Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: Mars Pathfinder Manager Brian Muirhead Named Engineer Of The Year
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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
Contact: Diane Ainsworth, JPL
Robert Tindol, Caltech, 626-395-3631
David Salyers, 312-346-3131
FOR IMMEDIATE RELEASE March 3, 1998
PATHFINDER MANAGER BRIAN MUIRHEAD NAMED ENGINEER OF YEAR
Brian Muirhead, manager of NASA's innovative and highly
successful Mars Pathfinder mission, has been named 1998 Engineer
of the Year by the readership of Design News, which represents a
national audience of engineers and aeronautics specialists.
Muirhead was cited by readers of the magazine for his
leadership of a high-risk, low-budget mission, developed on a
fast track, which demonstrated a novel approach to landing a
spacecraft on the surface of Mars. The Pathfinder mission,
developed and managed by NASA's Jet Propulsion Laboratory,
Pasadena, CA, landed on Mars on July 4, 1997, and returned a
phenomenal amount of data and images of the surface, atmosphere
and weather on Mars.
Muirhead, 46, will receive a $25,000 educational grant, to
be designated to his alma mater, the California Institute of
Technology, Pasadena, CA, from the magazine's Engineering
Education Foundation. He will also share an additional $10,000
educational grant with other winners of the magazine's Special
Achievement and Quality awards. Both grants have been earmarked
for economically disadvantaged engineering students attending
Caltech, where Muirhead earned his master's degree in
aeronautical engineering in 1982. He also holds a bachelor's
degree in mechanical engineering from the University of New
Mexico.
In its March 2 issue, Design News reports that the Mars
Pathfinder mission was an engineering demonstration and a radical
departure from the billion-dollar-class spaceflight projects of
the recent past. Operating on a skeleton budget of $170 million -
- a small fraction of the cost of the Viking missions of the mid-
1970s -- Pathfinder dove directly into the Martian atmosphere and
landed with the aid of a parachute, airbags and retro-rockets.
The spacecraft also delivered the first microrover ever to
photograph the surface of another planet and the first vehicle to
measure the chemical composition of Martian rocks.
In addition to its unique entry, descent and landing, the
Mars Pathfinder mission introduced more than 25 new technologies
and broke new ground in the application of commercially derived
hardware that could be used in the extremely harsh environment of
space, the magazine says. For example, Pathfinder relied on a
single radiation-hardened flight computer derived from an IBM
RS6000-series workstation.
Pathfinder also became a model of teamwork and an
inspiration for future missions by providing proof that NASA's
goal of faster, better and cheaper missions was a reality, the
magazine reports. New space missions of the 21st century --
destined for Mars, the outer solar system and asteroids and
comets -- will build on the legacy of Mars Pathfinder. Muirhead
himself will be moving into a managerial role on one of these new
missions, the fourth deep space technology validation mission to
be flown under NASA's New Millennium program, known as Deep Space
4/Champollion. This mission will attempt the first-ever
rendezvous and landing on the surface of a comet. Once on the
surface, the 100-kilogram (220-pound) lander will analyze the
surface composition and gather a sample for return to Earth.
Mars Pathfinder was exemplary as the first of these new-
generation, fast-track missions -- able to meet its development
schedule and cost constraints through the skill and dedication of
a tightly knit team, the magazine notes. Muirhead's leadership as
flight system manager was critical to the development of the
Pathfinder spacecraft and the spectacular success of this very
challenging mission.
Muirhead will be honored at an awards ceremony to be held
March 17 at the Ritz Carlton Hotel, Chicago. Contact David
Salyers of Salyers Carman & Associates, 312-346-3131, for
additional information about the banquet. For information about
Muirhead's grant to Caltech, contact Robert Tindol at the Caltech
Media Relations Office, 626-395-3631, or Diane Ainsworth at the
JPL Media Relations Office, 818-354-5011.
#####
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=SANA=
Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: Nakhla Mars Meteorite Available For Scientific Study
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Antarctic Meteorite Newsletter
February 1998
Nakhla To Be Distributed
By Dr. Monica Grady
Natural History Museum, London
Nakhla is a 1300 million year old Martian meteorite, the first one
in which carbonates were identified. Nakhla fell as a shower of
stones in 1911; several of the stones are in the collection of the
Natural History Museum in London.
One completely fusion-crusted stone has been kept unbroken since its
acquisition in 1913.
The Natural History Museum is now prepared to offer samples of this stone
to scientists for appropriate analyses. The Antarctic Meteorite Processing
Group had kindly agreed to allow the stone to be broken and sub-divided
at the Curatorial Facility at the Johnson Space Center in Houston, prior
to the LPSC in March.
There is no formal deadline for sample requests, but the material available
is limited. Coordinated approaches from groups of scientists undertaking
complementary studies are encouraged. Those requests submitted to the
Museum by April 3 will be processed in April. Those arriving later will
be delayed for several months.
For further details and to submit requests, contact:
Dr. Monica M. Grady
Dept. of Mineralogy
The Natural History Museum
Cromwell Road
London SW7 5BD
E-Mail: mmg@nhm.ac.uk
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=SANA=
Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: New Lunar Meteorite Discovered (EET96008)
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A new lunar meteorite has been discovered in the Antarctic. The meteorite
is labeled EET96008. It was discovered in the Elephant Moraine region
in the Antarctic, and was the 8th meteorite analyzed from the 1995-96
collecting season. Below is the technical decription of the meteorite
from the February 1998 issue of the Antarctic Meteorite Newsletter.
Ron Baalke
Sample no: EET96008
Location: Elephant Moraine
Dimensions (cm): 4.5 x 3.5 x 1.5
Weight (g): 52.97
Meteorite Type: Lunar Basaltic Breccia
Macroscopic Description: Kathleen McBride
50% of the meteorite is covered by a black glassy fusion crust. Areas
that lack fusion crust appear virtually unweathered. The fusion crust
is very thinly distributed over the surface of the rock. The matrix
is fine grained, medium gray and tan are are angular and subangular
in shape. Metal and rust are not visible. This is a breciated basalt,
possibly lunar in origin.
Thin section (,4) Description: Brian Mason
The section shows a microbreccia of pyroxene and plagioclase clasts, up
to 1.2 mm across; traces of nickel-iron and sulfide are present, as small
scattered grains. Microprobes analyses show that most of the pyroxene
ranges from Wo11Fs31 to Wo40Fs18, with a few more iron-rich grains;
plagioclase composition in An93-96. A few olivine grains of variable
compositions, Fa41-64, were analyzed. Fe/Mn in pyroxene is about 70.
The meteorite is a lunar basaltic breccia.
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=SANA=
Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: New Satellite Animation Shows El Nino Moisture In Atmosphere
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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
Contact: Mary Hardin (818) 354-0344
VIDEO & INTERNET ADVISORY March 3, 1998
NEW SATELLITE ANIMATION SHOWS EL NINO MOISTURE IN ATMOSPHERE
New satellite animation shows the movement of atmospheric water vapor
over the Pacific Ocean during the 1997-98 El Nino condition. Higher than
normal ocean water temperatures increase the rate of evaporation, and the
resulting warm moist air rises into the atmosphere, altering global weather
patterns. The February 1998 segment also shows high levels of atmospheric
moisture above Southern California.
The animation was created from data obtained by the Microwave Limb
Sounder (MLS) instrument onboard NASA's Upper Atmosphere Research Satellite
(UARS) from September 1997 to February 1998.
A NASA TV video file will feature the new animation at 9 a.m., noon,
3 p.m., 6 p.m. and 9 p.m. Pacific time today. NASA Television is available
on GE-2, transponder 9C at 85 degrees west longitude, with vertical
polarization. Frequency is on 3880.0 megahertz, with audio on 6.8 megahertz.
In addition, the most recent still images of the El Nino water vapor
are now available online at:
http://www.jpl.nasa.gov/elnino
The MLS instrument is managed by NASA's Jet Propulsion Laboratory,
Pasadena, CA, a division of the California Institute of Technology, also in
Pasadena.
#####
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=SANA=
Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: Galileo Experts Invite Public To Join Internet Chat
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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
Contact: Jane Platt
INTERNET ADVISORY March 4, 1998
GALILEO EXPERTS INVITE PUBLIC TO JOIN INTERNET CHAT
Scientists and engineers from NASA's Galileo Europa Mission will share
their knowledge and latest findings from the spacecraft with the general
public during a live Internet chat this Friday, March 6 from 1 p.m. to 4
p.m. Pacific Standard Time.
Cyberspace participants will have the opportunity to ask questions about
any aspect of the Galileo mission, which has spent two years orbiting
Jupiter and its moons. Web chat organizers anticipate a flurry of
questions about the icy moon, Europa, which may have a liquid ocean, and
therefore a greater potential for life than many other celestial bodies.
Anyone who would like to join in the web chat is invited to go to the
following URL:
http://www.jpl.nasa.gov/galileo/chat
Earlier this week, new Europa pictures were unveiled, showing new evidence
of slush on the moon's surface, intriguing views of ice cliffs as high as
the face of Mt. Rushmore, and images of icy surface plates which have
broken apart and moved around. The pictures were the closest ever taken of
Europa, obtained by Galileo during its December 16, 1997 flyby.
The Galileo spacecraft has completed its primary mission and is now in a
two-year extended journey, called the Galileo Europa Mission. The mission
includes seven more Europa flybys, as well as encounters with two of
Jupiter's other moons, Callisto and Io.
JPL manages the Galileo mission for NASA's Office of Space Science,
Washington, D.C. JPL is a division of California Institute of Technology,
Pasadena, CA.
General information and the latest Europa images can be found at the URL
http://www.jpl.nasa.gov/galileo
#####
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=SANA=
Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: Eileen Collins Named First Female Shuttle Commander
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Jennifer McCarter
Headquarters, Washington, DC March 5, 1998
(Phone: 202/358-1639)
Eileen Hawley/James Hartsfield
Johnson Space Center, Houston, TX
(Phone: 281/483-5111)
RELEASE: 98-37
COLLINS NAMED FIRST FEMALE SHUTTLE COMMANDER
Astronaut Eileen Collins (Lt. Col., USAF) will become the first woman to
command a Space Shuttle when Columbia launches on the STS-93 mission in
December 1998. First Lady Hillary Rodham Clinton made the announcement
today in the Roosevelt Room at the White House.
Collins will be joined on the flight deck by Pilot Jeffrey S. Ashby (Cmdr.,
USN) and Mission Specialists Steven A. Hawley, Ph.D., and Catherine G.
"Cady" Coleman, Ph.D (Major, USAF). CNES Astronaut Michel Tognini (Col.,
French Air Force) was named to the crew on November 12.
Selected as an astronaut in 1990, Collins has served as a pilot on her
two previous space flights. Her first space flight was STS-63 in February
1995 as Discovery approached to within 30 feet of Mir, in a dress rehearsal
for the first Shuttle/Mir docking. In May 1997, she visited the Mir space
station as pilot on board Atlantis for the sixth Shuttle/Mir docking mission,
delivering Astronaut Mike Foale and returning Jerry Linenger to Earth.
STS-93 will be the first flight for Ashby. Hawley will be making his fifth
space flight during STS-93, having flown previously on STS-41D in 1984,
STS-61C in 1986, STS-31 in 1990 and STS-82 in 1997. Coleman has one
previous space flight to her credit, having flown on STS-73, the second
United States Microgravity Laboratory mission in October/November 1995.
Tognini, who spent 14 days on the Mir space station in 1992, will be making
his first Shuttle flight on STS-93.
During the five-day mission, the crew will deploy the Advanced
X-ray Astrophysics Facility Imaging System (AXAF), which will conduct
comprehensive studies of the universe. AXAF will be the most advanced
X-ray telescope ever flown. When scientists begin using AXAF next year,
they will finally be able to unlock the secrets of some of the most distant,
powerful and violent objects known to exist in the universe. They will study
such exotic phenomena as exploding stars called supernovae, strange powerful
objects called quasars, and mysterious black holes which are so massive that
everything near them is pulled inside causing an explosion of X-rays that
AXAF can study.
For additional information on the STS-93 crew, or any astronaut,
see the NASA Internet biography home page at URL:
http://www.jsc.nasa.gov/Bios/.
-end-
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=SANA=
Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: Lunar Prospector Finds Evidence Of Ice At Moon's Poles
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Douglas Isbell
Headquarters, Washington, DC March 5, 1998
(Phone: 202/358-1753)
David Morse
Ames Research Center, Moffett Field, CA
(Phone: 650/604-4724)
John Gustafson
Los Alamos National Laboratory, Los Alamos, NM
Department of Energy
(Phone: 505/665-9197)
John Watson
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-6478)
RELEASE: 98-38
LUNAR PROSPECTOR FINDS EVIDENCE OF ICE AT MOON'S POLES
There is a high probability that water ice exists at both the
north and south poles of the Moon, according to initial scientific
data returned by NASA's Lunar Prospector.
The Discovery Program mission also has produced the first
operational gravity map of the entire lunar surface, which should
serve as a fundamental reference for all future lunar exploration
missions, project scientists announced today at NASA's Ames
Research Center, Moffett Field, CA.
Just two months after the launch of the cylindrical
spacecraft, mission scientists have solid evidence of the
existence of lunar water ice, including estimates of its volume,
location and distribution. "We are elated at the performance of
the spacecraft and its scientific payload, as well as the
resulting quality and magnitude of information about the Moon that
we already have been able to extract," said Dr. Alan Binder, Lunar
Prospector Principal Investigator from the Lunar Research
Institute, Gilroy, CA.
The presence of water ice at both lunar poles is strongly
indicated by data from the spacecraft's neutron spectrometer
instrument, according to mission scientists. Graphs of data ratios
from the neutron spectrometer "reveal distinctive 3.4 percent and
2.2 percent dips in the relevant curves over the northern and
southern polar regions, respectively," Binder said. "This is the
kind of data 'signature' one would expect to find if water ice is
present."
However, the Moon's water ice is not concentrated in polar
ice sheets, mission scientists cautioned. "While the evidence of
water ice is quite strong, the water 'signal' itself is relatively
weak," said Dr. William Feldman, co-investigator and spectrometer
specialist at the Department of Energy's Los Alamos National
Laboratory, NM. "Our data are consistent with the presence of
water ice in very low concentrations across a significant number
of craters." Using models based on other Lunar Prospector data,
Binder and Feldman predict that water ice is confined to the polar
regions and exists at only a 0.3 percent to 1 percent mixing ratio
in combination with the Moon's rocky soil, or regolith.
How much lunar water ice has been detected? Assuming a water
ice depth of about a foot and a half (.5 meters) -- the depth to
which the neutron spectrometer's signal can penetrate -- Binder
and Feldman estimate that the data are equivalent to an overall
range of 11 million to 330 million tons (10-300 million metric
tons) of lunar water ice, depending upon the assumptions of the
model used. This quantity is dispersed over 3,600 to 18,000
square miles (10,000-50,000 square kilometers) of water ice-
bearing deposits across the northern pole, and an additional 1,800
to 7,200 square miles (5,000-20,000 square kilometers) across the
southern polar region. Furthermore, twice as much of the water
ice mixture was detected by Lunar Prospector at the Moon's north
pole as at the south.
Dr. Jim Arnold of the University of California at San Diego
previously has estimated that the most water ice that could
conceivably be present on the Moon as a result of meteoritic and
cometary impacts and other processes is 11 billion to 110 billion
tons. The amount of lunar regolith that could have been "gardened"
by all impacts in the past 2 billion years extends to a depth of
about 6.5 feet (2 meters), he found. On that basis, Lunar
Prospector's estimate of water ice would have to be increased by a
factor of up to four, to the range of 44 million to 1.3 billion
tons (40 million to 1.2 billion metric tons). In actuality,
Binder and Feldman caution that, due to the inadequacy of existing
lunar models, their current estimates "could be off by a factor of
ten in either direction."
The earlier joint Defense Department-NASA Clementine mission
to the Moon used a radar-based technique that detected ice
deposits in permanently shadowed regions of the lunar south pole.
It is not possible to directly compare the results from Lunar
Prospector to Clementine because of their fundamentally different
sensors, measurement "footprints," and analysis techniques. However,
members of the Clementine science team concluded that its radar
signal detected from 110 million to 1.1 billion tons (100 million
to 1 billion metric tons) of water ice, over an upper area limit
of 5,500 square miles (15,500 square kilometers) of south pole terrain.
There are various ways to estimate the economic potential of
the detected lunar water ice as a supporting resource for future
human exploration of the Moon. One way is to estimate the cost of
transporting that same volume of water ice from Earth to orbit.
Currently, it costs about $10,000 to put one pound of material
into orbit. NASA is conducting technology research with the goal
of reducing that figure by a factor of 10, to only $1,000 per
pound. Using an estimate of 33 million tons from the lower range
detected by Lunar Prospector, it would cost $60 trillion to
transport this volume of water to space at that rate, with unknown
additional cost of transport to the Moon's surface.
From another perspective, a typical person consumes an
estimated 100 gallons of water per day for drinking, food
preparation, bathing and washing. At that rate, the same estimate
of 33 million tons of water (7.2 billion gallons) could support a
community of 1,000 two-person households for well over a century
on the lunar surface, without recycling.
"This finding by Lunar Prospector is primarily of scientific
interest at this time, with implications for the rate and
importance of cometary impacts in the history and evolution of the
Solar System," said Dr. Wesley Huntress, NASA Associate
Administrator for Space Science. "A cost-effective method to mine
the water crystals from within this large volume of soil would
have to be developed if it were to become a real resource for
drinking water or as the basic components of rocket fuel to
support any future human explorers."
Before the Lunar Prospector mission, historical tracking data
from various NASA Lunar Orbiter and Apollo missions had provided
evidence that the lunar gravity field is not uniform. Mass
concentrations caused by lava which filled the Moon's huge craters
are known to be the cause of the anomalies. However, precise maps
of lunar mass concentrations covering the moon's equatorial
nearside region were the only ones available.
Lunar Prospector has dramatically improved this situation,
according to co-investigator Dr. Alex Konopliv of NASA's Jet
Propulsion Laboratory, Pasadena, CA. Telemetry data from Lunar
Prospector has been analyzed to produce a full gravity map of both
the near and far side of the moon. Konopliv also has identified
two new mass concentrations on the Moon's nearside that will be
used to enhance geophysical modeling of the lunar interior. This
work has produced the first-ever complete engineering-quality
gravity map of the moon, a key to the operational safety and
fuel-efficiency of future lunar missions.
"This spacecraft has performed beyond all reasonable
expectations," said NASA's Lunar Prospector mission manager Scott
Hubbard of Ames. "The findings announced today are just the tip
of the iceberg compared to the wealth of information forthcoming
in the months and years ahead."
Lunar Prospector is scheduled to continue its current primary
data gathering mission at an altitude of 62 miles (100 kilometers)
for a period of ten more months. At that time, the spacecraft
will be put into an orbit as low as six miles (10 kilometers) so
that its suite of science instruments can collect data at much
finer resolution in support of more detailed scientific studies.
In addition, surface composition and structure information
developed from data returned by the spacecraft's Gamma Ray
Spectrometer instrument will be a crucial aspect of additional
analysis of the polar water ice finding over the coming months.
The third launch in NASA's Discovery Program of lower cost,
highly focused planetary science missions, Lunar Prospector is
being implemented for NASA by Lockheed Martin, Sunnyvale, CA, with
mission management by NASA Ames. The total cost to NASA of the
mission is $63 million.
Additional informaiton about the Lunar Prospector mission can
be found on the Internet at URL:
http://lunar.arc.nasa.gov
-end-
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=SANA=
Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: Don Yeomans To Lead US Science Team On Asteroid Lander Mission
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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
Contact: Mary Beth Murrill
FOR IMMEDIATE RELEASE March 5, 1998
YEOMANS TO LEAD U.S. SCIENCE TEAM ON ASTEROID LANDER MISSION
Astronomer Dr. Donald K. Yeomans has been named project scientist for
the NASA portion of a joint U.S.-Japanese mission that will be the first
ever to send a lander and robotic rover to an asteroid, and return an
asteroid sample back to Earth.
Yeomans is a senior research scientist at JPL and supervisor of the
Laboratory's Solar System Dynamics Group, which is responsible for tracking
all the planets, natural satellites, comets and asteroids in the solar
system. He specializes in identifying the orbital paths of comets, asteroids
and other bodies. Yeomans will lead the work of the U.S. science team in
utilizing the scientific instruments on the tiny book-size rover being built
at JPL for the asteroid lander mission, which is called MUSES-C. The U.S.
and Japanese science teams will collaborate on the analysis of scientific
data returned by the spacecraft, including work on the asteroid sample that
will be brought back to Earth.
Scheduled for launch from Kagoshima, Japan on a Japanese M5 rocket in
January 2002, MUSES-C will be the world's first asteroid sample return
mission and will be the first space flight demonstration of several new
technologies. "MUSES-C" stands for Mu Space Engineering Spacecraft (the "C"
signifies that it is the third in a series). It is part of a series of
flight technology and science missions managed by the Institute of Space and
Astronautical Science of Japan (ISAS). NASA's Jet Propulsion Laboratory
(JPL) in Pasadena, CA, is managing the U.S. portion of the mission. Ross M.
Jones is the project manager at JPL.
Asteroid 4660 Nereus, a small, near-Earth asteroid nearly one mile in
diameter, is the target of the MUSES-C mission that will set a lander down
on the asteroid's surface, let loose a miniature rover to gather photos of
the terrain, and collect and return to Earth three samples from the
asteroid's surface. The lander and sample return vehicles are provided by
Japan and the rover is being provided by JPL. All three vehicles will be
combined as one package for flight to the asteroid.
Asteroids are thought to be remnants of the material from which the
inner solar system was formed 4.6 billion years ago. They are representative
of the fundamental building blocks that coalesced into the terrestrial
planets -- Mercury, Venus, Earth and Mars. Scientists want to study
asteroids because of the clues these small bodies may hold to the origin and
evolution of the solar system. Eventually, metal-rich asteroids could also
serve as resources for space mining and human exploration.
Yeomans is well-known for his precise orbit determinations of solar
system objects. He provided the accurate position predictions that led to
the first telescope sighting of comet Halley on its return visit to the
inner solar system in 1982. He provided the predictions that led to the
successful flybys of five international spacecraft past comet Halley in
March 1986. Yeomans also provided the position predictions for asteroids 951
Gaspra and 243 Ida that helped the Galileo spacecraft to make the first
close-up images of an asteroid. More recently, he worked with Dr. Paul
Chodas, also of JPL, to provide the accurate predictions for the impacts of
comet Shoemaker-Levy 9 with Jupiter in July 1994. Yeomans is currently a
science investigator on a NASA mission to fly past three different comets.
He is also the radio science team chief for NASA's Near-Earth Asteroid
Rendezvous (NEAR) mission, a spacecraft headed for an encounter with the
asteroid Eros.
Yeomans has been given seven NASA awards including an Exceptional
Service Medal in 1986. In addition, he was presented with a Space
Achievement Award by the American Institute of Aeronautics and Astronautics,
an award of appreciation by the Goddard Space Flight Center, Greenbelt, MD.
Asteroid 2956 was re-named 2956 in Yeomans' honor. He has authored four
books and more than 80 technical papers on comets and asteroids.
A native of Rochester, NY, Yeomans received his bachelor's degree in
mathematics in 1964 from Middlebury College in Middlebury, VT, and a
master's degree in 1967 and doctorate in astronomy in 1970 from the
University of Maryland. Yeomans and his wife, Laurie, have two adult
children and reside in La Canada-Flintridge, CA
JPL is a division of the California Institute of Technology.
#####
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=SANA=
Дата: 06 марта 1998 (1998-03-06)
От: Alexander Bondugin
Тема: Pioneer 10 Update - March 2, 1998
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STATUS UPDATED: 2 March 1998
Pioneer 10
(Launched 2 March 1972)
* Distance from Sun (2 March 1998): 69.49 AU
* Speed relative to the Sun: 12.24 km/sec (27,380 mph)
* Distance from Earth: 10.43 billion kilometers (6.479 billion miles)
* Round-trip Light Time: 19 hours 19 minutes
HAPPY BIRTHDAY, PIONEER 10 (SEE EXPANDED FAQ's BELOW)! The Energizer bunny
of NASA spacecraft marches on - 26 years today! At approximately 22:10 GMT
on 17 February 1998, Voyager 1 caught up with Pioneer 10 to become the most
distant human-created object in space at a heliocentric distance of 6.46
billion miles (10.39 billion kilometers). The two are headed in almost
opposite directions away from the Sun. The Pioneer mission formally ended on
31 March 1997 at 19:35 GMT. However, we still contact the Pioneer spacecraft
on a non-interference basis to other NASA projects for the purpose of
training Lunar Prospector controllers in Deep Space Network coordination of
tracking activities. As part of the training program, we have now
successfully performed two CONSCAN precession maneuvers - 2 February 1998
and 9 August 1997 - both again in the blind, as was first done on the
maneuver of 26 January 1997. The Iowa Geiger Tube telescope instrument is
operating nominally. The Chicago charged particle instrument is cycled on
for 4 hour periods once every two weeks (when a round-trip light time (RTLT)
opportunity is available). Three-way Doppler data for Radio Science are
obtained whenever a RTLT is available. Current operation dips into the
batteries, sometimes resulting in a low value of 0.94 volts during a track.
This indicates further degradation of the RTGs. Nevertheless, we anticipate
the transmitter to continue working until sometime in 1998. Limited 70 meter
DSN coverage will be available through June of 1998.
Pioneer 10 will continue into interstellar space, heading generally for the
red star Aldebaran, which forms the eye of Taurus (The Bull). Aldebaran is
about 68 light years away and it will take Pioneer over 2 million years to
reach it.
Pioneer 11
(Launched 5 April 1973)
The Mission of Pioneer 11 has ended. Its RTG power source is exhausted.
The last communication from Pioneer 11 was received in November 1995,
shortly before the Earth's motion carried it out of view of the spacecraft
antenna.
The spacecraft is headed toward the constellation of Aquila (The Eagle),
Northwest of the constellation of Sagittarius. Pioneer 11 may pass near one
of the stars in the constellation in about 4 million years.
Frequently-asked Questions (FAQ's):
Question:
How far will Pioneer travel and on what path?
Answer:
Pioneer 10 will be in galactic orbit for billions of years. It is moving in
a straight line away from the Sun at a constant velocity of about 12 km/sec.
Until Pioneer 10 reaches a distance of about 1.5 parsec (309,000 AUs) -
about 126,000 years from now - it will be dominated by the gravitational
field of the Sun. After that Pioneer 10 will be on an orbital path in the
Milky Way galaxy influenced by the field of the stars that it passes.
Question:
Why does the RTG power decrease?
Answer:
Power for the Pioneer 10 is generated by the Radioisotope Thermoelectric
Generators (RTG's). Heat from the decay of the plutonium 238 isotope is
converted by thermoelectric couples into electrical current. The electrical
output depends on the hot junction temperature, the thermal path to the
radiator fins, and the cold junction temperature. It is the degradation of
the thermoelectric junction that has the major effect in decreasing the
power output of the RTG. In the 26-year time scale operation of Pioneer 10,
the 92 year half-life of the isotope does not appreciably affect the RTG
operation. The nuclear decay heat will keep the hot junction temperature hot
for many years but unfortunately will not be able to be converted into
enough electricity to power the transmitter for much longer.
Question:
How much has Pioneer been eroded?
Answer:
All the wear, pitting, and erosion that Pioneer 10 has sustained are
probably over now. The asteroid belt and the severe conditions of Jupiter
have already been experienced. Now, Pioneer is in the vacuum of space where
the average spatial density of molecules is one trillionth the density of
the best vacuum we can draw on Earth. We expect Pioneer to last an
indeterminate period of time, probably outlasting its home planet, the
Earth. In 5 billion years, the Sun will become a red giant, expand, envelop
the orbit of the Earth, and consume it. Pioneer will still be out there in
interstellar space. Erosional processes in the interstellar environment are
largely unknown, but are very likely less efficient than erosion within the
solar system, where a characteristic erosion rate, due largely to
micrometeoritic pitting, is of the order of 1 Angstrom/yr. Thus a plate
etched to a depth ~ 0.01 cm should survive recognizable at least to as
distance ~ 10 parsecs, and most probably to >> 100 parsecs. Accordingly,
Pioneer 10 and any etched metal message aboard it are likely to survive for
much longer periods than any of the works of Man on Earth.
Question:
What about Pioneer 1 to 5?
Answer:
Pioneers 1 through 5 were launched from 1958 through 1960 and made the first
thrusts into space toward the Moon and into interplanetary orbit. Pioneer 1
was the first spacecraft launched by NASA and provided data on the extent of
the Earth's radiation belts. Pioneer 2 suffered a launch vehicle failure.
Pioneer 3 discovered a second radiation belt around Earth. Pioneer 4 was the
first American spacecraft to escape Earth's gravitational pull as it passed
within 58,983 km (36,650 miles) of the moon. The spacecraft did return data
on the Moon radiation environment, although the desire to be the first
man-made vehicle to fly past the moon was lost when the Soviet Union's Luna
1 passed by the Moon several weeks before Pioneer 4. Pioneer 5 was designed
to provide the first map of the interplanetary magnetic field. The vehicle
functioned for a record 106 days and communicated with Earth from a record
distance of 36.2 million km (22.5 million miles). The early Pioneers were
exploratory missions that led to intriguing new questions that required more
advanced types of spacecraft capable of exploring space to considerable
distances within and beyond Earth's orbit. This led to the Pioneer 6 through
9 series that made the first detailed comprehensive measurements of the
solar wind, solar magnetic field, and cosmic rays.
Question:
Why and how is Pioneer 10 being maneuvered?
Answer:
The Pioneer spacecraft is spin-stabilized, spinning at approximately 4.28
rpm (Revolutions Per Minute), with the spin axis running through the center
of the dish antenna. If a person were to sit in the spacecraft, looking
through a hole in center of the dish antenna with a telescope, he would see
the Sun traveling very slowly to the left. The Earth's path would describe a
very narrow ellipse (the orbit is seen nearly edge-on) around the Sun. In
July the Earth is near the right hand edge of the ellipse, and 6 months
later will be near the left hand edge of the ellipse. The angle to the
spacecraft between the left edge of the ellipse and the right edge is less
than 2 degrees. In order to communicate with the spacecraft, the Earth has
to be within 0.8 degrees of the boresight of the spacecraft antenna. Since
the Earth moves by almost 2 degrees, the spacecraft has to be re-aimed at
the Earth about twice a year. This is done by a "CONSCAN (conical scan)
precession maneuver" executed by the spacecraft.
The radio signal transmitted from an antenna on Earth is focused and
reflected by the spacecraft dish antenna toward a small feed horn located on
a tripod which is centered in front of the spacecraft dish antenna, and then
conducted to a receiver in the spacecraft. During a CONSCAN maneuver, the
feed horn is physically moved by 8 inches to one side. A ground command
turns on a heater in a bellows filled with liquid Freon. The Freon boils,
the bellows expands, and moves a mechanical piston and cam attached to the
feed horn mounting plate against a mechanical stop. A micro switch cycles
the heater power on and off to keep the feed in the offset position.
With the feed in the offset position, the radio signal from the tracking
station is seen by the spacecraft receiver as varying sinusoidally in
amplitude (amplitude modulated). This error signal contains amplitude and
phase information on the pointing angle between the spacecraft spin axis and
the Earth and the direction to the Earth during the spin cycle. The minimum
amplitude occurs during the spin cycle when the antenna points to the Earth,
whereas the maximum occurs when the antenna dish points away from the Earth.
The frequency of the modulation is equal to the spacecraft spin rate (4.28
rpm). The error signal is processed on board the spacecraft to calculate the
timing requirements for firing the jets at the appropriate instant in the
spin cycle to precess the spin axis towards the Earth.
The CONSCAN processor averages the modulation over two revolutions of the
spacecraft. On the third revolution, it orders two hydrazine thrusters
(mounted 180 degrees apart on the rim of the dish antenna) to fire a short
pulse of 0.0312 seconds duration. This moves the spacecraft spin axis a tiny
amount toward the minimum amplitude value, i.e., the Earth, reducing the
amplitude of the modulation by a small amount. This process is repeated each
three revolutions, each time reducing the pointing angle error and the
modulation amplitude. When the pointing angle is within 0.3 degrees of
boresight, the processor terminates the maneuver automatically. Typically,
about 20 to 28 pulses are fired. A ground command then executes to turn off
the power to the feed offset heater, the liquid Freon condenses to pull the
mechanism back to the normal centered position, and the maneuver is
completed.
Question:
If the spacecraft are leaving the Solar System, why does the distance from
Earth sometimes get shorter?
Answer:
It is a matter of a hyperbolic escape trajectory, geometry, and relative
velocity vectors. The distance from the Sun is always increasing. However,
since the Earth travels around the Sun faster than the spacecraft moves away
from the Sun, the spacecraft-earth distance decreases for a few months, and
then rapidly increases again.
Project Manager: Dr. Lawrence Lasher (e-mail:llasher@mail.arc.nasa.gov)
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