the physics and astronomy faculty at Leiden included
such great scientists as Jan Woltjer, Willem de Sitter, Ejnar
Hertzsprung, and Paul Ehrenfest. Kuiper completed his bachelor of
science degree at Leiden in three years, and in 1927, began his Ph.D.
studies there. Kuiper's professors described him as a "bright, brash
researcher zealously dedicated to observational work."

Kuiper's incoming graduate "class," such as it was, consisted of just
two students, GPK and Bart J. Bok. Both young men were destined to
become 20th-century legends. Bok later recalled on meeting Kuiper,
that "After introduction formalities were over, Gerard asked me what
was my specialty field of interest in astronomy. I promptly replied
that I was interested in the Milky Way and Cepheid variable stars. He
responded, 'That is not an uninteresting field. But I expect to study
a more fundamental area, the problem of three bodies and related
questions about the nature and origin of the solar system.'"

Bok stayed with his interests in galactic astronomy, becoming one of
the leading authorities in the study of the Milky Way until his death
in 1983.

Kuiper, by contrast, might have meant to start out in solar system
astronomy, but so little was known reliably that he found himself
studying binary stars as, he hoped, an analogy to planetary formation.
Kuiper's doctoral thesis, mentored by Hertzsprung and the great
polymath astronomer Jan Oort (who was later to "discover" the Oort
Cloud), focused on the statistics of binary stars. When he finished in
1933, Kuiper immediately moved to the United States, where he took a
postdoctoral research fellowship at Lick Observatory in California. At
Lick, Kuiper continued his studies of binary stars, eventually finding
the then-surprising result that 50 percent of the nearest stars
belonged to binary systems.

Throughout the 1930s and the beginning of the 1940s, first at Lick,
then at Harvard, and later at Yerkes Observatory, Kuiper continued and
deepened his research specialty in stellar astronomy. During this
first period of his career, he made a seminal study of the
relationship between mass and luminosity for main sequence stars,
studied the evolution of stars, examined color-magnitude diagrams for
open star clusters, observed white dwarfs and refined their masses,
and (with Otto Struve and Bengt Stromgren) performed the classical
study of the eclipsing binary, Epsilon Aurigae. Kuiper's investigation
of the mass-luminosity relation for main-sequence stars remained a
standard in the field for 50 years. His landmark 1941 paper on the
star Beta Lyrae introduced the term "contact binary." And at one time
Kuiper had amassed two-thirds of all the white dwarf discoveries in
the world.

While at Harvard, Kuiper met and, in June 1936, married Sarah Parker
Fuller. The couple later produced two children, Paul and Lucy. Kuiper
took American citizenship in 1939-1940 and then joined the war effort
as a civilian in the War Department's Office of Scientific Research
and Development. Later in World War II, he worked in the Operational
Analysis Section of the 8th U. S. Army Air Force in England.

To Titan and Beyond 

During the War, Kuiper's thoughts began to turn to what would become
his most notable work: the exploration of the solar system. In
contrast to today, in the 1930s and 1940s planetary studies were
seldom undertaken and only a few researchers plied the solar system
for results. But Kuiper's budding interests would soon boom into an
energetic, full-blown assault on the solar system that would come to
completely dominate solar system research in North America.

Kuiper's first foray into this "new" area took place during a winter
leave from military-related duties in 1943. He undertook an observing
campaign at McDonald Observatory, which his home institution, Yerkes,
then operated, to search for evidence of atmospheres around the
satellites of planets. Using the 82-inch reflector, at that time the
third largest telescope in the world, GPK took high-resolution spectra
of almost a dozen moons in the outer solar system. He hit the jackpot
with Saturn's Titan, where he found clear and unambiguous evidence for
gaseous methane.

It was a landmark discovery. Never before had moons, those small
worlds revolving about larger ones, been known to possess atmospheres
as planets did. In fact, Henry Norris Russell had published an
influential review of planetary atmospheres in 1935 stating the
paradigm that giant planets had hydrogen atmospheres, smaller planets
had atmospheres with oxygen-bearing molecules, and the smallest
planets and satellites had no atmospheres at all. Yet Kuiper had found
proof that Titan was a satellite with an atmosphere -- a paradigm had
been shattered.

Although Kuiper's techniques were too primitive to detect the tenuous
atmospheres we now know to exist around the jovian moons Io and Europa
and Neptune's Triton, his studies of satellites continued for much of
his career. Among his most notable results were the discovery in 1948
of Uranus's fifth satellite, Miranda, and in 1949 of Neptune's second
moon, Nereid.

More notable still was Kuiper's application of new infrared technology
to the study of planets and their satellites and rings. In 1944 and
1945, he was a scientist sent by the U. S. Department of Defense
(officially the Department of War at that time) to "interview"
Axis-country scientists about their advanced technologies,
particularly in nuclear science and rocketry. While doing this, Kuiper
discovered that German scientists had perfected an infrared detector
with a sensitivity that was then unparalleled.

Kuiper realized that these devices, made of lead sulfide, could open
up a rich new arena for astronomy. When he returned to the United
States after the end of World War II, Kuiper used this knowledge,
which he worked to have declassified, to show Penn State researcher R.
J. Cashman the European recipe for perfecting lead-sulfide detectors,
which Cashman had previously tried but failed to make.

With Kuiper's information, Cashman succeeded, and the "Cashman cells"
thus produced gave Kuiper the capability to make dramatic new
discoveries in planetary science. Within a few short years after the
War, Kuiper discovered that Saturn's rings were made of water ice,
that carbon dioxide dominated the atmospheres of both Mars and Venus,
and that the martian polar caps underwent seasonal growth and
recession.

As the 1940s turned into the 1950s, Kuiper applied his ambition,
skill, and copious observing resources at Yerkes. He made the most
complete survey of the asteroid belt ever undertaken up to that time,
searched for moons around Pluto, attempted to measure Pluto's true
size (an effort at which he failed), and studied the dynamics of the
giant planets' atmospheres. At the same time, while undertaking two
stints as Director of Yerkes Observatory, Kuiper organized major
interdisciplinary conferences that brought physicists, chemists, and
meteorologists together with astronomers to explore the nature of
planetary atmospheres. In doing so, Kuiper sowed the seeds of the
modern discipline.

During the same period, Kuiper began his four volume encyclopedia of
the solar system (a project with no parallel), and later, his nine
volume set, Stars and Stellar Systems.

Around this time, Kuiper also began to apply his thoughts to the study
of the origin of the solar system. He proposed a new theory of
planetary origins in which each planet formed from its own gas cloud
and suggested that the high-speed solar wind was responsible for
dispersing most of the hydrogen of the primordial solar nebula. He
also proposed, based in part on his earlier studies of binary and
multiple star systems, that planetary systems, which astronomers
previously had thought to be exceedingly rare -- perhaps as rare as
only one in a trillion stars --might be found around up to 1 percent
of all stars.

And there was more. Kuiper published key studies on the nature of the
Hirayama asteroid families and the irregular satellites of Jupiter.
And he presciently proposed that just beyond the planets there likely
lay a vast debris belt of comets and other small bodies left over from
the formation of the solar system.

But the more GPK studied the outer solar system, the more he came to
realize that a body far closer might hold significant clues to the
study of how the solar system formed. This was how Kuiper came to turn
his attention to, of all things, Earth's moon.

Hot on the Moon 

Kuiper was correct in his intuition that the moon held many important
secrets about the earliest days of the solar system. And as the 1950s
turned into the 1960s, the world's burgeoning interest in space
exploration was about to explode into an era of lunar exploration no
one could have foretold. Soon, the Apollo program would be born, and
with it came dozens of robotic and nine human missions to the moon.

Kuiper himself began by studying the craters of the moon, carefully
building up a photographic database called the Photographic Lunar
Atlas. It became a rich source of both scientific results and mapping
information for the lunar exploration missions that would follow.

As Kuiper became increasingly interested in solar system studies, he
also became further isolated from mainstream astrophysics. Simply put,
planetary studies were viewed -- incorrectly, as it turned out -- as a
backwater of astronomy. This intellectual isolation, along with his
relatively autocratic leadership style and interpersonal struggles
with some of his senior colleagues at Yerkes, caused him to lose the
directorship of Yerkes Observatory at the start of 1960.

Being resourceful, Kuiper turned this setback to his advantage by
arranging to start a major center for solar system astronomy at the
University of Arizona in Tucson. Calling his new center the Lunar and
Planetary Laboratory (LPL), Kuiper moved himself and nine members of
his staff and student cadre to Tucson in mid-1960. By 1962, planetary
exploration was kicking into high gear. With NASA's Lunar Ranger,
Surveyor, and Apollo programs, as well as the Mariner series of
planetary flybys, LPL (sometimes referred to as the "Looney Lab")
employed 30 staff scientists, technicians, students, and aides. By
1966 the Laboratory's roster topped 100 individuals, with facilities
ranging from their own multistory office building to a suite of
telescopes in the Catalina Mountains north of Tucson and a set of
infrared astronomy instruments plying the stratosphere on both NASA
and military aircraft.

And all the while, Kuiper continued his research. He verified the
pressure at the base of Mars's atmosphere; he deduced that the lunar
maria were basaltic; he discovered a new class of absorption bands in
the spectra of cool stars; and he served as the principal scientist
for NASA on the Ranger program, the first series of lunar missions in
preparation for Apollo. The Ranger flights produced the first close-up
pictures of the lunar surface and showed that the moon's surface had
sufficient strength to support manned landers.

Even in the 1960s, three decades into his career, Kuiper loved to be
at the telescope. The eminent planetary scientist Dale Cruikshank,
then one of his students, described Kuiper's observing style as,
"Indefatigable .... [A] full nighttime schedule of infrared
spectroscopy of stars and planets was supplemented by a daytime
program of very bright stars, Venus, or Mars .... During these
periods, at times amounting to 14 consecutive clear days and nights at
McDonald, Kuiper would exist on three hours of sleep each day, while
another assistant and I would each work 10-hour shifts."

Although Kuiper's explorations and results kept up a furious pace
throughout the 1960s, his most well-known work concerned the origin of
the moon. Kuiper initially became interested in this problem at the
end of the 1940s and had pursued it throughout the 1950s. He had come
to believe that the moon formed in a hot, molten state and that the
surface geology seen in his mapping efforts was evidence. Kuiper's
arguments for a hot origin of the moon were also supported by
geochemical evidence.

This work was not without controversy, however, and in fact Kuiper was
engaged in a severe debate with the Nobel Prize-winning chemist Harold
Urey over whether the moon had formed cold or hot. The Kuiper-Urey
debate raged -- always vociferously and sometimes even bitterly -- for
more than 15 years. But when lunar samples were returned by Apollo
astronauts, the debate was finally settled: The Moon had indeed formed
hot - so hot, in fact, that it sported a magma ocean in its youth.
Kuiper had been right, not entirely for the correct reasons, as the
samples revealed, but he had been right.

Lasting Legacies 

As the Apollo program closed out in the early 1970s, Kuiper became
involved in both the Mariner 10 flyby of Mercury and the Pioneer 10
and 11 missions to reconnoiter the Jupiter system. He also retired, at
age 67, from the directorship of his creation, the Lunar and Planetary
Laboratory.

In late 1973, with Pioneer 10 making the first-ever crossing of the
asteroid belt on its way to Jupiter and Mariner 10 within weeks of its
first approach to Mercury, Kuiper left Tucson for a vacation to
Mexico. Without warning, on Christmas Eve 1973, he collapsed and died
while in Mexico City.

Although he was not able to participate in the historic planetary
explorations of Mercury and Jupiter that followed in the next several
weeks, nor to publish his long-anticipated new cosmogony of the solar
system, his life's work lived on.

The Apollo missions proved he was largely correct about the moon's
early, hot phase and the nature of its craters. So too, his work on
asteroid families, the origin of the jovian satellites, and the nature
of Mars's polar caps was confirmed. Most dramatically, however, his
once-fantastical prediction of a debris belt of comets just beyond the
planets was borne out in the late 1980s and early 1990s. And in his
honor, that structure, the Edgeworth-Kuiper Belt, now bears his name.

Kuiper's work also lives through the contributions of the many fine
Ph.D. students whom he trained. These include Alan Binder, Dale
Cruikshank, Tom Gehrels, Dan Harris, Bill Hartmann, Toby Owen, and
Carl Sagan.

After Kuiper died, NASA named its airborne infrared observatory in his
honor, the Kuiper Airborne Observatory. And the University of Arizona
named the LPL building the Kuiper Space Sciences Building. His
scientific colleagues named prominent craters on the moon, Mars, and
Mercury for him w an honor no other human being has earned. Yet
perhaps the best commemoration of his life is the simple statement
that, Gerard Kuiper, more than anyone else, was responsible for
restoring solar system astronomy to prominence in an era dominated by
stellar and galactic research.

Surveyed asteroid belt and families

Discovered atmosphere of Venue made mostly of carbon dioxide

Discovered atmosphere of Mars made mostly of carbon dioxide

Deduced lunar maria contained basalts

Discovered Saturn's rings were made of water ice

Discovered atmosphere on Saturn's moon Titan

Discovered Uranus's fifth moon, Miranda

Discovered Neptune's second moon, Nereid

Suggested existence of Kuiper Belt

PHOTO (BLACK & WHITE): Gerard Kuiper (middle) stands outside Yerkes
Observatory with Subrahmanyan Chandrasekhar (left) and Otto Struve.

PHOTO (BLACK & WHITE): Kuiper served as principal scientist for
Ranger, which sent ...

Kuiper served as principal scientist for Ranger, which sent back the
first close-up pictures of the moon's surface.

PHOTO (COLOR): Discovered by Kuiper in 1948, Uranus's moon Miranda
showed ...

Discovered by Kuiper in 1948, Uranus's moon Miranda showed its complex
geology to the Voyager spacecraft.

PHOTO (COLOR): The first member of the Kuiper Belt ever seen ...

The first member of the Kuiper Belt ever seen was this inconspicuous
point of light (circle) designated 1992 QB[sub 1].

PHOTO (COLOR): Kuiper discovered the thick, hazy atmosphere of
Saturn's moon Titan, seen here up close by Voyager's camera.

~~~~~~~~

By S. Alan Stern

S. Alan Stern is a planetary scientist in the Southwest Research
Institute's research group in Boulder, Colorado. He and Jacqueline
Mitton recently co-authored Pluto and Charon: Ice Worlds on the Ragged
Edge of the Solar System (John Wiley & Sons, 1997).
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Source: Astronomy, Mar99, Vol. 27 Issue 3, p40, 6p, 3c, 2bw.
Item Number: 1587301
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