Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/jplnews2/1203.pr

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PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE [phone]


FOR IMMEDIATE RELEASE                           June 23, 1988


          When a rocket rose into the sky north of Los

Angeles in a dazzling evening launch 10 years ago this week,

the satellite it carried was destined to usher in a new era

of space research focusing on unsolved questions of the

world's oceans and weather.

          The satellite, Seasat, tested a payload of advanced

sensing instruments. During its 3-1/2-month mission, Seasat

collected what scientists have called an explosion of

oceanographic information -- comparable to a century's worth
of observations from a fleet of ships.

          Because of the way it showed how space sensors

could be used in oceanography, Seasat also became parent to a

new generation of missions planned by a handful of countries.

          Those missions could provide answers to some of the

world's most baffling -- and threatening -- weather

phenomena.

          Seasat's influence has reached beyond oceanography

to affect other research work at JPL. Instruments derived

from the 10-year-old mission are due to fly to Venus and Mars

on interplanetary probes in next year's Magellan mission and

1992's Mars Observer.

          An international symposium celebrating Seasat's  ▄j▄î
launch anniversary will be hosted in London next Tuesday

through Thursday (June 28-30) by the British National Space

Centre. Gene Giberson, JPL's project manager for Seasat,

and Peter Woiceshyn, a JPL scientist who has worked on Seasat

continuously since its inception, will be featured speakers.

          "The impacts Seasat has had on both Earth science
studies and even deep-space research at JPL have been

remarkable," said Giberson. "This single mission has produced

offspring that have shaped the future direction of many of

our programs."

          Launched on June 26, 1978, on an Atlas-Agena rocket

from Vandenberg Air Force Base, Calif., Seasat carried a

payload of five scientific instruments unlike any package on

any previous remote-sensing satellite.

          Previous Earth remote-sensing satellites were

generally equipped with a camera and perhaps one or two other

passive instruments.

          Seasat, on the other hand, carried a complex array

of active sensing devices, such as radars and other

microwave instruments, to monitor a broad range of

oceanographic phenomena.

          (Passive sensors simply collect natural energy such

as sunlight reflected by the Earth -- similar to a camera

taking pictures in available light. Active sensors such as

radars emit energy of their own to collect data -- somewhat

like a camera equipped with its own flash attachment.)

          Among the experimental instruments Seasat pioneered ▄j▄
were a synthetic aperture radar, which provided highly

detailed images of ocean and land surfaces; a radar

scatterometer, to measure near-surface wind speed and

direction; a radar altimeter, to measure the height of the

ocean surface and waves; and a scanning multichannel

microwave radiometer, to measure surface temperature, wind

speeds and sea ice cover. The satellite also carried a

passive visual and infrared radiometer to provide supporting
data for the other four experiments.

          With Seasat's proof that the instruments would work

as intended, other projects at JPL and at space centers

around the world have borrowed from the mission's concepts.

          Key among them is a host of international projects

scheduled over the next decade to probe the world's oceans

and weather in unprecedented detail. Scientists say those


missions can help solve currently baffling questions that

would provide a variety of benefits with a possibly enormous

cost savings -- and could avert potential disasters.

          El Nino, an unusual water warming in the eastern

Pacific Ocean in 1982 and 1983, for example, caused billions

of dollars in damage and considerable loss of life.

Scientists have also been puzzled by an increase of carbon

dioxide in the atmosphere, which could have severe

consequences on plants and animal life. Missions derived from

Seasat are expected to help scientists understand both

phenomena.

          In addition, the new generation of oceanographic  ▄j▄î
missions is expected to provide important, cost-saving aids

for such industries as fishing, shipping and offshore oil

production, and for agencies such as the National Oceanic and
Atmospheric Administration (NOAA) and the U.S. Navy.

          Among the new projects are two NASA efforts managed

by JPL -- TOPEX/Poseidon and the NASA Scatterometer (NSCAT).

          TOPEX/Poseidon, a joint satellite mission with the

French space agency, is scheduled for a late 1991 launch on

an Ariane rocket. It will map the circulation of the world's

oceans using a radar altimeter.

          NSCAT is a second-generation instrument being

developed to measure wind speed and direction over the

oceans' surfaces. A proposal to fly NSCAT as part of the

payload on Japan's planned Advanced Earth Observation

Satellite (ADEOS) is currently under review.

          Both TOPEX/Poseidon and NSCAT are intended to

support oceanographic studies during the 1990s under the

World Ocean Circulation Experiment (WOCE) and the Tropical

Oceans Global Atmospheres Experiment (TOGA). These decade-

long programs, sponsored by the World Climate Research

Program, involve studies at and below the ocean surface in

all parts of the world's seas.


          Still another U.S. mission whose heritage can be

traced to Seasat is Geosat, a U.S. Navy satellite launched in

1985 with an altimeter similar to Seasat's.

          International projects scheduled for the near

future include the European Space Agency's first remote- ▄j▄î
sensing satellite, Earth Resources Satellite 1 (E-ERS-1), due

for launch in 1990; Japan's Earth Resources Satellite 1

(J-ERS-1), scheduled for a 1992 launch; Japan's ADEOS,

proposed for launch in 1993; and the international Radarsat,
a proposed 1994 mission that would be a cooperative venture

between Canada and the United States.

          Seasat's impacts, however, have not been limited to

satellite oceanography. Instruments that are direct

descendants of those in Seasat's payload have found their way

into a variety of other NASA missions at JPL.

          One of the most prominent is JPL's Shuttle Imaging

Radar (SIR), a series of synthetic aperture radar experiments

flown on NASA's Space Shuttle. They are direct follow-ons of

Seasat's synthetic aperture radar, which marked the first

time NASA had flown that advanced radar instrument in space.

          The first and second experiments in the series --

SIR-A, which flew on a shuttle mission in 1981, and SIR-B, a

shuttle payload in 1984 -- offered scientists several

unexpected discoveries. During airborne tests, for example,

SIR-A pierced cloud-covered rain forests of Guatemala to

reveal previously unknown agricultural canals dug by the

ancient Maya. SIR-B "saw" through the sands of Egypt to

produce a picture of a riverbed buried for many centuries.

          JPL is currently working on SIR-C, the third SIR

experiment, slated for a 1991 shuttle mission. Also planned

is an advanced radar system that will be flown on an Earth

Observing System (Eos) platform as part of NASA's Space  ▄j▄î
Station program in the late 1990s.

          A radar like the one first flown on Seasat is also

set to go into deeper space on the NASA/JPL Magellan mission


to Venus in April 1989. Magellan will use a synthetic

aperture radar to pierce Venus' dense cloud cover to provide

the most complete, highest-resolution images of the planet's

surface ever made.

          Another planetary mission benefiting from Seasat is

Mars Observer, scheduled for launch in 1992. That spacecraft

will orbit the red planet to conduct extensive studies of the

Martian surface with instruments including an altimeter

derived from the Seasat payload.

          At JPL, Giberson was Seasat project manager; Dr.

James A. Dunne was project scientist. S. W. McCandless Jr.

was Seasat program manager at NASA Headquarters in

Washington, D.C.

          Seasat was funded by NASA's Office of Space Science

and Applications.

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