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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

Mars Global Surveyor Mission Status
Thursday, September 17, 1998

An error in the software commands sent to Mars Global Surveyor to turn its solar arrays to the
proper Sun angle for the start of aerobraking caused significant discharge of the spacecraft's
batteries and, subsequently, sent it into a "contingency" mode. In this mode, all non-essential
onboard spacecraft operations are temporarily suspended as the spacecraft awaits new commands
from the ground.

Fault protection software detected the low battery charge and aborted the sequence before
Global Surveyor began its maneuver at 3:30 a.m. Pacific Daylight Time. This stopped initiation of the
aerobraking maneuver.

"We will be able to recharge the battery later today and resume aerobraking probably on
Wednesday," said Glenn E. Cunningham, manager of the Mars Multimission Operations team and
Mars Global Surveyor project manager.

The spacecraft remains stable, with communications being performed using Surveyor's low-gain
antennas. The flight team at Lockheed Martin Astronautics, Denver, will spend the next several days
evaluating onboard hardware changes that may have occurred as a result of the low battery charge
and subsequent contingency mode.

A new schedule for returning Global Surveyor to its proper aerobraking configuration will be
announced as soon as possible, but will not impact the aerobraking phase or the start of the science
mapping mission in April 1999.

Contact: Diane Ainsworth

FOR IMMEDIATE RELEASE

September 11, 1998

MARTIAN MOON PHOBOS HIP-DEEP IN POWDER

New temperature data and close-up images of the Martian moon Phobos gathered by NASA's
Mars Global Surveyor indicate the surface of this small body has been pounded into powder by
eons of meteoroid impacts, some of which started landslides that left dark trails marking the steep
slopes of giant craters.

New temperature measurements show the surface must be composed largely of finely ground
powder at least one meter (three feet) thick, according to scientists studying infrared data from the
thermal emission spectrometer instrument on the spacecraft. Measurements of the day and night
sides of Phobos show such extreme temperature variations that the sunlit side of the moon rivals a
pleasant winter day in Chicago, while only a few kilometers away, on the dark side of the moon, the
climate is more harsh than a night in Antarctica. High temperatures for Phobos were measured at -4
degrees Celsius (25 degrees Fahrenheit) and lows at -112 Celsius (-170 degrees Fahrenheit).

The extremely fast heat loss from day to night as Phobos turns in its seven-hour rotation can be
explained if hip-deep dust covers its surface, said Dr. Philip Christensen of Arizona State University,
Tempe, principal investigator for the experiment on the Mars Global Surveyor spacecraft.

"The infrared data tells us that Phobos, which does not have an atmosphere to hold heat in
during the night, probably has a surface composed of very small particles that lose their heat rapidly
once the Sun has set," Christensen said. "This has to be an incredibly fine powder formed from
impacts over millions of years, and it looks like the whole surface is made up of fine dust."

New images from the spacecraft's Mars orbiter camera show many never-before seen features
on Phobos, and are among the highest resolution ever obtained of the Martian satellites. A
10-kilometer-diameter (six-mile) crater called Stickney, which is almost half the size of Phobos itself,
shows light and dark streaks trailing down the slopes of the bowl, illustrating that even with a gravity
field only about 1/1000th that of the Earth's, debris still tumbles downhill. Large boulders appear to
be partly buried in the surface material.

Infrared measurements of Phobos were made on August 7, 19 and 31 from distances ranging
between 1,045-1,435 kilometers (648-890 miles), far enough away to capture global views of the
Martian moon in a single spectrum. The instrument has been able to obtain the first global-scale
infrared spectra of Earth and Mars in addition to the new Phobos data, bringing new insights about
the composition of these three very different worlds.

"Of the three, Earth has the most complex infrared spectra, primarily due to the presence of
carbon dioxide, ozone and water vapor in its atmosphere," Christensen said. "Mars, which is much
colder than Earth because of its distance from the Sun, is less complex and shows only significant
amounts of carbon dioxide. The spectrum of Phobos, however, has little structure because it has no
atmosphere and the energy it emits is coming entirely from its surface."

The new Phobos images and thermal spectrometer measurements are available on the Internet
at: http://mars.jpl.nasa.gov/mgs, http://www.jpl.nasa.gov, http://photojournal.jpl.nasa.gov/,
http://www.msss.com/ and at http://emma.la.asu.edu .

On Monday, September 14, Mars Global Surveyor begins its second phase of aerobraking,
using the friction from repeated passes through Mars' atmosphere to lower and circularize the
spacecraft's orbit. Over the next four-and-a-half months, the spacecraft's flight path will be lowered
from the current 11.6- hour elliptical orbit to a two-hour, nearly circular orbit over the Martian polar
caps. The magnetometer and thermal spectrometer will be turned on through December to gather
data each time the spacecraft passes closest to Mars' surface. In addition, the radio science team will
be conducting gravity field experiments by measuring small shifts in the spacecraft's velocity as it
passes behind the planet or is blocked from view by the Sun.

The spacecraft team at JPL and Lockheed Martin Astronautics, Denver, is continuing to study
possible options for deployment of the spacecraft's high-gain antenna once it has reached its
low-altitude mapping orbit next spring.

Mars Global Surveyor is part of a sustained program of Mars exploration, managed by the Jet
Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. Lockheed Martin
Astronautics, Denver, CO, which built and operates the spacecraft, is JPL's industrial partner in the
mission. JPL is a division of the California Institute of Technology, Pasadena, CA.

06:27 PM ET 07/06/98

Another attack on idea of life in Mars meteorite


            WASHINGTON (Reuters) - Scientists launched a fresh attack
Monday against the idea that a Martian meteorite contained
evidence of life.
            The researchers, who have been disputing the NASA claims all
along, say their latest tests indicate that what look like tiny
worm-like fossils are actually the remnants of high-temperature
processes.
            John Bradley of the Georgia Institute of Technology, along
with Hap McSween of the University of Tennessee in Knoxville and
Ralph Harvey of Case Western Reserve University in Cleveland,
Ohio, say they have examined and reexamined their evidence, but
still do not think the meteorite, known as ALH84001, shows
evidence of life.
            A team at NASA's Johnson Space Center (JSC) astounded the
world with the announcement that the meteorite, found in
Antarctica, contained evidence of tiny, fossilized bacteria.
            Bradley and colleagues immediately attacked their ideas,
saying that geological and not biological processes formed the
little holes and left other chemical traces attributed to
ancient bacteria.
            Don McKay and colleagues at NASA stood by their thesis,
saying that Bradley's team was looking in the wrong place.
            But writing in the July issue of the journal Meteoritics and
Planetary Science, Bradley and colleagues say they went back and
checked, using the techniques that McKay recommended.
            They used transmission electron microscopy, and decided the
examination showed a process known as epitaxy formed the tiny
structures. ``This process is an ordered growth of one mineral
on top of another,'' the Georgia Institute of Technology said in
a statement.
            They said the way crystals in the rock grew mean the
structures, which include magnetites and carbonates, must have
grown simultaneously at temperatures much greater than 120
degrees Celsius (250 degrees F).
            ``These three papers in combination basically invalidate
much of their evidence,'' Bradley said in the statement.
            ``Early skepticism has evolved into international consensus
among meteoriticists and planetary scientists, with the
exception of the JSC team, that this rock does not contain
Martian nanofossils. I do not know of a single other individual
who believes it at this point,'' he added.
            McKay's team has stood by its findings.
            ``Unless the JSC team concedes, the debate will never die,''
Bradley said. ``When this news first became public, the debate
was quickly deflected into one about whether life exists or once
existed on Mars. But there are really two debates here --
whether there is evidence of life in this meteorite and whether
life exists on Mars.''
            Bradley said he thinks it could be possible there is, or
was, life on Mars. He says this meteorite is not evidence of it.
            ``It may be down in the depths. We now know that life
thrives in very extreme conditions on Earth,'' he said.
         ^REUTERS@

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