Alan Brown

NASA Dryden Flight Research Center, Edwards, CA


Nancy Lovato

NASA Jet Propulsion Laboratory, Pasadena, CA



The most volcanically active region in the world-the Pacific Rim-is center
stage for a comprehensive Earth-observing mission being conducted by NASA
and a team of scientists from several research institutions over the next 2
1/2 months.

The ambitious program to collect data in more than 15 countries around the
Pacific Ocean got underway July 31 with the deployment of NASA’s DC-8
Flying Laboratory from NASA’s Dryden Flight Research Center at Edwards, CA.
Operated by the Airborne Science Directorate at NASA Dryden, the
highly-modified aircraft is carrying a suite of precision instruments to
document geographic and atmospheric factors throughout the Pacific Rim area
on its scientific odyssey.

Among the areas where data will be collected during the Pacific Rim 2000
(PacRim II) mission conducted by NASA’s Earth Science Enterprise are
Cambodia’s Angkor Wat Temple, French Polynesia, Papua New Guinea, the
Philippines and the Australian coastal wetlands.

“The mission of PacRim 2000 includes gathering geographic and atmospheric
data for coastal analysis and oceanography, forestry, geology, hydrology
and archaeology,” said Ellen O’Leary, PacRim 2000 mission coordinator at
NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, CA. “This mission will
provide a great deal of valuable information to each of the countries in
which we are gathering data.”

The primary PacRim II instrument is the Airborne Synthetic Aperture Radar
(AIRSAR). Designed and built by JPL. AIRSAR is NASA’s radar technology
testbed and is used to demonstrate technology for spaceborne radar
missions, such as the Shuttle Radar Topography Mission (STS-99) that flew
in February 2000, according to Dr. David Imel, JPL’s AIRSAR project

AIRSAR also collects data for Earth Science research purposes and is an
all-weather imaging tool able to see through clouds and collect data at
night. Radar’s ability to collect data of the Earth’s surface, even in
cloud-covered regions, makes it a particularly valuable tool for the
tropical areas around the Pacific Rim which are often covered with clouds.
The instrument’s longer wavelengths can also penetrate into the forest
canopy, providing scientists with data at different levels in the forest.

The AIRSAR radar antenna panels are mounted on the outside of the aircraft
and the instrument looks to the side of the flight path. The radar
transmits microwaves and the return signal is collected after the Earth
reflects it. Rough areas, such as cities, mountains and forests, have more
surfaces from which the signal can reflect, and therefore they return more
of the radar signal to the antenna appearing brighter on the resulting
radar image.

In contrast, smooth areas, such as deserts, roads and water surfaces,
return less of the radar signal and appear darker on the radar images.
Trees with differing branch and leaf structures will also return different
amounts of the radar signal to the antenna. The resulting data can be used
for forest and land cover classification purposes.

In addition to collecting data about the roughness characteristics of the
surface, AIRSAR can also collect data that is processed to high-resolution
digital elevation models (DEMs), which are three-dimensional topographic
maps of the surface.

A third type of AIRSAR data is used to measure motion of currents and
waves. DEM data are particularly important to disaster managers around the
Pacific Rim who are responsible for developing plans to mitigate and
respond to natural hazards such as typhoons, earthquakes and volcanic
eruptions which affect nearly everyone around the Pacific Rim “Ring of

Also onboard the DC-8 is the MASTER instrument, which is the MODIS/ASTER
airborne simulator. The Moderate Resolution Imaging Spectroradiometer
(MODIS) and the Advanced Spaceborne Thermal Emission and Reflection
Radiometer (ASTER) are two instruments on NASA’s Earth Observing System
(EOS) Terra satellite launched in December 1999. The MASTER instrument is
used to obtain detailed maps of land surface temperature, emissions and

PacRim II is the first mission to operate both the AIRSAR and MASTER
instruments simultaneously on the DC-8. Michael Fitzgerald, manager of EOS
simulation data production for the Airborne Sensor Facility at NASA’s Ames
Research Center, Moffett Field, CA, anticipates exciting results from
combining AIRSAR and MASTER data collected over the same site. For example,
MASTER data can be draped over digital elevation model data generated by
AIRSAR, providing scientists with additional insight on how topography
affects the vegetation and land surface temperature as seen in the MASTER

NASA’s DC-8 Flying Laboratory, a dash-72 version powered by four CFM-56
high-bypass turbofan engines, is a former long-range jetliner that has been
converted into a world-class airborne scientific laboratory. It can carry
30,000 pounds of scientific instruments and equipment along with scientists
and experimenters, cruising at altitudes up to 42,000 feet. Its range is
5,400 nautical miles, and it has a flight duration of up to 12 hours. The
aircraft is scheduled to return to NASA Dryden on October 23.

Photos of the DC-8 are available on the internet under NASA Dryden Research
Aircraft Photo Gallery, URL:

Information about the Airborne Science Program of the DC-8 is available at:

Additional information about AIRSAR is available at:

Additional information about MASTER is available at: