Search focused on a small group of asteroids that may be orbiting near the

Southwest Research Institute (SwRI), in collaboration with NASA’s Dryden
Flight Research Center at Edwards, Calif., has begun an innovative
high-altitude observation program to search for a long-sought population of
diminutive asteroids that may be circling near the sun in the innermost
frontier of the solar system.

Called “vulcanoids” after the Roman god of fire and metallurgy, this
hypothesized population of small asteroids is exceedingly difficult to
observe from the ground because they orbit so near the sun. Researchers have
made previous ground-based searches for vulcanoids during total solar
eclipses, during the brief twilight period after sunset before the
vulcanoids themselves set, and just before sunrise after the vulcanoids have
peaked above the horizon. So far, those observations have succeeded only in
placing limits on how many vulcanoids might exist, with no vulcanoids yet

SwRI theoretical models suggest that a modest population of a few hundred
kilometer-size and larger vulcanoids could have survived the harsh dynamic
environment of the solar system, far interior to the orbit of the planet
Mercury, from primordial times to the present. The relative faintness of the
vulcanoids against a twilight sky, along with atmospheric hazes and
turbulence, have restricted ground-based searches to fairly bright limiting
magnitudes corresponding to objects at least 12 to 37 miles (20-60
kilometers) across.

During the three-flight observation campaign, two SwRI astronomers took a
sophisticated digital imaging system, the Southwest Universal Imaging
System–Airborne (SWUIS-A), into the stratosphere in a high-performance
F/A-18 jet aircraft used by NASA Dryden to support flight research missions.
This was the first phase of two observation series this year, with the
second scheduled about the time of the autumnal equinox.

“Our vulcanoids search program, conducted from an altitude of 49,000 feet
over the Mojave Desert, gave us a view of the twilight sky near the sun that
is far darker and clearer than can be obtained from the ground,” said
principal investigator Dr. Daniel D. Durda, a senior research scientist in
the SwRI Space Studies Department in Boulder, Colo.

“Our observations with the SWUIS-A imaging system will result in the most
comprehensive, constraining search yet conducted for these objects,” added
co-investigator Dr. Alan Stern, director of the SwRI Space Studies
Department. “SWUIS-A is a versatile and capable, low-cost astronomical
imaging system developed by SwRI that operates in the in the broadband
visible light and near-infrared spectrums. It has been successfully flown
since 1997 in cooperation with NASA Johnson Space Center and NASA Dryden
Flight Research Center. Another version was flown on two space shuttle
missions during the late 1990s, focusing on cometary, lunar and planetary
observations in the ultraviolet regions of the spectrum.”

NASA research pilot Rick Searfoss, a former space shuttle astronaut and
Dryden’s project manager for this year’s airborne astronomy missions, said
the opportunity to fly SwRI’s SWUIS-A instrument on one of Dryden’s two-seat
F/A-18B aircraft is a unique win-win project.

“In employing high-performance operational aerospace vehicles like a space
shuttle orbiter or F/A-18 Hornet, sensors and telescopes aboard the vehicles
can obtain better data than equivalent ground-based systems,” he said.
“While space shuttle-based astronomy missions have produced phenomenal
results, any space mission is a very expensive and difficult undertaking.

“This small airborne astronomy project is being done at absolutely no
additional cost to NASA or the public,” Searfoss added. “Our research pilots
must fly a certain number of night flights anyway for our proficiency
requirements, but in working with SwRI, we can also contribute to an
exciting pure research goal. It’s the perfect blend of science and flight

The vulcanoids zone is one of the few dynamically stable niches of the solar
system that remains largely unexplored. Researchers believe this presumed
reservoir of small objects could contain a sample of planet-building
material left over from the earliest days of the inner solar system. Because
of the intense thermal conditions and comparatively harsh collisional
environment characteristic of this region, the vulcanoids population also
might contain unique mineral assemblages not seen in other populations
farther from the sun, such as asteroids and comets. In addition, because
vulcanoids would impact and crater Mercury yet spare nearby bodies, knowing
how many vulcanoids may exist will aid researchers’ understanding of that
planet’s surface chronology and the impact history of the other planets in
the inner solar system, including Earth.

This innovative asteroid observation program is funded by grants from the
NASA Planetary Astronomy Program, the National Geographic Society, the
American Astronomical Society, and the Fund for Astrophysical Research, Inc.
Initial results from the spring observation phase are expected in late



For more information on the search for vulcanoids or the SWUIS-A system,
visit on the Internet.

Still photos are available on the NASA Dryden Flight Research Center
Internet web site to support this release at:

Hard copy photos prints are also available from the Dryden Public Affairs
Office by calling (661) 276-2665.

NASA Dryden news releases are also available on the Internet at: