NASA News: NASA Spacecraft Reveals Dramatic Changes In Mars' Atmosphere
WASHINGTON -- NASA's Mars Reconnaissance Orbiter (MRO) has discoveredthe total amount of atmosphere on Mars changes dramatically as the
tilt of the planet's axis varies. This process can affect the
stability of liquid water if it exists on the Martian surface and
increase the frequency and severity of Martian dust storms.
Researchers using MRO's ground-penetrating radar identified a large,
buried deposit of frozen carbon dioxide, or dry ice, at the Red
Planet's south pole. The scientists suspect that much of this carbon
dioxide enters the planet's atmosphere and swells the atmosphere's
mass when Mars' tilt increases. The findings are published in a
report in the journal Science.
The newly found deposit has a volume similar to Lake Superior's nearly
3,000 cubic miles. The deposit holds up to 80 percent as much carbon
dioxide as today's Martian atmosphere. Collapse pits caused by dry
ice sublimation and other clues suggest the deposit is in a
dissipating phase, adding gas to the atmosphere each year. Mars'
atmosphere is about 95 percent carbon dioxide, in contrast to Earth's
much thicker atmosphere, which is less than .04 percent carbon dioxide.
"We already knew there is a small perennial cap of carbon-dioxide ice
on top of the water ice there, but this buried deposit has about 30
times more dry ice than previously estimated," said Roger Phillips of
Southwest Research Institute in Boulder, Colo. Phillips is deputy
team leader for MRO's Shallow Radar instrument and lead author of the report.
"We identified the deposit as dry ice by determining the radar
signature fit the radio-wave transmission characteristics of frozen
carbon dioxide far better than the characteristics of frozen water,"
said Roberto Seu of Sapienza University of Rome, team leader for the
Shallow Radar and a co-author of the new report.
Additional evidence came from correlating the deposit to visible
sublimation features typical of dry ice.
"When you include this buried deposit, Martian carbon dioxide right
now is roughly half frozen and half in the atmosphere, but at other
times it can be nearly all frozen or nearly all in the atmosphere," Phillips said.
An occasional increase in the atmosphere would strengthen winds,
lofting more dust and leading to more frequent and more intense dust
storms. Another result is an expanded area on the planet's surface
where liquid water could persist without boiling. Modeling based on
known variation in the tilt of Mars' axis suggests several-fold
changes in the total mass of the planet's atmosphere can happen on
time frames of 100,000 years or less.
The changes in atmospheric density caused by the carbon-dioxide
increase also would amplify some effects of the changes caused by the
tilt. Researchers plugged the mass of the buried carbon-dioxide
deposit into climate models for the period when Mars' tilt and
orbital properties maximize the amount of summer sunshine hitting the
south pole. They found at such times, global, year-round average air
pressure is approximately 75 percent greater than the current level.
"A tilted Mars with a thicker carbon-dioxide atmosphere causes a
greenhouse effect that tries to warm the Martian surface, while
thicker and longer-lived polar ice caps try to cool it," said
co-author Robert Haberle, a planetary scientist at NASA's Ames
Research Center in Moffett Field, Calif. "Our simulations show the
polar caps cool more than the greenhouse warms. Unlike Earth, which
has a thick, moist atmosphere that produces a strong greenhouse
effect, Mars' atmosphere is too thin and dry to produce as strong a
greenhouse effect as Earth's, even when you double its carbon-dioxide content."
The Shallow Radar, one of MRO's six instruments, was provided by the
Italian Space Agency and its operations are led by the Department of
Information Engineering, Electronics and Telecommunications at
Sapienza University of Rome. NASA's Jet Propulsion Laboratory in
Pasadena, Calif., manages the MRO project for NASA's Science Mission
Directorate at the agency's headquarters in Washington. Lockheed
Martin Space Systems in Denver built the spacecraft.
For more information about MRO, visit:
http://www.nasa.gov/mro
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Tweetup At NASA's JPL Previews Missions To Mars, Jupiter And More
PASADENA, Calif. -- NASA's Jet Propulsion Laboratory (JPL) inPasadena, Calif., will host a Tweetup for approximately 120 Twitter
followers on Monday, June 6.
With four space missions launching this year and an asteroid belt
encounter nearly underway, 2011 will be one of the busiest ever in
planetary exploration. Tweetup participants will interact with JPL
scientists and engineers about these upcoming missions: Aquarius, to
study ocean salinity; Grail, to study the moon's gravity field; Juno
to Jupiter; and the Mars Science Laboratory/Curiosity rover.
Participants also will learn about the Dawn mission and its upcoming
encounter with the asteroid Vesta.
The Tweetup will include a tour of JPL, robotics demonstrations and a
last chance to see the Curiosity rover before it ships to Florida to
prepare for a November launch. Tour stops will include the Spacecraft
Assembly Facility where Curiosity is under construction, the mission
control center of NASA's Deep Space Network, and JPL's new Earth
Science Visitor Center.
Tweetup participants also will mingle with fellow attendees and the
staff behind the tweets on @NASA, @NASAJPL, @MarsRovers,
@AsteroidWatch and more.
Registration for the event opens at noon PDT on Tuesday, April 26, and
it closes at noon on Wednesday, April 27. For more information about
the Tweetup and to sign up, visit:
http://www.nasa.gov/tweetup
NASA Television will broadcast portions of the Tweetup on June 6 at:
http://www.ustream.tv/channel/
and
http://www.ustream.tv/nasajpl2
Find all the ways to connect and collaborate with NASA at:
http://www.nasa.gov/connect
For more information about JPL, visit:
http://www.nasa.gov/jpl
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NASA And Partners Fund New Climate Impact Studies On Species And Ecosystems
WASHINGTON -- NASA is partnering with other federal agencies to fundnew research and applications efforts that will bring the global view
of climate from space down to Earth to benefit wildlife and key ecosystems.
NASA, the U.S. Geological Survey, National Park Service, U.S. Fish and
Wildlife Service and Smithsonian Institution will provide $18 million
for 15 new research projects during the next four years.
Organizations across the United States in academia, government and
the private sector will study the response of different species and
ecosystems to climate changes and develop tools to better manage
wildlife and natural resources. The projects were selected from 151 proposals.
NASA's Earth Science Division in the Science Mission Directorate has
funded several ecosystem and biodiversity research projects during
recent years. This is the first time the agency has targeted research
investigating the intersection of climate and biological studies.
The wildlife species that will be studied include polar bears in
Greenland, bowhead whales in the Arctic Ocean, and migratory birds
and waterfowl in the United States. Other studies will focus on
species of commercial interest such as clams, oysters and other
bivalves in U.S. coastal waters, and Atlantic bluefin tuna in the
Gulf of Mexico.
To learn more about climatic effects on plants, researchers will focus
on the loss of cordgrass marshes in coastal wetlands of the
southeastern states. They also will examine the stresses to native
tree species, many of commercial value, across the western states and Canada.
"We know very little about how the majority of species and ecosystems
will respond to environmental changes related to changing climates,"
said Woody Turner, manager of NASA's Ecological Forecasting program
in Washington. "These projects bring together NASA's global satellite
data of the physical environment with ground-based data on specific
species and ecosystems and computer modeling to detect and understand
biological responses to climate. As a result, we will improve our
management and mitigation of the impact of changing climate."
The studies will use long-term observations of Earth from space,
including data on sea surface temperature, vegetation cover,
rainfall, snow cover, sea ice and the variability in the microscopic
marine green plants that form the base of ocean food chains.
One study seeks to determine how waterfowl and forest bird populations
respond to extreme events such as long-term droughts, heat waves and
cold snaps. Wildlife biologists like Patricia Heglund of the U.S.
Fish and Wildlife Service in La Crosse, Wis., the leader of the
study, have several hypotheses, including lower reproduction rates
and adult mortality. Satellite data will be used to map the habitats
and identify extreme events in the continental United States.
Another study will seek to explain why the distribution of native tree
species across the western states and Canada is changing and why some
species are dying as the climate becomes progressively warmer and
drier. Scientists have used computer models to explain how
environmental stresses have affected tree species in the Pacific
Northwest. The new study, led by Richard Waring of Oregon State
University in Corvallis, will extend that research to the entire
Rocky Mountain west and 25 native tree species, including aspen and
lodgepole pine.
A project led by Mitchell Roffer of Roffer's Ocean Fishing Forecasting
Service in West Melbourne, Fla., aims to improve existing models to
predict spawning habitat of Atlantic bluefin and other migratory
tunas in the Gulf of Mexico. The model will assess possible effects
of future climate change scenarios on fish populations.
According to Turner, the most ambitious project in terms of scale will
use a global inventory of data from about 1,000 species, merged with
satellite and ground-based observations of the environment and
climate. These data will be used to assess climate's impact on
biodiversity during the past 40 years in two 20-year increments. The
study, led by Walter Jetz of Yale University, will focus on
land-based mammals, birds, reptiles and amphibians.
For a complete list of the new projects, visit:
http://www.nasa.gov/topics/
For more information about NASA and agency programs, visit:
http://www.nasa.gov
Source: NASA
