Identified the type of impact capable of producing
the Earth-Moon system through a single giant collision; published in Nature
(Dr. Robin Canup, Dr. Erik Asphaug
of the University of California Santa Cruz).
Discovered the origin of the axial tilt of
Saturn as a result of a resonant interaction; in press at the
Astronomical Journal (Dr. Bill Ward,
Dr. Douglas Hamilton of the University of Maryland).
A new model describing the origin of the four
large moons of Jupiter -- the so-called Galilean satellites -- reconciles
the moons' major properties with the formation of the satellites from a disk
of gas and small particles orbiting Jupiter during the very end stages of the
planet's growth, published in the Astronomical Journal (Dr.
Robin Canup, Dr. Bill Ward).
Discovered the source of the high-speed solar wind;
published in Science (Dr. Don Hassler, et al.).
Determined the very young age of the surface of Europa, the
possible ocean-bearing moon of Jupiter, using images taken by the Galileo spacecraft (Dr. Clark Chapman, Dr. Bill Merline, et al.) and theoretical
studies of the orbital evolution of comets and other small bodies in the outer solar
system (Dr. Hal Levison).
Made the first detection of argon, in surprisingly large
abundance, in Comet Hale-Bopp, suggesting that it formed in the Uranus-Neptune zone (Dr.
Alan Stern, et al.).
Using the Hubble Space Telescope, SwRI scientists discovered the
only existing observational evidence of Kuiper Belt objects of the sizes occasionally seen
in the inner solar system (Dr. Hal Levison,
Dr. Alan Stern, Dr. Peter Tamblyn, Dr. Anita Cochran of the
University of Texas at Austin). Discovered strong evidence for an unexpectedly high
primordial mass for the Kuiper Belt of comets (Dr. Alan Stern).
Developed the best-ever maps of Pluto (Dr. Eliot Young, who used ground-based telescopic
data, and Dr. Alan Stern, who used the
Hubble Space Telescope).
Developed the theory that there should be a "scattered
disk" of Kuiper Belt objects, which was later confirmed by observers (Dr. Hal Levison, et al.).
Found evidence for asteroids in the Oort comet cloud (Dr. Hal Levison, Paul Weissman of the Jet
Proposed a new model in which the Kuiper Belt
objects originally formed closer to the Sun and were pushed outward to their
current locations by Neptune's migration, thus offering a potential
resolution to difficulties in forming these objects in situ;
published in Nature (Dr. Hal
Levison, Dr. Alessandro Morbidelli of the Nice Observatory).
Developed a dynamical explanation for the origin
of the newly discovered and distant solar system objects 2000 CR105 and 2003
V12 (Sedna) involving encounters with other stars; in press at Astronomical
Journal (Dr. Alessandro Morbidelli of the Nice Observatory, Dr.
The highest resolution computer simulations of potential lunar-forming
impacts performed to date have been used to identify the specific regions of
material that contribute to the Moon; published in Icarus (Dr.
Disk models used to study planetary origin are being applied to the origin
of the large satellites of the outer planets (Dr.
Robin Canup, Dr. Bill Ward).
Smooth particle hydrodynamic simulations are being utilized to identify
planetary collisions capable of producing the Pluto-Charon binary (Dr.
Performed laboratory experiments to simulate the surface environment of Mars and
to determine the origin of the martian soil. The results showed that low
temperature alteration of Martian volcanic rocks by water under present
martian conditions is most likely responsible for the
salty Martian soil (Dr. Mark Bullock,
collaborators at the NASA Ames Research Center).
Co-directed an NSF-funded program for undergraduates, called "Global Climate
Change and Society." Twelve students visited Boulder during the
summers of 2001-2003 to work with Dr. Bullock and scientists at the National
Center for Atmospheric Research and the University of Colorado. They studied
the science of global climate changes as well as its societal impacts,
philosophy, and public policy, and engaged in original research projects
related to these program themes (Dr.
Observing cloud motions on Venus using NASA's Infrared Telescope Facility
on Mauna Kea, Hawaii. The lower clouds of Venus on the night side are back-lit
by heat radiation from below. Observed Venus for up to 10 nights in a row
and traced horizontal winds in Venus' middle atmosphere (Dr.
Eliot Young, Dr. Mark Bullock).
Neptune's giant moon Triton has been known to undergo mysterious, periodic
reddening, possibly related to cryo-volcanism. By monitoring Triton using NASA's
Infrared Telescope Facility in Hawaii, the staff determined that the nitrogen frosts on
Triton are distributed in unexpected ways, giving scientists new thoughts
about how the surface and atmosphere are coupled on Triton and on its
cousin, Pluto (Dr. Leslie Young,
Dr. Eliot Young).
The temperature of Jupiter's massive atmosphere is only partly
understood. The staff led an investigation into how a type of atmospheric motion,
called gravity waves, may be heating the stratosphere of Jupiter (Dr.
Although the general features of Mars' global atmospheric motion are
understood, details of the local weather, important for future missions to
Mars, are not. Staff members developed a detailed weather model for Mars in order to
understand small-scale convection, the creation of dust devils, and the role
of clouds and topography on regional weather patterns. The team successfully predicted
the winds at the two Mars Exploration Rover landing sites (Dr.
Scot Rafkin, Dr. Tim Michaels).
Discovered that sunlight can have surprisingly important effects on the
spins of small asteroids. The study indicates that sunlight may play a more
important role in determining asteroid spin rates than collisions, which were
previously thought to control asteroid spin rates (Dr.
Bill Bottke, Dr. David Vokrouhlicky of Charles University in Prague).
Used the Extreme-Ultraviolet Imaging Telescope to discover solar tsunamis
(also called "EIT waves"), huge propagating waves that are triggered along
with coronal mass ejections and can travel the entire diameter of the sun.
SwRI researchers are applying this unusual phenomenon to new studies of the
solar corona (Dr. Meredith
Identified a recent asteroid breakup event in the main asteroid belt.
Computer simulations showed that the event occurred 5.8 million years ago,
when a 15-mile-wide asteroid in the main belt region shattered into numerous
fragments following a collision. This observation marks the first time that an
asteroid disruption event has been precisely dated (Dr.
David Nesvorny, Dr. Bill Bottke,
Dr. Hal Levison).
Found that large asteroids are gently nudged over hundreds of millions or
even billions of years by the absorption and re-emission of sunlight, enough
so the asteroids may eventually enter Earth orbits (Dr.
Bill Bottke, Dr. David Vokrouhlicky and Miroslav Broz of Charles
University in Prague, Dr. David
Nesvorny, Dr. Alessandro Morbidelli of the Observatoire de la Cote d'
Computers are being used to study the evolution of climate on
Earth's neighboring planets, Venus and Mars. On Venus there may have been a dramatic climate change
in the past billion years. Research shows that many of Venus' mountains may have been
created when its surface literally buckled in response to wide swings in its always-hot
surface temperature (Dr. Mark Bullock, Dr. David Grinspoon,
Dr. Scot Rafkin, Sean Solomon of the
Carnegie Institution of Washington).
Helped to develop the Torino Scale, analogous to the
Richter Scale for earthquakes, to help place the likelihood and seriousness of potential
comet or asteroid impacts into context. The Torino Scale has recently been adopted by the
International Astronomical Union. The project is further described in the current issue of
Sky & Telescope magazine (Dr. Richard Binzel of the Massachusetts Institute
of Technology, Dr. Clark Chapman).
Participating in the first spacecraft mission
to the planet Mercury since 1975. The NASA Discovery Mercury Surface, Space Environment,
Geochemistry, and Ranging Mission (MESSENGER) will carry seven instruments into orbit
around the closest planet to the sun. It was launched in 2004 and will begin work in 2008 to
study Mercurys shape, interior, magnetic field, and surface. SwRI scientists will
primarily study surface geology by means of craters and surface colors (Dr. Clark Chapman, Dr. Bill Merline).
Analyzed the crater populations on the jovian moons Europa,
Ganymede, and Callisto. The sparse numbers of impact craters on Europa indicate that its
icy surface is very young, perhaps only 20 million years old, compared with the heavily
cratered surfaces of Ganymede and Callisto. Analyses show that Europa may be geologically
active and harbor an ocean of water beneath its crust (Dr. Clark Chapman, Dr. Bill Merline,
Beau Bierhaus, Shawn Brooks).
Studying the sources and history of water in the atmosphere and
crust of Mars. By studying the ratio of heavy hydrogen to ordinary hydrogen,
scientists hope to learn if most martian water came from comets (Dr. David Grinspoon).
Observed, for the first time, the two-dimensional structure of
the solar wind, coming from the edges of honeycomb-shaped patterns of magnetic fields at
the surface of the sun. These observations, made with the Solar and Heliospheric
Observatory (SOHO) led to a better understanding of the solar wind, the supersonic outflow
of charged particles from the sun (Dr. Don
Working with Jet Propulsion Laboratory artificial intelligence
mathematicians and engineers to develop smart software to fly aboard future planetary
missions. This work should allow future flyby and orbiter spacecraft to react in near
real-time to data they collect, making decisions much like a scientist would if aboard the
spacecraft (Dr. Bill Merline, Dr. Clark Chapman, Dr. Alan Stern,
Searching for small, hypothetical asteroids, called
vulcanoids, orbiting inside Mercurys orbit near the sun (Dr. Alan Stern, Gary Emerson, et al.). A
theoretical study concluded that any vulcanoids that may have once have existed have
probably collided with each other so much that they have been ground down to dust and
vanished (Dr. Dan Durda, Dr. Alan Stern).
Developed a theory to explain the unusually small eccentricity
of the planet Neptune as a consequence of its gravitational interactions with the Kuiper
Belt. Neptune drives waves in the belt; the back reaction on the planet damps its
eccentricity over the age of the solar system (Dr.
Bill Ward, Joseph Hahn).
Awarded the 2004 Dirk Brouwer Prize from the American Astronomical
Society's Division on Dynamical Astronomy. The Brouwer Prize recognizes
outstanding contributions to the field of dynamical astronomy (Dr.
Awarded the 2003 Harold C. Urey Prize from the American Astronomical
Society's Division of Planetary Sciences, and the 2004 James B. Macelwane
Medal of the American Geophysical Union. Both prizes recognize outstanding
achievements in planetary and geophysical sciences by a young scientist (Dr.
Developed the widely used SyMBA, SWIFT, and SWIFTER orbital integrator packages
for studying the orbits of solar system bodies over billions of years (Dr. Hal Levison).
Originated the EKO-News e-mail newsletter concerning the
Edgeworth-Kuiper Belt of primordial comets (Dr.