Дата: 23 января 1998 (1998-01-23)
От: Alexander Bondugin
Тема: This Week on Galileo - January 19-25, 1998
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THIS WEEK ON GALILEO
January 19-25, 1998
The Galileo spacecraft has resumed transmitting pictures and science data to
Earth at normal speed. Transmission of the data, which is stored on board
the spacecraft, had been slowed down by two incidents of anomalous behavior
by Galileo's attitude control system. The anomalies had caused the
spacecraft's radio antenna to be aimed 10 degrees from Earth. However, the
spacecraft successfully completed a turn that pointed its antenna within 3
degrees of Earth, which is a normal angle. The turn was performed early last
week.
The cause of the anomalous behavior in the spacecraft's attitude control
subsystem remains unknown. The leading candidate continues to be one of the
spacecraft's two gyroscopes, but no definite evidence has been found as of
today. The project has formed a team of hardware experts to continue
analysis of the available engineering data.
Scheduled for this week is the execution of the mission's next orbit trim
maneuver. This maneuver was orginally scheduled for last week, but was
delayed due to the anomalous behavior of the attitude control subsystem.
Remember that these maneuvers are performed to keep the spacecraft traveling
around Jupiter along the desired orbital path. The series of commands that
will control the execution of this orbit trim maneuver will be built with
additional safeguards. If the behavior of the attitude control subsystem
becomes anomalous, these safeguards will prevent a reoccurance of any
activity that would lead to undesireable spacecraft pointing.
The science data processing and transmission schedule for this week focuses
on two areas. Remaining on the schedule is the return of high time
resolution fields and particles information of the interaction between
Europa and Jupiter's magnetic and electric field environment. New to the
schedule is a series of three observations taken by the spacecraft's Solid
State imaging camera. These images show a region of Europa characterized by
wedge shaped features which will provide information on how surface
spreading or cracking may have occurred on Europa. The first will have an
image resolution of 15 meters (49 feet) per picture element and, the second,
30 meters (98 feet) per picture element. Together these two observations are
expected to allow the creation of a stereo image of this region. The third
image is of slightly lower resolution and at 50 meters (164 feet) per
picture element will provide regional context information for the previous
two images. This region of Europa was also imaged during the Callisto-Orbit
3 encounter of Galileo's primary mission.
For more information on the Galileo spacecraft and its mission to Jupiter,
please visit the Galileo home page:
http://www.jpl.nasa.gov/galileo/
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Дата: 23 января 1998 (1998-01-23)
От: Alexander Bondugin
Тема: Galileo Update - January 20, 1998
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MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Galileo Europa Mission Status
January 20, 1998
Members of the Galileo flight team are analyzing data from a test
performed Friday night, which they hope will shed light on the cause of two
recent incidents of anomalous behavior by the spacecraft. While the
investigation continues, the spacecraft has resumed normal transmission to
Earth of pictures and other science information stored on its onboard tape
recorder.
While one anomaly occurred during the spacecraft's December 16, 1997
flyby of Europa, and the other after the flyby, both involved the attitude
control subsystem, which controls where the spacecraft and scan platform are
pointing. Team members suspect the cause may have been one of the
spacecraft's two gyroscopes. The gyroscopes are used to point the spacecraft
when very precise pointing control and knowledge of the spacecraft's
position and orientation are needed, usually for camera and other remote
sensing science observations or for maneuvers that adjust the spacecraft's
flight path.
The anomalies were not considered serious, but they did cause a
temporary slowdown in the rate at which information was transmitted to
Earth. That's because the anomalies caused Galileo's radio antenna to point
in a direction about 10 degrees from Earth, about eight degrees greater than
the normal attitude for ideal data transmission. However, information is now
being transmitted at a normal rate once again, thanks to a spacecraft turn
performed last week which pointed Galileo's antenna within 3 degrees of
Earth, a normal angle.
Galileo has begun sending back to Earth some high-resolution pictures
taken during the Dec.16 Europa encounter. That flyby was the closest ever to
be performed by Galileo, with the spacecraft dipping down to 200 kilometers
(124 miles) above the icy moon's surface. This week, Galileo will also
return fields and particles information on the interaction between Europa
and Jupiter's magnetic and electric field environment.
A flight path maneuver is planned for Thursday evening, Jan. 22 to
prepare for Galileo's upcoming Europa encounter on Feb. 10. Special
precautions have been taken in the design of this maneuver to minimize its
vulnerability to any gyro problems. Because of its proximity to solar
conjunction, when the Sun will be between Galileo and Earth, no data
collection is planned except for radio science information.
The spacecraft recently began a two-year extended mission, known as
the Galileo Europa Mission, which will include a total of eight Europa
flybys, four of Callisto, and one or two of Io, depending on spacecraft
health.
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Дата: 23 января 1998 (1998-01-23)
От: Alexander Bondugin
Тема: Additional Experiments Selected For Mars 2001 Missions
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Michael Braukus
Headquarters, Washington, DC January 22, 1998
(Phone: 202/358-1979)
Douglas Isbell
Headquarters, Washington, DC
(Phone: 202/358-1753)
RELEASE: 98-13
ADDITIONAL EXPERIMENTS SELECTED FOR MARS 2001 MISSIONS
NASA has selected additional instruments for the Mars
Surveyor 2001 missions, which will study Mars' environment.
The Mars Surveyor 2001 missions will follow two other robotic
Mars missions to be launched in late 1998 and early 1999. All are
part of NASA's long-term, systematic exploration of Mars in which
two missions are launched to the planet approximately every 26
months.
"In a sense, these missions allow virtual presence by humans
and provide precursor data and subsequent infrastructure for
possible human missions in the 21st century," said Arnauld
Nicogossian, Associate Administrator of NASA's Office of Life and
Microgravity Sciences and Applications. "By adding capability to
missions already planned, this near term effort will result in
cost effective, tangible progress in carrying out the Human
Exploration and Development of Space strategy and contribute to
the Origins program of NASA's Office of Space Science."
NASA's Office of Life and Microgravity Sciences and
Applications has selected the following investigations for the
Mars 2001 Orbiter, due for launch in March of that year, and the
Mars 2001 Lander/Rover, due for launch in April 2001:
* The Martian Radiation Environment Experiment will
characterize the radiation environment in the orbit and on the
surface of Mars simultaneously. This experiment will consist of
radiation spectrometers on both the Mars 2001 Orbiter and on the
Mars 2001 Lander. Dr. Guatam Badhwar from NASA's Johnson Space
Center, Houston, TX, is the principal investigator.
* The Mars Environmental Compatibility Assessment will
characterize Martian dust and soil to identify potential
undesirable and harmful interactions with human explorers and
associated hardware, and to evaluate properties of the soil
related to its use as a construction material. Dr. Thomas Meloy
from West Virginia State University is the principal investigator.
A team consisting of NASA's Jet Propulsion Laboratory (JPL),
Pasadena, CA, and Lockheed Martin Astronautics, Denver, CO, will
develop the missions, led by JPL.
The radiation and dust investigations were selected from 39
proposals submitted to NASA in August 1997.
Both of the 2001 missions are part of an ongoing NASA series
of robotic Mars exploration spacecraft that began with the
launches of the Mars Global Surveyor in November 1996. The 2001
missions represent the first step in a NASA initiative to
integrate the requirements for Space Science and the Human
Exploration and Development of Space program into a single robotic
exploration program.
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Дата: 23 января 1998 (1998-01-23)
От: Alexander Bondugin
Тема: MISSION TO PLANET EARTH ENTERPRISE NAME CHANGED TO EARTH SCIENCE
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Douglas Isbell
Headquarters, Washington, DC January 21,
1998
(Phone: 202/358-1753)
RELEASE: 98-12
MISSION TO PLANET EARTH ENTERPRISE
NAME CHANGED TO EARTH SCIENCE
NASA has renamed the Mission to Planet Earth enterprise the
Earth Science enterprise. The Earth Science enterprise is one of
the four strategic enterprises of the Agency, responsible for a
long-term, coordinated research effort to study the total Earth
system and the effects of natural and human-induced changes on the
global environment.
In announcing the change of name, Acting Associate
Administrator for Earth Science William Townsend said, "We feel
that 'Earth Science' more clearly conveys to the American people
the goals of our program, and more directly focuses on the
research that we're conducting. 1998 will include several major
launches in the enterprise, including the first Earth Observing
System missions, and we are pleased to enter this era with the new
name."
The Earth Science enterprise is pioneering the emerging
discipline of Earth system science, with a near-term emphasis on
global climate change. Earth science research capabilities under
development will yield a variety of new scientific understandings
and practical benefits to humankind.
The goals of the Earth Science enterprise are to expand
scientific knowledge of the Earth system using NASA's unique
vantage points of space, aircraft, and in situ platforms, creating
an international capability to forecast and assess the health of
the Earth system; to widely disseminate information about the
Earth system; and to enable the productive use of Earth science
results and related technology in the public and private sectors.
The title "Mission to Planet Earth" originated ten years ago
in a report on future directions for the U.S. civil space program
by a commission led by former astronaut
Dr. Sally Ride. The term and the concept of looking at Earth as
NASA looks at other planets were furthered by the 1990 Report of
the Advisory Committee on the Future of the U.S. Space Program,
prepared by a team of experts chaired by Dr. Norman Augustine.
Since that time, NASA has organized its activities into four
strategic enterprises, including Human Exploration and Development
of Space, Aeronautics and Space Transportation, and Space Science.
In a manner similar to the way that the Space Science
enterprise has been broadened to include questions about the
origins and destiny of the Universe, the Mission to Planet Earth
enterprise has been reshaped to answer key questions in five major
Earth system science disciplines: land surface cover, near-term
and long-term climate change, natural hazards research and
atmospheric ozone.
The renaming of the enterprise to "Earth Science" is
effective immediately. NASA will continue to use all supplies,
such as stationery, that bear the former name of "Mission to
Planet Earth" until such supplies are depleted, so as to avoid any
unnecessary cost to the Agency.
-end-
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Дата: 23 января 1998 (1998-01-23)
От: Alexander Bondugin
Тема: NASA COMMITS TO SECOND VEHICLE FOR X-34 PROGRA
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Jim Cast
Headquarters, Washington, DC January 21, 1998
(Phone: 202/358-1779)
Dom Amatore
Marshall Space Flight Center, Huntsville, AL
(Phone: 205/544-0031)
Barron Beneski
Orbital Sciences Corp., Dulles, VA
(Phone: 703/406-5528)
RELEASE: 98-11
NASA COMMITS TO SECOND VEHICLE FOR X-34 PROGRAM
NASA has modified its X-34 contract with Orbital Sciences
Corp., Dulles, VA, to produce a second flight vehicle for the X-34
Program. "The purpose of a second vehicle is to reduce risk to
the X-34 program," said deputy program manager Mike Allen of
NASA's Marshall Space Flight Center, Huntsville, AL. "One of the
lessons we learned from the Clipper Graham program is that it is
desirable to have a second flight vehicle available, especially if
it can be acquired at a relatively low cost." Clipper Graham was
a previous technology demonstrator that NASA flew four times in
1996, until it was destroyed during landing.
Under the new arrangement, X-34 test objectives are being
expanded, adding, for example, unpowered tests to the flight
profile. A second vehicle also will provide flexibility in
demonstrating various technologies, Allen said, allowing testing
that requires repetitive flights to continue at the same time as
tests which require significant, time-consuming changes to the
vehicle.
In August 1996 NASA entered into a $50 million contract with
Orbital Sciences Corp. to design, build and test-fly the X-34, a
small, reusable technology demonstrator. An additional $10
million was committed by NASA to be spent in direct support of X-
34 by NASA Centers and other government agencies. Now the
contract has been increased by $7.7 million to purchase long lead-
time hardware, including a new wing, fuselage, avionics set,
hydraulic pump and actuator system, and more. NASA has committed
$2 million more for the government to provide wind tunnel testing,
additional testing and analysis, and a second leading-edge Thermal
Protection System.
An $8.5 million option calls for purchase of shorter lead-
time hardware, such as navigation systems, while a $1.8 million
option has been added for assembly of piece parts into subsystems,
integration and final assembly. These options should be formally
exercised shortly.
The X-34 is a single-engine rocket with short wings and a
small tail surface. The vehicle is 58.3 feet long, 27.7 feet wide
at wing tip and 11.5 feet tall from the bottom of the fuselage to
the top of the tail. Capable of flying eight times the speed of
sound and reaching an altitude of 250,000 feet, the X-34 will
demonstrate low-cost reusability, autonomous landing, subsonic
flights through inclement weather, safe abort conditions, and
landing in 20-knot cross winds.
The X-34 is designed to bridge the gap between the earlier
Clipper Graham, or DC-XA, subsonic demonstrator vehicle, and the
larger, more advanced X-33 vehicle. The X-34 will demonstrate key
technologies applicable to development of a future Reusable Launch
Vehicle. The overall goal of these vehicle programs is to
demonstrate the key technologies needed to dramatically lower the
cost of putting a pound of payload into space.
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Дата: 23 января 1998 (1998-01-23)
От: Alexander Bondugin
Тема: EARTH SWINGBY PUTS NEAR SPACECRAFT ON FINAL APPROACH TO EROS
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Donald Savage
Headquarters, Washington, DC January 20, 1998
(Phone: 202/358-1547)
Helen Worth
The Johns Hopkins University Applied Physics Laboratory, Laurel,
MD
(Phone: 301/953-5113)
RELEASE: 98-9
EARTH SWINGBY PUTS NEAR SPACECRAFT ON FINAL APPROACH TO EROS
NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft,
built by The Johns Hopkins University Applied Physics Laboratory
(APL) in Laurel, MD, will become the first interplanetary
spacecraft that can possibly be seen with the naked eye when it
swings by Earth Jan. 22-23. The spacecraft's solar panels will
reflect the Sun's rays onto the Earth in a greeting as it flies by
for an adjustment of its trajectory to correctly align the
spacecraft for a rendezvous with asteroid 433 Eros, its mission
target.
Launched Feb. 17, 1996, NEAR completed a flyby of the
asteroid Mathilde in June 1997 and is now on its way back to
Earth. Late Thursday, Jan. 22, the spacecraft will approach Earth
over the Pacific Ocean traveling at about 20,000 mph. Because the
United States will be in darkness as NEAR approaches, if there is
no cloud cover, several geographic areas will be able to see the
Sun reflecting off the spacecraft's solar panels, which will act
as large mirrors. These sunglints will be visible on the East
Coast, Friday, Jan. 23, at about 1:30 a.m. EST and the West Coast
at about 1:45 a.m. EST (Thursday, 10:45 p.m. PST).
The spacecraft then swings around the Aleutian Islands and
over Siberia before reaching its closest point to Earth, about 336
miles above Ahvaz in southwest Iran, Friday, Jan. 23, at 11:23
a.m. local time (2:23 a.m. EST), traveling at about 29,000 mph,
its fastest speed for the swingby. Although NEAR will be close to
Earth at this time, daylight may obscure its image.
The spacecraft then swings over Africa and on to
Antarctica before pulling away from the Earth at a speed of about
15,000 mph. The swingby will have changed NEAR's trajectory to
approximately 11 degrees south of the Earth's ecliptic plane, the
orbital path the Earth takes as it circles the Sun, and put the
spacecraft on target for its Jan. 10, 1999, rendezvous with Eros.
NEAR scientists and engineers are using the swingby as an
opportunity to test performance and calibration of the
spacecraft's six instruments and to practice coordinated multi-
instrument observations of the type that will be used at Eros.
The Multispectral Imager, a visible light camera that will
help determine the physical characteristics of Eros, and the NEAR-
Infrared Spectrograph, used to study surface minerals, will be
calibrated by comparing their readings of geological features with
proven measurements of the same areas. These instruments will
also be used to take images of the Earth along the spacecraft's
path. NEAR's Magnetometer will be calibrated by comparing swingby
data with known measurements of the Earth's magnetic field.
Other activities during the swingby will include using the
X-Ray/Gamma-Ray Spectrometer to observe celestial gamma ray bursts
and to collect data on gamma ray and X-ray backgrounds. These
data are needed so scientists can better remove background
impurities from the measurements to be made at Eros.
NEAR is expected to capture its first images of Eros, a 25-
mile-long near-Earth asteroid, a few months prior to the 100th
anniversary of the asteroid's discovery on
Aug. 13, 1898. After reaching Eros, the spacecraft will start its
orbit about 600 miles above the asteroid's surface, descending to
200 miles by February and coming as close as 10 miles during its
yearlong study. Scientists will thoroughly map Eros and will
examine its surface composition and physical properties. On Feb.
6, 2000, the mission is expected to end with a controlled descent
onto the asteroid, sending dozens of high-resolution pictures as
the spacecraft closes in on Eros.
The NEAR mission will be the first close-up study of an
asteroid. APL, the first non-NASA center to conduct a NASA
planetary mission, is managing the mission for NASA's Office of
Space Science, Washington, DC.
Information on the NEAR mission, including a list of areas
most likely to see NEARХs sunglint and how to find NEAR as it
swings by Earth, is available on the Internet at: http://sd-
www.jhuapl.edu/NEAR/
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