Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/jplpaper/921218.uni

Text File | 1993-08-11 | 20KB | 372 lines

Jet Propulsion Laboratory UNIVERSE
Pasadena, California - Vol. 22, No. 36 - December 18, 1992
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Galileo on course for Jupiter

     NASA's Galileo spacecraft flew by the Earth Dec. 8 at 7:09
a.m. PST at an altitude of 304 kilometers (189 miles) above the
South Atlantic Ocean, completing a three-year gravity-assist
program and setting a course to reach Jupiter in December 1995.
     "How sweet it is," said Galileo Project Manager William
O'Neil. "We are on the way to Jupiter."
     This, the third gravity-assist for Galileo, added about 3.7
kilometers per second (8,300 mph) to the spacecraft's speed in
its solar orbit and changed its direction slightly, so that its
elliptical orbit now will reach to the orbit of Jupiter, about
780 million kilometers (480 million miles) from the sun.
     Traveling at over 48,000 kilometers per hour (30,000 mph) on
its way to the Earth encounter, the spacecraft flew 110,000
kilometers (about 68,000 miles) north of the moon at 7:58 p.m.
PST Dec. 7. Departing from the Earth in a slightly southerly
direction, it crossed the moon's orbit at about 6:15 p.m. PST on
Dec. 8.
     JPL's Galileo flight team programmed the spacecraft to
measure the near-Earth environment and observe Earth and moon
during this flyby. Scientists will obtain a great many images and
spectral scans of the northern regions of the moon and of various
areas on Earth over a period lasting several days. This provides
scientific data from new perspectives in some cases, and helps
the scientists calibrate their instruments for the Jupiter
orbital mission planned for 1995-97.
     O'Neil said the project is very much looking forward to
"unprecedented" views of the Earth and moon, and that color
images, shot about every 15 minutes during a 14-hour period, will
be compiled into a video that is expected to be released Dec. 22.
"For 14 hours, we'll be able to construct effectively a movie of
the moon traversing the foreground of the Earth," he said.
     On the way to Jupiter, Galileo will fly within 960
kilometers (600 miles) of the asteroid Ida on Aug. 28, 1993.
     The Galileo orbiter will fly 10 different elliptical orbits
of Jupiter, with close passes by each of the major satellites and
extended observations of the planet and its magnetosphere.
Galileo's atmospheric probe, which will descend into Jupiter's
atmosphere on Dec. 7, 1995 to observe that environment for the
first time, is being checked out during the near-Earth flight.
###
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Earthquake fault motion observed in
videotape produced by JPL geologist

By Mary Hardin
     Using satellite images taken before and after the June 28
Landers earthquake, JPL geologist Dr. Robert Crippen has produced
a video which shows the motion of the Emerson and Homestead
Valley faults in the Mojave Desert.
     "This is the first time fault motion has been observed
through the use of images acquired from space," said Crippen,
from the Tectonics and Geophysics Group, Geology and Planetology
Section 326. "The observation from space of newly fractured
ground along fault zones is also believed to be a first," he
added.
     Crippen used images from the French Satellite Pour
l'Observation de la Terre (SPOT) acquired under a data exchange
agreement between NASA and the French space agency, Centre
National d'Etudes Spatiales (CNES).
     The technique used to create the fault motion video is
similar to how weather satellite images are used to show cloud
motion on television weather reports.
     Crippen took a "before" SPOT image of the Landers quake site
that was taken on July 27, 1991, nearly a year before the
magnitude-7.5 earthquake, and he then matched that up with an
"after" image that was taken on July 25, 1992, only 27 days after
the quake.
     In order to minimize distortions, he said, it was important
to use matching images that were taken from the same orbital
position and on nearly the same day of year, to achieve the same
seasonal effects and sun angle.
     After precisely lining up enlarged portions of the images on
a computer display, Crippen flickered between the two and
observed the differing ground motions across each of the faults.
He repeated this process with other parts of the images taken of
several different sites along the faults, and in some cases, he
observed newly formed cracks in the fault zones.
     Working with JPL colleague Dr. Ronald Blom, Crippen is also
using the images as digital maps that show where the ground was
before the earthquake and where it ended up after the quake. By
using a supercomputer, the scientists hope to measure ground
motions at a level of geographic detail that has never been
achieved before, Crippen said.
     "By observing the details of fault motions we hope to better
understand the mechanisms of fault breakage and ultimately,
contribute to the understanding of the threats that earthquakes
pose to society," Crippen explained.
     Crippen presented his finding last week at the fall meeting
of the American Geophysical Union in San Francisco. ###
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News briefs

     The Lab's recently completed United Way campaign exceeded
contribution goals, said Assistant Lab Director and campaign
chairman Kirk Dawson.
     The two-week campaign which ended Nov. 6 netted $600,118 in
pledges from JPL employees, edging the target figure of $600,000,
he said.
     Dawson recently recognized more than 300 volunteer
campaigners, telling them, "JPL is a place where goals are
established and achieved. (The United Way Steering Committee) set
a goal for you, and you met it."
     Campaigners whose sections made exceptional contributions or
showed marked improvement from previous years were presented with
complimentary one-year JPL parking passes as well as an
assortment of gifts donated to the JPL United Way Committee by
local businesses.

     JPL's 1992 Savings Bond Drive realized an all-time high in
dollars invested at more than $1.4 million -- some $230,000 above
the 1991 campaign.
     In addition, participation in the program increased from 34
percent to 35.4 percent, according to campaign chairman Dr. R.
Rhoads Stephenson, and per capita investment was up more than $33
from the prior year.
     Campaigner awards were presented to Division 890 (for
divisions with under 25 employees) for increasing its
participation by 31 percent; Division 180 (26-79 employees), up
16 percent; and Section 384 (80 or more employees), up 9 percent.
     The Savings Bond Drive took place last spring, but employees
may sign up for bonds throughout the year at the ERC.

     Children of the Shepherd, a nonprofit organization that aids
the homeless, is asking for donations of new or used blankets,
jackets, and socks and shoes of all sizes (especially those for
babies and children).
     Kathy Jones of the Quality Assurance Ground Systems Section
511, who is a member of the board of directors of the
organization, said Children of the Shepherd focuses on homeless
teenagers, but offers offers hot meals, hygiene items and
clothing to anyone who is in need.
     The group also provides counseling as well as shelter,
medical and job referrals. Contact Jones at ext. 4-6730. ###
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OSSI announces 1993
mission briefing series

     JPL's Office of Space Science and Instruments (OSSI) has
announced a 1993 schedule for a lecture series designed to inform
Lab personnel of NASA missions being studied by JPL, according to
Assistant Lab Director Dr. Charles Elachi.
     Elachi said the briefings will be held in von Karman
Auditorium, from 11 a.m. to 12:30 p.m., on the first working
Friday of each month next year (except for June). The first one
will be presented Jan. 8, when Pre-Project Manager Robert Staehle
will discuss the Pluto Fast Flyby mission.
     JPL Director Dr. Edward Stone said OSSI plays a major role
in fulfilling the Lab's mission to serve NASA.
     "The needs of our primary customers, NASA, are changing, and
we must be responsive," said  Stone. "In particular, the large
budgets available in the 1980s for space science missions will be
smaller in the 1990s, and we are being challenged to develop
lower-cost missions that are still scientifically meaningful."
     Added Elachi, "NASA Administrator Daniel Goldin has been
outspoken in his desire for NASA and JPL to take advantage of new
technology, developed primarily by the Defense Department, to
enable smaller, more efficient and less costly spacecraft."
     Elachi said that OSSI, which is responsible for developing
future NASA mission concepts, is looking at not only new
technology but is streamlining the missions as much as possible.
     John Beckman, manager of Planetary and Space Physics Pre-
Projects, said the lectures are geared for all JPL employees, and
that a question-and-answer session will follow each presentation.
###
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JPL/Caltech study offers
new leads on ozone layer

By Karre Marino
     A JPL/Caltech collaboration has offered new leads in
science's attempts to understand how chlorine-containing
chemicals destroy the earth's ozone, the layer that protects us
from the sun's ultraviolet rays.
     Dr. Tim Minton, a member of the technical staff in the Space
Materials Science and Engineering Section 355, and Mitchio
Okumura, a Caltech professor of chemistry, studied chlorine
nitrate, which serves as a temporary trap for chlorine in the
stratosphere. Their research essentially raises questions about
how chlorine is released into the atmosphere.
     Their findings, which were published in the Nov. 20 issue of
Science magazine, have little effect on the models that are used
to predict ozone depletion, but may offer insight on chlorine
peroxide, a molecule believed to account for about 70 percent of
ozone destruction over Antarctica. "Chlorine peroxide is thought
to be involved in a sequence of reactions that leads to ozone
depletion. The crucial step in this sequence is how these
molecules break down in the presence of light," said Minton.
     Although Stan Sander's group in the Atmospheric and
Oceanographic Sciences Section 322 is deeply involved in
laboratory studies of stratospheric chemistry, said Minton, he
and Okumura believed they could use JPL's Crossed Molecular Beams
Apparatus in Section 355 to complement the ongoing research at
JPL. Accordingly, they applied for and were awarded a Caltech
President's Fund grant.
     Minton and Okumura, along with Caltech graduate students
Christine Nelson and Teresa Moore, used the Crossed Molecular
Beams Apparatus to study what happens when a chlorine nitrate
molecule decomposes following exposure to ultraviolet light. A
laser was fired at a beam of chlorine nitrate molecules, and
about 50 percent of the time, an ozone-depleting free chlorine
molecule was created -- yet,  previous research had suggested
that the yield of chlorine atoms was almost 100 percent.
     These results caused Minton and Okumura to wonder how a
related molecule, namely chlorine peroxide, would react in the
presence of light. "If chlorine peroxide behaved like chlorine
nitrate, then the chlorine-peroxide reaction cycle would not be
efficient enough to account for as much of ozone depletion as has
been reported," said Minton. In fact, "a reduction in the number
of chlorine atoms released when chlorine peroxide breaks apart
would suggest that some other chemical process also plays a large
role," he said.
     It is generally assumed that certain sequences of chemical
reactions lead to destruction of ozone. In the set of reactions
involving chlorine peroxide, the key step, said Minton, is a
breakdown in the presence of light. "This breakdown can create
different products through different decomposition pathways. One
possible pathway leads to harmful chlorine atoms, while another
leads to chlorine oxide, which isn't so bad," he explained.
     Minton noted that most studies had supported a fairly simple
picture of the decomposition process involving only a single
pathway to the production of chlorine atoms. "But we've shown
that the decomposition of chlorine nitrate is very complex and
that this simple picture doesn't hold up," he said. "That's why
we need to take a closer look at the very important and related
species, chlorine peroxide."
     Ultimately, the question of the right mechanism is important
because "it is predicted that an ozone hole like that over the
South Pole could occur in the Northern Hemisphere," said Okumura.
     Minton and Okumura, who did research together at the
University of California at Berkeley, noted that if scientists
had a greater understanding of how the ozone is depleted, then
the ability to predict ozone loss, particularly over the Northern
Hemisphere, would be improved.
     Next on the scientists' agenda is a two-year program to
study chlorine peroxide. ###
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TOPEX data show role of
eddies in ocean circulation

By Mary Hardin
     Preliminary results from the TOPEX/Poseidon satellite's
radar altimeter have enabled scientists to create a global image
of the world's oceans that shows how swirls of ocean currents,
called eddies, change over distances of tens to hundreds of
kilometers during time periods that range from weeks to months.
     "Eddies play an important role in ocean circulation because
they transport an enormous amount of heat, salt, nutrients and
other chemicals in the ocean," said JPL Project Scientist Dr.
Lee-Lueng Fu. It is this process of ocean circulation that helps
to shape the global climate, he continued.
     "The data were collected during a 10 day period from Oct. 3
to 12, 1992 and were processed using preliminary algorithms that
have not yet been adjusted based on post-launch calibrations," Fu
said.
     The altimeter measures the height of the sea surface along
the satellite's ground track which covers the entire global ocean
every 10 days.  After subtracting a model of the mean sea surface
height from the satellite measurements, JPL's Oceanography Group
produced the image showing sea surface height due to changes in
ocean current.
     "This is a snapshot that doesn't coincide with the multi-
year average of past ocean observations," Fu said, "It shows that
the ocean changes constantly."
     Areas of sea surface height greater than 25 cm occur mainly
in regions of the following strong currents: The Gulf Stream off
the east coast of the United States, the Kuroshio current off the
east coast of Japan, the East Australian Current, the Agulhas
Current south of South Africa, the Somali Current off Somalia,
and the convergence of the Brazil Current and the Falkland
Current off the central east coast of South America. A chain of
secondary highs can be seen north of Antarctica.
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Lab awards university grant for fiber optical research

By Toni Lawson
     Eager to continue doing its share to help in the struggle to
diversify the scientific work force, JPL's Minority Science and
Engineering Initiatives Office (MSEIO) has awarded a $60,000
research grant to Clark Atlanta University (CAU) that has the
potential of adding valuable data to flight projects, such as
Cassini, and supporting other space-borne research.
     "This grant is as important to JPL as it is to this
historically black university because it gives the Lab a chance
to develop a good scientific research relationship with a school
whose capabilities are not fully utilized," said David Shaw, a
member of technical staff for the Electronic Parts Reliability
Section 514 and the MSEIO representative for his division, the
Office of Engineering and Review. "This research effort exposes
students to practical work experience that will hopefully
cultivate a desire for these minority students to stay in the
scientific field and maybe come to work for JPL," he added.
     MSEIO is responsible for JPL programs to increase the Lab's
involvement with predominantly minority educational institutions,
and works to increase the college and university pool of
available underrepresented minority engineers and scientists.
     CAU was chosen to conduct research for the Electronic Parts
Reliability Section's Failure Analysis Group, after the group's
supervisor, Edward Cuddihy, submitted an announcement of
opportunity for experimental measurements to be taken of the
physical and mechanical properties of a new polarization-
maintaining optical fiber.
     Specifically, CAU students are responsible for measuring the
stress-strain curve and long-term reliability of the
polarization-maintaining optical fiber for an advanced spacecraft
inertial unit, called the fiber optic rotation sensor (FORS).
This advanced unit has no moving parts, unlike standard
mechanical inertial units, which use a spun mass -- similar to a
child's spinning toy top -- that senses rotation rate and is used
to measure the position for a spacecraft. FORS may be used for
future missions like Cassini (scheduled for a 1997 launch to
Saturn) to control a spacecraft's attitude and stability.
     When FORS technology was maturing in the early '80s, the Lab
envisioned that it would be the common inertial sensor for the
original Mariner Mark II missions and other missions that
required navigation grade inertial sensors, said Christopher
Jones, manager of spacecraft development for the Cassini Project.
During budget reductions this year, the Mariner Mark II missions
were restructured as Cassini.
     Cassini "may carry FORS as a flight experiment to conduct
tests for future missions like ours," Jones said, although "as of
now, because of budget constraints, Cassini has decided to use
the traditional spun-mass gyros that have already been flight-
qualified by industry." But CAU's continued research on FORS has
greatly advanced the unit's development, he added.
     Also benefiting from CAU's research is JPL's fiber optic
experiment on the Long-Duration Exposure Facility (LDEF), a space
shuttle-launched experimental satellite that was returned by a
second shuttle crew in January 1990 after 5 1/2 years in low
earth orbit. All 10 cable samples on board were found functional
and exhibited no measurable change in performance, indicating
that conventional fiber optic cables can perform satisfactorily
in space.
     Ron Hartmayer, a member of the technical staff for the
Robotic Systems and Advanced Computer Technology Section 347 --
which is analyzing LDEF's fiber-optic experiment -- said, "most
conventional mechanical testing methods will destroy the fiber
optic cables and the project needs to preserve its limited
supply.
     "CAU's research is applicable to our testing of the fiber
optic cable from LDEF because the university is also researching
non-destructive methods to measure and test cable and fiber optic
strength," Hartmayer added.
     Cuddihy said CAU is the perfect candidate for this project
because it is a minority school that has an established High
Performance Polymers and Ceramics Research Center, which is
funded by NASA, and has a partnership with Georgia Institute of
Technology (a majority school) to use its research facility.
"With these qualifications, CAU is not only bound to produce data
that may be valuable to significant JPL/NASA projects, but will
also build relationships with majority institutions that will
enable CAU to expose its students to a broader base of scientific
knowledge in the future," Cuddihy said.
     He added that CAU is continuing its relationship with JPL by
planning follow-up work in support of FORS.
     "I am glad I used a minority school for this project because
I understand the need to develop minority talent and encourage
them to pursue science and engineering," Cuddihy said. "I plan to
use many more minority institutions in the future," he added. ###