MARS OBSERVER PRESS KIT

SEPTEMBER 1992



PUBLIC AFFAIRS CONTACTS


NASA HEADQUARTERS, WASHINGTON, D.C.

Office of Space Science and Applications
Paula Cleggett-Haleim

Donald L. Savage


Office of Communications
Dwayne C. Brown



JET PROPULSION LABORATORY, PASADENA, CALIF.
Robert J. MacMillan
Diane Ainsworth



KENNEDY SPACE CENTER, FLA.
Dick Young
Karl Kristofferson
George H. Diller



MARSHALL SPACE FLIGHT CENTER, HUNTSVILLE, ALA.
Dom Amatore
Jerry Berg



LEWIS RESEARCH CENTER, CLEVELAND
Marilyn S. Edwards
Mary Ann Peto



CONTENTS


General Release 1

Mars Observer Science Objectives 6

Mission Design 7

Spacecraft Science Instruments 9

Mapping Cycle 17

The Spacecraft System 18

Spacecraft Description 19

Titan III Launch Vehicle 20

Titan III Facts 21

Transfer Orbit Stage 23

Launch Vehicle and Payload Processing 27

Launch Countdown and Flight Control 28

Countdown Milestone Events 29

Mars Observer/Titan III/TOS Tracking Support 30

Salient Facts on Speed and Distance 31

Science Operations 32

Mars Observer Investigators 33

Interdisciplinary Scientists 36

Mars Observer Management 37








MARS OBSERVER READY TO TAKE THE NEXT STEP IN MARS EXPLORATION

RELEASE: 92-142


NASA will continue the exploration of Mars -- started by the Mariner IV
spacecraft 28 years ago -- when Mars Observer is launched in September. The
last U.S. spacecraft to visit Mars was Viking 2 in 1976.

"Mars Observer will examine Mars much like Earth satellites now map our
weather and resources," said Dr. Wesley Huntress, Director of NASA's Solar
System Exploration Division, Washington, D.C. "It will give us a vast amount of
geological and atmospheric information covering a full Martian year. At last
we will know what Mars is actually like in all seasons, from the ground up,
pole to pole.

"In the mid 1960s, the Mariner flybys resulted in the historic first
pictures of the cratered surface of Mars," Huntress continued. "Then, the
Viking landers looked for signs of life at two landing sites. The Viking
orbiters also made global maps which gave us a good picture primarily of
surface features. Now, the Mars Observer mission marks the next phase in
planetary exploration."

"Mars Observer will tell us far more about Mars than we've learned from
all previous missions to date," said David Evans, Project Manager, NASA's Jet
Propulsion Laboratory (JPL), Pasadena, Calif. "We want to put together a global
portrait of Mars as it exists today and, with that information, we can begin to
understand the history of Mars.

"By studying the evolution of Mars, as well as Venus', we hope to develop
a better understanding as to what is now happening to planet Earth," Evans
said. "As we look even further into the future, this survey will be used to
guide future expeditions to Mars. The first humans to set foot on that planet
will certainly use Mars Observer maps and rely on its geologic and climatic
data," Evans said.

Launch and Cruise to Mars

Mars Observer is scheduled for launch aboard a Titan III rocket in late
September from Cape Canaveral Air Force Station, Fla. The beginning of the
launch opportunity is Sept. 16, 1992. The launch window opens at 1:02 p.m.
EDT and closes at 3:05 p.m. EDT. The daily launch window will vary slightly on
subsequent days. The 28-day launch opportunity extends through Oct. 13, 1992.

Mars Observer will be lofted into Earth orbit aboard a Titan III launch
vehicle. After separation from the Titan, an upper stage vehicle -- the
Transfer Orbit Stage (TOS) -- will fire to free the spacecraft from Earth's
gravity and send it on to Mars.

"During its 11-month transit from Earth to Mars, known as the cruise
phase, Mars Observer will deploy four of its six solar panels to begin drawing
solar power," said George Pace, Spacecraft Manager at JPL.

"The dish-shaped, high-gain antenna will be deployed and the
Magnetometer and Electron Reflectometer (MAG/ER) and the Gamma Ray Spectrometer
(GRS) will be partially deployed," Pace said. "Four trajectory correction
maneuvers are planned during the cruise phase to guide the spacecraft to its
destination."

On Aug. 19, 1993, Mars Observer will arrive in the vicinity of Mars. As
it approaches the planet, the spacecraft will fire onboard rocket engines to
slow its speed and allow the gravity of Mars to capture it in orbit around the
planet.

Mars Observer will first enter a highly elliptical orbit. Then, over a
period of 4 months, onboard rocket thrusters will gradually move the spacecraft
into a nearly circular orbit inclined 93 degrees to the planet's equator at 204
nautical miles (378 kilometers) above the Martian surface. In this orbit, the
spacecraft will fly near the Martian poles.

Global Mapping Mission and Science Operations

Mars Observer will provide scientists with an orbital platform from which
the entire Martian surface and atmosphere will be examined and mapped. The
measurements will be collected daily from the low-altitude polar orbit, over
the course of 1 complete Martian year -- the equivalent of 687 Earth days.

"The scientific payload consists of seven science instruments to examine
Mars from the ionosphere -- an envelope of charged particles that surrounds
Mars -- through the atmosphere and to the surface," said Dr. Arden Albee,
Project Scientist at the California Institute of Technology.

"The science instruments will provide teams of experimenters with daily
global maps of the planet," Albee said. "Mars Observer's camera (MC) will
resolve objects far smaller than was previously possible -- down to about 33
feet (10 meters) in diameter."

Scientists will control their spaceborne experiments from their home
institutions through a computer network linking them to the Mars Observer
operations center at JPL. They can access data from their experiments daily
using special workstations and electronic communications links and distribute
results to other mission science teams.

International Participation

Near the end of its prime mission in the fall of 1995, Mars Observer may
be joined by the Russian "Mars '94" spacecraft. Current plans call for the
Russian spacecraft to deploy penetrators as well as small surface stations.
Mars Observer's Mars Balloon Relay (MBR) radio-receiver equipment, supplied by
the Centre National d'Etudes Spatiales (CNES) in France, is designed to relay
data from the penetrators and surface stations to Earth.

The Mars Observer mission also includes scientists from three countries
besides the United States on its seven investigation teams, both as team
members and as co- investigators. In addition, four foreign participating
scientists will join the teams in October 1992.

Also in October, 11 participating scientists from Russia will be added to
the teams as part of the continuing formal U.S. - Russian cooperation in
planetary exploration.

Program and Mission Management

The Mars Observer spacecraft was built under contract to NASA and JPL by
the Astro-Space Division of General Electric, Princeton, N.J.

NASA's Lewis Research Center in Cleveland, Ohio, managed the commercial
launch services contract with Martin Marietta Commercial Titan, Inc., Denver,
which supplied the Titan III launch vehicle.

The Transfer Orbit Stage (TOS) was built by Martin Marietta under contract
to Orbital Sciences Corp., Vienna, Va. The TOS project was managed by NASA's
Marshall Space Flight Center, Huntsville, Ala.

Launch Complex 40 at the Cape Canaveral Air Force Station was completely
refurbished for the launch by Martin Marietta and the Bechtel Corporation under
contract to the U.S. Air Force.

NASA's Deep Space Network (DSN) will support the launch, mission
operations and tracking of the spacecraft throughout its primary mission.
Tracking and data retrieval through the DSN are managed by JPL for NASA's
Office of Space Communications, Washington, D.C.

The Mars Observer Project Manager is David D. Evans of JPL. Dr. Arden
Albee of the California Institute of Technology is the Project Scientist. Dr.
William L. Piotrowski of NASA Headquarters is the Mars Observer Program Manager
and Dr. Bevan French is the Program Scientist.

JPL manages the mission for the Solar System Exploration Division of
NASA's Office of Space Science and Applications at NASA Headquarters,
Washington, D.C.

- end of general release -


MARS OBSERVER SCIENCE OBJECTIVES


The Mars Observer mission will study the geology, geophysics and climate
of Mars. The primary objectives are to:

% identify and map surface elements and minerals;
% measure the surface topography and features;
% define globally the gravitational field;
% determine the nature of the magnetic field;
% determine the distribution, abundance, sources and destinations of
volatile material (carbon dioxide, water) and dust over a seasonal
cycle; and
% explore the structure and aspects of the circulation of the
atmosphere.

The mission will provide scientists with a global portrait of Mars as it
exists today using instruments similar to those now used to study the Earth.
The seven instruments have been selected so that observations from one provide
a complimentary approach to the mission objectives. For example, the
composition of surface minerals will be addressed by both the Gamma Ray
Spectrometer (chemical composition) and the Thermal Emission Spectrometer
(mineral composition).

The interdisciplinary investigations of the Mars Observer mission also
will combine data from more than one instrument to explore questions that cross
boundaries between scientific disciplines and individual investigations. The
six interdisciplinary investigations are:

% atmospheres/climatology;
% data management/archiving and surface weathering processes;
% geosciences;
% polar atmospheric sciences;
% surface-atmosphere interactions; and
% surface properties and morphology.

The mission will provide a major increase in available scientific data
about Mars. During its 687-day mapping mission, Mars Observer will return about
120 megabytes of data per day, for a total of about 80 - 90 gigabytes (about
600 billion bits of information). This amounts to more scientific information
than has been returned by all previous planetary missions, whether to Mars or
elsewhere, not including the current Magellan mission.


Mission Design


Following launch and insertion into a trans-Martian trajectory by TOS, the
spacecraft will perform four trajectory correction maneuvers (TCM) to correct
and adjust the trajectory. TCM-1, scheduled for L+15 days (Oct. 1, 1992), will
correct any errors from injection. Following TCM-2, both the GRS and the
MAG/ER will be activated to collect data on the space environment. On Jan. 20,
1993, the MOC will be powered on to take two narrow angle images as a
check-out.

The Mars orbit insertion phase is the transition from the interplanetary
cruise phase to the mapping orbit. Since direct transition into the mapping
orbit would require undesirable out-of-plane maneuvers, a series of seven orbit
insertion maneuvers will be performed to bring the spacecraft into the proper
orbit for mapping. During these maneuvers there will be limited scientific
activity.

The polar orbit chosen for the Mars Observer mission is low enough to
allow close-range study of Mars, but high enough so that the atmosphere does
not drag excessively on the spacecraft. The orbit also is sun-synchronous,
meaning that the spacecraft will pass over Mars' equator at the same local time
during each orbit -- about 2 p.m. on the day side and about 2 a.m. on the night
side. This orbit is essential for a number of measurements, as it helps
distinguish daily atmospheric variations from seasonal variations.

During the mission's mapping cycle, which begins in earnest on Jan. 13,
1994, data reception from the spacecraft and command updates to the spacecraft
and individual science instruments will be conducted on a daily basis.

Once the primary task is completed, the Mars Observer mission may be
extended -- if the spacecraft and instruments are still in good condition and
if there is enough fuel to control the spacecraft's altitude and orientation.



SPACECRAFT SCIENCE INSTRUMENTS


Collectively, Mars Observer's seven scientific instruments will cover much
of the electromagnetic spectrum and form a complementary array. Each
instrument produces sets of data that contribute to a wide variety of
scientific investigations.

Gamma Ray Spectrometer (GRS)

The Gamma Ray Spectrometer will characterize the chemical elements present
on and near the surface of Mars with a surface resolution of a few hundred
kilometers. The data will be obtained by measuring the intensities of gamma
rays that emerge from the Martian surface. These high-energy rays are created
from the natural decay of radioactive elements or can be produced by the
interaction of cosmic rays with the atmosphere and surface.

By observing the number and energy of these gamma rays, it is possible to
determine the chemical composition of the surface, element by element. The GRS
also can measure the presence of any volatiles, such as water and carbon
dioxide, as "permafrost" in the surface materials and the varying thickness of
the polar caps.

Mars Observer Camera (MOC)

The Mars Observer Camera system will photograph the Martian surface with
the highest resolution ever accomplished by an orbiting civilian spacecraft.
Resolution is a measure of the smallest object that can be seen in an image.

Low-resolution global images of Mars -- a daily 'weather map' -- also will
be acquired each day using two wide-angle cameras operated at 4.7-mile
(7.5-kilometer) resolution per picture element (pixel). These same cameras
will acquire moderate-resolution photographs at 787 feet (240 meters) per
pixel.

A separate camera will acquire very-high-resolution images at 4.6 feet
(1.4 meters) per pixel for features of special interest. Each of these camera
systems uses a line array of several thousand detectors and the motion of the
spacecraft to create the images.

The low-resolution camera system will capture global views of the Martian
atmosphere and surface so that scientists may study the Martian weather and
related surface changes on a daily basis. Moderate-resolution images will
monitor changes in the surface and atmosphere over hours, days, weeks, months
and years. The high-resolution camera system will be used selectively because
of the high data volume required for each image.


Thermal Emission Spectrometer (TES)

The Thermal Emission Spectrometer will measure infrared thermal radiation
emitted from the Martian atmosphere and surface. The thermal properties of
Martian surface materials and their mineral content may be determined from
these measurements. When viewing the surface beneath the spacecraft, the
spectrometer has six fields of view, each covering an area of 1.9 by 1.9 miles
(3 by 3 kilometers).

The spectrometer, a Michelson interferometer, will determine the
composition of surface rocks and ice and map their distribution on the Martian
surface. Other capabilities of the instrument will investigate the advance and
retreat of the polar ice caps, as well as the amount of radiation absorbed,
reflected and emitted by these caps. The distribution of atmospheric dust and
clouds also will be examined over the 4 seasons of the Martian year.

Pressure Modulator Infrared Radiometer (PMIRR)

This radiometer will measure the vertical profile of the tenuous Martian
atmosphere by detecting infrared radiation from the atmosphere itself. For the
most part, the instrument will measure infrared radiation from the limb, or
above the horizon, to provide high-resolution (3-mi./5-km.) vertical profiles
through the atmosphere.

The measurements will be used to derive atmospheric pressure and determine
temperature, water vapor and dust profiles from near the surface to as high as
50 miles above the surface. Using these measurements, global models of the
Martian atmosphere, including seasonal changes that affect the polar caps, can
be constructed and verified.

Mars Observer Laser Altimeter (MOLA)

The Mars Observer Laser Altimeter uses a very short pulse of laser light
to measure the distance from the spacecraft to the surface with a precision of
several meters. These measurements of the topography of Mars will provide a
better understanding of the relationship among the Martian gravity field, the
surface topography and the forces responsible for shaping the large-scale
features of the planet's crust.

Radio Science

The Radio Science investigation will use the spacecraft's
telecommunication system and the giant parabolic (dish-shaped) antennas of
NASA's Deep Space Network to probe the Martian gravity field and atmosphere.
These measurements will help scientists determine the structure, pressure and
temperature of the Martian atmosphere.

Each time the spacecraft passes behind the planet or reappears on the
opposite side, its radio beam will pass through the Martian atmosphere briefly
on its way to Earth. The way in which the radio waves are bent and slowed will
provide data about the atmospheric structure at a much higher vertical
resolution than any other Mars Observer experiment.

During that part of the orbit when the spacecraft is in view of Earth,
precise measurements of the frequency of the signal received at the ground
tracking stations will be made to determine the velocity change (using the
Doppler effect) of the spacecraft in its orbit around Mars. These Doppler
measurements, along with measurements of the distance from the Earth to the
spacecraft, will be used to navigate the spacecraft and to study the planet's
gravitational field.

Gravitational field models of Mars will be used along with topographic
measurements to study the Martian crust and upper mantle. By the end of the
mission, as a result of the low altitude of the orbit and the uniform coverage
of Mars Observer, scientists will have obtained unprecedented global knowledge
of the Martian gravitational field.

Magnetometer and Electron Reflectometer (MAG/ER)

Mars is now the only planet in the solar system, aside from Pluto, for
which a planetary magnetic field has not yet been detected. In addition to
searching for a Martian planetary magnetic field, this instrument also will
scan the surface material for remnants of a magnetic field that may have
existed in the distant past. The magnetic field generated by the interaction
of the solar wind with the upper atmosphere of Mars also will be studied.

Mars Balloon Relay (MBR)

The spacecraft carries a radio system supplied by the French Centre
National d'Etudes Spatiales (CNES) to support the Russian Mars 94 mission. The
Mars 94 spacecraft consists of an orbiter, to be launched in October 1994,
which will deploy penetrators and small stations designed to land and operate
on the Martian surface.

The landers and penetrators will carry instruments to directly sample both
the atmosphere and the surface. The landers and penetrators will send data to
the Mars 94 orbiter, or to Mars Observer as a back up, for subsequent relay to
Earth. Both the landers and penetrators are designed to operate for several
years.

The MBR equipment consists of a transmitter/receiver that will
periodically receive and relay scientific and engineering data to Earth.

If it is still operating on an extended mission, Mars Observer also may
support the Russian Mars '96 mission, which is planning to release a balloon
into the Martian atmosphere and possibly deploy landed stations or rover
vehicles which can move about on the surface under their own power, operated
either by remote control from Earth or autonomously under computer control.
Following a launch during the 1996 window, the Mars '96 spacecraft would reach
Mars in 1997.



MAPPING CYCLE

In its near-circular mapping orbit, the Mars Observer spacecraft will
rotate once per orbit to keep the instruments pointed at the planet. This will
allow all instruments to view the planet continuously and uniformly during the
entire Martian year.

The spacecraft, instruments and mission were designed so that sufficient
resources, especially power and data rate, are available to power all
instruments as they collect data simultaneously and continuously on both the
day and night sides of the planet. The camera system takes photos only on the
day side and will acquire additional images every 3 days during real-time radio
transmissions to the Deep Space Network.

The rotation and orientation of the spacecraft are controlled by horizon
sensors, a star sensor, gyroscopes and reaction wheels, as is common on
Earth-orbiting satellites. The horizon sensors, adapted from a terrestrial
design, continuously locate the horizon, providing control signals to the
spacecraft. The star sensor will be used for attitude control during the
11-month cruise and as a backup to the horizon sensors during the mapping
orbit.

Once during each 118-minute orbit, the spacecraft will enter the shadow of
Mars and rely on battery power for about 40 minutes. The battery is charged by
the spacecraft's large solar panel, which generates more than a kilowatt of
power when it is in the sunlight.

Control of the spacecraft and instruments is accomplished through the use
of onboard microprocessors and solid-state memories. Scientific and
engineering data are stored on tape recorders for daily playback to Earth.
Additional data operations will allow information to be returned in real-time
from selected instruments whenever Earth is in view.

The lifetime of the spacecraft will most likely be determined by the
supply of attitude-control fuel and the condition of the batteries.


THE SPACECRAFT SYSTEM


The Mars Observer spacecraft uses, where possible, existing Earth-orbiting
satellite component designs. The craft's main body is shaped like a box and is
about 3.25 feet (1.1 meters) high, 7.0 feet (2.2 meters) wide, and 5.0 feet
(1.6 meters) deep. Mars Observer was built by General Electric's Astro-Space
Division in Princeton, N.J.

With its fuel, the spacecraft and its science instruments weigh about
5,672 pounds (2,573 kilograms). The spacecraft has a 3-year design lifetime
and is equipped with one large solar array, consisting of six 6 x 7.2 x
0.3-foot (183 x 219 x 9.1-centimeter) solar panels.

At launch, the spacecraft's main communication antenna, instrument booms
and solar array will be folded close to the spacecraft. During the cruise
phase these structures will be partially extended. The two 20-foot (6-meter)
instrument booms carry two of Mars Observer's seven scientific instruments, the
Magnetometer and Electron Reflectometer and the Gamma Ray Spectrometer.

After the Mars Observer spacecraft reaches its mapping orbit at Mars, the
solar array and instrument booms will be fully unfolded. The main
communication antenna -- a 4.75- foot (1.45-meter) diameter parabolic antenna
-- will be raised on a 20-foot (6-meter) boom and rotated to have a clear view
of Earth. The spacecraft then will power its instruments to begin conducting
the mission experiments.

Spacecraft Statistics

GENERAL
Design Life 3 years
Mapping Orbit Mars polar, nearly circular
Altitude Above Mars 400 km (242 miles), nominal
Key Features Seven science instruments
(two mounted on 6-m booms)
Bi- and monopropulsion
systems
Three-axis control system
(highly stabilized)
Semiautonomous operation
(stores up to 2000 commands)
Reliability Redundancy used to avoid
single-point failures
Payload Weight 156 kg (343 lb)
Total Weight 2573 kg (5672 lb)
Size (launch configuration):
Length 1.6 m (5.0 ft)
Width 2.2 m (7.0 ft)
Height 1.1 m (3.25 ft)

COMMUNICATIONS
Command Rate 12.5 commands/s (max)
Uplink Data Rate 500 bits/s (max)
Downlink Data Rate 85.3 kbits/s (max)
Antennas 1.45-m-diam. high-gain
parabolic articulating (on
6-m boom)
Three low-gain
Downlink RF Power 44 watts
Tape Recorders 1.38 x 109-bit capacity

PROPULSION
Bipropellant System Monomethyl hydrazine and
nitrogen tetroxide
Monopropellant System Hydrazine
Thrusters (24 total) (4) 490 N
(4) 22 N
(8) 4.5 N (orbit trim)
(8) 0.9 N (momentum
unloading and steering)
Total Propellant Weight 1346 kg (2961 lb)

ATTITUDE AND ARTICULATION CONTROL
Pointing Accuracy Control: 10 mrad
Knowledge: 3 mrad
Pointing Stability 1 mrad (for 0.5 s)
3 mrad (for 12 s)

ELECTRICAL POWER
Solar Array 6 panels, each 183 ~ 219 cm
Array Output Power 1130 watts
Batteries 42-amp-hr NiCd (2)
Electronics Bus voltage regulation

Definitions:
mrad = milliradian (E 0.057!)
N = newton (E 0.225 lb force)


TITAN III LAUNCH VEHICLE


Launch Services Contract

The NASA Lewis Research Center, Cleveland, is responsible for the
management of the Titan III launch services contract with Martin Marietta
Corp., Denver, for the launch of the Mars Observer.

Lewis is responsible for the management, technical oversight and
integration of the payload with the Titan launch system which includes the
analytical, physical, environmental and operational integration activities.

Lewis, along with the Jet Propulsion Laboratory and the Marshall Space
Flight Center, is responsible for integrated trajectory design, including
development of an integrated sequence of events from lift-off through planetary
spacecraft separation from the upper stage.

Launch Vehicle

The Titan III can place payloads in excess of 31,000 pounds into low-Earth
orbit and up to 11,000 pounds into a geosynchronous transfer orbit. The Titan
III is a member of the Titan launch vehicle series that has been in use by the
U.S. Air Force and NASA for more than 20 years, including use in the Gemini
program. The Titan III also was used for NASA's Voyager missions as well as
the two Viking missions, the last U.S. spacecraft to Mars.

The core vehicle consists of two liquid-propellant booster stages that are
the central propulsion element. Twin 10.2-foot diameter solid-propellant
rocket motors (SRMs) are attached to the core vehicle and provide thrust during
initial lift-off and boost phase.


TITAN III FACTS

SOLID ROCKET MOTORS (2) Length: 90.4 feet (27.6 meters)
Diameter: 10.2 feet (3.1 meters)
Motor Thrust: 1.4 million pounds
(6,200 kiloNewtons) per motor
Weight: 552,000 pounds (250,387
kilograms) per motor
Propellants: UTP-30001B solid
Contractor: United Technologies

FIRST STAGE Length: 78.6 feet (24 meters)
Diameter: 10 feet (3 meters)
Engine Thrust: 548,000 pounds
(2,43 kiloNewtons)
Propellants: Aerozine 50, nitrogen
tetroxide
Contractor: Martin Marietta

SECOND STAGE Length: 32.7 feet (10 meters)
Diameter: 10 feet (3 meters)
Engine Thrust: 105,000 pounds (467
kiloNewtons)
Propellants: Aerozine 50,
nitrogen tetroxide
Contractor: Martin Marietta

PAYLOAD FAIRING Diameter: 13.1 feet (4 meters)
Overall Length: 34.2 feet (10.4
meters)
Contractor: Contraves AG

EXTENSION MODULE Single Payload Mission
Length: 4.4 feet (1.34 meters)
Diameter: 13.1 feet (4 meters)
Contractor: Dornier GmbH

LAUNCH SITE Launch Complex 40 and associated
processing facilities at Cape
Canaveral Air Force Station, Fla.

COMMERCIAL TITAN United Technologies, Chemical Systems
CONTRACTOR TEAM Division (solid rocket motors)
Aerojet TechSystems Co. (liquid-
propellant engines)
General Motors' Delco Systems
Contraves AG (payload fairing)
Dornier GmbH (extension module)


Transfer Orbit Stage


A new upper stage vehicle, known as the Transfer Orbit Stage (TOS), will
make its maiden flight during the Mars Observer mission. Following launch
aboard the Titan III rocket, the TOS will propel the spacecraft on its 11-month
interplanetary journey to Mars.

TOS is a single-stage, solid-propellant upper stage vehicle used to propel
a spacecraft from low-Earth orbit toward its ultimate destination. It is a
versatile addition to NASA's inventory of upper stage vehicles, designed to
retain reliability and reduce cost.

Under the terms of a 1983 agreement with Orbital Sciences Corp., Fairfax,
Va., NASA provided technical assistance during the development of TOS. NASA's
TOS Project Office at the Marshall Space Flight Center, Huntsville, Ala.,
ensured vehicle performance, reliability and compliance with launch vehicle and
spacecraft integration and flight-safety requirements.

TOS Vehicle Description

The Mars Observer TOS weighs 24,000 pounds, with a diameter of
approximately 11.5 feet and length of just under 11 feet. The TOS system
consists of flight vehicle hardware and software, as well as associated ground
support equipment. This vehicle uses a United Technologies Chemical Systems
Division ORBUS-21 solid rocket motor main propulsion system, a Honeywell, Inc.,
laser inertial navigation system, a hydrazine reaction control system, and
sequencing and power subsystems. It has an inertial guidance and three-axis
control system, allowing the spacecraft to roll, pitch and yaw.

The propulsion systems for TOS are a main propulsion system and an
attitude control system. The ORBUS-21 solid rocket motor, the main propulsion
for TOS, has a gimbaled, or pivoting, nozzle to provide pitch and yaw control
during motor firing.

For the Mars Observer mission, TOS will be loaded with approximately
22,000 pounds of the solid propellant HTPB (hydroxyl terminated
poly-butadiene). The motor can be loaded with a reduced propellant quantity --
as low as 50 percent of the full load -- to handle a wide range of mission
payload and energy requirements.

Motor ignition is provided by a pyrotechnically initiated solid propellant
ignitor system. The vehicle's hydrazine-powered reaction control system
provides for attitude control of the TOS and TOS/spacecraft combination during
solid rocket motor firing and during periods when the large solid rocket motor
is not firing. The system uses 12 attitude control system thrusters, or small
maneuvering rockets.

TOS avionics hardware and software perform guidance functions, manage the
in-flight data, initiate the sequence of events, determine the distance
traveled and send back engineering data on rocket systems operation during the
boosting phase of the mission.

The laser inertial navigation system is the heart of the package which
provides the required guidance, navigation and control functions.

The First TOS Mission

Fifteen minutes after liftoff, the Titan III will separate from the TOS
and the Mars Observer spacecraft. For about the next 20 minutes, TOS will
provide attitude control of the movements of the spacecraft. It will perform
the necessary calculations and generate the proper commands, including rotating
the spacecraft for thermal control, to ensure the spacecraft is placed into the
proper position for rocket motor ignition which will propel Mars Observer on
its interplanetary course.

Approximately 20 minutes after separation from the Titan III, the TOS
solid rocket motor will fire for its 150-second burn. The powered-flight
period of TOS operation will last approximately 2.5 minutes, during which the
spacecraft/TOS combination will reach a speed of 25,575 miles per hour. Then,
having done its job, it will separate from the Mars Observer.



Launch Vehicle and Payload Processing


On June 19, the Mars Observer spacecraft arrived at the Kennedy Space
Center (KSC) in an over-the-road environmentally controlled payload transporter
known as PETS, the Payload Environmental Transportation System. It was taken to
Hangar AO located on Cape Canaveral Air Force Station to begin checkout.
Spacecraft subsystem testing was performed, the integrity of the onboard
propulsion system was checked and compatibility with the world-wide Deep Space
Network tracking stations was verified.

On July 9, Mars Observer was again moved by the PETS from Hangar AO to the
Payload Hazardous Servicing Facility (PHSF) on KSC. There, final electrical
testing was completed, the spacecraft was fueled with its flight load of
hydrazine propellant and a weight and balance measurement was taken.

On Aug. 3, it was mated to the upper stage vehicle, the Transfer Orbit
Stage (TOS). The TOS arrived at the PHSF on Jan. 10 to begin processing and
electrical testing which was completed in late June.

The Titan III rocket arrived from Martin Marietta in Denver by C-5
aircraft on Feb. 28 and was taken to the Vertical Integration Building (VIB) to
begin build up. The first and second stage engine installation activity began
in mid-March, and on March 26 the vehicle was erected on the launch platform.

Meanwhile, in the near-by Solid Rocket Motor Assembly Building (SMAB) the
build-up of the solid rocket boosters also began in mid-March and was completed
on May 18. On June 24, the Titan core vehicle was moved from the VIB to the
SMAB for mating to the twin solid rocket booster stack. The rollout of the
complete Titan III vehicle to Launch Complex 40 occurred on June 2.

The integrated Mars Observer/Transfer Orbit Stage payload was encapsulated
in the Titan III nose fairing at the PHSF on Aug. 19. It was transported to
Launch Complex 40 on Cape Canaveral Air Force Station on Aug. 21 and hoisted
into the clean room of the gantry-like mobile service tower and mated to the
rocket.

On Aug. 25 a routine inspection of the payload revealed particulate
contamination on the surface of the spacecraft. The payload was demated and
returned to the PHSF for cleaning on Aug. 29. On Sept. 4 the payload was
scheduled to be mated to the launch vehicle. A countdown dress rehearsal is
scheduled for Sept. 17, with launch scheduled for Sept. 25.


LAUNCH COUNTDOWN AND FLIGHT CONTROL


The countdown for the launch of the Titan III with the Mars Observer
spacecraft will be conducted from a combination of NASA and U.S. Air Force
Facilities on Cape Canaveral Air Force Station. The primary facility from which
management decisions will be made is the Mission Director's Center (MDC)
located in Hangar AE. This is the nerve center of expendable vehicle launch
operations. From here and the adjacent Launch Vehicle Data Center (LVDC), the
health of the launch vehicle and the Mars Observer spacecraft will be monitored
before launch.

Actual control of the Titan III rocket before launch, and from where the
terminal launch countdown events are initiated, will be from the Vertical
Integration Building (VIB) in the Titan complex. Control of the upper stage
before launch, the Transfer Orbit Stage, will be from the TOS Payload
Operations Control Center (POCC) on Kennedy Space Center.

Also in Hangar AE is where NASA's central telemetry facility, or telemetry
lab, is located. During powered flight performance data from the Titan III,
the TOS and Mars Observer will arrive here. The data will be recorded and
displayed, then forwarded to flight control areas. Among those areas are the
MDC and LVDC in Hangar AE, the Mars Observer Mission Operations Center in
nearby Hangar AO and the TOS POCC.

All events which occur during powered flight will be monitored and
displayed in the Mission Director's Center. Vehicle flight data will also be
displayed in the LVDC and the VIB. After payload separation, primary monitoring
will be from the Mars Observer Mission Operations Center in Hangar AO, the TOS
POCC at KSC and from Jet Propulsion Laboratory in Pasadena.


Countdown Milestone Events:


T-Time
(minutes:seconds)
Call to stations
T-420 Power-up TOS
T-410 Titan Inertial Guidance System alignment
complete
T-400 Range Safety holdfire checks
T-345 Load Mars Observer star catalog
T-255 Begin Titan III final checks
T-230 Titan III checks complete
T-150 Poll launch team for mobile service tower
rollback
T-100 Mobile service tower in launch position
T-30 Enter planned 50-minute built-in hold
T-30 Resume countdown
T-25 Mars Observer to flight mode
T-10 Enter 10-minute built in hold/poll launch team
T-10 Resume countdown
T-07 Poll launch team for final status checks
T-05 Resume countdown
T-04 Mars Observer to internal power
T-2:30 Range Safety clear to launch
T-2:00 Start data recorders
T-1:55 Arm firing chain relay
T-1:05 Start launch sequence
T-1:03 Enter terminal count
T-0:50 TOS to inertial guidance
T-0:37 TOS to internal power
T-0:32 Titan III to internal power
T-0:16 Arm Range Safety Command Destruct system
T-0:02 Titan to inertial guidance/arm booster
igniters
0.0 Sold rocket booster ignition
0.2 Liftoff
00:54 Maximum dynamic pressure
01:48 Titan core vehicle ignition
01:56 Solid rocket booster jettision
03:51 Jettision payload fairing
04:28 Stage 2 ignition
04:29 Stage 1 separation
08:06 Stage 2 cutoff
15:00 Vehicle/payload separation
31:20 TOS ignition
33:56 TOS burnout
53:31 TOS/Mars Observer separation
68:30 Deploy solar array for cruise
71:40 Deploy high gain antenna
75:26 Deploy Gamma Ray Spectrometer boom for cruise
76:00 Deploy Magnatometer boom for cruise
76:10 Turn on attitude control system
80:42 Turn on low gain transmitter

MARS OBSERVER/TITAN III/TOS TRACKING SUPPORT

Tracking data and telemetry for the Mars Observer/Titan III/TOS launch
will be provided by a combination of NASA and U.S. Air Force ground stations
down range and around the world.

Spacecraft X-band tracking data and telemetry will be received by the Deep
Space Network (DSN) managed by the Jet Propulsion Laboratory, Pasadena, Calif.

Titan III and TOS S-band tracking data and telemetry information and also
coverage by C-band radars for ballistic trajectory information will be handled
by U.S Air Force tracking stations and the NASA Spacecraft Tracking and Data
Network (STDN).

Data coverage also will be supplemented by U.S. Air Force Advanced Range
Instrumentation Aircraft (ARIA). Two ARIA will provide support over the
Atlantic Ocean and three other ARIA will provide support in the Indian Ocean
region.

Following is a partial list of primary tracking station locations and the
role they play, either S-band for telemetry and tracking data or C-band for
radar coverage and the span of time during the flight when data can be supplied
if the launch occurs at the opening of the launch window:

% Merritt Island/Cape Canaveral (NASA S-band/USAF S-band C-Band) 0:00-8:00
% Jupiter Inlet (USAF S-band/C-band) 0:30 - 8:05
% Bermuda (NASA S-band/C-band) 4:12 - 10:48
% Antigua Island (USAF S-band/C-band) 6:10 - 11:48
% ARIA-Atlantic Region (USAF S-band) 13:00 - 17:00
% Canberra, Australia (NASA S-band/X-band) 49:00 - end of support

Communication After Launch

NASA's DSN has the responsibility to communicate with the Mars Observer
following injection into its trajectory to Mars. The three Deep Space
Communications Complexes, located in Goldstone, Calif., Madrid, Spain and
Canberra, will provide the air-to-ground links communication links with the
spacecraft in Mars orbit. At its maximum distance from Earth, the time
required for a signal to be sent to the spacecraft and be returned to Earth
(called the round trip light time) will be approximately 40 minutes.

Communications links which tie together all elements of the project team
on Earth are provided by the NASA Communications Network (NASCOM) and the
Program Support Communications Network (PSCN).

NASA's Office of Space Communications provides the overall program
management for the communication system. The STDN and NASCOM networks are
managed by GSFC. The PSCN is managed by the Marshall Space Flight Center,
Huntsville, Ala. The DSN is managed by JPL, in concert with Spain and
Australia.

SALIENT FACTS ON SPEED AND DISTANCE


Speed in Earth orbit
(with respect to Earth) 17,300 mph (7.73 km/s)

Speed at TOS burnout
(with respect to Earth) 25,700 mph (11.5 km/s)

Average speed during cruise
(with respect to Sun) 56,000 mph (25.0 km/s)

Speed before Mars orbit insertion
maneuver (with respect to Mars) 11,800 mph (5.28 km/s)

Speed after Mars orbit insertion maneuver
(with respect to Mars) 10,200 mph (4.56 km/s)

Speed in mapping orbit
(with respect to Mars) 7,500 mph (3.35 km/s)

Distance traveled between Earth and Mars 450 million miles
(7.24 x 108 km)

Distance from Earth at Mars arrival 210 million miles
(3.4 x 108 km )

Distance from Earth during Min: 62 Mmi (108 km)
mapping phase Max: 230 Mmi (3.7 x 108 km)

Time for command to reach spacecraft Min: 5.5 minutes
during mapping phase Max: 20.5 minutes

Maximum acceleration on spacecraft (postlaunch) 0.1 G
(occurs during transfer to low orbit)

Navigation target diameter at Mars 300 miles (480 km)
(less than 1/10 of planet diameter)


SCIENCE OPERATIONS


The Mars Observer mission operations at the Jet Propulsion Laboratory will
be supported by NASA's Deep Space Network (DSN) and the JPL Advanced
Multimission Operations System. The 34-meter (111- foot), high-efficiency
subnetwork, the newest of the DSN antenna subnets, will provide daily uplink
and downlink communications with the spacecraft at X-band frequencies of 8.4
gigahertz. The 70- meter (230-foot) antenna network also will provide periodic
very-long-baseline interferometry and real-time, high-rate telemetry and radio
science support to the mission.

The DSN facilities are located in Pasadena and Goldstone, Calif.;
Canberea, Australia; and Madrid, Spain.

The instrument scientists will remain at their home institutions, from
which they will access Mars Observer data via a project database at JPL. Using
workstations and electronic communications links, scientists also will be
connected to the mission planning activities at JPL.

In the same way, data products returned to the JPL database from the home
institution for each of the instruments will be sent electronically to other
investigators at their home institutions. This will allow scientists to have
ready access to science data without moving to JPL for the duration of the
mission.

More than 60 workstations will be connected to the project database at
JPL, a centralized repository for downlink science and engineering telemetry
data, ancillary data including navigation data, and uplink command and sequence
data. This database, with about 30 gigabytes of on- line storage, will be
electronically available to the science instrument investigators via NASCOM
data links.

During the mapping phase, the instrument investigations will return
processed science data products to the database at JPL for access by the
interdisciplinary scientists and the other investigation teams.

Forty-two participating scientists from universities and scientific
institutions in the United States, Russia, France, Germany and Great Britain
will join the permanent Mars Observer science team once the mission is under
way in October 1992.








MARS OBSERVER INVESTIGATORS

Gamma Ray Spectrometer (GRS)
TEAM LEADER: William V. Boynton, University of Arizona
James R. Arnold, University of California, San Diego
Peter Englert, San Jose State University
William C. Feldman, Los Alamos National Laboratory
Albert E. Metzger, Jet Propulsion Laboratory
Robert C. Reedy, Los Alamos National Laboratory
Steven W. Squyres, Cornell University
Jacob L. Trombka, Goddard Space Flight Center
Heinrich Wnke, Max Planck Institute for Chemistry
Johannes Brckner, Max Planck Institute for Chemistry
Darrell M. Drake, Los Alamos National Laboratory
Larry G. Evans, Computer Sciences Corporation
John G. Laros, Los Alamos National Laboratory
Richard D. Starr, Catholic University
Yu A. Surkov, Russia

Mars Observer Camera (MOC)
PRINCIPAL INVESTIGATOR: Michael C. Malin, Malin Space Science Systems, Inc.
G. Edward Danielson Jr., California Institute of Technology
Andrew P. Ingersoll, California Institute of Technology
Laurence A. Soderblom, U.S. Geological Survey
Joseph Veverka, Cornell University
Merton E. Davies, The RAND Corporation
William K. Hartmann, Science Applications International
Philip B. James, University of Toledo
Alfred S. McEwan, U.S. Geological Survey
Peter C. Thomas, Cornell University

Thermal Emission Spectrometer (TES)
PRINCIPAL INVESTIGATOR: Philip R. Christensen, Arizona State University
Donald A. Anderson, Arizona State University
Stillman C. Chase, Santa Barbara Research Center
Roger N. Clark, U.S. Geological Survey
Hugh H. Kieffer, U.S. Geological Survey
Michael C. Malin, Malin Space Science Systems, Inc.
John Pearl, Goddard Space Flight Center
Todd R. Clancy, University of Colorado
Barney J. Conrath, Goddard Space Flight Center
R.O. Kuzmin, Russia
Ted L. Roush, San Francisco State University
A.S. Selivanov, Russia

Pressure Modulator Infrared Radiometer (PMIRR)
PRINCIPAL INVESTIGATOR: Daniel J. McCleese, Jet Propulsion Laboratory
Robert D. Haskins, Jet Propulsion Laboratory
Conway B. Leovy, University of Washington
David A. Paige, University of California, Los Angeles
John T. Schofield, Jet Propulsion Laboratory
Fredric Taylor, University of Oxford
Richard W. Zurek, Jet Propulsion Laboratory
Michael D. Allison, Goddard Space Flight Center
Jeffrey R. Barnes, Oregon State University
Terry Z. Martin, Jet Propulsion Laboratory
Peter L. Read, University of Oxford

Mars Observer Laser Altimeter (MOLA)
PRINCIPAL INVESTIGATOR: David E. Smith, Goddard Space Flight Center
Herbert V. Frey, Goddard Space Flight Center
James B. Garvin, Goddard Space Flight Center
James W. Head, Brown University
James G. Marsh, Goddard Space Flight Center
Duane Muhleman, California Institute of Technology
Gordon H. Pettengill, Massachusetts Institute of Technology
Roger J. Phillips, Southern Methodist University
Sean C. Solomon, Massachusetts Institute of Technology
Maria T. Zuber, Goddard Space Flight Center
H. Jay Zwally, Goddard Space Flight Center
Bruce W. Banerdt, Jet Propulsion Laboratory
Thomas C. Duxbury, Jet Propulsion Laboratory

Radio Science (RS)
TEAM LEADER: G. Leonard Tyler, Stanford University
Georges Balmino, Centre National d'Etudes Spatiales (CNES), France
David Hinson, Stanford University
William L. Sjogren, Jet Propulsion Laboratory
David E. Smith, Goddard Space Flight Center
Richard Woo, Jet Propulsion Laboratory
E. L. Akim, Russia
John W. Armstrong, Jet Propulsion Laboratory
Michael F. Flasar, Goddard Space Flight Center
Richard A. Simpson, Stanford University

Magnetometer and Electron Reflectometer (MAG/ER)
PRINCIPAL INVESTIGATOR: Mario H. Acuna, Goddard Space Flight Center
Kinsey S. Anderson, University of California, Berkeley
Sigfried Bauer, University of Graz
Charles W. Carlson, University of California, Berkeley
Paul Cloutier, Rice University
John E. P. Connerney, Goddard Space Flight Center
David W. Curtis, University of California, Berkeley
Robert P. Lin, University of California, Berkeley
Michael Mayhew, National Science Foundation
Norman F. Ness, University of Delaware
Henri Reme, University of Paul Sabatier
Peter J. Wasilewski, Goddard Space Flight Center
M. Menvielle, University of Paris Sud, France
Diedrich Mhlmann, German Aerospace Research Establishment, Germany
A.A. Ruzmaikin, Russia
James A. Slavin, Goddard Space Flight Center
A.V. Zakharov, Russia


INTERDISCIPLINARY SCIENTISTS

Raymond E. Arvidson, Washington University
Bruce Fegley Jr., Washington University
Michael H. Carr, U.S. Geological Survey
A. T. Bazilevsky, Russia
Matthew Golombek, Jet Propulsion Laboratory
Harry Y. McSween Jr., University of Tennessee
Andrew P. Ingersoll, California Institute of Technology
Howard Houben, Space Physics Research Institute
Bruce M. Jakosky, University of Colorado
L.V. Ksanfomality, Russia
Aaron P. Zent, Search for Extraterrestrial Intelligence (SETI) Institute
James B. Pollack, Ames Research Center
Robert M. Haberle, Ames Research Center
V.I. Moroz, Russia
Laurence A. Soderblom, U.S. Geological Survey
Ken Herkenhoff, Jet Propulsion Laboratory
Bruce C. Murray, California Institute of Technology






MARS OBSERVER MANAGEMENT


NASA HEADQUARTERS, WASHINGTON, D.C.

Office of Space Science and Applications
Dr. Lennard A. Fisk, Associate Administrator
Alphonso V. Diaz, Deputy Associate Administrator
Dr. Wesley T. Huntress, Director, Solar Systems Exploration Div.
Douglas R. Broome, Deputy Director, Solar System Exploration Div.
Dr. William L. Piotrowski, Chief, Flight Programs Branch and Mars
Observer Program Manager
William C. Panter, Mars Observer Deputy Program Manager
Dr. Bevin M. French, Mars Observer Program Scientist
Guenter K. Strobel, Planetary Flight Support Manager
Charles R. Gunn, Director, Expendable Launch Vehicles Office
B.C. Lam, Upper Stages Program Manager

Office of Space Communications
Charles T. Force, Associate Administrator for Space Communications
Jerry J. Fitts, Deputy Associate Administrator for Space Communications
Robert M. Hornstein, Director, Ground Networks Div.


JET PROPULSION LABORATORY, PASADENA, CALIF.
Dr. Edward C. Stone, Director
Larry N. Dumas, Deputy Director
John R. Casani, Assistant Laboratory Director, Flight Projects
David D. Evans, Mars Observer Project Manager
Glenn E. Cunningham, Mars Observer Deputy Project Director
Dr. Arden L. Albee, Mars Observer Project Scientist
Frank D. Palluconi, Mars Observer Deputy Project Scientist
Thomas E. Thorpe, Mars Observer Science Manager
George D. Pace, Mars Observer Spacecraft Manager
Gary L. Reisdorf, Mars Observer Payload Manager
Dr. Saterios S. Dallas, Mars Observer Mission Manager
Joseph Shaffer, Mars Observer Launch Vehicle Manager
Gail K. Robinson, Mars Observer Administration and Finance Manager
T. David Linich, Multi-Mission Operations Support Manager
Eugene S. Burke, Multi-Mission Operations Manager
Marvin Traxler, Tracking and Telecommunications Data Systems Manager
Dr. Peter Poon, Coordinator with Multimission Operations Systems Center

KENNEDY SPACE CENTER, FLA.
Robert L. Crippen, Director
James A. "Gene" Thomas, Deputy Director
John T. Conway, Director, Payload Management and Operations
James L. Womack, Director, Expendable Vehicles
George E. Looschen, Chief, Launch Operations Division
David C. Bragdon, Launch Vehicle/Payload Integration Manager
Floyd A. Curington, Chief, Project Planning and Support
James W. Meyer, Tracking and Range Coordinator
JoAnn H. Morgan, Director, Payload Projects Management
Gayle C. Hager, Mars Observer Launch Site Support Manager
Julie A. Scheringer, TOS Launch Site Support Manager


LEWIS RESEARCH CENTER, CLEVELAND
Lawrence J. Ross, Director
Dr. J. Stuart Fordyce, Deputy Director
Thomas H. Cochran, Director, Space Flight Systems
John W. Gibb, Manager, Launch Vehicle Project Office
Steven V. Szabo, Jr., Director, Engineering Directorate
Edward G. Stakolich, Titan Mission Manager
Edwin R. Procasky, Chief, System Engineering Office
Edwin T. Muckley, Chief, Mission and Vehicle Integration Office


MARSHALL SPACE FLIGHT CENTER, HUNTSVILLE, ALA.
Thomas J. Lee, Director
Dr. J. Wayne Littles, Deputy Director
Sidney P. Saucier, Manager, Space Systems Projects
Alvin E. Hughes, Manager, Upper Stage Projects
Robert W. Hughes, Upper Stages Chief Engineer


GODDARD SPACE FLIGHT CENTER, GREENBELT, MD.
Dr. John Klineberg, Director
Peter T. Burr, Deputy Director
Dr. Dale W. Harris, Director, Flight Projects Directorate
Jeremiah J. Madden, Associate Director of Flight Projects for Earth Observing
System (EOS)
Martin J. Donohoe, Project Manager for EOS Instruments Projects
Dr. Douglas D. McLennan, Manager for Mars Observer GRS
Bertrand L. Johnson, Jr., Manager for Mars Observer MOLA



====PRESS RETURN TO CONTINUE====


Enter an option number, 'G' for GO TO, ? for HELP, or
press RETURN to redisplay menu...