Conference 7.286::space

Brian Dunbar
Headquarters, Washington, D.C.                          September 26, 1991

Jessie Katz
Goddard Space Flight Center, Greenbelt. Md.

RELEASE:  91-155

        Preliminary data from NASA's Upper Atmosphere Research Satellite
(UARS) are providing scientists with a three-dimensional, global map of
ozone in the upper atmosphere and a global view of chlorine monoxide, a
key chemical in ozone depletion.  The results appear to confirm existing
aircraft and ground-based research about the chemical processes that lead
to ozone depletion.

        These first data were obtained from UARS' Microwave Limb Sounder,
one of 10 instruments aboard the new research satellite deployed by Space
Shuttle Discovery on Sept. 15.  The satellite's orbit, 363 miles above the
Earth at a 57-degree inclination to Earth's Equator, provides greatly
extended geographic ozone coverage.  UARS' side-mounted instruments
provide a three-dimensional view of the developing ozone "hole" over
Antarctica.

        As the first major element of NASA's new Mission to Planet Earth
program, UARS has begun the global-scale study of the Earth as a complete
environmental system.  UARS will provide scientists with the first
comprehensive data set on the chemistry, wind directions and energetics
of Earth's upper atmosphere.

        UARS's main focuses are the processes involved in ozone depletion.
Ozone, a molecule made up of three atoms of oxygen, blocks the Sun's
ultraviolet radiation that poses a health risk to humans and endangers food
crops.

        Previous studies using aircraft and ground-based instruments have
indicated that reactive chlorine atoms, freed from chemicals such as
chlorofluorocarbons, destroy ozone in the upper atmosphere or
stratosphere.  Chlorine atoms capture oxygen atoms from ozone, creating a
molecule of chlorine monoxide and a molecule of oxygen, which does not
block ultraviolet light.  The chlorine monoxide atom then is broken up,
freeing the chlorine atom.  Repetition of the cycle leads to the destruction
of thousands of ozone molecules by a single chlorine atom.

        The Microwave Limb Sounder instrument aboard UARS continuously
measures ozone, chlorine monoxide, temperature and water vapor.  It is a
collaborative effort with the United Kingdom.  Dr. Joe Waters of NASA's Jet
Propulsion Laboratory, Pasadena, Calif., and Dr. Gordon Peckham of Herrot
Watt University, Edinburgh, Scotland, are the instrument's principal
investigators.

        UARS is still undergoing testing and is scheduled to begin full
science operations in mid-October.  Eight other instruments have been
activated and spacecraft controllers report verification and testing have
been successful.

        UARS is managed by the Goddard Space Flight Center, Greenbelt,
Md., for NASA Headquarters Office of Space Science and Applications,
Washington, D.C.
 

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771

UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) WEEKLY STATUS REPORT
October 2, 1991

CURRENT STATUS OF OBSERVATORY: Activation of instruments and
spacecraft systems continues.  The spacecraft is functioning
nominally with no known problems.


DEVELOPMENTS SINCE LAST STATUS REPORT:  A -10 degree roll maneuver
was executed successfully by the UARS spacecraft the evening of
September 30.  The roll maneuver was performed to obtain data for
gyro calibration.  The maneuver consisted of two parts,
accomplished approximately five hours (three orbits) apart.  The
first part of the maneuver, begun at 5:00 p.m. EDT, rolled the
instrumented "cold side" of the UARS spacecraft 10 degrees away
from the Earth limb.  The spacecraft maintained the rolled attitude
for the next three orbits, successfully tracking stars and the
Tracking and Data Relay Satellite communications satellites.  All
spacecraft components functioned as expected.  The second part of
the maneuver was begun at 9:55 p.m. EDT.  At this time, the UARS
spacecraft was returned to its nominal attitude with the
instruments viewing the Earth limb.



     INSTRUMENTS:

     Cryogenic Limb Array Etalon Spectrometer (CLES):  Continues to
collect science data.  Instrument checkout continues and various
atmospheric observation modes are being systematically verified.

     Improved Stratospheric and Mesospheric Sounder (ISAMS):
Continues normal science operation.

     Microwave Limb Sounder (MLS):  Continues to acquire scientific
data.

     Halogen Occultation Experiment (HALOE):  Continues outgassing
and operation in the stow position.   The telescope door has been
opened.

     High Resolution Doppler Imager (HRDI):  Performing
calibrations.

     Wind Imaging Interferometer (WINDII):  Conducted the sixth
engineering checkout performing internal optical checks, Charged
Coupled Detector (CCD) checks, and conducted high resolution star
mapping at various locations on the sensor unit CCD.  Following the
checkout, a trial measurement orbit was initiated which measured
winds, temperatures and emission rates.  This trial measurement
data will provide initial data for use both in assessing instrument
operation and using the scientific software.

     Solar Ultraviolet Spectral Irradiance Monitor (SUSIM):
Instrument operation is nominal.  All temperatures and currents are
stable.  Activation and outgassing will continue this week.  The
first solar observations are scheduled for October 10.

     Solar Stellar Irradiance Comparison Experiment (SOLSTICE):
Instrument activation has been completed.  The argon gas filling
the cavity was vented and the doors sealing the instrument were
opened at 2:40 a.m. EDT Wednesday.

     Particle Environment Monitor (PEM):  The instrument has
completed activation and is acquiring science data.

     Active Cavity Radiometer Irradiance Monitor (ACRIM II):
Continues thermal stabilization and outgassing.


UPCOMING EVENTS:

*  First solar observations by the SUSIM  and HALOE instruments.

*  ACRIM II will begin obtaining solar data.

*  Activation of all instruments to be completed by next week.
 

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771

November 8, 1991

UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) MONTHLY STATUS REPORT



NASA's Goddard-managed Upper Atmosphere Research Satellite (UARS)
observatory continues to operate well and according to plan. All
ten instruments aboard the observatory have been activated and
routine observations are underway.  Instrument teams report that
instrument performance meets or exceeds their expectations.

On November 1, UARS entered an Earth-pointing Safe Hold mode.
This occurred during the loading of Inertial Reference Unit
calibration parameters in the On Board Computer (OBC).  The
observatory continued to operate with reduced pointing accuracy
(within two degrees) using Earth sensors.  Safe hold recovery was
completed on November 2, approximately 12 hours after it began,
and normal operation resumed.  Although unplanned, this
occurrence verified that the OBC Failure Detection Correction
logic performed as designed.

The Solar Stellar Pointing Platform (SSPP) is now fully
functional and is tracking the Sun and stars selected by the
Principal Investigator of  Solar Steller Irradiance Comparison
Experiment, one of three instruments mounted on the SSPP.  The
other two instruments mounted on the platform are the Solar
Ultraviolet Spectral Monitor and the Active Cavity Radiometer
Irradiance Monitor.

UARS successfully completed a forward-to-backward yaw maneuver
during this reporting period.  The purpose of the maneuver is to
keep the solar array on the Sun side of the spacecraft and to
keep the instruments in the correct orientation angle with
respect to the Sun.  This maneuver is required approximately
every 34 days.

On November 2, another yaw around maneuver was executed.  The
observatory, which was flying backward, has been turned and is
now flying forward again.

On November 3, two drag makeup orbit adjust burns were performed.
These burns were scheduled to compensate for atmospheric drag and
to maintain a frozen orbit (when the perigee is held to a fixed
position in relation to the Earth.)

The solar array is operating nominally and is generating more
power than predicted.  In addition, the two observatory star
trackers and the alignment parameters for the fine-Sun sensor
have been calibrated in orbit, refining the attitude calculations
aboard the satellite.

The communications and data handling subsystem is operating as
planned.  Transponder B is cycled on and off for normal
operations using the high-gain antenna, transmitting real-time
and tape recorder playback data through the Tracking and Data
Relay Satellite System.  Also, Transponder A is on continuously,
transmitting one kilobit-per-second telemetry via the omni
antenna for back-up support.

Both passive and active thermal systems, which keep the
instruments at their proper operating temperatures, are
performing well.

The Cryogenic Limb Array Etalon Spectrometer instrument, which
measures gas concentrations and temperatures in the stratosphere,
has experienced a minor anomaly in a calibration mode.  Analysis
and simulation of this infrequent anomaly are being conducted.
In the meantime, the instrument is operating normally and
continues to obtain science data.

All other instruments continue their normal observations.  Data
is being received and processed by the UARS Central Data Handling
Facility.  A sampling of science data is expected to be released
during the next reporting period.

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771

December 2, 1991

UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) MONTHLY STATUS REPORT
                          November 1991

     The on-orbit operation of NASA's Upper Atmosphere Research
Satellite (UARS) continues to go well, according to project
officials.  As of November 30, the observatory has been in orbit
77 days.  Goddard officials report the spacecraft systems are
meeting or exceeding specifications.
     The satellite instruments have measured in the upper
atmosphere:  chlorine monoxide, ozone, sulfur dioxide, nitric
oxide, water vapor, stratospheric temperature, energetic
particles that cause the aurora, and the solar ultraviolet
spectrum.  Many additional measurements are expected as the 10
instruments aboard the spacecraft complete their scheduled
validation testing.  Instruments and ground data processing
software are expected to complete the validation process on
schedule in March 1992.
     Several spacecraft instruments have experienced some  minor
hardware anomalies that have been addressed successfully.  These
anomalies affecting the Cryogenic Limb Array Etalon Spectrometer
and the Improved Stratospheric and Mesospheric Sounder (ISAMS)
required revision of operating software procedures resulting in
fully satisfactory performance of the instruments.
     Data processing for the Microwave Limb Sounder, Solar
Ultraviolet Spectral Irradiance Monitor, Solar/Stellar Irradiance
Comparison Experiment, ISAMS, and Particle Environment Monitor
continues.  Wind Imaging Interferometer and High Resolution
Doppler Imager data processing operations are being re-evaluated
based on planned upcoming software refinements.
     Major enhancements were performed to the Central Data
Handling Facility (CDHF) hardware.  A new bank of magnetic disk
drives and two additional optical disk drives were installed, and
changes were made in the local area network configuration to
increase system performance.
      The next yaw maneuver, to change the observatory from
forward to backward flight, is scheduled for December 4.  The
purpose of the maneuver, implemented approximately every 34 days,
is to keep the solar array on the Sun side of the spacecraft and
to keep the instruments in the correct orientation angle with
respect to the Sun.
     The UARS is managed and operated by Goddard for NASA's
Office of Space Science and Applications.
 

Brian Dunbar
Headquarters, Washington, D.C.                            December 5, 1991

Jessie Katz
Goddard Space Flight Center, Greenbelt, Md.

James Wilson
Jet Propulsion Laboratory, Pasadena, Calif.

RELEASE:  91-199


        Early results from NASA's Upper Atmosphere Research Satellite
(UARS) have confirmed the link between the presence of chlorine
monoxide and the depletion of ozone in Earth's upper atmosphere.

        The UARS, launched by Space Shuttle Discovery on Sept. 12, 1991, is
studying the upper atmosphere to better understand the processes at work
in this vital region of the Earth's environment.  The early results indicate
that UARS is a powerful new tool for detecting and tracking ozone
depletion and the factors that cause it, officials at the Goddard Space Flight
Center, Greenbelt, Md., said today.

        Data from the satellite have provided the first global-scale picture of
the distribution of chlorine monoxide in the lower stratosphere.  Chlorine
monoxide is one of the main chemical species involved in the depletion of
the Earth's ozone layer and is the dominant constituent causing the
Antarctic ozone hole.

        UARS has helped show that the more chlorine monoxide present, the
less ozone will be observed.  Chlorine monoxide, in the upper atmosphere,
results from the breakdown of the man-made chlorofluorocarbons by the
Sun's ultraviolet radiation.  UARS has observed high chlorine monoxide
over Antarctica, while simultaneously measuring the ozone depletion that
accompanies it.  These data confirm the relationship in the upper
atmosphere between the two chemicals.

        The relationship between high concentrations of chlorine monoxide
and low concentrations of ozone previously have been made from the
ground and by NASA ER-2 aircraft.  However, the ground and aircraft
measurements have been conducted over a much smaller geographical area
than is now being done by UARS.

        The UARS data examined to date show that extremely high amounts
of chlorine monoxide (greater than about one molecule of chlorine
monoxide for every 1 billion "air" molecules) occur only where ozone is
severely depleted. Those data also show great variation of chlorine
monoxide levels within the Antarctic hole and are expected to improve
scientific understanding of the ozone depletion process occurring there as
well as at other places on the globe.

        These first results from the UARS were obtained with the Microwave
Limb Sounder (MLS), one of the 10 scientific instruments aboard the
satellite.  MLS detects microwave radiation emitted from chlorine
monoxide, ozone, sulfur dioxide and water vapor in the atmosphere.  That
radiation is then analyzed to produce chemical concentration and
temperature data at altitudes throughout the upper atmosphere over nearly
the entire Earth as the UARS spacecraft orbits at an altitude of 363.5 miles.

        The MLS also is seeing the effects of the large eruption of Mount
Pinatubo in the Philippines on June 15, 1991.  The volcano injected huge
amounts of sulfur dioxide into the stratosphere, the remnants of which
appear to the MLS as a band of high sulfur dioxide concentrations over the
tropics.  Aerosol particles formed from volcanic sulfur dioxide could lead to
significant ozone loss in the vicinity of the plume.

        Nothing comparable to the very high chlorine monoxide
concentration over Antarctica has as yet been detected by the UARS in the
volcanic plume.  The satellite will maintain a watch for such effects as the
volcanic plume spreads northward during the next several months and
gradually subsides.  Patches of enhanced sulfur dioxide also have been
detected in the southern hemisphere and are probably from the smaller
Mount Hudson eruption in Chile in August 1991.

        All instruments aboard the UARS have been activated and are
operating successfully.  In addition to chlorine monoxide, ozone and sulfur
dioxide, the satellite instruments also have measured nitric oxide, water
vapor, stratospheric temperature, energetic particles that cause the aurora,
and the solar ultraviolet spectrum.  All spacecraft systems are meeting or
exceeding specifications, Goddard officials said.  Many additional
measurements are expected as the instruments complete their scheduled
validation testing.

        The Microwave Limb Sounder was developed and is operated on the
UARS by NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., in
collaboration with United Kingdom groups at Heriot-Watt University,
Edinburgh University and the Rutherford-Appleton Laboratory.  Dr. Joe W.
Waters of JPL is Principal Investigator.

        UARS, the first major project of NASA's Mission to Planet Earth
program, will provide scientists with the first comprehensive data set on
the chemistry, wind velocities and energetics of Earth's upper atmosphere.
UARS is managed and operated by the Goddard center for NASA's Office of
Space Science and Applications, Washington, D.C.

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771

December 24, 1991


UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) MONTHLY STATUS REPORT
                          December 1991



At the UARS Science Team meeting this month, all investigators
reported that instrument performance continues to be very good.
By the end of 1991, UARS will have been in orbit 108 days.

There have been several instances of irregularities with the
onboard computers resulting in the loss of some data.  The
computers have since returned to normal operation.  The High
Resolution Doppler Imager (HRDI) instrument computer has stopped
three times.  The first time, on December 4, has been traced to a
software error in revised code loaded earlier that day.  The
subsequent stoppages on December 9 and 15 are also related to
software errors.  Instrument operations have resumed using the
"old" code.

The Solar/Stellar Irradiance Comparison Experiment (SOLSTICE)
instrument experienced anomalies on December 9 and 13.  Both
incidents were caused by incorrect computer instructions to the
instrument.

Several minor adjustments were made to enhance the spacecraft
systems' operating efficiency.  On December 8, the rate at which
the solar array adjusts itself to obtain the maximum energy from
the Sun's rays was changed to keep the array at the best angle to
the Sun.

Revised alignment and calibration parameters were uplinked to the
Solar Stellar Pointing Platform.  It is now well within the
pointing limits of .05 degrees in both the vertical and
horizontal axis.

Another routine yaw maneuver, switching the observatory from
forward to backward flight, was executed December 4.  The purpose
of the maneuver, executed approximately every 36 days, is to keep
the solar array on the Sun side of the spacecraft and to keep the
instruments in the correct orientation angle with respect to the
Sun.  The next yaw-around maneuver, which will change the
observatory from backward to forward flight, is scheduled for
January 14, 1992, according to project officials.

During this reporting period, the Mass Storage System (MSS) in
the Central Data Handling Facility (CDHF) was upgraded with the
addition of two more optical disk drives.  This and future
additions will occur as the need for data handling capability
increases.

Early results from the Microwave Limb Sounder (MLS), one of the
10 scientific instruments aboard the observatory, have confirmed
the link between the presence of chlorine monoxide and the
depletion of ozone in Earth's upper atmosphere.  The data showed
that extremely high amounts of chlorine monoxide occur only where
ozone is severely depleted.  Those data are expected to improve
scientific understanding of the ozone depletion process.

The MLS also is seeing the effects of the large eruption of Mount
Pinatubo in the Philippines on June 15, 1991.  The volcano
injected huge amounts of sulfur dioxide into the stratosphere,
the remnants of which appear to the MLS as a band of high sulfur
dioxide concentrations over the tropics.

In another result, the High Resolution Doppler Imager (HRDI)
aboard UARS has discovered large, violent windstorms in the
mesosphere 43 to 60 miles (69.2 to 96.5 kilometers) above Earth's
surface.  HRDI looks at the mesosphere to measure wind speeds in
various directions.  The biggest windstorm HRDI detected
stretches from western Australia across southern Africa and
halfway across the Atlantic Ocean.

The UARS is managed and operated by Goddard for NASA's Office of
Space Science and Applications.

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771


January 21, 1992

UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) STATUS REPORT

Spacecraft:  Another routine yaw maneuver, executed approximately
every 36 days, took place Jan. 14.  The observatory is now flying
"forward" again.  The maneuver keeps the solar array on the Sun
side of the spacecraft and the instruments in the correct
orientation angle with respect to the Sun.

Instruments:  On Saturday, Jan. 18, the chopper wheel system for
the Improved Stratospheric and Mesospheric Sounder (ISAMS), one of
the 10 instruments aboard UARS, ceased operation.  According to
project officials, attempts to restart the chopper motor have been
unsuccessful to date.  Officials believe the problem lies in the
motor drive's circuitry for which there is no redundant system.
The chopper wheel breaks up or "chops" the incoming light beam
being analyzed so the ISAMS can differentiate it from
other light in the instrument.  Without incoming light beam
chopping, no scientific measurements from this instrument can be
made.  Attempts to restart the motor will continue.

ISAMS studies atmospheric temperature, water vapor, ozone, methane,
carbon monoxide and several oxygen-nitrogen coumpounds.  UARS
instruments were selected to provide redundant critical
measurements, and all ISAMS measurements except carbon monoxide are
made by other instruments.  ISAMS measures carbon monoxide, a very
important gas in the lower atmosphere, in the upper atmosphere as
an indicator of the exchange of gases between the lower and upper
atmosphere.  However, carbon monoxide is not an important compound
in the chemical processes that lead to ozone depletion, and its
measurement is secondary to the UARS mission.  Therefore, loss of
carbon monoxide measurements will not significantly affect
the mission's primary goal of obtaining data on stratospheric ozone
depletion for input to future policy decisions.

The Principal Investigator for ISAMS is Dr. Fred W. Taylor,
University of Oxford, United Kingdom.  ISAMS is supported by the
United Kingdom's Science and Engineering Research Council and
coordinated with the British National Space Center under a
cooperative agreement with NASA.

Science Results:  There were two sessions devoted to UARS at the
Annual Meeting of the American Meteorological Society in January.
The papers presented preliminary results from the Halogen
Occultation Experiment, High-Resolution Doppler Imager, Cryogenic
Limb Array Etalon Spectrometer, and Microwave Limb Sounder
experiments aboard UARS.

The UARS is managed and operated by Goddard for NASA's Office of
Space Science and Applications.

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771


On-orbit observatory operations of NASA's Upper Atmosphere
Research Satellite (UARS) are continuing satisfactorily.  As of
February 29, UARS will have been in orbit 168 days.

On February 14, a routine forward to backward yaw-around was
executed to keep the solar array on the Sun side of the
spacecraft and the instruments in the correct orientation angle
with respect to the Sun.  The maneuver will also allow the
Microwave Limb Sounder and Cryogenic Limb Array Etalon
Spectrometer along with several other atmosphere measuring
instruments aboard the UARS to resume their observations of
chemicals such as chlorine monoxide and ozone in the Arctic
regions.

Goddard controllers report at least 50 scientific teams
throughout the country are scheduling their observations of the
upper atmosphere to coincide with measurements made on the
spacecraft.  Most of the participants in this correlative data
program were chosen through the Upper Atmosphere Research Program
at NASA Headquarters.  These daily, round-the-clock  correlative
measurements will be compared to and help validate UARS data and
provide complimentary data for scientific research.  The
correlative data program uses measurements not only from ground-
based instruments and high altitude balloons, but also from the
Nimbus 7/Total Ozone Mapping Spectrometer (TOMS) instrument and
data to be collected by the Atmospheric Laboratory for
Applications and Science (ATLAS) currently scheduled for launch
in March aboard the Space Shuttle Atlantis.

The UARS is managed and operated by Goddard Space Flight Center
for NASA's Office of Space Science and Applications.

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771

UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) STATUS REPORT


On-orbit operations of NASA's Upper Atmosphere Research Satellite
(UARS) are continuing satisfactorily after a software error
caused a power down of the observatory's instruments.

A flaw in the coding of the on-board battery monitoring software
caused the UARS instrument's turn off at 5:30 a.m. on March 17,
according to Goddard Deputy Project Manager John Donley.  The
software is designed to power down the instruments when the
observatory's batteries register below a predetermined voltage
level and the state of charge is below acceptable limits.  The
software sensed the lower battery voltage but not the correct
state of charge and turned the instruments off.   The batteries
were reacting normally to a new method of setting their charge.

All instruments were operating again by 3:00 a.m. EST on March
18.  Because they were powered up in stages, from 12 to 20 hours
of observing time was lost, depending upon the instrument.
Project officials have found the source of the software flaw and
are correcting it.

The Validation Working Group of the UARS Science Team held a one-
week workshop in Oxford, England from March 2-6.  The meeting was
held to compare and study temperature and chemical species
concentration measurements from the Microwave Limb Sounder,
Halogen Occultation Experiment, Improved Stratospheric and
Mesospheric Sounder, Cyrogenic Limb Array Etalon Spectrometer,
and appropriate correlative measurements.

As of March 31, UARS will have been in orbit 199 days.
The UARS is managed and operated by Goddard Space Flight Center
for NASA's Office of Space Science and Applications.

From:	DECPA::"[email protected]" 30-APR-1992 
        15:17:24.00
To:	[email protected]
Subj:	UARS Finds Arctic Ozone Depletion Averted

Brian Dunbar
Headquarters, Washington, D.C.              April 30, 1992
(Phone:  202/453-1547)

Jessie Katz
Goddard Space Flight Center, Greenbelt, Md.
(Phone:  301/286-5566)

James H. Wilson
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone:  818/354-5011)

RELEASE:  92-56

NASA SPACECRAFT FINDS LARGE ARCTIC OZONE DEPLETION AVERTED

     A rise in stratospheric temperatures in late January apparently
prevented severe ozone depletion from occuring in the Arctic this
year, says a scientist at NASA's Jet Propulsion Laboratory (JPL),
Pasadena, Calif.  The temperature increase is thought to eliminate
polar stratospheric clouds, microscopic ice particles that can sustain
high levels of ClO and lead to the large and fast ozone depletion
characteristic of the Antarctic. 

     An alarming spread of chlorine monoxide (ClO), the dominant form
of chemically active chlorine that destroys ozone, was detected in
January over Greenland, the north Atlantic, northern Europe and Russia
by the Microwave Limb Sounder (MLS) on NASA's Upper Atmosphere
Research Satellite (UARS). 

     When the MLS continued its monthly northern hemisphere
observations in mid-February, the ClO was reduced from mid- January,
said Dr. Joe Waters, Microwave Limb Sounder principal investigator at
JPL.  Although the January data indicated severe ozone depletion was
possible during the northern winter of 1991-92, Waters said his recent
ozone data indicate that it did not occur.  However, because the
sources of chlorine are long-lived in the stratosphere, ozone
depletion remains a threat in future years. 

     "This tells me that conditions in the upper atmosphere are n a
very delicate balance," said Waters.  "With so much chlorine in the
stratosphere, a slight temperature difference can make an enormous
difference in the potential for ozone depletion." 

     In February, "lesser abundances of ClO were detected," said
Waters.  "These were still very much at an unwanted level and of
substantial concern.  But they were not at the levels we saw in
January which, had they persisted, could have led to a substantial
northern ozone depletion this year." 

     Scientists believe most of the chlorine in the stratosphere is
from the release of commercially produced chlorofluorocarbons (CFCs). 
A delicate combination of sunlight, ice clouds and weather conditions
can initiate reactions that lead to ozone depletion.  The CFCs also
are believed to be involved worldwide in a slower chain of reactions
that are eroding ozone on a global scale and do not require the
special conditions inside a polar "hole." 

     In the Antarctic, said Waters, conditions are regular enough that
scientists can predict with some confidence the annual formation of an
ozone hole.  In the south, winter stratospheric winds blow mainly in
an east-west direction and form a vortex, or circular air pattern,
around the Antarctic. The vortex inhibits warmer air from entering
polar regions. 

     "The air in this vortex gets very, very cold in the southern
winter with no sunlight," said the atmospheric scientist.  "So when
sunlight arrives around early September, both conditions -- cold and
sunlight -- are present that, in an atmosphere which has already been
loaded with chlorine monoxide,  can lead to an ozone hole."  The
southern ozone hole generally persists through October and dissipates
in November or December as the air warms and the vortex breaks up. 

     The scenario is not so simple in Earth's northern hemisphere,
where the more complex pattern of continents and oceans cause circulation 
patterns with a more variable and less intense northern vortex. 

     Because the northern circulation patterns are more complicated
than in the south, "We cannot yet predict details of ozone depletion
in the northern polar vortex," said Waters. "We know the season when
severe ozone depletion might be expected, but it's like predicting
hurricanes -- you may know the general season, but you can't predict
the exact time, location and severity.  The problem will grow as more
chlorine is added to the atmosphere." 

     Although the northern winter is over for this year, Waters said
he plans to continue monitoring the global situation, closely watching
his satellite data for years to come. 

     The UARS spacecraft, launched Sept. 12, 1991, carries 10
instruments to study the chemistry, dynamics and energetics of the
upper atmosphere.  Its mission is to provide scientists the first
comprehensive, three-dimensional global picture of the upper
atmosphere, including the processes of ozone depletion. 

     UARS is managed by NASA's Goddard Space Flight Center, Greenbelt,
Md., for the Office of Space Science and Applications.  JPL, with
collaboration from organizations in the United Kingdom, developed and
operates the Microwave Limb Sounder. 

EDITOR'S NOTE:  A photo (color:  92-HC-254;  B&W: 92-H-290) depicting
abundances of stratospheric chlorine monoxide during the winter of
1991-92, measured by the Microwave Limb Sounder on UARS is available
to accompany this release at the NASA Headquarters Broadcast and
Audio-visual Branch by calling 202/453-8373. 

     Also available is a photo (color: 92-HC-253;  B&W: 92-H- 289)
depicting ozone levels measured over two 4-year periods by NASA's Total 
Ozone Mapping Spectrometer instrument aboard the Nimbus-7 satellite. 

     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [email protected]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Denial is always the first
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | symptom.
|_____|/  |_|/       |_____|/                     | 

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771

May 1, 1992


UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) STATUS REPORT


     On-orbit operations of NASA's Upper Atmosphere Research
Satellite (UARS) are continuing satisfactorily.

     The batteries are developing differences in their voltage
characteristics.  Because the satellite's charge control system
is designed to charge the batteries identically, this may have a
future impact on the batteries' ability to be fully charged.
There is no immediate impact on spacecraft operation, according
to John Donley, UARS Deputy Project Manager.

     Because of problems related to microprocessor loading and a
sofware error. several days of planned operations of the High
Resolution Doppler Imager (HRDI) were lost.  The load problem and
software error were corrected and normal operations resumed.

     Another routine yaw maneuver, executed approximately every
36 days, is scheduled for May 1.  The maneuver keeps the solar
array on the Sun side of the spacecraft and the instruments in
the correct orientation angle with respect to the Sun.

     As of April 30, UARS will have been in orbit 229 days. The
 UARS is managed and operated by Goddard Space Flight Center,
Greenbelt, MD, for NASA's Office of Space Science and
Applications, Washington, D.C.

Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771

June 10, 1992

UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) STATUS REPORT


     The Upper Atmosphere Research Satellite (UARS) project
office continues to investigate a problem with the solar array
drive.  UARS was put in a safe mode on June 2 after the solar
array had difficulty rotating and was unable to track the Sun
properly.

     The Flight Operations Team (FOT) noted the solar array drive
was not operating smoothly during a real time pass at
approximately 5:00 p.m. EDT, Tuesday, June 2, 1992.  At that
time, the solar array was about 140 degrees off the Sun.  The FOT
issued commands that repositioned the array to a "high noon"
position so that the array receives solar energy for one-half of
each orbit.    This position generates enough power to charge the
spacecraft's batteries.  The team put the observatory in a safe
mode shutting science instruments and some redundant spacecraft
systems.  The UARS can remain in this condition indefinitely.
The observatory was using the "B" side Solar Array Drive and
Deployment Electronics (SADDE) when the incident occurred.

     On Monday, June 1, 1992, while using the "A" side
electronics, the solar array stopped rotating shortly after a
command to reverse rotation was issued.  The array drive
automatically switched to the redundant "B" side and tracking was
maintained until the June 2 incident.  UARS project officials are
analyzing spacecraft data to determine the cause of the "A" side
anomaly and its coupling into the "B" side drive before resuming
operations on the "B" side.

     On June 5, project officials used
the "B" side electronics to successfully rotate the solar array
10 degrees either direction.  Further investigation will be
needed before the cause of the problem is determined and more
tests can be conducted.

     As of June 10, UARS had been in orbit 270 days. The UARS
is managed and operated by Goddard Space Flight Center,
Greenbelt, MD, for NASA's Office of Space Science and
Applications, Washington, D.C.

Article: 1408
Newsgroups: sci.space.news
From: [email protected] (Ron Baalke)
Subject: UARS Monthly Status Report
Sender: [email protected] (Usenet)
Organization: Jet Propulsion Laboratory
Date: Thu, 9 Jul 1992 04:17:02 GMT
 
Jessie Katz
Office of Public Affairs
Goddard Space Flight Center
Greenbelt, MD 20771
 
July 6, 1992
 
UPPER ATMOSPHERE RESEARCH SATELLITE (UARS) STATUS REPORT
 
     The solar array of the Upper Atmosphere Research Satellite (UARS)
remains in a "high noon" position which allows the array to receive
solar energy for one-half of each orbit.  Project officials put the
solar array in this "parked" condition after the array had difficulty
tracking the Sun properly.  In this condition, there is adequate power
to resume limited instrument operations. 
 
     At the present time, two of the 10 instruments on board UARS, the
Cryogenic Limb Array Etalon Spectrometer (CLAES) and the Microwave
Limb Sounder (MLS), have been turned on.  All instruments were turned
off when the solar array drive anomaly first occurred.  CLAES became
fully operational again on Wednesday, June 10; MLS became fully
operational again on Sunday, June 14.  However, the 183 GHz channel
aboard MLS was turned off on June 19 to reduce the observatory power
load.  In this configuration, the MLS instrument continues to make its
primary measurements of ozone and chlorine monoxide in the upper
atmosphere with the remaining two channels.  The CLAES instrument is
fully operational measuring temperature, ozone, methane, CFC-11,
CFC-12, and several nitrogen compounds. 
 
     Tests of the solar array drive system completed on June 29
indicated that the "A" drive clutch has not been returned to a neutral
condition.  New options for solar array operations are under study. 
The failure review team continues to investigate the cause of the "A"
drive clutch fault. 
 
     As of July 1, UARS has been in orbit 291 days. The UARS is
managed and operated by Goddard Space Flight Center, Greenbelt, Md.,
for NASA's Office of Space Science and Applications, Washington, D.C. 

     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | [email protected]
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | In 1991 there were 16 names
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | listed on the FBI's ten
|_____|/  |_|/       |_____|/                     | most wanted list.
 

Brian Dunbar
Headquarters, Washington, D.C.                 July 20, 1992


Jessie Katz
Goddard Space Flight Center, Greenbelt, Md.



RELEASE:  92-117

     NASA's Upper Atmosphere Research Satellite (UARS) has
resumed full science operations following the resolution of
problems with the satellite's solar array drive.

     "All 10 instruments are turned on and should be fully
operational by late July 20," said John Donley, UARS Deputy
Project Manager, NASA's Goddard Space Flight Center,
Greenbelt, Md.

     Flight controllers placed UARS in a "safe mode" and
turned off the instruments June 2 after observing the solar
array drive was not operating smoothly and the solar array
itself was not properly tracking the Sun.

     The team issued commands that repositioned the array to
"high noon," allowing the array to receive maximum solar
energy for one-half of each orbit.

     With the solar array parked, UARS had enough power in
its "safe" mode to operate two instruments, the Cryogenic
Limb Array Etalon Spectrometer (CLAES) and the Microwave
Limb Sounder (MLS), which were turned on June 10 and June
14, respectively.  The two instruments continued to obtain
unprecedented data on levels of ozone and chemicals involved
in ozone depletion in the upper atmosphere.

     In this condition, the spacecraft remained healthy
while UARS project officials ran extensive diagnostic tests
and analyzed the problem.  Working with a failure review
team, project officials determined that a spring on the
solar array's "A" side drive was not completely releasing
from the shaft of the solar array.

     The condition was such that the redundant "B" side
drive, which was otherwise operational, could not be used.
However, based on a thorough review of the test data,
project officials determined that engineers could operate
the solar array using the "A" drive and allow all 10
instruments to perform normally.

     On July 8, the operations team began rotating the solar
array.  The array responded as expected, and the flight
operations team began turning on several more of the
instruments.

       This process was stopped, and the solar array parked
once again on July 13 when UARS made its yaw maneuver, a
normal turning of the spacecraft from front to back or back
to front.  This procedure takes place approximately every 36
days to adjust the viewing angle of the instruments relative
to the Sun. The rotation was subsequently resumed in
preparation for full operation.

     On July 14, the Halogen Occultation Experiment (HALOE)
was turned on.  On July 16, CLAES resumed operating, and by
late July 20 all instruments were expected to be operating.

        UARS was launched Sept. 12, 1991, aboard the Space
Shuttle Discovery. It is providing scientists with their
first comprehensive data on the chemistry, dynamics and
energetics of the Earth's upper atmosphere, focusing
particularly on ozone depletion.  UARS is the first major
satellite element of NASA's Mission to Planet Earth, a
coordinated, long-term program to study the Earth as a
global environmental system.

   The UARS is managed and operated by Goddard Space Flight
Center for NASA's Office of Space Science and Applications,
Washington, D.C.
 

UPPER ATMOSPHERE RESEARCH SATELLITE (UARS): Attempts to restart
the Improved Stratospheric and Mesospheric Sounder (ISAMS)
chopper wheel motor have not been successful.  The motor stopped
working on July 29. The chopper wheel breaks up or "chops" the
incoming light beam for analysis. Automated attempts to restart
the chopper motor continue. ISAMS measures ozone, nitrogen
compounds and other gasses important in ozone depletion. Most of
these compounds are measured by other UARS instruments, so the
loss of ISAMS has minimal impact on the UARS science mission at
this time.  UARS launched September 12, 1991 from the Space
Shuttle Discovery.

UARS:  UARS is operating nominally.  However, attempts to restart
the UARS Improved Stratospheric and Mesospheric Sounder (ISAMS)
chopper wheel motor still have not been successful and so ISAMS
remains inoperative.  The motor stopped working on July 29.
Automated attempts to restart the motor continue.  On September 21,
the observatory made a routine forward to backward yaw around.
This maneuver, executed approximately every 36 days, keeps the
solar array on the Sun side of the observatory and the instruments
in the correct orientation with respect to the Sun.  UARS launched
September 12, 1991 from the Space Shuttle Discovery.
Contact: Jessie Katz (301) 286-5566

     The UARS Science Team held two very successful data validation
workshops the week of October 12 concerning measurements of wind, temperature,
aerosols andatmospheric chemicals.  In addition, data acquired over the past
several months by UARS indicate that much of the chemical and physical
environment related to the formation of the Antarctic ozone hole were in place
in the early southern winter, as opposed to being formed late in the winter, as
previously thought.  The area of this environment also extended to lower
latitudes than expected.  The observatory is currently looking at the breakup
of The Antarctic ozone hole.  UARS launched September 12, 1991 from the Space
Shuttle Discovery.
 

      The observatory is performing nominally with all instruments performing
scheduled operations except the Improved Stratospheric and Mesospheric Sounder
(ISAMS).  The power system continues to be stable and is performing well.
Differential voltages have been stable for all three batteries.  Attempts to
restart ISAMS have continued and were rewarded November 13, by a significant
sudden change in the thermal behavior of the chopper system.  The cause of this
change is not clear, but the restart attempts are continuing more
optimistically and the telemetry is being closely monitored for any signs of
chopper rotation.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61