Space Shuttle Columbia's Last Flight Formed Clouds Over Antarctica(Forwarded)

American Geophysical Union
University of Illinois at Urbana-Champaign
Joint Release

AGU Contact:
Harvey Leifert, +1 (202) 777-7507,

UIUC Contact:
James E. Kloeppel, +1 (217) 244-1073,

For Immediate Release: 6 July 2005

AGU Release No. 05-23

Space Shuttle Columbia's Last Flight Formed Clouds Over Antarctica

WASHINGTON -- A burst of high altitude cloud activity over Antarctica in
January 2003 was caused by the exhaust plume of the space shuttle Columbia
during its final flight, reports a team of scientists who studied
satellite and ground-based data from three different experiments. The data
call into question the role these clouds may play in monitoring global
climate change.

"Our analysis shows that the Columbia's exhaust plume approached the South
Pole three days after launch," said Michael H. Stevens, a scientist at the
Naval Research Laboratory and lead author of a paper published in
Geophysical Research Letters on 6 July. "The lower temperatures and high
concentrations of water vapor over Antarctica caused a significant
increase in polar mesospheric cloud activity."

Polar mesospheric clouds are the highest on Earth, forming at an altitude
of about 84 kilometers [52 miles]. They normally form when temperatures
fall below minus 125 degrees Celsius [minus 193 degrees Fahrenheit].

"Because the brightness, occurrence, and range of the clouds have been
increasing, some scientists have suggested that they are indicators of
global climate change," said Xinzhao Chu, a research scientist at the
University of Illinois at Urbana-Champaign and a co-author of the paper.
"That role needs to be reconsidered, however, because of the potential
influence of water vapor in shuttle plumes."

On 16 January 2003, Columbia lifted from Kennedy Space Center in Florida
on its final flight before the loss of the crew and orbiter 16 days later.
As with previous shuttle flights, Columbia released about 400 tonnes
[tons] of water, the primary product of its liquid hydrogen and liquid
oxygen fuel, while flying nearly horizontally at an altitude of 110
kilometers [68 miles]. The resulting plume was about three kilometers [two
miles] in diameter and about 1,000 kilometers [650 miles] long.

"The plume was detected and tracked by the Global Ultraviolet Imager
[GUVI] on NASA's Thermosphere, Ionosphere, Mesosphere, Energetics and
Dynamics satellite," Stevens said. "The GUVI images reveal rapid movement
of the shuttle plume toward the South Pole."

At the Rothera Research Station in Antarctica, Chu was measuring upper
altitude iron densities and polar mesospheric clouds, using a special
lidar system designed at the University of Illinois and operated in
collaboration with the British Antarctic Survey. Three days after the
launch, the lidar detected iron in the atmosphere at altitudes much higher
than usual.

"In addition to a persistent layer of iron near an altitude of 90
kilometers [56 miles], produced from ablating meteoroids entering Earth's
atmosphere, three anomalous iron features were found at altitudes between
[100 and 110 kilometers] 64 and 71 miles," Chu said. Too high to be caused
by meteoroids, these iron features originated in the shuttle plume, the
researchers report, and had been produced by the normal ablation [shedding
of particles] of main engine components during launch.

"Within the next two weeks we measured almost all of the polar mesospheric
clouds we were to see that season," Chu said. "Only four hours of cloud
observations were recorded before mid-January. From January 19 to 26,
however, 18 hours of cloud observations were recorded." The increase in
polar mesospheric clouds was also observed with the Solar Backscatter
Ultraviolet instrument on the NOAA-16 satellite.

Additional evidence that the shuttle plume was responsible for the burst
of cloud activity can be found in the mesopause temperature, inferred from
the iron observations near an altitude of 90 kilometers [56 miles], the
researchers report. At Rothera, the mesopause temperature was minus 120
degrees Celsius [minus 184 degrees Fahrenheit], which is too warm for
polar mesospheric clouds to form under typical water vapor concentrations.
By dumping so much water vapor into the mesosphere, the shuttle raised the
concentration enough to allow the clouds to form.

"Our data will force scientists to rethink the role of polar mesospheric
clouds in monitoring global climate change," Stevens said. "Any
interpretation of recent trends in cloud activity must consider the
potential influence of the space shuttle program."

Co-authors of the paper with Stevens and Chu are Robert R. Meier of George
Mason University, Matthew T. DeLand at Science Systems and Applications
Inc., and John M.C. Plane at the University of East Anglia.

The National Science Foundation, NASA, and the Office of Naval Research
supported this work.

Notes for Journalists:
Journalists (only) may obtain a pdf copy of this paper upon request to
Jonathan Lifland: . Please provide your name, name of
publication, phone, and email address. The paper and this press release
are not under embargo.

Title:
Antarctic mesospheric clouds formed from space shuttle exhaust

Authors:
Michael H. Stevens, E.O. Hulbert Center for space Research, Naval Research
Laboratory, Washington, D.C., USA;
Robert R. Meier, School of Computational Sciences, George Mason
University, Fairfax, Virginia, USA;
Xinzhao Chu, Department of Electrical and Computer Engineering, University
of Illinois at Urbana-Champaign, Urbana, Illinois, USA;
Matthew T. DeLand, Science Systems and Applications Inc., Lanham,
Maryland, USA;
John M. C. Plane, School of Environmental Sciences, University of East
Anglia, Norwich, United Kingdom.

Citation:
Stevens, M. H., R. R. Meier, X. Chu, M. T. DeLand, and M. C. Plane (2005),
Antarctic mesospheric clouds formed from space shuttle exhaust, Geophys.
Res. Lett., 32, L13810, doi:10.1029/2005GL023054.

Contact information for authors:
Michael Stevens:
+1 (202) 767-2773 [3-8 July: +1 (410) 570-4919] or


Robert Meier:
+1 (202)767-2773 or

Xinzhao Chu:
+1 217-333-3172;

John Plane:
+44-1603-593108 or

*****

Naval Research Laboratory
Washington, DC

NRL Press Release: 7/6/2005

36-05r

NRL Study Finds Shuttle Exhaust is Source of Mysterious Clouds in
Antarctica

A new study, funded in part by the Naval Research Laboratory and the
National Aeronautics and Space Administration (NASA) reports that exhaust
from the space shuttle can create high-altitude clouds over Antarctica
mere days following launch, providing valuable insight to global transport
processes in the lower thermosphere. The same study also finds that the
shuttle's main engine exhaust plume carries small quantities of iron that
can be observed from the ground, half a world away.

The international team of authors of the study, to appear in the July 6
issue of Geophysical Research Letters, used the STS-107 Shuttle mission as
a case study to show that exhaust released in the lower thermosphere, near
110 kilometers altitude, can form Antarctic polar mesospheric clouds
(PMCs). The thermosphere is the highest layer in our atmosphere, with the
mesosphere (between 50-90 kilometers above the Earth), stratosphere, and
troposphere below.

New observations presented by the research team from the Global
Ultraviolet Imager (GUVI) on NASA's Thermosphere, Ionosphere, Mesosphere,
Energetics and Dynamics (TIMED) satellite reveal transport of the STS-107
exhaust into the southern hemisphere just two days after the January 2003
launch. Water from the exhaust ultimately led to a significant burst of
PMCs during the 2002-2003 southern polar summer, observed by the Solar
Backscatter Ultraviolet (SBUV) satellite experiment. The inter-hemispheric
transport followed by Antarctic PMC formation were unexpected.

PMCs, also known as noctilucent clouds, appear near 83 kilometers altitude
and are made up of water ice particles created through microphysical
processes of nucleation, condensation, and sedimentation. They typically
appear in the frigid polar summer mesosphere where temperatures plummet
below 130 deg Kelvin (-220 deg F). Little is known about the specific
processes that lead to PMC formation.

According to the study's lead author, Dr. Michael Stevens, a research
physicist at the E.O. Hulburt Center for Space Research at the Naval
Research Laboratory, the research produced multiple groundbreaking science
results.

"This research is exciting in that it extends a new explanation for the
formation of these clouds by demonstrating the global effect of a Shuttle
exhaust plume in a region of the atmosphere that has traditionally not
been well understood," said Stevens.

Some believe that the impact of anthropogenic change in the lower
atmosphere is reflected in these upper atmospheric clouds. Although
historically PMCs have only been seen in the polar region, in recent years
PMCs have been spotted at lower latitudes as far south as Colorado and
Utah, renewing interest and sparking debate on the implications. However,
the findings of this work, "call into question the interpretation of the
impact of late 20th century PMC trends solely in terms of global climate
change," Stevens said. The team concludes that the water from a space
shuttle's exhaust plume can contribute a remarkable 10-20 percent to PMCs
observed during one summer season in Antarctica.

A key piece of data that confirmed the plume's arrival in Antarctica was
the ground-based observation of iron atoms near 110 km. The presence of
iron at this altitude originally perplexed scientists because there is no
known natural source there. The data imply that iron ablated, or
vaporized, by the main engines of the Shuttle was transported along with
the water plume, arriving in Antarctica three to four days after the
January 2003 launch. Both the water plume and the presence of iron
demonstrate that the mean southward wind inferred from the team's data is
much faster than gleaned from global circulation models or wind
climatologies.

"This tells us something new and exciting about transport in this region
of the atmosphere," said Stevens. "It can be so fast that a shuttle plume
can form ice over Antarctica before other loss processes can really take
effect. We must take great care in interpreting the long-term implications
to observations and features of these clouds because of this contribution
from the shuttle and the potential contribution from many other smaller
launch vehicles."

NRL and NASA funded the study, with contributions from the National
Science Foundation, the British Antarctic Survey in Cambridge, United
Kingdom, and the University of Illinois, Urbana-Champaign. Other
researchers on the study include Robert Meier of George Mason University,
Fairfax, Va.; Xinzhao Chu of the University of Illinois, Urbana-Champaign;
Matthew DeLand of Science Systems & Applications, Inc., Lanham, Md.; and
John Plane of the University of East Anglia, Norwich, United Kingdom.

IMAGE CAPTIONS:

[Figure 1:
http://www.nrl.navy.mil/pao/PressRel...figure1-sm.jpg (168KB)]
New satellite data from the Global Ultraviolet Imager (GUVI) on NASA's
Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED)
satellite reveal the STS-107 main engine exhaust plume a day after the 16
January, 2003 launch (shuttle ground track overplotted in yellow). GUVI
measures solar scattered Lyman (radiation near 121.6 nm from atomic
hydrogen, produced by photodissociated water vapor within the plume. A
portion of the plume is shown moving south, where it is ultimately
observed from the ground over Rothera (located at the "R"). After that, a
burst of polar mesospheric clouds was observed over Antarctica, formed
from the water vapor within the shuttle plume.

[Figure 2:
http://www.nrl.navy.mil/pao/PressRel...figure2-sm.jpg (138KB)]
The Rothera research station in Antarctica (67.6 S and 292.0 E), where the
University of Illinois iron lidar is located and where the STS-107 main
engine exhaust plume was observed.