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Conference 7.286::space

Title:Space Exploration
Notice:Shuttle launch schedules, see Note 6
Moderator:PRAGMA::GRIFFIN
Created:Mon Feb 17 1986
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:974
Total number of notes:18843

816.0. "TOPEX/POSEIDON Earth Satellite" by VERGA::KLAES (Slaves to the Metal Hordes) Thu Jul 30 1992 18:20

From:	DECWRL::"[email protected]" 30-JUL-1992 
To:	[email protected]
CC:	
Subj:	TOPEX/Poseidon Press Kit

PUBLIC AFFAIRS CONTACTS

Brian Dunbar
Headquarters, Washington, D.C.
(Phone:  202/358-0873)

Mary Hardin
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone:  818/354-5011)


CONTENTS

General Release.............................................................1

Mission Overview And Science Objectives.....................................3

Satellite Tracking..........................................................4

TOPEX/POSEIDON Satellite....................................................5

Science Instruments And Spacecraft..........................................6

Mission Phases..............................................................8

Mission Timeline............................................................9

Spacecraft Specifics.......................................................10

U.S.-French Cooperation....................................................10

Mission Management.........................................................11


RELEASE 92-126

U.S., FRANCE SATELLITE TO STUDY OCEANS AND CLIMATE

	On Aug. 10, the United States and France will undertake a mission to
help provide a new understanding of Earth's environment by determining
how the global system of the Earth's oceanic currents influence climate.

	The means to this end is the TOPEX/POSEIDON satellite, a joint
mission of NASA and France's space agency, the Centre National d'Etudes
Spatiales (CNES).

	"TOPEX/POSEIDON is an investment in our future," said NASA's
Program Scientist Dr. William Patzert.  "Without TOPEX/POSEIDON, there is
no possibility of meaningful long-term climate forecasts."

	"TOPEX/POSEIDON sets a precedent for international studies of global
change," said Patzert.  "In a future of limited resources, it is imperative
that all nations work together to study our atmosphere and oceans.  We will
have to share our understanding to develop common solutions.  Climate knows no
national boundaries."

Ocean Topography

	TOPEX/POSEIDON will use the global perspective available only from
space to develop maps of ocean topography showing the barely perceptible
hills and valleys of the sea surface.  This effort will significantly expand
the knowledge developed from shipboard research which was limited to specific
locations.

	From the TOPEX/POSEIDON data, scientists will calculate the speed
and direction of ocean currents worldwide to better understand how the
oceans transport heat from the Earth's equatorial region toward the poles,
thus regulating global climate.

	The spacecraft's six scientific instruments are designed to function
for 3 to 5 years.  The resulting data base will help scientists develop more
precise long-term climate forecasts, understand and predict the timing of
the El Nio phenomenon and better comprehend the ocean's role in
regulating overall global climate.



	TOPEX/POSEIDON will be launched from the Guiana Space Center in
Kourou, French Guiana, aboard an Ariane 42P expendable launch vehicle.
The satellite will be placed into an orbit 830 miles (1,336 km) above the
Earth, inclined 66 degrees to the Earth's equator.  Launch is scheduled for
7:08 p.m. EDT.  The launch window is 44 minutes in duration.

International Cooperation

	The TOPEX/POSEIDON launch will help commemorate 1992 as the
International Space Year.  The joint science team includes 38 principal
investigators from nine countries including the United States, France,
Australia, South Africa, Germany, Norway, Japan, the Netherlands and the
United Kingdom.  Data from TOPEX/POSEIDON eventually will be made
available to global change researchers around the world for their analysis.

	TOPEX/POSEIDON is the second major satellite in NASA's Mission to
Planet Earth, a coordinated, long-term program to study the Earth as a
complete environmental system.  Mission to Planet Earth began in
September 1991 with the launch of the Upper Atmosphere Research
Satellite and continued last March with the ATLAS-1 Space Shuttle mission.

	The next element of Mission to Planet Earth is the Italian-built
LAGEOS II satellite, scheduled for launch aboard the Space Shuttle Columbia
in October.  LAGEOS II will be used to study the dynamics of the Earth's
crust.

	The U.S. portion of the TOPEX/POSEIDON project is managed by
NASA's Jet Propulsion Laboratory, Pasadena, Calif., for the agency's Office of
Space Science and Applications.  The French portion of TOPEX/POSEIDON
is managed by CNES' Toulouse Space Center, Toulouse, France.


MISSION OVERVIEW

	TOPEX/POSEIDON will be launched by the European Ariane 42P
rocket from Kourou, French Guiana.  The spacecraft will be placed in a
nearly circular orbit with an altitude of 830 miles (1,336 kilometers),
inclined 66 degrees from the equator.  This relatively high altitude will
minimize atmospheric drag on the spacecraft, reduce the effects of gravity
field variations and simplify maneuvers needed to maintain the orbit.

	The satellite's orbital period is 112 minutes.  TOPEX/POSEIDON will
repeat the same ground track every 10 days (127 revolutions), allowing
scientists to measure changes in the sea surface topography using a
sampling technique that matches changes in the global ocean currents.

	This mission builds upon the knowledge gained from three previous
ocean-observing satellites Q GEOS-3 in 1975, Seasat in 1978 and Geosat in
1985 Q which demonstrated that altimetry could measure ocean circulation.
Like these prior missions, the primary instrument on-board the
TOPEX/POSEIDON satellite is a radar altimeter.

	The altimeter is similar to aircraft radar, but the satellite altitude
and the required height precision are many times greater.  The
TOPEX/POSEIDON altimeter bounces radar pulses off the sea surface and
measures the time it takes the signals to return to the satellite.  A
microwave radiometer will correct for any errors in the time delay that is
caused by water vapor in the path through the atmosphere.

	The adjusted round-trip travel time is used to calculate the distance
between the spacecraft and the sea surface.  When this distance is combined
with the measurements of the satellites exact location in space, scientists
will first determine the height of the sea surface relative to the Earth's
center and then calculate fluctuations in currents and tides.

SCIENCE OBJECTIVES

	The primary objective of the TOPEX/POSEIDON project is to make
precise and accurate global observations of the sea level for several years,
substantially increasing understanding of global ocean dynamics.  Members
of the TOPEX/POSEIDON science team will share their data with scientists
working with the World Ocean Circulation Experiment (WOCE).  Together
they will be able to determine the general circulation of the ocean and its
variability.

	The satellite also will increase understanding of how heat is
transported in the ocean.  The ocean absorbs the sun's heat and
redistributes it.  Active currents such as the Gulf Stream carry warm water
from the tropics to the poles where it cools and sinks into the deep ocean.

	Without this circulation, the difference in temperature between
equatorial and polar waters would be much greater than it is today.  How the
water circulates in the ocean determines the speed at which the heat is
transported and how the exchange of energy regulates the world's climate.

El Nio

	Another short-term climate change influenced by the ocean is the
phenomenon known as El Nio.  Every 3 to 7 years, usually beginning
around Christmas time, there is a dramatic rise in the sea surface
temperatures in the eastern Pacific Ocean.  At the same time, atmospheric
patterns shift, causing severe environmental consequences around the globe.

	The El Nio event of 1982-83 was the worst so far this century.
Massive flooding and landslides killed hundreds of people in Ecuador and
Peru and caused millions of dollars in damage along the Southern California
coast.  Cyclones left 25,000 people homeless in Tahiti and severe droughts
plagued the southern hemisphere, especially Australia, Indonesia, the
Philippines and South Africa.

	TOPEX/POSEIDON will improve our knowledge of upper-ocean
circulation in the tropical Pacific, which is essential for reliable
prediction of these El Nio events.

	The ocean also is influenced by gravity and the Earth's rotation.
If the Earth did not rotate, the shape of the resting ocean would conform to
the Earth's gravity, a condition scientists refer to as the geoid.  But the
Earth is not still, and ocean currents raise or lower sea level from the
geoid.  The elevation of sea level relative to the geoid is called ocean
topography.

	Sea currents contribute to the low hills and shallow valleys in the
ocean which are similar to the high and low pressure systems that occur in
the atmosphere.  Sea water flows around these hills and valleys just as winds
blow around the highs and lows of atmospheric surface pressure.
TOPEX/POSEIDON will measure these changes in ocean topography, and
scientists will calculate the speed and direction of ocean surface currents.

SATELLITE TRACKING

	TOPEX/POSEIDON is equipped with instruments that enable
scientists to accurately pinpoint the satellite's location.  Precise orbit
determination is crucial because errors in locating the spacecraft would
distort the sea level measurement calculated from the altimeter readings.

	TOPEX/POSEIDON will measure the distance from the satellite to the
sea surface within 1.2 inches (3 cm).  Three independent tracking systems
will determine the position of the spacecraft within 4 inches (10 cm).  The
first, the NASA laser retroreflector array (LRA) will reflect laser beams from
a network of 10 to 15 ground-based laser ranging stations under clear skies.
	The second, for all-weather, global tracking, will be provided by the
CNES Doppler Orbitography and Radiopositioning Integrated by Satellite
tracking system receiver (DORIS).  This device uses microwave doppler
techniques (changes in radio frequency corresponding to relative velocity)
to track the spacecraft.  DORIS consists of an on-board receiver and a global
network of 40 to 50 ground-based transmitting stations.

	The third system utilizes an on-board experimental Global Positioning
System (GPS) demonstration receiver to precisely determine the satellite's
position continously by analyzing the signals received from the U.S Air
Force's GPS constellation of Earth orbiting satellites.

	TOPEX/POSEIDON also will fly over two verification sites so that
scientists can compare data taken on the ground to the readings obtained
from the satellite.  These sites are located on the Texaco Harvest Oil
Platform off Point Conception, Calif., (the NASA site) and near Lampedusa
Island in the Mediterranean Sea (the CNES site).  Throughout the mission,
comparisons of the information collected at these sites will ensure that the
satellite's instruments are calibrated very precisely.

THE SATELLITE

	The TOPEX/POSEIDON spacecraft is based on the existing
Multimission Modular Satellite (MMS) bus, modified to meet the needs of
this mission.  Built by Fairchild Space, the satellite is comprised of the MMS
and an instrument module which houses the sensors.

	The MMS command and data handling subsystem contains the main
computer on-board TOPEX/POSEIDON.  It interprets and executes
commands and receives data from all subsystems and sensors for
transmission to the ground.  The command and data handling subsystem
houses three tape recorders used for engineering telemetry and science
data storage.  Each tape recorder will record for about four revolutions or 8
hours of data before playback.

	This subsystem also provides telecommunications using a steerable
high-gain antenna dish and two omni antennas.  During normal operations,
the satellite communicates with the ground via the Tracking and Data Relay
Satellite System (TDRSS).  This link handles all commands, science data,
engineering telemetry and the operational orbit tracking for navigation and
mission planning.

	The attitude determination and control subsystem maintains the
proper spacecraft attitude during mission operations and points and
stabilizes the satellite during all orbit adjustments.  It also will
automatically "take charge" to put the satellite into a "safing" mode if
it detects a problem with its own performance or if it does not receive
the periodic "I'm OK" signal from the on-board computer.

	The spacecraft's electrical power subsystem contains the solar array
and three batteries.  The solar array is the main power source and the first
item to be deployed, 2 minutes after separation from the launch vehicle.
After deployment, the on-board controller rotates the array so that the
panels face the sun.

	The batteries provide power from about 10 minutes before launch
until the solar array takes over.  The batteries also are used to keep the
instruments operating while the spacecraft is orbiting the night side of the
Earth.

SCIENCE INSTRUMENTS

	TOPEX/POSEIDON carries five scientific instruments.  Three are
provided by NASA and two by CNES.

The Dual-Frequency TOPEX Radar Altimeter (ALT)

	The primary instrument onboard the satellite is the dual-frequency
NASA radar altimeter (ALT).  Provided by NASA and managed by the
Goddard Spaceflight Center, the altimeter was built by the John Hopkins
University's Applied Physics Laboratory.  The instrument is designed to
measure the height of the satellite above the sea at two frequency channels,
13.6 GHz and 5.30 GHz.  This is the first altimeter to use two channels to
correct for measurement errors caused by free electrons above the Earth's
atmosphere.

The TOPEX/POSEIDON SPACECRAFT

TOPEX Microwave Radiometer (TMR)

	The companion TOPEX microwave radiometer, developed by NASA's
Jet Propulsion Laboratory, Pasadena, Calif., operates at three frequencies
(18 GHz, 21 GHz and 37 GHz)  The radiometer measures water vapor, which can
delay the return of the radar pulse to the spacecraft, along the path viewed
by the altimeter and corrects the altimeter data.  The 21 GHz channel is the
primary channel for water vapor measurement.  The 18 GHz and 37 Ghz
channels are used to remove the effects of wind speed and cloud cover,
respectively, in the water vapor measurement.

Single-Frequency Poseidon Altimeter (SSALT)

	SSALT is an experimental precision altimeter designed by CNES and
built by Alcatel Espace.  This instrument is being flown as an experiment to
validate improved solid-state technology, which results in smaller, lower-
power and lower-weight altimeters for future missions.

	SSAlt uses the same antenna as the NASA altimeter but operates at a
single frequency of 13.6 GHz.  During the first 6-month verification phase,
the SSALT will operate about 12 percent of the time to assess its
performance.  For the remainder of the mission, NASA and CNES will
determine an antenna sharing plan to optimize data collection.

Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS)

	The DORIS tracking system will provide important tracking data for
precision orbit determination using microwave Doppler techniques.  This is
a proven system manufactured by the French aerospace firms, Dassault,
CEPE and STAREC, and was first flown by CNES on the SPOT-2 satellite.

	The system is made up of an on-board receiver and a network of 40 to
50 ground transmitter stations.  Operating in all weather conditions, DORIS
receives signals at two frequencies (401.25 MHz and 2036.25 MHz) which
allows the total electron content of the ionosphere to be estimated.  This
allows the removal of SSALT altitude errors introduced by traveling through
the ionosphere.

Global Positioning System Demonstration Receiver (GPSDR)

	The GPSDR is an experimental receiver developed by JPL and
manufactured by Motorola to provide a unique tracking data type for
continuous precision orbit determination.  This new technique
simultaneously measures the satellite's position relative to the U.S. Air
Force's Global Positioning System and ground stations.  By adding the
ground stations, the exact locations of which have been precisely measured,
the new system promises to revolutionize orbit determination by providing
continuous satellite tracking with a potential accuracy of 4 inches (10 cm)
or better.  The GPS receiver operates at 1227.6 MHz and 1575.4 MHz.
MISSION PHASES

	The French-provided Ariane 42P launch vehicle, manufactured by
Arianespace, is a three-stage, liquid-propelled rocket, approximately 215
feet (60 meters) long, with two strap-on first-stage solid propellant motors.
The first two stages of the core vehicle are powered by hydrazine and
nitrogen tetroxide.  Stage three contains cryogenic liquid oxygen and
hydrogen.  The vehicle equipment bay is located between the third stage
and the payload compartment, and its inertial reference system and
computer conduct the ascent attitude control, guidance and sequencing.

	The spacecraft arrived at the Centre Spatial Guyanais in Kourou,
French Guiana, on June 23 to undergo a series of performance tests prior to
launch.  Five days before launch, the encapsulated satellite will be mated to
the launch vehicle.

	After that, the satellite will continue functional testing and battery
charging cycles in preparation for flight.  Final configuring for the launch
is achieved 90 minutes before liftoff, with the exception of the tape
recorders and transmitters.

	Transmitter A is turned on 2 hours before launch.  Two tape recorders
are commanded to record at launch minus 20 minutes.  At launch minus 10
minutes, the satellite is switched to internal battery power and the umbilical
disconnect process, which takes about 40 seconds, begins a minute later.

	After the umbilical is disconnected, real-time monitoring of the
satellite's functions will be conducted through the satellite's telemetry
transmitter.

Tracking During Launch

	Launch vehicle telemetry is coordinated primarily through the Guiana
tracking facilities at Kourou.  After injection (which occurs approximately 17
minutes after launch), real-time satellite telemetry is available through the
NASA tracking station at Bermuda.

	Telemetry also is recorded on two satellite tape recorders for later
playback.  Several critical events, including injection, the orientation
maneuver, satellite separation and solar array deployment occur while the
Bermuda station is tracking the satellite.

	Madrid is the first Deep Space Network (DSN) station to track the
satellite after launch.  This pass starts 20 minutes after launch
(approximately 1 minute after separation) and continues for 12 minutes.
The DSN 26-meter antennas are the primary method of communicating
during the first day.

	Beyond that, the DSN only will be used as an emergency method of
communicating.  For the balance of the mission, the primary method of
communicating between the satellite and the ground will be via the
Tracking and Data Relay Satellite System (TDRSS).  The first TDRSS contact
is established approximately 1 hour after launch.

MISSION TIMELINE

Mission Elapsed Time	Event
L-1 day	Launch vehicle propellant loading
L-09:30:00	Satellite functional tests
L-06:30:00	Battery cycling
L-02:00:00	Satellite Transmitter A ON
L-02:00:00	Final RF tests
L-01:30:00	Configure Satellite for Launch
L-00:20:00	Configure tape recorders/trackers
L-00:10:00	Set internal battery power
L-00:09:00	Start umbilical demate
L-00:06:00	Begin Ariane automatic launch seq.
L-00:00:09	Release Ariane inertial platform
L-00:00:00	LIFTOFF
L+00:01:28	Solid separation
L+00:03:19	Stage 1 burn out
L+00:03:48	Payload fairing jettisoned
L+00:05:30	Stage 2 burn out
L+00:17:38	Stage 3 shutdown/Orbit Injection
L+00:19:28	Separation
L+00:21:28	Solar Array Deployment
L+00:26:28	High Gain Antenna Deployment
L+00:27:28	GPS Antenna Deployment

Assessment Phase

	The assessment phase begins when the satellite separates from the
Ariane rocket.  For the first 45 days after launch, the satellite's sensors
and instruments will undergo check-out and assessment.  The first spacecraft
maneuver is scheduled for 7 days after launch to refine the satellite's
orbit.  Up to six additional maneuvers will be performed to attain the
precise observational orbit.

Initial Verification Phase

	This phase occurs after the assessment phase and gives the project
team time to calibrate the instruments against ground data they are
receiving from the two laser verification sites.  This phase lasts about 6
months.



Observational Phase

	The key objective of the observational phase is the production and
distribution of the Geophysical Data Records which contains sea surface
height, sensor corrections and geophysical information.  The science data
team is responsible for distributing and archiving these sensor and
geophysical data products.

SPACECRAFT SPECIFICS

Design lifetime:	3 years prime; 2 years extended mission
Length:	18 feet (5.5m)
Width:	9.2 feet (2.8m)
Solar panel:	28.5 feet x 10.8 feet (8.7m x 3.3m)
Power:	2,100 Watts
Mass:	5,500 pounds (2,500kg)

U.S.-FRENCH COOPERATION

	TOPEX/POSEIDON is only one area in which the U.S. and French
space programs are cooperating.  French scientists are principal
investigators or co-investigators on NASA's Galileo and Wind spacecraft and
the Upper Atmosphere Research Satellite.

	There has been substantial collaboration on several Spacelab missions,
including Space Life Sciences-1 in 1991 and the ATLAS-1 and International
Microgravity Laboratory-1 missions in 1992.

	There has been substantial collaboration on several Spacelab missions,
including Space Life Sciences-1 in 1991 and the ATLAS-1 and International
Microgravity Laboratory-1 missions in 1992.  The agencies are cooperating
in development of the Visual and Infrared Mapping Spectrometer to fly on
NASA's Cassini mission to Saturn in 1997.

	U.S.-French cooperation extends back to joint solar studies in the
1960s.  In 1978, CNES provided the ARGOS data collection system that flew
on the TIROS-N satellite and subsequent satellite search-and-rescue
equipment based on ARGOS technology.  In 1985, French payload specialist
Patrick Baudry flew on Space Shuttle mission 51-G, which deployed three
satellites.


MISSION MANAGEMENT

NASA Headquarters

Daniel Goldin	        Administrator

Aaron Cohen	        Acting Deputy Administrator

Dr. L.A. Fisk	        Associate Administrator,
	                Office of Space Science and Applications

Alphonso V. Diaz        Deputy Associate Administrator
	                Office of Space Science and Applications

Dr. Shelby G. Tilford	Director, Earth Science and Applications Division

Dr. W. Linwood Jones	Program Manager

Dr. William Patzert	Program Scientist


Centre Nationale d'Etudes Spatiales

Dr. Jean-Louis Fellous	Program Manager

Michel Dorrer	        Project Manager

Dr. Alain Ratier	Program Scientist

Dr. Michel Lefebvre	Project Scientist
	                Jet Propulsion Laboratory

Charles Yamarone Jr.	Project Manager

Dr. Lee-Lueng Fu	Project Scientist

     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [email protected]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Most of the things you 
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | worry about will never
|_____|/  |_|/       |_____|/                     | happen.
T.RTitleUserPersonal
Name		DateLines
816.1ARIANE V52VERGA::KLAESSlaves to the Metal HordesMon Aug 03 1992 12:01134
Article: 46773
Newsgroups: sci.space
From: [email protected] (Dean Adams)
Subject: Ariane V.52
Sender: [email protected] (netnews admin account)
Organization: University of Denver, Dept. of Math & Comp. Sci.
Date: Sat, 1 Aug 92 11:30:25 GMT
 
ARIANESPACE FLIGHT 52
 
The 52nd Ariane launch is to place the TOPEX/POSEIDON satellite and two
auxiliary payloads, KITSAT-A and S80/T, into a quasi-circular 66 degree 
inclined orbit using an Ariane 42P launch vehicle equipped with 2 solid
strap-on boosters (PAPs).  This will be the 2nd launch of an Ariane 4
in the 42P configuration.  It will be launched from the Ariane launch 
complex ELA 2, in Kourou- French Guiana.
 
The launch vehicle performance requirement is 2,661 kg (5,868 lb), of
which 2,502 kg (5,517 lb) represent the satellite mass.  The total
vehicle mass at liftoff is 320,587 kg. 
 
Required Orbit Characteristics:

  Perigee Altitude ..... 1322 km
  Apogee Altitude ...... 1330 km 
  Inclination ..........   66 degrees
 
The Ariane 42P lift-off for Flight 52 is scheduled on Monday August 10,
1992, as soon as possible within the following launch window:
 
     Kourou Time       GMT               Washington, DC
     20:08 - 20:53     23:08 - 23:53     19:08 - 19:53
  
Launch Vehicle:
 
Ariane 42P.  This is a three-stage liquid fueled launcher with solid fueled 
strap-on boosters.  The first stage (L220) is built by Aerospatiale, and is 
powered by 4 liquid fueled Viking V engines.  The second stage (L33) is built
by MBB Erno and is powered by a single Viking IV engine.  Both the Viking IV
and V engines are manufactured by SEP.  The first and second stages use a 
biliquid UH25/N2O4 fuel.  The third stage (H10) is built by Aerospatiale, 
and is powered by a cryogenic LH2/LO2 fueled HM-7B engine built by SEP. 
The two strap-on boosters (PAP) are built by BPD and use a solid Flexadrine
propellant.  The fully assembled launch vehicle stands 55.2 meters high on 
the pad.  It uses the Ariane Type 2 payload fairing.
  
Flight Profile:
 
+01:29  Solid strap-on booster jettison
+03:24  First stage separation
+03:48  Fairing jettison
+05:35  Second stage separation
+17:37  Third stage shutdown / orbit injection
+19:29  TOPEX/POSEIDON separation
+23:36  KITSAT-A and S80/T separation
+27:46  End of Ariane mission 52
  
Payloads:
 
TOPEX/POSEIDON is a cooperative program between NASA and CNES for studying
the ocean surface topography.  The satellite is built by FAIRCHILD SPACE
under contract to NASA/JPL.  For 3 to 5 years the altimeter payload will
survey the ocean circulation on a global scale.
 
  Total mass at lift-off .... 2,402 kg
  Dry mass .................. 2,185 kg     
  On-board power ............ 2,140 W (end of life)
  Solar panel span .......... 8.7 m
  Orbital altitude .......... 1336 km
 
 Instruments:  

   NASA altimeter and CNES altimeter (POSEIDON) for measuring ocean 
     surface topography by radar.

   TMR (TOPEX Microwave Radiometer) to measure atmospheric water 
     vapor for correcting altimetric data.
 
 Three systems of orbit determination to give precision 
 satellite position:

   LRA (Laser Reflective Array)
   GPS (Global Positioning System)
   DORIS (Doppler Orbitography and Radio positioning Integrated from Space)
 
 In-flight operations:

   Deployment of solar panels .... about 3 minutes after separation  
   Deploy of high-gain antenna ... about 8 minutes after separation  
   Deployment of GPS antenna ..... about 11 minutes after separation  
   Transition from DSN to TDRSS communications ... 16 minutes after separation
   Beginning of high-gain TDRSS operations ....... 25 hours after separation
   Beginning of maneuver to operational orbit .... about 7 days after launch 
 
Auxiliary Payloads:
 
KITSAT-A uses the UOSAT platform built at University of Surrey (U.K.) for
the Korean Advanced Institute of Science and Technology.  It will be used
for store and forward communications and various experiments.
 
  Mass ...................... 50 kg     
  On-board power ............ 21 W (end of life)
  Nominal lifetime .......... 5 years     
  Satellite is 0.35 x 0.35m in size, with a 6m deployable mast
 
 Instruments:  

   Two CCD cameras with 4 km and 400 m resolution
   Digital signal processing experiment
   Transponder for store and forward communications
   In-orbit radiation measurement experiment 
 
S80/T is built by MATRA MARCONI SPACE for CNES, also using a platform of
the UOSAT type.  It will be used to study use of the VHF band for mobile
communications.
 
  Mass ...................... 50 kg     
  On-board power ............ 26 W 
  Nominal lifetime .......... 1 year
  Satellite is 0.35 x 0.35m in size, with a 6m deployable mast
 
 Payload:  

   1 transponder- 148-149.9 mhz reception
                  137-138.0 mhz transmission 
  
Launch coverage:
 
All Ariane missions are broadcast live via satellite from Kourou. Coverage
begins at 30 minutes before launch, and continues until all payloads have 
been deployed.  NASA Select-TV will also broadcast this mission on F2/13.
 
-{ Dean Adams }-
816.2TOPEX/Poseidon Press Kit availablePRAGMA::GRIFFINDave GriffinMon Aug 10 1992 21:338
Same as .0, but formatted like my space shuttle press kits...

pragma::public:[nasa]topex_poseidon.ps

6 pages.


- dave
816.3Status Report - 24-Aug-1992PRAGMA::GRIFFINDave GriffinTue Aug 25 1992 15:3326
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109



                  TOPEX/POSEIDON STATUS REPORT
                         August 24, 1992

          The TOPEX/Poseidon satellite is healthy and performing nominally.
The attitude control computer, batteries, telecommunications and on-board
computer are all functioning properly.

          Tape recorder playback has occurred as planned since last Friday.

          The Centre National d'Etude Spatiales' Solid State Altimeter (SSALT)
is in a four day check out period.  CNES is processing the data in Toulouse and
engineers there report all looks good.  The NASA altimeter will be commanded to
the track mode after the CNES altimeter is turned off.

          The TOPEX Microwave Radiometer is working well.

          An inclination maneuver is planned for Thursday to boost the
satellite to its 66 degree inclination toward the Earth.
816.4TOPEX/Poseidon status 8/28/92 PRAGMA::GRIFFINDave GriffinMon Aug 31 1992 15:4845
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. (818) 354-5011



                  TOPEX/POSEIDON STATUS REPORT
                         August 28, 1992

          The TOPEX/Poseidon satellite entered into safe hold
mode on Aug. 27, 1992 at approximately 11:13 a.m. PDT.  This
incident occurred during the inclination maneuver about 6 seconds
from the end of the propulsion burn.

          The inclination maneuver was successful and placed the
satellite in the proper 66 degree inclination toward the Earth.

          Project managers have determined that the safe hold
mode was the result of a "bug" in the software code which set the
failure detection correction limit for a roll angle of 3 degrees,
not 7 degrees as intended.  This was a result of residual LANDSAT
code which did not correlate to the program design language.

          All satellite hardware is functioning properly based on
detailed review of the maneuver playback data.  Reconfiguration
of the satellite back to the standard configuration prior to safe
hold mode is in process at this time and is expected to be
completed tonight.

          The solar array was offset to -55 degrees at 12:45 p.m.
PDT today prior to the start of occultation.  This was done so as
to not overcharge the batteries when the Sun hits the solar array
after coming from eclipse.

          Since the inclination maneuver goals were achieved, the
flight team is proceeding with the nominal maneuver campaign.
There are four more maneuvers to go.  In-Plane Maneuver One is
planned for Wednesday, Sept. 2, 1992.

          The NASA radar altimeter was turned off when the
satellite entered the safe hold mode.  It will be turned back on
about 6:30 p.m. PDT tonight.  Initial data from the NASA
altimeter prior to the incident looked very good.
816.5TOPEX/Poseidon Status - 8/31/92PRAGMA::GRIFFINDave GriffinWed Sep 02 1992 14:2427
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109.



                  TOPEX/POSEIDON STATUS REPORT
                         August 31, 1992

          The TOPEX/Poseidon satellite has fully recovered from the safe hold
that it experienced last Thursday. Today the satellite is performing nominally
and is healthy.  Attitude control, solar array, batteries, telecommunications,
and the on- board computer are all functioning normally.

          Today, the NASA altimeter is in the track mode and obtaining good
data.

          Since launch, the navigation team and the precision orbit
determination team have been observing a slight decay in orbit.  It is
currently about 10 cm a day, which is down from 30 cm a day last week.  The 10
cm/day appears to be expected drag on the satellite.  The higher decays
observed previously were probably due to outgassing.

          The next major satellite event is the In-Plane Maneuver One is
planned for Wednesday, Sept. 2, 1992.
816.6Topex/Poseidon status 9/9/92PRAGMA::GRIFFINDave GriffinThu Sep 10 1992 13:0128
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109



                  TOPEX/POSEIDON STATUS REPORT
                        September 9, 1992

          The TOPEX/Poseidon satellite is performing nominally
and is healthy.  Attitude control, solar array, batteries,
telecommunications, and the on-board computer are all functioning
normally.

          In-Plane Maneuver #2 was performed successfully
Tuesday, Sept. 8 at 11:47 a.m. PDT.  The next In-Plane Maneuver
is scheduled for Monday, Sept. 14 and this maneuver will use the
1 Newton thrusters for the first time.

          The solar array bias has been changed by an additional
+2.5 degrees to a total bias of +57.5 degrees.  This was done so
as to not overcharge the batteries when the Sun hits the solar
array after coming from eclipse.

          On Friday, the NASA altimeter will be placed in the
idle mode and the CNES SSALT altimeter will be turned on.
816.7Topex/Poseidon Status 9/14/92PRAGMA::GRIFFINDave GriffinThu Sep 17 1992 09:4935
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109.



                  TOPEX/POSEIDON STATUS REPORT
                       September 14, 1992

          The TOPEX/Poseidon satellite is performing nominally and is healthy.
Attitude control, solar array, batteries, telecommunications, and the on-board
computer are all functioning normally.

          In-Plane Maneuver #3 was performed successfully today.  This was the
first burn performed using the four, small 1 Newton thrusters.  The next TRIM
Maneuver is scheduled for Monday, Sept. 21.

          The NASA altimeter remain in idle mode while the SSALT is in track
mode.  The SSALT will be turned off today and the NASA altimeter will be
commanded to track.  Over the weekend, the SSALT had near overflights of both
the NASA and CNES verification sites.  The SSALT, also, overflew hurricane
Iniki on several obit passes over the Pacific Ocean. Before it was put into
idle mode, the NASA altimeter recorded 24-foot waves in the Pacific, presumably
due to the hurricane.

          Project engineers are analyzing why the Global Positioning System
Data Recorder failed to come out of idle mode today when it was commanded to
track.  Over the weekend the GPSDR memory was reloaded, readout, and a checksum
was verified.

          The satellite is now sharing TDRSS resources with the shuttle.  TDRSS
support continues to be excellent with no significant impact to our mission.
816.8TOPEX/Poseidon status 9/21/92PRAGMA::GRIFFINDave GriffinTue Sep 22 1992 14:1831
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109



                  TOPEX/POSEIDON STATUS REPORT
                       September 21, 1992

          The TOPEX/Poseidon satellite successfully completed the
last of six maneuvers today that places the satellite in the
required orbit and ground track to begin the operational orbit
phase of its mission.   The TRIM maneuver was performed at 12:43
p.m. PDT.

          The Global Positioning System Demostration Receiver
(GPSDR) Almanac was loaded and placed in track mode at 7:30 this
morning PDT.  The GPSDR appears to be working nominally.

          The NASA Altimeter automatically reset itself Friday
after it experienced a single event upset.  The instrument fully
recovered within a few minutes of the event and was tracking
nominally until the CNES SSALT Altimeter was turned on this
morning.   The SSALt will operate for four days while the NASA
Altimeter is in the idle mode.

          The navigation team reports that data received over the
weekend showed the satellite's orbit has leveled off with no
unexpected decay.
816.9Topex/Poseidon Status Report - October, 1992PRAGMA::GRIFFINDave GriffinWed Nov 11 1992 09:4426
TOPEX/POSEIDON STATUS REPORT
October 26, 1992

          The satellite has entered the initial verification phase of its
mission which is designed to calibrate and assess satellite-based measurements
with in-situ data taken at the two verification sites.  These sites are located
on the Texaco Harvest Oil Platform off Point Conception, Calif. (the NASA site)
and at Lampione Rock near Lampedusa Island in the Mediterranean Sea (the CNES
site).  The satellite supported a successful overflight of the Harvest Platform
on Saturday, Oct. 24.  The weather was clear, the seas were calm and all
instruments performed nominally.  The precision orbit determination and
verification team (PVT) reports that data from the French DORIS and laser
tracking agreed to within two centimeters.

          Overall, the satellite and sensors are performing nominally and all
data products are being produced as planned.

          New almanacs were loaded on the Global Positioning System
Demonstration Receiver (GPSDR) this morning and the GPSDR was commanded to
track mode.

          The Ku-band NASA radar altimeter has produced preliminary results of
wave height over the global ocean.  The data were recorded from Sept. 25 to
Oct. 4, 1992.  The highest waves were observed in the Southern Ocean south of
South Africa and Australia, where giant waves as high as eight meters (26 feet)
were recorded.
816.10The role of eddies in ocean circulationVERGA::KLAESI, RobotTue Dec 22 1992 15:1557
Article: 2709
Newsgroups: sci.space.news
From: [email protected] (Ron Baalke)
Subject: TOPEX Data Show Role of Eddies in Ocean Circulation
Sender: [email protected] (Usenet)
Organization: Jet Propulsion Laboratory
Date: Sat, 19 Dec 1992 07:05:27 GMT
 
From the "JPL Universe"
December 18, 1992
 
TOPEX data show role of eddies in ocean circulation
By Mary Hardin
 
     Preliminary results from the TOPEX/Poseidon satellite's
radar altimeter have enabled scientists to create a global image
of the world's oceans that shows how swirls of ocean currents,
called eddies, change over distances of tens to hundreds of
kilometers during time periods that range from weeks to months.

     "Eddies play an important role in ocean circulation because
they transport an enormous amount of heat, salt, nutrients and
other chemicals in the ocean," said JPL Project Scientist Dr.
Lee-Lueng Fu. It is this process of ocean circulation that helps
to shape the global climate, he continued.

     "The data were collected during a 10 day period from Oct. 3 to
12, 1992 and were processed using preliminary algorithms that have not
yet been adjusted based on post-launch calibrations," Fu said. 

     The altimeter measures the height of the sea surface along
the satellite's ground track which covers the entire global ocean
every 10 days.  After subtracting a model of the mean sea surface
height from the satellite measurements, JPL's Oceanography Group
produced the image showing sea surface height due to changes in
ocean current.

     "This is a snapshot that doesn't coincide with the multi-
year average of past ocean observations," Fu said, "It shows that
the ocean changes constantly."

     Areas of sea surface height greater than 25 cm occur mainly
in regions of the following strong currents: The Gulf Stream off
the east coast of the United States, the Kuroshio current off the
east coast of Japan, the East Australian Current, the Agulhas
Current south of South Africa, the Somali Current off Somalia,
and the convergence of the Brazil Current and the Falkland
Current off the central east coast of South America. A chain of
secondary highs can be seen north of Antarctica.

     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [email protected]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in you life.
816.11Update - December 22VERGA::KLAESI, RobotThu Dec 31 1992 11:5561
Article: 2745
Newsgroups: sci.space.news
From: [email protected] (Ron Baalke)
Subject: TOPEX Update - 12/22/92
Sender: [email protected] (Usenet)
Organization: Jet Propulsion Laboratory
Date: Mon, 28 Dec 1992 15:24:53 GMT
 
Forwarded from:
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. (818) 354-5011
 
                  TOPEX/POSEIDON STATUS REPORT
                       December 22, 1992  
 
          The satellite continues to be operational and healthy. 
On Dec. 21, the ninth 10-day repeat track cycle was completed.
 
          A second orbit maintenance maneuver was also
successfully performed yesterday at the start of cycle 10.  Two
small thrusters were fired for four seconds  to raise the
satellite's 830 mile altitude by about 22 feet. The fine-tuning
of the orbit maintains the repeating ground tracks within the
desired band.
 
          On Saturday, Dec. 19, the altimeter experienced a 17
hour loss of altimeter data.  Engineering data was received
during this gap.  While the cause of the data loss is still under
investigation, a single event upset is thought to be the likely
culprit.  The data gap ended when the altimeter reset itself. 
The altimeter is currently tracking nominally.
 
          On Dec. 10, the project participated in a special
TOPEX/Poseidon session at the American Geophysical Union meeting
in San Francisco.   Participants from NASA and CNES confirmed
that the initial science data is good and said they are  pleased
with how quickly data is being processed and made available to
the science community.  
 
          Early results from the NASA Altimeter have been
processed to show wave height, eddies and ocean topography. 
Scientists report that these preliminary results show that the
satellite is working as expected.
 
          On Dec. 8 the first improved attitude control system
calibration parameters were sent to the satellite resulting in
dramatic improvement in the altimeter pointing and its
variations.  Today, the altimeter bias offset was changed by 0.1
degree to further reduce the small altimeter pointing error.
 
                              #####
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [email protected]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
|_____|/  |_|/       |_____|/                     | a day in your life.
816.12Update - January 18VERGA::KLAESI, RobotTue Jan 19 1993 14:3955
Article: 2885
Newsgroups: sci.space.news
From: [email protected] (Ron Baalke)
Subject: TOPEX Update - 01/18/93
Sender: [email protected]
Organization: Jet Propulsion Laboratory
Date: Tue, 19 Jan 1993 04:13:00 GMT
 
Forwarded from: 
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. (818) 354-5011
 
                  TOPEX/POSEIDON STATUS REPORT
                        January 18, 1993
 
          The satellite is healthy and all instruments continue
to operate normally.
 
          The science data team has delivered the tenth 10-day
science data cycle to JPL's Physical Oceanography Data Active
Archive Center.  This satisfies the fight team's goal of
providing 10 cycles of data to the principal investigators for
experiment processing and presentation at a verification workshop
to be held at JPL Feb. 22 to 25, 1993. 
 
          The satellite pointing remains good since the attitude
control system calibration results were implemented in late
December.  Consequently, the altimeter performance is good and
100 percent of the data are typically received from three daily
playbacks.  
 
          The batteries are performing well and show no signs of
degradation.  The flight team continues to implement "tender
loving care" for the batteries following all recommendations of
the project battery team to ensure that they do not overcharge
the batteries.
 
          Today the French solid-state altimeter was turned on so
the French can take data when the satellite overflies the Centre
National d'Etudes Spatiales verification site in the
Mediterranean Sea.  
 
          Since launch on Aug. 10, 1992, the flight team has sent
more than 1 million commands to the satellite.
 
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [email protected]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Every once in a while,
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | try pushing your luck.
|_____|/  |_|/       |_____|/                     |
816.13TOPEX/Poseidon STATUS REPORT January 27,1993PRAGMA::GRIFFINDave GriffinFri Jan 29 1993 20:079
TOPEX/Poseidon  STATUS REPORT           January 27,1993
Jet Propulsion Laboratory



The satellite is healthy, and all scientific instruments are performing
normally, typically providing three playbacks per day.  To date, eleven 10-day
science-data cycles have been collected for processing and verification as
planned.  TOPEX/Poseidon was launched August 10, 1992, aboard Ariane 52.
816.14TOPEX Observes Giant Waves PONIL::J_BUTLERE pur, si muove...Wed Mar 31 1993 18:2675
Article 3375 of sci.space.news:
Newsgroups: sci.space.news
Path: nntpd2.cxo.dec.com!pa.dec.com!decwrl!ames!dont-send-mail-to-path-lines
From: [email protected] (Ron Baalke)
Subject: TOPEX Observes Giant Waves from Storm of the Century
Message-ID: <[email protected]>
To: [email protected]
Followup-To: sci.space
News-Software: VAX/VMS VNEWS 1.41    
Keywords: TOPEX, JPL, CNES
Sender: [email protected]
Nntp-Posting-Host: kelvin.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
Date: Wed, 31 Mar 1993 21:13:00 GMT
Approved: [email protected]
Lines: 56

Brian Dunbar
Headquarters, Washington, D.C.                       March 31, 1993
(Phone:  202/358-0873)

Mary A. Hardin
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone:  818/354-5011)


TOPEX/POSEIDON OBSERVES GIANT WAVES IN STORM OF THE CENTURY

	As the "storm of the century" hit the eastern part of the United States
on March 14, giant waves measuring up to approximately 40 feet (12 meters) high
were observed in the North Atlantic by the U.S.-French TOPEX/POSEIDON
satellite.

	The highest waves measured by the radar altimeter onboard the satellite
were observed halfway between the United States and Europe at the latitude of
New York City - approximately 41 degrees North.  Strong winds of 45 miles per
hour (20 meters per second) also were recorded in the high waves vicinity.

	"The TOPEX/POSEIDON mission studies the dynamics of the world's
ocean currents by measuring the shape of the sea surface using a radar
altimeter," said Dr. Lee Fu, Project Scientist at NASA's Jet Propulsion
Laboratory, Pasadena, Calif.

	"The height of the waves and the speed of the wind over the ocean also
are measured by the radar as byproducts of the mission," he continued.
Measuring sea level allows oceanographers to study changes in ocean currents
and global circulation and to determine how those changing currents affect
world climate.

	In related activities, scientists at the Naval Research Laboratory in
Mississippi report that their recent analysis of TOPEX/POSEIDON data, as well
as measurement taken by tide gauges and buoys confirms that the Kelvin wave
pulse that they predicted in February has arrived at the South American coast
as they anticipated.

	A Kelvin wave is a large warm water mass that moves along the equator
in the Pacific Ocean.  These pulses sometimes contribute to El Nino conditions
in the eastern equatorial Pacific.

	JPL manages the NASA portion of the TOPEX/POSEIDON mission for
NASA's Office of Mission to Planet Earth.  Launched Aug. 10, 1992 from Kourou,
French Guiana, TOPEX/POSEIDON is the second satellite in the Mission to
Planet Earth Program, NASA's long-term effort to study Earth as a global
environmental system.

-end-
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [email protected]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Don't ever take a fence 
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | down until you know the
|_____|/  |_|/       |_____|/                     | reason it was put up.
816.15TOPEX/POSIEDON Fact SheetCXDOCS::J_BUTLERE pur, si muove...Fri Jun 18 1993 11:32230
Article 4023 of sci.space.news:


FACT SHEET:             TOPEX/POSEIDON
                          June 1993

     NASA's Jet Propulsion Laboratory and the Centre National
d'Etudes Spatiales (CNES), the French space agency, are turning
their scientific sights on Earth with a joint satellite mission
designed to map the circulation of the world's oceans.

     The Ocean Topography Experiment, or Topex, has been combined
with France's Poseidon mission.  Together, the Topex/Poseidon
satellite is the most sophisticated attempt yet to measure and
map sea level from space.

     Topex/Poseidon was launched on Aug. 10, 1992 by an Ariane
42P booster rocket from the Arianespace Guiana Space Center in
Kourou, French Guiana.

     Designed for a three- to five-year mission, Topex/Poseidon's
primary science goal is to improve our understanding of how the
oceans circulate.  Such information will allow oceanographers to
study the way the oceans transport heat and nutrients and how the
oceans interact with weather patterns.  Such studies will
increase our understanding of the ocean's role in global change.

       In the past, oceanographers have studied the sea from
ships.  This provided only a snapshot of the oceans' character
because the ships took spotty measurements from fixed locations.  
Topex/Poseidon will provide a long-term, coherent, panoramic
picture of the oceans.  Such global information offers potential
societal benefits such as improved long-range weather
forecasting.

     Topex/Poseidon will also aid in efforts to predict phenomena
such as El Nino, an unusual water warming that occurs in the
eastern Pacific and has been associated with global weather
changes that have caused billions of dollars in damage worldwide.

     Scientists have analyzed a prominent Kelvin wave which has
appeared in Topex/Poseidon altimetry data.  A Kelvin wave is a
pool of warm water that moves along the equator in the Pacific
and can contribute to El Nino conditions in the eastern
equitorial Pacific.

     Scientists at the Naval Research Laboratory at the Stennis
Space Center in Mississippi report that their analysis of
Topex/Poseidon data, as well as measurements taken by tide gauges
and buoys, confirms that the Kelvin wave pulse which they
predicted in February 1993 arrived at the South American Coast as
they anticipated.


MISSION OVERVIEW

     The main instrument on the Topex/Poseidon satellite is a
radar altimeter.   This device is similar to ones that were flown
on NASA's GEOS 3 satellite in 1975, on Seasat in 1978 and on the
U.S. Navy's Geosat in 1985.

     As Topex/Poseidon orbits the Earth, the altimeter bounces
radar signals off the ocean's surface.  The device records the
time it takes the signal to return to the satellite and that
gives it a precise measurement of the distance between
Topex/Poseidon and the sea surface.

     This data will be combined with measurements from other
instruments that pinpoint the satellite's exact location in
space.  Scientists will then be able to produce a detailed map of
ocean topography, or sea level relative to the Earth's center.  
     Sea level is directly related to ocean currents, eddies and
other features of the ocean surface.  When they examine the
influence of the Earth's gravity field on sea level, researchers
will also be able to study major features on the ocean floor. 
Information contained in the radar return signals can also be
used to calculate wave height and wind speed, two elements that
are important for monitoring the global sea state.

     Planning by NASA and CNES calls for the United States to
provide the satellite, altimeter, a microwave radiometer, an
experimental satellite tracking receiver and various spacecraft
subsystems.  The French will supply the launch vehicle and two
other instruments -- a solid-state altimeter and a Doppler
tracking receiver. 

     In 1987, an international team of 38 principal investigators
was selected to participate in the Topex/Poseidon mission through
a joint U.S.-French announcement of opportunity.  These
scientists have been working closely with the project to refine
the mission design and scientific plans.  After launch they will
conduct a wide range of oceanographic and geophysical studies to
accomplish the mission science goals.

     Topex/Poseidon will complement other important oceanographic
experiments planned for the 1990s:

       -- The European Remote Sensing Satellite (ERS-1), launched
by the European Space Agency, carries an altimeter and a
scatterometer in addition to other instruments.  The altimeter,
when used in conjunction with Topex/Poseidon data, will increase
the sampling and coverage area.  The scatterometer's measurements
of global wind speed and direction, together with the altimetric
sea-level measurements, will help scientists study how winds
produce ocean currents and waves.

       -- The NASA Scatterometer (NSCAT) is a JPL-managed
instrument scheduled for launch aboard the Japanese Advanced
Earth Observing Satellite (ADEOS) in February 1995.   NSCAT will
make frequent measurements of wind speeds and direction over the
global ocean.

     Oceanographers from around the world will also conduct
studies using Topex/Poseidon data as part of the World Ocean
Circulation Experiment (WOCE) and the Tropical Oceans Global
Atmospheres Experiment (TOGA).  These decade-long programs are
sponsored by the World Climate Research Program.


SATELLITE DESIGN

     Fairchild Space of Germantown, Maryland, is providing the
spacecraft which is based on NASA's Multi-Mission Spacecraft
(MMS) design.

     Topex/Poseidon will orbit the Earth at a relatively high
altitude of 830 miles (about 1,340 kilometers).  This will
minimize atmospheric drag on the spacecraft, reduce the influence
of errors in measuring Earth's gravity field, and simplify
maneuvers needed to maintain the orbit position.  The satellite
orbit will be inclined 66 degrees from Earth's equator. 

     The satellite's position in space must be known as precisely
as possible in order to produce extremely accurate maps of sea
level.  Special laser and radio tracking on the ground will
pinpoint Topex/Poseidon's position to within five inches (13
centimeters).  By comparison, the orbit of Seasat was known to an
accuracy of 20 to 40 inches (50 to 100 centimeters).

     The NASA radar altimeter will operate at two frequencies,
13.6 and 5.3 gigahertz.  Measurements of the same ocean area
taken at both frequencies will help correct for path-delay errors
caused by electrons in the ionosphere.

     A microwave radiometer, built by JPL, will measure radiation
emitted from water vapor between the satellite and the ocean. 
This will be used to correct for path-delay errors caused by
atmospheric water vapor.

     The French space agency will provide an experimental solid-
state altimeter on board the satellite.  This altimeter operates
at the single frequency of 13.65 gigahertz.  It is provided under
contract to CNES Toulouse Space Center by Alcatel Espace Systems.
The two altimeters will share the same antenna with the NASA
altimeter being turned off a small part of the time so the French
instrument can operate without interference.

     The French will also provide a new radio-tracking system
that will measure the position and velocity of the spacecraft. 
It is called Doppler Orbitography and Radiopositioning Integrated
by Satellite (DORIS) and is a dual Doppler receiver which
operates with a network of 50 uplink ground stations.  DORIS is
provided under contract to CNES by Electronique Serge Dassault
and will be used with the laser tracking system.

     The United States is conducting a Global Positioning System
precision orbit determination experiment along with this mission
to test a new high-precision tracking system.  A GPS
demonstration receiver is being built by Motorola Inc. of
Chandler, Arizona, under contract to NASA/JPL.  It receives
tracking signals from the constellation of Navstar satellites
established under the GPS program.  Tracking information is sent
to the ground for processing in the test ground operations
system.


MISSION BENEFITS

     The results of the scientific studies using data from
Topex/Poseidon will increase our understanding of the ocean's
role in global change and are expected to provide information
about specific environmental problems.

       -- Carbon Dioxide.  The burning of fossil fuels, combined
with deforestation, is causing a significant increase of carbon
dioxide in the atmosphere.  This could ultimately produce
catastrophic warming of the Earth.  The impact appears to be
critically dependent upon how fast carbon dioxide is absorbed by
the ocean and how efficient the ocean interacts with the
atmosphere to slow down the potential global warming.  Both
factors rely, in part, on ocean currents.   Detailed knowledge of
ocean circulation could help scientists determine what threat
increased carbon dioxide in the atmosphere may pose for the
Earth's future.

       -- Weather Forecasting.  Weather patterns in North America
are heavily influenced by events over the ocean -- in this case,
the Pacific.  Analysis of Topex/Poseidon data will eventually
help forecasters predict general weather trends a season ahead,
enabling the agriculture industry to adjust crop selection.  Such
predictions would also benefit energy planning in the Northeast
United States by forecasting unusually cold or warm winters.

       -- Offshore oil, mining, and coastal power plants.  Such
facilities must be designed to withstand severe wave and storm
surges, such as those caused by hurricanes along the United
States' Gulf Coast.  Observations from Topex/Poseidon will
provide information for better planning in the location and
construction of oil rigs, drill ships, mining operations and
coastal nuclear power plants.

       -- Seabed disposal of dangerous wastes.  The safety of
such disposal depends partly on the rate at which currents may
carry potentially hazardous leakage from disposal sites toward
fishing grounds and coastal areas.

     Topex/Poseidon is managed by JPL for NASA's Office of
Mission to Planet Earth.  Charles Yamarone of JPL is the project
manager and Dr. Lee-Lueng Fu of JPL is project scientist.

                              #####
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [email protected]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Don't outlive your money.
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | 
|_____|/  |_|/       |_____|/                     |
816.16TOPEX/Poseidon maps precise global sea levelPRAGMA::GRIFFINDave GriffinTue Jun 29 1993 16:5556
Brian Dunbar
Headquarters, Washington, D.C.                    June 28, 1993

Mary A. Hardin
Jet Propulsion Laboratory, Pasadena, Calif.

RELEASE:  93-122


     During the first 6 months of their mission, scientists using the U.S.-
French TOPEX/Poseidon oceanographic satellite have recorded the most accurate
measurements to date of global sea level changes.

     The data will be used by oceanographers to calibrate the computer models
that help forecast future climate changes.

     "The changes in sea level we have observed during the first 6 months from
October 1992 to March 1993 are a combination of the effects of seasonal warming
and cooling as well as wind forcing," said Lee-Lueng Fu, TOPEX/Poseidon Project
Scientist at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif.

     In the Northern Hemisphere, the sea level in the Gulf Stream off the
United States East Coast and the sea level in the Kuroshio regions east of
Japan dropped by more than 12 inches (30 centimeters).  Most of this drop was
caused by the winter cooling of the ocean by the cold continental air mass
blown off the North American and Asian continents, Fu said.

     In the Southern Hemisphere, a corresponding sea level rise occurred at
similar latitudes which resulted from the warming of the summer atmosphere.

     "It takes an increase or decrease of 1 degree Celsius (1.8 degrees
Fahrenheit) in the average temperature of a water column 50 meters (165 feet)
deep to cause the sea level to rise or fall by 1 centimeter (0.4 inches)," Fu
explained.

     The sea level change in the Northern Hemisphere is larger than that in the
Southern Hemisphere because the larger land mass of the Northern Hemisphere
creates colder continental air mass that cools the ocean water off the east
coasts of North America and Asia.

     Seasonal changes in the trade winds caused a drop in sea level at the
equator in both the Pacific and Atlantic oceans, Fu said.  The rise in sea
level in the eastern tropical Pacific Ocean off the coast of South America was
the remnant of the Kelvin wave pulses that began in December 1992.  A Kelvin
wave pulse creates a surge of warm water that moves eastward along the equator
and can contribute to El Nino conditions.

     In the Indian Ocean, reversing seascaused a fall in sea level in the
eastern and southern regions and a rise in sea level in the northwestern
region.

     JPL manages the NASA portion of the joint U.S.-French mission for NASA's
Office of Mission to Planet Earth. Launched Aug. 10, 1992, the satellite is
part of NASA's long-term effort to study Earth as a global environmental
system.
816.17TOPEX and El NinoCXDOCS::J_BUTLERE pur, si muove...Sun Nov 14 1993 07:1284
 
 
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
 
Contact:  Mary A. Hardin
 
FOR IMMEDIATE RELEASE                            November 9, 1993
 
     Sea surface measurements taken by the U.S./French
TOPEX/Poseidon satellite have confirmed that conditions are ripe
for development of an El Nino event in the eastern equatorial
Pacific Ocean this winter.
 
     Data from the radar altimeter onboard TOPEX/Poseidon reveal
a new Kelvin wave moving toward the western coast of South
America.  A Kelvin wave is a large warm water mass that moves
along the equator in the Pacific Ocean.  Such Kelvin wave pulses
sometimes give rise to El Nino conditions in the eastern
equatorial Pacific.
 
     Using near real-time data from TOPEX/Poseidon, this most
recent wave pulse has been confirmed by Drs. Jim Mitchell and
Gregg Jacobs of the Naval Research Laboratory (NRL) at NASA's
Stennis Space Center in Mississippi.
 
     "This wave was generated in early August at the equator
around 160 East longitude and moved eastward in the form of a
bulge of sea surface elevation of 10 to 15 centimeters above
normal,"  said Jacobs.
 
     The Kelvin wave pulse which began in August may have faded
in strength in early October.  At this time, the rise of sea
surface in the west is indicative of the onset of a stronger
Kelvin wave.
 
     The NRL team continues to monitor these developments in
addition to using numerical ocean models to better understand the
evolution of the Kelvin wave's strength, Mitchell said.
 
     The data confirm an advisory issued recently by the National
Oceanographic and Atmospheric Administration's Climate Analysis
Center that El Nino conditions would continue in 1993-94.
 
     This Kelvin wave, plus other oceanographic and
meteorological indicators, has indicated a strong potential for
the redevelopment of the El Nino conditions that have persisted
through two consecutive winters in 1991 and 1992, according to
the NOAA advisory.
 
     "The rise of warm water hinders cold deep waters from
reaching the surface.  Off the coast of South America, cold deep
waters bring vital nutrients to sea life.  When the Kelvin wave
reaches South America, the deep waters no longer reach the
surface and the fish stocks become severely depleted,"  according
to Jacobs.
 
     The El Nino phenomenon has been blamed for causing
devastating weather conditions around the world including severe
floods in the Midwest, colder than normal winters in the eastern
United States and wetter than normal conditions in California.
 
     The TOPEX/Poseidon mission is addressing long-term climate
issues.  By mapping the circulation of the world's oceans over
several years, scientists can better understand how the ocean
transports heat, influences the atmosphere and affects long-term
climate, said Dr. Lee-Lueng Fu, TOPEX/Poseidon project scientist
at JPL.
 
     Data from the satellite are distributed monthly for analysis
by more than 200 scientists around the world.
 
     JPL manages the NASA portion of the joint U.S./French
TOPEX/Poseidon mission.  Launched Aug. 10, 1992, it is the second
satellite in NASA's Mission to Planet Earth program, a long-term
effort to study Earth as a global environmental system.
 
                              #####
 
11-9-93 MAH
# 1535
816.18TOPEX Release 93-205CXDOCS::J_BUTLERE pur, si muove...Sun Nov 14 1993 07:1383
 
Brian Dunbar
Headquarters, Washington, D.C.           November 9, 1993
(Phone:  202/358-0872)
 
Mary A. Hardin
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone:  818/354-5011)
 
 
RELEASE:  93-205
 
TOPEX/POSEIDON DATA CONFIRMS EL NINO PREDICTIONS
 
     Sea surface measurements taken by the U.S.-French 
TOPEX/Poseidon satellite have confirmed that conditions are ripe 
for development of an El Nino event in the eastern equatorial 
Pacific Ocean this winter.
 
     The El Nino phenomenon has been blamed for causing 
devastating weather conditions around the world including the 
severe floods in the U. S. Midwest, colder than normal winters in 
the eastern United States and wetter than normal conditions in 
California.
 
     The TOPEX/Poseidon mission is addressing long-term climate 
issues.  By mapping the circulation of the world's oceans over 
several years, scientists can better understand how the ocean 
transports heat, influences the atmosphere and affects long-term 
climate, said Dr. Lee-Lueng Fu, TOPEX/Poseidon Project Scientist 
at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif.
 
     Data from the radar altimeter onboard TOPEX/Poseidon reveal a 
new Kelvin wave moving toward the western coast of South America.  
A Kelvin wave is a large warm water mass that moves along the 
equator in the Pacific Ocean.  Such Kelvin wave pulses sometimes 
give rise to El Nino conditions in the eastern equatorial Pacific.
 
     Using near real-time data from TOPEX/Poseidon, this most 
recent wave pulse has been confirmed by Drs. Jim Mitchell and 
Gregg Jacobs of the Naval Research Laboratory (NRL) at NASA's 
Stennis Space Center, Mississippi.
 
     "This wave was generated in early August at the equator 
around 160 East latitude and moved eastward in the form of a bulge 
of sea surface elevation of  about 4 to 6 inches (10 to 15 
centimeters) above normal," said Jacobs. 
 
     The Kelvin wave pulse that began in August may have faded in 
strength in early October.  The NRL team continues to monitor 
these developments in addition to using numerical ocean models to 
better understand the evolution of the Kelvin wave's strength, 
Mitchell said.
 
     The TOPEX/Poseidon data confirm an advisory issued recently 
by the National Oceanographic and Atmospheric Administration's 
Climate Analysis Center that the El Nino event would continue in 
1993-94.
 
     This Kelvin wave, plus other oceanographic and meteorological 
indicators, has indicated a strong potential for the redevelopment 
of the El Nino conditions that have persisted through two 
consecutive winters in 1991 and 1992, according to the NOAA 
advisory.
 
     Data from the satellite are distributed monthly for analysis 
by more than 200 scientists around the world.
 
     JPL manages the NASA portion of the joint U.S./French 
TOPEX/Poseidon mission.  Launched Aug. 10, 1992, it is the second 
satellite in NASA's Mission to Planet Earth.
 
     NASA's Mission to Planet Earth (MTPE) studies how the global 
environment is changing.  Using the unique perspective available 
from space, NASA and its partners are observing, monitoring and 
assessing large-scale environmental processes that affect climate 
change.
 
     MTPE satellite data, complemented by aircraft and ground 
data, will allow humans to better understand natural environmental 
changes and to distinguish natural changes from human-induced 
worldwide, will be essential to humans making informed decisions 
about protecting their environment.
816.19Update - June 3MTWAIN::KLAESKeep Looking UpTue Jun 07 1994 15:5832
From:	US4RMC::"[email protected]" "MAIL-11 Daemon"  4-JUN-1994 
To:	[email protected]
CC:	
Subj:	TOPEX/Poseidon status 6/3/94

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

                  TOPEX/POSEIDON MISSION STATUS
                          June 3, 1994

     The TOPEX/Poseidon satellite remains healthy and its science
instruments continue to collect oceanographic data on schedule.

     The satellite has completed more than 8,500 revolutions of Earth
since its launch on Aug. 10, 1992.  The mission is mapping global sea
level changes to an unprecedented accuracy of less than 5 centimeters
(about 2 inches).  This performance far exceeds the original mission
requirements to measure global sea level to an accuracy of 14
centimeters (5-1/2 inches). 

     The science data team continues to generate interim geophysical
data records which are made available to the science community through
the Physical Oceanography Distributed Active Archive Center.  The data
maps of global sea level change help scientists improve their understanding 
of seasonal warming and cooling, winds and global climate change. 

     The mission will continue to operate well into 1998.
816.20July 1MTWAIN::KLAESHouston, Tranquility Base here...Fri Jul 01 1994 13:5431
From:	US4RMC::"[email protected]" "MAIL-11 Daemon" 30-JUN-1994 
To:	[email protected]
CC:	
Subj:	TOPEX/Poseidon status 7/1/94

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

                     TOPEX/POSEIDON STATUS REPORT
                             July 1, 1994

     The ocean observing TOPEX/Poseidon satellite continues to
operate well as it begins its 66th 10-day cycle of data collection.

     The NASA altimeter and the French solid-state altimeter
operate under a sharing plan with the French altimeter tracking
on an average of one out of every 10 cycles.  It is scheduled to
track again during cycle 79 which begins in early November.

     The weekly ephemeris loads, which contain all the satellites
routine instructions, are good for 10 days.  However, the loads
are uplinked weekly to maintain adequate high-gain antenna
pointing.  Ephemeris loads consist of two table loads. One
provides for adequate pointing of the high-gain antenna for
communications through NASA's Tracking and Data Relay satellites,
and the other load maintains the underside of the satellite
pointing to Earth.
816.21August 1MTWAIN::KLAESHouston, Tranquility Base here...Mon Aug 01 1994 17:1126
From:	US4RMC::"[email protected]" "MAIL-11 Daemon" 30-JUL-1994 
To:	[email protected]
CC:	
Subj:	TOPEX/Poseidon status 8/1/94

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

                      TOPEX/POSEIDON MISSION STATUS
                            August 1, 1994

     The flight team has concluded its annual sensor performance
workshop which formally reviews the satellite's performance and
documents any current issues.  Team members concluded that the
satellite is healthy and performing exceptionally well.

     The satellite is now in cycle 68 of its mission operations.
Geophysical data records of the last four cycles have been
shipped to the Physical Oceanography Distributed Active Archive
Center at JPL.

                                #####
816.22French space agency awards Topex-Poseidon teamMTWAIN::KLAESNo Guts, No GalaxyThu Aug 11 1994 17:3664
From:	US1RMC::"[email protected]" "Smith Woody System Administrator" 
        10-AUG-1994 22:12:18.50
To:	[email protected]
CC:	
Subj:	NASA HQ Official Press Release 94-132

Brian Dunbar
Headquarters, Washington, D.C.
August 10, 1994
(Phone:  202/358-1547)

Release:  94-132

FRENCH SPACE AGENCY HONORS TOPEX-POSEIDON TEAM

     The French space agency honored members of the U.S.-French
TOPEX/POSEIDON management team today by awarding them the CNES Medal
in recognition of their achievements.  The Centre Nationale d'Etudes
Spatiales (CNES) awards the medal periodically in recognition of
highly successful projects.

     CNES General Director Jean-Daniel Levi presented the award to
seven team members from NASA Headquarters, Washington, D.C.; NASA's
Jet Propulsion Laboratory (JPL), Pasadena, Calif.; and the CNES
project office.  Receiving the award were:

  Dr. Lee-Leung Fu, JPL Project Scientist;
  W. Linwood Jones, NASA Kennedy Space Center, former NASA Program
     Manager;
  Dr. Michel Lefebvre, CNES Project Scientist;
  Dr. William Patzert, JPL, former Program Scientist;
  William Townsend, Deputy Associate Administrator, Office of Mission
     to Planet Earth, and former NASA Program Manager;
  Dr. W. Stanley Wilson, National Oceanic and Atmospheric
     Administration (NOAA) Assistant Administrator, National Ocean
     Service, former NASA  Program Scientist; and
  Charles Yamarone, JPL Project Manager.

     Launched August 10, 1992, TOPEX/POSEIDON is studying the
topography of the oceans, providing scientists with the data they need
to better understand how ocean circulation distributes heat around the
Earth and how the oceans affect climate.

     In two years, the satellite has completed 9,350 orbits and 69,
ten-day science data-gathering cycles, collecting more than one
trillion bits of data.  The satellite is measuring sea level to an
accuracy of 2.2 inches (5.7 centimeters), and the data have been
distributed to the international science team for their analysis.

     TOPEX/POSEIDON is the first mission to provide such precise and
accurate observations of sea level, allowing scientists to study
complex global ocean dynamics.  Eventually, scientists will use the
data to help them determine how ocean currents contribute to
world-wide climate change.

- end -

% ====== Internet headers and postmarks (see DECWRL::GATEWAY.DOC) ======
% Date: Wed, 10 Aug 1994 15:47:09 -0400
% From: [email protected] (Smith Woody System Administrator)
% To: [email protected]
% Subject: NASA HQ Official Press Release 94-132
% Sender: [email protected]
816.23September 1MTWAIN::KLAESNo Guts, No GalaxyThu Sep 01 1994 17:4230
Article: 6333
From: [email protected]
Newsgroups: sci.space.news
Subject: TOPEX/Poseidon status 9/1/94
Date: 1 Sep 1994 10:57:15 -0700
Organization: Jet Propulsion Laboratory - Pasadena CA
Sender: [email protected]
 
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
 
                   TOPEX/POSEIDON MISSION STATUS
                        September 1, 1994
 
     The joint U.S.-French oceanographic satellite and its sensors
continue to perform well just over two years into their mission of
measuring global sea levels. 
 
     Science data processing activities are proceeding on schedule. 
The science data team continues to process sensor data records and
interim geophysical data records.  There are 254 passes of science
data collected and processed during each 10-day data cycle.  Each
10-day cycle represents a complete topographic map of the world's
oceans for oceanographic study. 
 
                              #####
816.24TOPEX/Poseidon status 10/1/9456821::BATTERSBYSat Oct 01 1994 10:4829
Article: 6501
From: [email protected]
Newsgroups: sci.space.news
Subject: TOPEX/Poseidon status 10/1/94
Date: 30 Sep 1994 20:55:57 -0700
Organization: Jet Propulsion Laboratory - Pasadena CA
Sender: [email protected]
 
PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
 
                 TOPEX/Poseidon Mission Status
                        October 1, 1994
 
     The satellite is performing well, and science data
processing activities are proceeding on schedule. Science data
have been acquired during 75 10-day cycles and TOPEX/Poseidon has
completed 10,000 orbits of Earth since launch two years ago.
 
     Each 10-day cycle represents a a complete topographic map of
the world's oceans for oceanographic study.
 
     Six orbit maintenance maneuvers have been performed, and a
seventh is scheduled for October 6.
 
                              #####