Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/DAILY_1/930324.DFC

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4/24/93: EVIDENCE POINTS TO OCEANS, LIGHTNING ON EARLY VENUS


Paula Cleggett-Haleim
Headquarters, Washington, D.C.                   March 24, 1993

Peter Waller
Ames Research Center, Mountain View, Calif.


RELEASE:  93-51

        The last findings by the Pioneer Venus Orbiter spacecraft have provided
strong new evidence that planet Venus once had three and a half times more
water as thought earlier -- enough water to cover the entire surface between 25
and 75 feet deep (762 and 2286 centimeters).

        These findings also give new support for the presence of lightning on
Venus and discoveries about the ionosphere and top of the atmosphere of Venus.
Considered Earth's twin planet, Venus today is very dry and searing hot.

        Pioneer entered Venus' atmosphere on Oct. 8, 1992, and burned up soon
after, ending 14 years of exploration.

        "Many of us have long thought that early in its history Venus had
temperate conditions and oceans like Earth's," said Dr. Thomas Donahue,
University of Michigan, head of the Pioneer Venus science steering group.

        "Findings that Venus was once fairly wet does not prove that major
oceans existed, but make their existence far more likely," he said. "The new
Pioneer data provides evidence that large amounts of water were definitely
there," said Donahue.

        "Most scientists think Venus' early oceans vaporized and 'blew off' 3
billion years ago in a runaway greenhouse effect when the cool early sun
increased its luminosity and heated the planet very hot," he said. "The oceans
evaporated.  Solar ultraviolet radiation split the water molecules into
hydrogen and oxygen, and the hydrogen was lost to space.

        "Pioneer Venus Probe and Orbiter data showed early in the mission,"
Donahue said, "that on Venus heavy habundant relative to ordinary hydrogen than
on Earth and everywhere else we've looked in the solar system -- Mars, Comet
Halley, meteorites, Jupiter and Saturn." Venus' remarkable hydrogen/deuterium
ratio has since been confirmed by independent measurements.

        Abundant deuterium is taken as clear evidence that Venus once had 150
times as much water in its atmosphere as today, he said.  This is because the
water's ordinary hydrogen has escaped.  But most of the water's heavy hydrogen
(deuterium - twice as heavy as hydrogen) stayed behind because of its weight.

        When the Orbiter made its final descent to unexplored regions only 80
miles (129 kilometers) above Venus' surface, it found evidence for 3.5 times as
much water as previously suggested by the deuterium ratio.

        "We found a new and important easy-escape mechanism, which accelerates
hydrogen and deuterium away from the planet," he said. "This means that much
more hydrogen had to escape to build up the present high deuterium
concentration.  A lot more hydrogen lost means a lot more water early on," he
said. "This also rules out theories of a dry-from-the-beginning Venus, whose
present meager supply of water comes from an occasional comet impact."

        The data also show that at Pioneer's lowest altitude 80 miles (129
kilometers) "whistler" radio signals, believed generated by Venus' lightning,
were the strongest ever detected.  Pioneer has long measured such "lightning"
signals.  They are the same as the radio signals used in most lightning studies
on Earth.

        In its final orbits, Pioneer penetrated 7 miles (11 kilometers) below
the peak of Venus' ionosphere, which tends to block these radio signals.  Here
also, the magnetic fields which channel the signals were the strongest ever
seen on Venus' night side.

        "These results are best explained by a strong and persistent source of
lightning in the Venus atmosphere," said Robert Strangeway of UCLA, Pioneer
electric field investigator.

         Some scientists continue to doubt Venus lightning.  They say only
optical sightings can prove lightning.  A Russian spacecraft has reported
visible-light sightings of lightning.  Four Russian spacecraft and the U.S.
Galileo craft also have observed radio signals believed from lightning.

        Pioneer found the peak density of Venus' ionosphere for the first time
- at 87 miles (139 kilometers).  The ionosphere was much different between
solar maximum and minimum, which are high and low periods of storm activity on
the sun and in the solar wind.  At minimum, it was far smaller.  It was gone
altogether above 85 miles (136 kilometers), and its lower layer was half as
dense.  It was more variable, much cooler, and full of small structures (1-60
miles in size (1.6-96 kilometers).

        For the ionosphere on the night side, at solar minimum, hydrogen ions
were reduced 20 times.  Its lower layer was half as dense as at maximum.

        Over 3 months, Pioneer provided data from 80 to 210 miles (129 to 336
kilometers) altitude.  It found the beginning of Venus' real, mixed atmosphere
(transition from oxygen to carbon dioxide) at 80 miles (129 kilometers).  Below
85 miles (136 kilometers), it identified various waves and a 4-day oscillation
of Venus' atmosphere top.  The neutral atmosphere above 185 miles (296
kilometers) was more than 10 times denser and 2120 F (1,000 degrees Celsius)
hotter than thought.

        Working with Donahue were Drs. Richard Hartle and Joseph Grebowsky of
NASA's Goddard Space Flight Center, Greenbelt, Md. Ames Research Center manages
the Pioneer project for the Office of Space Science, NASA Headquarters,
Washington, D.C.

- end -
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
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KSC SHUTTLE STATUS 3/24/93


                SPACE SHUTTLE DAILY STATUS REPORT
                    Wednesday, March 24, 1993

Mitch Varnes
NASA Kennedy Space Center


VEHICLE: OV-102/Columbia                 MISSION: STS-55
CURRENT LOCATION: Launch Pad 39-A        ORBITAL ALTITUDE: 184 sm
PAYLOADS: Spacelab D-2/SAREX             INCLINATION: 28.45 deg.
LAUNCH DATE: TBD                         LANDING SITE: KSC
MISSION DURATION: 8 days, 22 hours       CREW SIZE: 7


IN WORK:

- Scrub turnaround work is continuing.
- Testing and troubleshooting of Shuttle Main Engines (SSME).
- Trickle purge of Orbital Maneuvering System.

WORK SCHEDULED:

- Disconnection of ordnance is scheduled for Thursday.
- SSME testing and troubleshooting will continue for at least the
  next couple of days.
- Removal of 4 check valves from SSME #3 is planned for Friday.
- Removal of engine heat shields to begin on Friday.

WORK COMPLETED:

- Middeck payload experiment samples were removed yesterday.
- Drying of main engines was completed this morning.
- Cryogenic reactants were offloaded this morning.




OTHER BUSINESS:

STS-56/ATLAS-2                                OV-103/Discovery

Loading of Discovery's storable hypergolic propellants is con- tinuing at
launch pad 39-B.  This operation will continue throughout today.

Space Shuttle managers will convene at KSC tomorrow for the STS- 56 Flight
Readiness Review. The announcement of a launch date is possible but not
expected to be released following the conclusion of the meeting.

STS-57/SPACEHAB                               OV-105/Endeavour

Endeavour was transported to the Vehicle Assembly Building at about 9 a.m.
today.  Mating of the orbiter with its tank and boosters is planned to begin
late this afternoon.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
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Daily News/TV Sked 3/24/93

Daily News
Wednesday, March 24, 1993
Two Independence Square,
Washington, D.C.
Audio Service: 202/358-3014



 % STS-56 FRR scheduled for tomorrow at KSC;
 % Work continues on Endeavour;

* * * * * * * * * * * * * * * *

Space Shuttle managers will meet at the Kennedy Space Center for the STS-56
Flight Readiness Review. Workers at the Kennedy Space Center are continuing to
prepare Space Shuttle Discovery for its upcoming launch.  Discovery will carry
the ATLAS-2 payload and the mission is scheduled to last 8 days.

* * * * * * * * * * * * * * * *

Technicians continue to prepare Space Shuttle Endeavour for its May launch.
Endeavour was transported to the Vehicle Assembly Building earlier today.
Workers will begin to mate the tank and boosters to the orbiter.  Space Shuttle
Endeavour's STS-57 mission is scheduled to last 7 days and carry the Spacehab-1
as its major payload.  The crew will also retrieve the Eureca satellite during
this mission.

* * * * * * * * * * * * * * * *


Here's the broadcast schedule for Public Affairs events on NASA Select TV. Note
that all events and times may change without notice and that all times listed
are Eastern. Live indicates a program is transmitted live.



Wednesday, March 24, 1993

                12:00 pm        Inflatable Lunar Habitat
                12:15 pm        Aeronautics & Space Report
                12:30 pm        Safe Computing
                  1:00 pm       Apollo 13: "Houston we have a problem"
                  1:30 pm       Life on the Moon
                  2:00 pm       Star Finder 23: Dataglove
                  2:30 pm       Birth of NASA
                  3:00 pm       TQM 63




NASA TV is carried on GE Satcom F2R, transponder 13, C-Band, 72 degrees West
Longitude, transponder frequency is 3960 MHz, audio subcarrier is 6.8 MHz,
polarization is vertical.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
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3/24/93:  DIAZ NAMED TO SPACE SCIENCE POST

Paula Cleggett-Haleim
Headquarters, Washington, D.C.          March 24, 1993


RELEASE:  93-53

        Alphonso V. Diaz was named today as the Deputy Associate Administrator
for NASA's new Office of Space Science, effective immediately.

        In making the announcement, NASA Administrator Daniel S. Goldin said,
"Al is widely recognized as an accomplished manager.  His leadership ability
and technical expertise are vital as we reestablish the focus of NASA's science
and exploration programs."

        During his extensive career at NASA, Diaz served as Deputy Associate
Administrator for Space Science and Applications, managed the Galileo and
Ulysses programs in the Solar System Exploration Division and developed space
science programs for Space Station Freedom.

        Diaz began his NASA career at the Langley Research Center, Hampton,
Va., in 1964 as a cooperative education student.  Later at Langley, he worked
on the technical development of one of the Viking Mars exploration experiments.

        Diaz received a B.S. degree from St. Joseph's University, Philadelphia,
in 1966; a M.S. degree in physics from Old Dominion University, Norfolk, in
1970; and a M.S. degree in management from Massachusetts Institute of
Technology, Cambridge, as a NASA- sponsored Sloan Fellow in 1986.  He was
awarded the NASA Medal for Outstanding Scientific Achievement in 1977 for his
work on the Viking experiment.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
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- Current Two-Line Element Sets #162 -

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MISSION HIGHLIGHTS STS-54

An Educational Publication of the National Aeronautics and Space Administration

Space Shuttle Endeavour
January 13-19, 1993

Commander: John H. Casper (COL, USAF)
Pilot: Donald R. McMonagle (LTCOL, USAF)
Mission Specialist: Mario Runco, Jr. (LCDR, USN)
Mission Specialist: Gregory J. Harbaugh
Mission Specialist: Susan Helms (MAJ, USAF)

Major Mission Accomplishments

% Successfully deployed the Tracking Data and Relay Satellite-6.

% Obtained the first direct evidence that a mysterious X-ray glow emanating
        from seemingly empty space actually originates from vast invisible
        clouds of hot gas.  The Diffuse X-ray Spectrometer that made this
        discovery is a joint experiment of NASA and the University of
        Wisconsin, Madison, Wisconsin.

% Conducted a four-hour, 28-minute spacewalk to evaluate extravehicular
        techniques and define the differences between training simulations and
        actual spacewalks.  The spacewalk was conducted in preparation for
        Space Station Freedom activities.

% Successful shut down and restart of one of three of Endeavour's
        electricity-producing fuel cells to verify that fuel cells can be
        restarted in space.  The experiment continues NASA's preparation for
        Space Station Freedom operations.

% Conducted a live interactive classroom event on the topic of Physics of Toys.
        Students in New York, Ohio, Michigan, and Oregon schools participated
        directly in the event.  Elementary school children in over 6,000
        schools throughout the U.S. watched the experiments performed on cable
        TV. Additional toys were tested for a follow-up educational videotape
        to be released to schools in the fall. (The Physics of Toys experiment
        was sponsored by the Houston Museum of Natural Science.)

% Completed 98 percent of the science objectives in the Commercial Generic
        Bioprocessing Apparatus experiment.

% Obtained excellent video of strips of burning plastic in the Solid Surface
        Combustion Experiment.

% Collected many Earth resources photographs for scientific analysis of
        changing environmental conditions.


        Following a smooth countdown, the Space Shuttle Endeavour lifted off on
its third mission since it began service 8 months ago.  Designated STS-54, this
diversified flight included: the deployment of a communications satellite, a
space walk for two crewmembers in preparation for future Space Station Freedom
activities, a variety of scientific tests, and an innovative educational
activity that linked crewmembers with students in four schools across the
United States.

        Six hours after liftoff, the crew deployed the Tracking and Data Relay
Satellite-6 (TDRS-6) from Endeavour's payload bay.  The 2,540 kg satellite was
attached to a 14,850 kg solid propellant Inertial Upper Stage (IUS) booster
rocket.  With Endeavour moved to a safe distance, the IUS fired and accelerated
TDRS-6 to its planned 36,000 km altitude.  Following systems checkout, TDRS-6
will be moved to a position of 46 degrees west longitude, serving as a backup
to the TDRS constellation.  The TDRS system, now consisting of five satellites
in geostationary orbit, relays voice, video, and data communications between
Space Shuttle crews and Mission Control in Houston, Texas. The system makes it
possible for crew and controllers to remain in nearly continuous contact (85%
or more of each orbit).  In addition, TDRS can provide communications services
for as many as 24 Earth-orbiting spacecraft simultaneously.  The TDRS system
presently communicates with all low Earth-orbiting scientific satellites
including the Compton Observatory, Hubble Space Telescope, and the Upper
Atmosphere Research Satellite.

        During the mission, the flight crew maneuvered Endeavour so that the
Diffuse X-ray Spectrometer (DXS) instrument in the orbiter's payload bay could
study so-called Soft X-ray diffuse background radiation within the Milky Way
Galaxy. Since the beginnings of X-ray astronomy in the early 1960s, scientists
have puzzled over the origin of low-energy X-rays that emanate from seemingly
empty space.  The DXS instrument obtained the first direct evidence that these
puzzling X-rays emanate from clouds of invisible hot gas.  If the scientists
are correct in their initial evaluation of DXS data, the invisible gas was
heated by the blast wave of a supernova that occurred approximately 300,000
years ago in the neighborhood of our solar system.  Likened to an "echo from
the past," the gas became so hot that it glows in X-rays.

        Flight day four permitted extensive Earth photography activities.  The
photographs taken will aid scientists in monitoring changes in Earth's surface,
oceans, and atmosphere.  Crewmembers reported that atmospheric dust from the
eruption of Mt. Pinatubo in the Philippines appears to be clearing.

        On flight day five, crewmembers Mario Runco and Greg Harbaugh donned
spacesuits for a 4-hour, 28-minute spacewalk.  This was the first in a series
of spacewalks to be performed periodically on future Shuttle missions to
prepare for extra-vehicular activities on Space Station Freedom. While
operating in Endeavour's payload bay, Runco and Harbaugh evaluated the
difficulties involved in moving heavy masses.  For the test, one crew-member
served as the heavy mass while the other moved him about.  Another objective of
the spacewalk was to define the differences between training simulations on
Earth and the actual spacewalk.  Following the activity, Runco and Harbaugh
conducted an extensive debriefing with their fellow crewmembers to analyze
their experiences.

        Two of the middeck experiments conducted on the mission studied
processing of biologic materials.  In its second flight on the Shuttle, the
Commercial Generic Bioprocessing Apparatus (CGBA) was used to mix, heat, and
process biological samples in microgravity.  Crewmembers accomplished nearly
100 percent of the experiment's objective.  Individual experiments within the
apparatus studied immune systems, bone marrow cultures, tissue regeneration,
cell division, seed germination, etc.  The experiments were designed by
researchers at universities in Alabama, Kansas, Colorado, and Florida. Results
from the experiments could help in the development and testing of new drugs to
treat cancer, osteoporosis, and AIDS. The second experiment, the Bioreactor,
used a special apparatus to examine fluid and nutrient flow through a rotating
chamber.  The device will be flown on a later flight carrying cancer cells.  On
the ground, cells in a nutritional fluid tend to bump into the wall of a
chamber and become damaged or distorted.  But, in space, the cells remain
suspended in fluid contained within the Bioreactor chambers allowing full
development without disturbance.

        In other STS-54 activities, crewmembers performed tests to evaluate the
effectiveness of the Shuttle's star trackers to help in the alignment of the
onboard navigation system and a restart test of one of Endeavour's
electricity-producing fuel cells.  Turning off and restarting fuel cells will
be a routine activity when Space Shuttle orbiters visit Space Station Freedom.
Powering down equipment and shutting down fuel cells will permit the
conservation of cryogenic fuels.  Although designed to restart in space, this
capability of the fuel cells has never been tested in orbit.  The fuel cell
restarted without any problems.

        In the Solid Surface Combustion Experiment (SSCE) research was
conducted on the burning of plastics to study the combustion process in the
absence of convection currents, studies of electronic still photography, and
evaluation of a new microgravity toilet.  Medical studies on human lymphocytes,
aerobic exercise, and vestibular function were also conducted.  In addition,
eight rodents were carried onboard for later study of the microgravity effects
on the muscular-skeletal system in the Physiological and Anatomical Rodent
Experiment (PARE).  The rodents were returned to Earth in excellent condition.

        As a part of NASA's commitment to education, the STS-54 crew
participated in a live interactive classroom event from space.  Working with
students in four elementary schools located in New York, Ohio, Michigan, and
Oregon, crewmembers responded to student questions by conducting scientific
demonstrations of common children's toys.  Through the use of toys in the
microgravity environment of Earth orbit, basic scientific principles can be
investigated in ways not possible on Earth. Students participating directly in
the lesson attended schools that are alma maters of four of the STS-54
crewmembers.  In addition, students in many thousands of schools were also able
to observe the lesson through satellite or cable television.  A videotape of
the live lesson will be distributed to schools through NASA's Teacher Resource
Center network in the spring.  A second tape, containing demonstrations of
other toys carried on the flight will be distributed during the fall semester
of the 1993-94 school year.


Mission Facts

Orbiter:  Endeavour
Mission Dates:  January 13-19, 1993
Commander: John H. Casper (COL, USAF)
Pilot: Donald R. McMonagle (LTCOL, USAF)
Mission Specialist: Mario Runco, Jr. (LCDR, USN)
Mission Specialist: Gregory J. Harbaugh
Mission Specialist: Susan Helms (MAJ, USAF)

Mission Duration: 5 days, 23 hours, 38 minutes
Kilometers Traveled: 4,027,056
Orbit Inclination: 28.45 degrees
Orbits of Earth: 96
Orbital Altitude: 296 km
Payload Weight Up: 18,611 kg
Orbiter Landing Weight: 93,181 kg
Landed:  Kennedy Space Center, Runway 33



Payloads and Experiments:


TDRS-6 -  Tracking Data and Relay Satellite
DXS -     Diffuse X-Ray Spectrometer
CHROMEX-  Chromosome Plant Cell Division in Space
PARE-02 - Physiological and Anatomical Rodent Experiment Human Lympocyte
          Locomotion in Microgravity
SSCE -    Solid Surface Combustion Experiment
CGBA -    Commercial Generic Bioprocessing Apparatus

EVA for Space Station Freedom Applications
Fuel Cell Shutdown/Restart
Educational Activities
Physics of Toys Interactive Event
Educational Videotaping


Crew Biographies

Commander: John H. Casper (COL, USAF) John Casper was born in Greenville, South
Carolina, but calls Gainesville, Georgia, home.  He earned a bachelor of
science degree in engineering science from the U.S. Air Force Academy and a
master of science degree in astronautics from Purdue University. He is also a
graduate of the Air Force Air War College. He flew 229 combat missions during
th e Vietnam War. He has been a test pilot and served at USAF Headquarters at
the Pentagon as an action officer for the Deputy Chief of Staff, Plans and
Operations, and later as deputy chief of the Special Projects Office. Casper
has logged over 6,000 flying hours in 50 different aircraft.  He was named an
astronaut in 1984.  He flew as pilot aboard STS-36.

Donald R. McMonagle (LTCOL, USAF) Donald McMonagle was born in Flint, Michigan.
He earned a bachelor of science degree in astronautical engineering from the
U.S. Air Force Academy and a master of science degree in mechanical engineering
from Californi a State University-Fresno. He served as an F-4 pilot at Kunsan
Air Base, South Korea, before assignment to Holloman Air Force Base, New
Mexico, where he flew F-15s. He was the operations officer and a project test
pilot for a technology demonstration aircraft, the F- 16, while stationed at
Edwards Air Force Base, California. McMonagle has over 4,200 hours of flying
time in several aircraft.  He became an astronaut in 1987, and flew as a
mission specialist aboard STS-39.

Gregory J. Harbaugh (Mr.) Gregory Harbaugh was born in Cleveland, Ohio, but
Willoughby, Ohio, is his hometown.  He received a bachelor of science degree in
aeronautical and astronautical engineering from Purdue University and a master
of science degree in physical science from the University of Houston, Clear
Lake. He has held engineering and technical management positions in various
areas of Space Shuttle flight operations at NASA's Johnson Space Center. He
also holds a commercial pilot's license and has logged over 1,000 hours flying
time.  Harbaugh was named an astronaut in 1987.  Harbaugh flew as a mission
specialist aboard STS-39.

 Mario Runco, Jr. (LCDR, USN) Mario Runco, Jr., was born in the Bronx, New
York, but considers Yonkers, New York, to be his hometown.  He earned a
bachelor of science degree in meteorology and physical oceanography from the
City College of New York and a master of science degree in meteorology from
Rutgers University. He has worked as a research hydrologist for the U.S.
Geological Survey and a New Jersey State Trooper before entering the U.S.
Navy. In the Navy he served as research meteorologist and later became the
commanding officer of Oceanographic Unit Four embarked in USNS Chauvenet
(T-AGS-29).  Runco was selected as a NASA astronaut in 1987.  Runco was a
mission specialist on STS-44.

Susan J. Helms (MAJ, USAF) Susan Helms was born in Charlotte, North Carolina,
but calls Portland, Oregon, her hometown.  She earned a bachelor of science
degree in aeronautical engineering from the U.S. Air Force Academy and a master
of science degree in aeronautics/astronautics from Stanford University. While
at Eglin Air Force Base, Florida, she was an F-16 weapons separation engi neer
and later lead engineer for F-15 weapons separation.  She subsequently was
assigned to the faculty of the USAF Academy where she held the position of
assistant professor.  She has flown in 30 different types of U.S. and Canadian
aircraft.  Helms was named an astronaut in 1990.
     Source:NASA Spacelink    Modem:205-895-0028  Internet:192.149.89.61
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MISSION WATCH STS-56

Atmospheric Laboratory for Applications and Science - 2

An Educational Publication of the National Aeronautics and Space Administration


One of the linchpins of NASA's Mission to Planet Earth is the series of
Atmospheric Laboratory for Applications and Science (ATLAS) missions to be
flown on the Space Shuttle. Mission to Planet Earth is NASA's contribution to
the United States Global Change Research Program, a unified study of the planet
and its components, from its interior to its outermost atmospheric regions.  In
turn, Mission to Planet Earth is a cooperative element of the International
Geosphere/Biosphere Research Program, one of the most comprehensive scientific
undertakings of all time.

        The primary goal of the ATLAS program is to help scientists
characterize the chemical and physical components of the middle part of Earth's
atmosphere, including the effect of the Sun's energy on those components. (The
middle atmosphere or stratosphere and mesosphere contain Earth's protective
ozone layer.  Chemical processes there contribute to problems such as ozone
depletion and global warming.)

        Because no single space mission can provide enough information to
accomplish this goal or provide data on possible long-term changes, NASA has
planned a series of ATLAS missions. (ATLAS-1 flew between March 24 through
April 2, 1992.) Each mission will carry a core of seven instruments designed to
gather data under a variety of atmospheric conditions over both the Northern
and Southern Hemispheres. Some of the instruments focus primarily on
atmospheric observations while others measure solar energy.  Both sets of data
are essential for proper interpretation of the conditions and processes at work
in the middle atmosphere.

ATLAS-2 Mission

The ATLAS-2 mission, planned for spring of 1993, features a core payload of six
instruments that are carried to space on a Spacelab pallet and one instrument
that is carried in two cannisters mounted to the payload bay wall.  The pallet,
a U-shaped cradle, fits inside the payload bay of the Space Shuttle Discovery
like a back porch.  As a mounting platform, the pallet exposes instruments
directly to the conditions of outer space.  Normally, the instruments will be
operated by radio control from the ground, but crewmembers may also operate the
instruments from within the orbiter's cabin.  Attached to the pallet in the bay
is the Spacelab igloo.  The igloo is a white cannister that houses Spacelab
subsystems, pumps, and power boxes to provide the science equipment with power,
communication links, and environmental control.

        Liftoff of the eight day mission is planned for nighttime to make
sunrise observations at high northern latitudes.  NASA managers will decide
during the mission if an extra day can be flown for additional science
observations.

ATLAS-2 Instruments

The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument will survey
concentrations of trace molecules by measuring absorption of solar infrared
radiation.  This instrument will help scientists determine what chemicals are
present in the middle atmosphere, what their concentrations are, where they are
located, and what chemical reactions they influence.

        The Millimeter-wave Atmospheric Sounder (MAS) will also study
atmospheric constituents.  MAS will measure ozone concentrations, temperatures,
water vapors and chlorine monoxide in the middle atmosphere.  Chlorine monoxide
is a key trace molecule involved in the destruction of ozone.

        Two instruments, the Solar Spectrum Measurement (SOLSPEC) and the Solar
Ultraviolet Spectral Irradiance Monitor (SUSIM) will characterize the solar
radiation that drives chemical reactions in the middle atmosphere.  The SUSIM
will only measure ultraviolet radiation, but will cover a broader range of
ultraviolet radiation (120-400 NM) than will the SOLSPEC instrument. (A
nanometer is a metric unit equal to one-billionth of a meter.  The SOLSPEC
instrument's range of 180 to 3,200 nanometers covers the electromagnetic
spectrum from ultraviolet to infrared radiation.) Both instruments, when flown
over many missions, will yield long-term records of solar radiation and its
variations.

        The Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument measures
both solar ultra-violet output and stratospheric ozone.  This instrument has
flown previously on four other Space Shuttle missions.

        Two other ATLAS instruments measure the total solar irradiance.  The
Active Cavity Radiometer Irradiance Monitor (ACRIM) and the Measurement of
Solar Constant (SOLCON) seek to measure the total amount of energy the Sun
delivers to the Earth. This amount is referred to as the solar constant,
although it varies by a small amount from year to year.  The variance in the
solar constant is significant because small changes in incoming energy can have
dramatic effects on the climate.  By measuring incoming energy above the
atmosphere, scientists can get more precise data.

        In addition to taking measurements, the instruments on this mission are
invaluable for calibrating similar instruments on scientific satellites.  The
longer a satellite operates in space, the greater is the chance that
high-energy radiation or other harsh conditions can damage the hardware and
skew the data gathered.  Comparison of the ATLAS data with that of free-flying
satellites can help scientists recalibrate their instruments on the satellites
and ensure their long term accuracy.  In particular, ATLAS-2 will underfly the
Upper Atmosphere Research Satellite (UARS) to enhance its data.

Unique Science Opportunities

Measurements taken by ATLAS-2 are particularly crucial in light of recent
atmospheric conditions.  Data gathered from the UARS and from an airborne
sampling mission in the Arctic indicate unprecedented levels of the chemical
chlorine monoxide at high northern latitudes during the winter of 1991-1992.
Given these high concentrations, atmospheric models suggest that, under
appropriate meteorological conditions, significant ozone depletion over the
Arctic is possible. (The ozone layer serves as a filter that blocks harmful
ultraviolet radiation from the Sun. When ozone amounts decrease, more
ultraviolet radiation can reach Earth's surface and damage living things.)

        Chlorine monoxide is a key compound in a cyclic process where small
amounts of chlorine may efficiently destroy much larger amounts of ozone in the
stratosphere.  Sunrise is the best time to measure the concentration of several
stratospheric molecules.  Since these molecules form at night and are destroyed
during the day, the concentration is largest at sunrise.

Other Mission Objectives

On flight day 3, the crew will deploy the Spartan Solar Wind Physics
Experiment. The Spartan is a free- flying platform that is deployed by the
orbiter's Remote Manipulator System (RMS) for independent operations.  Two
instruments onboard Spartan will gather data about the corona, the outer most
layer of the Sun, and the acceleration of the solar wind (charged particle
streams emanating from the Sun) in a variety of locations in the Sun's corona.
The RMS will retrieve Spartan after about 40 hours of operation in space.

        Other mission activities include biological and medical experiments,
radiation studies, materials processing experiments, and contact with amateur
radio operators through Shuttle Amateur Radio Experiment (SAREX).

        In their continuing support of education, the crewmembers will
videotape a variety of preplanned scenes on living in space to be used for an
elementary level educational videotape.  The tape will be available to teachers
through the NASA Teacher Resource Center network later in the year.


STS-56 Quick Facts

Crew:   Kenneth D. Cameron (COL, USMC) - Commander
        Stephen S. Oswald - Pilot
        Michael Foale (Ph.D.) - Mission Specialist
        Kenneth D. Cockrell - Mission Specialist
        Ellen Ochoa (Ph.D.)  - Mission Specialist

Vehicle:        OV-103, Discovery       Mission Duration:       8+1 days
Orbital Inclination:    57 degrees      Orbital Altitude:       296 km
Primary Payload
and Experiments:

        ATLAS-2         Atmospheric Laboratory for Applications and Science
        SSBUV/A-02      Shuttle Solar Backscatter Ultraviolet experiment
        SPTN-201        Shuttle Pointed Autonomous Research Tool for Astronomy
        CMIX            Commercial Materials Dispersions Apparatus Assembly
        PARE            Physiological and Anatomical Rodent Experiment
        STL             Space Tissue Loss
        CREAM           Cosmic Ray Effects and Activation Monitor
        SUVE            Solar Ultraviolet Experiment
        RME III         Radiation Monitoring Experiment III
        HERCULES        Hand-held, Earth-oriented, Real-time, Cooperative,
                        User-friendly, Location targeting, and Environmental
                        System
        SAREX           Shuttle Amateur Radio Experiment


Educational Activities: Videotaping for an elementary level program on living
                        in space.



Classroom Activities and Questions

1.  The entire progress of the mission from launch to landing can be observed
on television if your school has a satellite dish.  Direct the dish to the
SATCOM F2R satellite at 72 degrees west longitude.  Tune in to NASA Select,
transponder 13, 3960 megahertz.  If your school does not have a satellite dish
but does have a cable television hookup, call your local cable company and
request that they receive NASA Select and either distribute it on one of their
channels or tape it for your use.  Check local news services for updates on
Discovery's liftoff or call the NASA Kennedy Space Center at 407-867-2525 for a
recorded message.

2.  Collect current newspaper and magazine articles on environmental problems
relating to Earth's atmosphere.  Contact NASA SPACELINK (see below) for
additional information.

3.  What are some of the consequences of atmospheric ozone depletion and global
warming?  What are the sources of chemicals that trigger ozone depletion?

4.  Contact the American Radio Relay League for the name of a local amateur
radio operator who might be willing to provide a SAREX demonstration for your
classroom.  The league coordinates educational activities related to the
experiment, which is expected to fly again on several future Shuttle missions.

        American Radio Relay League
        225 Main Street
        Newington, CT 06111


References and Resources

% To request copies of the publications below, write:

NASA Education Division
Code FET
NASA Headquarters
Washington, DC 20546

% Publication text is also available from NASA SPACELINK. See references and
resources section below.

NASA (1992), The Atmosphere Below (videotape), Liftoff to Learning series.
Comes with a video resource guide for the teacher.  NASA Education Division,
Washington, D.C.

NASA (1992), ATLAS Educator Slide Set, NASA Education Division, Washington,
D.C.

NASA (1991), Earth's Mysterious Atmosphere - ATLAS 1 Teacher's Guide with
Activities, EP-282/11-91,

NASA Education Division, Washington, D.C.

NASA (1989), The Upper Atmosphere, A Program to Study Global Ozone Change,
3/89:20K.

NASA SPACELINK provides information about current and historic NASA programs,
lesson plans, the text from previous Mission Watch and Mission Highlights fact
sheets.  Anyone with a personal computer, modem, communications software, and a
long distance telephone line can communicate directly with NASA SPACELINK. Use
your computer to dial 205-895-0028 (8 data bits, no parity, and 1 stop bit).


Mission Patch for STS-56

The STS-56 patch is a pictorial representation of the STS-56/ATLAS-2 mission as
seen from the crew's viewpoint.  The payload bay is depicted with the ATLAS-2
pallet, Shuttle Solar Backscatter Ultra Violet (SSBUV) experiment, and Spartan,
the primary scientific payloads on the flight.  ATLAS-2 is a "Mission To Planet
Earth," so the Earth is featured prominently.  The mission's two primary areas
of study are the atmosphere and the Sun. To highlight this, the Earth's
atmosphere is depicted as a stylized visible spectrum and the sunrise is
depicted with an enlarged two-colored corona.  The commander's and pilot's
names are written in the Earth field and the names of the mission specialists
are in the space background.
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LIVING AND WORKING IN SPACE: THE COUNTDOWN HAS BEGUN

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Venus
        Veiled by dense cloud cover, Venus -- our nearest planetary neighbor
-- was the first planet to be explored. The Mariner 2 spacecraft, launched
on August 27, 1962, was the first of more than a dozen successful
American and Soviet missions to study the mysterious planet. As
spacecraft flew by or orbited Venus, plunged into the atmosphere or
gently landed on Venus' surface, romantic myths and speculations about
our neighbor were laid to rest.
        On December 14, 1962, Mariner 2 passed within 34,839 kilometers
(21,648 miles) of Venus and became the first spacecraft to scan another
planet; onboard instruments measured Venus for 42 minutes. Mariner 5,
launched in June 1967, flew much closer to the planet. Passing within
4,094 kilometers (2,544 miles) of Venus on the second American flyby,
Mariner 5's instruments measured the planet's magnetic field, ionosphere,
radiation belts and temperatures. On its way to Mercury, Mariner 10 flew
by Venus and transmitted ultraviolet pictures to Earth showing cloud
circulation patterns in the Venusian atmosphere.
        In the spring and summer of 1978, two spacecraft were launched to
further unravel the mysteries of Venus. On December 4 of the same year,
the Pioneer Venus Orbiter became the first spacecraft placed in orbit
around the planet.
        Five days later, the five separate components making up the second
spacecraft -- the Pioneer Venus Multiprobe -- entered the Venusian
atmosphere at different locations above the planet. The four small,
independent probes and the main body radioed atmospheric data back to
Earth during their descent toward the surface. Although designed to
examine the atmosphere, one of the probes survived its impact with the
surface and continued to transmit data for another hour.
        Venus resembles Earth in size, physical composition and density
more closely than any other known planet. However, spacecraft have
discovered significant differences as well. For example, Venus' rotation
(east to west) is retrograde (backward) compared to the west-to-east
spin of Earth and most of the other planets.
        Approximately 96.5 percent of Venus' atmosphere (95 times as
dense as Earth's) is carbon dioxide. The principal constituent of Earth's
atmosphere is nitrogen. Venus' atmosphere acts like a greenhouse,
permitting solar radiation to reach the surface but trapping the heat that
would ordinarily be radiated back into space. As a result, the planet's
average surface temperature is 482 degrees Celsius (900 degrees
Fahrenheit), hot enough to melt lead.
        A radio altimeter on the Pioneer Venus Orbiter provided the first
means of seeing through the planet's dense cloud cover and determining
surface features over almost the entire planet. NASA's Magellan
spacecraft, launched on May 5, 1989, has been in orbit around Venus since
August 10, 1990. The spacecraft uses radar-mapping techniques to provide
ultrahigh-resolution images of the surface.
        Magellan has revealed a landscape dominated by volcanic features,
faults and impact craters. Huge areas of the surface show evidence of
multiple periods of lava flooding with flows lying on top of previous ones.
An elevated region named Ishtar Terra is a lava-filled basin as large as
the United States. At one end of this plateau sits Maxwell Montes, a
mountain the size of Mount Everest. Scarring the mountain's flank is a 100
-kilometer (62-mile) wide, 2.5-kilometer (1.5-mile) deep impact crater
named Cleopatra. (Almost all features on Venus are named for women;
Maxwell Montes, Alpha Regio and Beta Regio are the exceptions.) Craters
survive on Venus for perhaps 400 million years because there is no water
and very little wind erosion.
        Extensive fault-line networks cover the planet, probably the result
of the same crustal flexing that produces plate tectonics on Earth. But on
Venus the surface temperature is sufficient to weaken the rock, which
cracks just about everywhere, preventing the formation of major plates
and large earthquake faults like the San Andreas Fault in California.
        Venus' predominant weather pattern is a high-altitude, high-speed
circulation of clouds that contain sulfuric acid. At speeds reaching as high
as 360 kilometers (225 miles) per hour, the clouds circle the planet in
only four Earth days. The circulation is in the same direction -- west to
east -- as Venus' slow rotation of 243 Earth days, whereas Earth's winds
blow in both directions -- west to east and east to west -- in six
alternating bands. Venus' atmosphere serves as a simplified laboratory for
the study of our weather.



4/24/93: EVIDENCE POINTS TO OCEANS, LIGHTNING ON EARLY VENUS


Paula Cleggett-Haleim
Headquarters, Washington, D.C.                   March 24, 1993

Peter Waller
Ames Research Center, Mountain View, Calif.


RELEASE:  93-51

        The last findings by the Pioneer Venus Orbiter spacecraft have provided
strong new evidence that planet Venus once had three and a half times more
water as thought earlier -- enough water to cover the entire surface between 25
and 75 feet deep (762 and 2286 centimeters).

        These findings also give new support for the presence of lightning on
Venus and discoveries about the ionosphere and top of the atmosphere of Venus.
Considered Earth's twin planet, Venus today is very dry and searing hot.

        Pioneer entered Venus' atmosphere on Oct. 8, 1992, and burned up soon
after, ending 14 years of exploration.

        "Many of us have long thought that early in its history Venus had
temperate conditions and oceans like Earth's," said Dr. Thomas Donahue,
University of Michigan, head of the Pioneer Venus science steering group.

        "Findings that Venus was once fairly wet does not prove that major
oceans existed, but make their existence far more likely," he said. "The new
Pioneer data provides evidence that large amounts of water were definitely
there," said Donahue.

        "Most scientists think Venus' early oceans vaporized and 'blew off' 3
billion years ago in a runaway greenhouse effect when the cool early sun
increased its luminosity and heated the planet very hot," he said. "The oceans
evaporated.  Solar ultraviolet radiation split the water molecules into
hydrogen and oxygen, and the hydrogen was lost to space.

        "Pioneer Venus Probe and Orbiter data showed early in the mission,"
Donahue said, "that on Venus heavy habundant relative to ordinary hydrogen than
on Earth and everywhere else we've looked in the solar system -- Mars, Comet
Halley, meteorites, Jupiter and Saturn." Venus' remarkable hydrogen/deuterium
ratio has since been confirmed by independent measurements.

        Abundant deuterium is taken as clear evidence that Venus once had 150
times as much water in its atmosphere as today, he said.  This is because the
water's ordinary hydrogen has escaped.  But most of the water's heavy hydrogen
(deuterium - twice as heavy as hydrogen) stayed behind because of its weight.

        When the Orbiter made its final descent to unexplored regions only 80
miles (129 kilometers) above Venus' surface, it found evidence for 3.5 times as
much water as previously suggested by the deuterium ratio.

        "We found a new and important easy-escape mechanism, which accelerates
hydrogen and deuterium away from the planet," he said. "This means that much
more hydrogen had to escape to build up the present high deuterium
concentration.  A lot more hydrogen lost means a lot more water early on," he
said. "This also rules out theories of a dry-from-the-beginning Venus, whose
present meager supply of water comes from an occasional comet impact."

        The data also show that at Pioneer's lowest altitude 80 miles (129
kilometers) "whistler" radio signals, believed generated by Venus' lightning,
were the strongest ever detected.  Pioneer has long measured such "lightning"
signals.  They are the same as the radio signals used in most lightning studies
on Earth.

        In its final orbits, Pioneer penetrated 7 miles (11 kilometers) below
the peak of Venus' ionosphere, which tends to block these radio signals.  Here
also, the magnetic fields which channel the signals were the strongest ever
seen on Venus' night side.

        "These results are best explained by a strong and persistent source of
lightning in the Venus atmosphere," said Robert Strangeway of UCLA, Pioneer
electric field investigator.

         Some scientists continue to doubt Venus lightning.  They say only
optical sightings can prove lightning.  A Russian spacecraft has reported
visible-light sightings of lightning.  Four Russian spacecraft and the U.S.
Galileo craft also have observed radio signals believed from lightning.

        Pioneer found the peak density of Venus' ionosphere for the first time
- at 87 miles (139 kilometers).  The ionosphere was much different between
solar maximum and minimum, which are high and low periods of storm activity on
the sun and in the solar wind.  At minimum, it was far smaller.  It was gone
altogether above 85 miles (136 kilometers), and its lower layer was half as
dense.  It was more variable, much cooler, and full of small structures (1-60
miles in size (1.6-96 kilometers).

        For the ionosphere on the night side, at solar minimum, hydrogen ions
were reduced 20 times.  Its lower layer was half as dense as at maximum.

        Over 3 months, Pioneer provided data from 80 to 210 miles (129 to 336
kilometers) altitude.  It found the beginning of Venus' real, mixed atmosphere
(transition from oxygen to carbon dioxide) at 80 miles (129 kilometers).  Below
85 miles (136 kilometers), it identified various waves and a 4-day oscillation
of Venus' atmosphere top.  The neutral atmosphere above 185 miles (296
kilometers) was more than 10 times denser and 2120 F (1,000 degrees Celsius)
hotter than thought.

        Working with Donahue were Drs. Richard Hartle and Joseph Grebowsky of
NASA's Goddard Space Flight Center, Greenbelt, Md. Ames Research Center manages
the Pioneer project for the Office of Space Science, NASA Headquarters,
Washington, D.C.

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