TRW-BUILT OZONE-MAPPING SATELLITE SET FOR JUNE LAUNCH.

REDONDO BEACH, Calif--(BUSINESS WIRE)--June 24, 1996--The TRW-built Total Ozone Mapping Spectrometer-Earth Probe (TOMS-EP), the first satellite dedicated to mapping the Earth's ozone layer, is scheduled for launch early in the morning on Saturday, June 29.

Once in orbit, the satellite will allow NASA to resume its long-term program of daily, space-based mapping of the global distribution of the Earth's ozone layer, a process critical to monitoring the Earth's environmental health.

The lightweight satellite, which will carry a NASA-developed instrument for measuring ozone, will be launched aboard an expendable Pegasus-XL rocket from Vandenberg Air Force Base, Calif. The launch has been delayed since summer 1994 due to launch vehicle problems.

"NASA has been mapping the ozone layer from space since 1978, but all of its previous TOMS instruments have been 'piggybacked' on other science missions," said Paul Sasaki, vice president and general manager of TRW's Civil & International Systems Division.

"TOMS-EP has only one mission: to gather data on the ozone layer. We're delighted to be able to help NASA restore its ability to provide scientists with consistent, long-term records of ozone levels. We believe that TOMS data will play a key role in helping the world science community understand, predict, and mitigate the effects of global ozone depletion."

Ozone is a naturally occurring form of oxygen found high in the Earth's atmosphere. It acts as a protective shield to life on Earth by absorbing most of the sun's cancer-causing ultraviolet radiation. The last satellite to carry a TOMS instrument, the Russian Meteor-3 satellite, completed its mission in December 1994.

TRW Space & Electronics Group built the 650-pound (295 kilograms) satellite and integrated the TOMS instrument, built by Orbital Sciences Corp., Dulles, Va., for NASA Goddard Space Flight Center, Greenbelt, Md.

The high resolution TOMS instrument will measure "total columnar ozone," the amount of ozone found in a "column" of air extending from the Earth's surface to the top of the atmosphere.

It measures total ozone by observing both incoming solar energy and backscattered ultraviolet radiation at six wavelengths. Backscattered radiation is solar radiation that has penetrated the Earth's lower atmosphere and been reflected by air molecules and clouds back through the stratosphere to the satellite sensors.

TOMS-EP is part of NASA's Mission to Planet Earth (MTPE) initiative to gather data on the global environment. NASA scientists use TOMS data in conjunction with atmospheric chemistry measurements from other satellites such as the Upper Atmosphere Research Satellite (UARS) to understand the processes that drive the global creation, destruction and distribution of the Earth's ozone layer.

UARS, the first major component of MTPE, was launched in September 1991. As part of its ozone mapping mission, TOMS-EP will also measure sulfur dioxide released in volcanic eruptions.

Scientists suspect such emissions may affect the ozone layer. As a secondary benefit, the U.S. Federal Aviation Administration will use TOMS measurements to detect volcanic ash clouds that are hazardous to commercial aviation.

TOMS-EP will fly in a sun synchronous, polar orbit of about 312 miles (500 kilometers). In a sun-synchronous orbit, the satellite passes over the same point on Earth at the same local time every day. Therefore, the TOMS instrument, which is always pointed at the Earth, can collect data under the same conditions of sun illumination daily.

TRW Space & Electronics Group, which has headquarters in Redondo Beach, has built more than 185 communications, scientific and defense spacecraft; produced more than 130 payloads; developed more than 200 advanced space instruments; and integrated some 550 experiments into spacecraft.

It is an operating unit of TRW Inc. (NYSE:TRW), which provides advanced technology products and services for the automotive and space and defense markets worldwide. TRW Inc.'s 1995 sales were more than $10 billion. -0-

                                 TOMS-EP
                        Technical Specifications

Physical Characteristics:
- Dimensions:
  -- With solar arrays stowed:  70 inches long X 44 inches wide
     (1.8 X 1.1 meters)
  -- With solar arrays deployed:  96 inches long X 153 inches wide
     (2.4 X 3.9 meters)
- Weight:  637 pounds (289 kilograms)

Power:
- 128 watts orbit average power
-  2 fixed solar arrays, cells on both sides
-  9 amp hours battery

Bus Components:
- Orbit adjust module contains complete hydrazine propulsion subsystem
- Equipment module contains avionics and attitude control components
- Modular design makes it easy to test, easy to grow

Propulsion System:
- System used for orbit adjustment and attitude control
- 4 dual seat, dual redundant thruster modules (total: 8 thrusters)
- Tank capacity: 160 pounds (72 kilograms) of monopropellant hydrazine
- Mission uses 100 pounds (45 kilograms) of propellant

Attitude Control:
- 3-axis stabilized
- Pointing knowledge (per axis): better than 0.25 degrees
- Pointing accuracy (per axis): better than 0.5 degrees pitch/roll;
  better than 1 degree yaw

Command and Data Handling:
- 16 megabytes of electronic data storage
- Uploadable program memory
- S-band omni antennas coverage
  -- 2 kilobits-per-second (kbps) uplink rate, redundant receivers
  -- Three downlink rates:  1.1 kbps; 50 kbps; 200 kbps

Operational Features:
- 24-hour autonomous operation
- Autonomous safe modes with ground-supported recovery
- Two-year mission design life; three-year mission goal

Reliability:
- Greater than 95 percent reliability for two years
- Greater than 90 percent reliability for three years

Launch/Mission Features:
- Pegasus XL small expendable launch vehicle (via Lockheed-1011)
  -- Separation at 210 X 592 miles (340 X 955 kilometers)
- Onboard propulsion system adjusts to 312 mile (500 kilometer)
  circular sun-synchronous orbit

Instrument:  Total Ozone Mapping Spectrometer (TOMS)
Weight:  70 pounds (32 kilograms)
Power required:  25 watts average power

CONTACT: TRW, Redondo Beach

A. Brooks McKinney, 310/814-8177 (office)

800/467-3700 (pager at launch site)

Access via PIN 602.7255