NASA News: NASA Seeks Proposals for Green Propellant Technology Demonstrations
WASHINGTON -- NASA is seeking technology demonstration proposals forgreen propellant alternatives to the highly toxic fuel hydrazine. As
NASA works with American companies to open a new era of access to
space, the agency seeks innovative and transformative fuels that are
less harmful to our environment.
Hydrazine is an efficient and ubiquitous propellant that can be stored
for long periods of time, but is also highly corrosive and toxic. It
is used extensively on commercial and defense department satellites
as well as for NASA science and exploration missions. NASA is looking
for an alternative that decreases environmental hazards and
pollutants, has fewer operational hazards and shortens rocket launch
processing times.
"High performance green propulsion has the potential to significantly
change how we travel in space," said Michael Gazarik, director of
NASA's Space Technology Program at the agency's headquarters in
Washington. "NASA's Space Technology Program seeks out these sort of
cross-cutting, innovative technologies to enable our future missions
while also providing benefit to the American space industry. By
reducing the hazards of handling fuel, we can reduce ground
processing time and lower costs for rocket launches, allowing a
greater community of researchers and technologists access to the high frontier."
Beyond decreasing environmental hazards and pollutants, promising
aspects of green propellants also include reduced systems complexity,
fewer operational hazards, decreased launch processing times and
increased propellant performance.
Maturing a space technology, such as green propellants, to mission
readiness through relevant environment testing and demonstration is a
significant challenge from a cost, schedule and risk perspective.
NASA has established the Technology Demonstration Missions Program to
perform this function, bridging the gap between laboratory
confirmation of a technology and its initial use on an operational mission.
NASA anticipates making one or more awards in response to this
solicitation, with no single award exceeding $50 million. Final
awards will be made based on the strength of proposals and
availability of funds. The deadline for submitting proposals is April 30.
The Technology Demonstration Missions Program is managed by NASA's
Marshall Space Flight Center in Huntsville, Ala. To view the
announcement and instructions for submissions, visit:
http://go.usa.gov/Qbx
For more information about NASA's Space Technology Program and
Technology Demonstration Missions, visit:
http://www.nasa.gov/oct
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NASA Mission Takes Stock of Earth's Melting Land Ice
WASHINGTON -- In the first comprehensive satellite study of its kind,a University of Colorado at Boulder-led team used NASA data to
calculate how much Earth's melting land ice is adding to global sea
level rise.
Using satellite measurements from the NASA/German Aerospace Center
Gravity Recovery and Climate Experiment (GRACE), the researchers
measured ice loss in all of Earth's land ice between 2003 and 2010,
with particular emphasis on glaciers and ice caps outside of
Greenland and Antarctica.
The total global ice mass lost from Greenland, Antarctica and Earth's
glaciers and ice caps during the study period was about 4.3 trillion
tons (1,000 cubic miles), adding about 0.5 inches (12 millimeters) to
global sea level. That's enough ice to cover the United States 1.5
feet (0.5 meters) deep.
"Earth is losing a huge amount of ice to the ocean annually, and these
new results will help us answer important questions in terms of both
sea rise and how the planet's cold regions are responding to global
change," said University of Colorado Boulder physics professor John
Wahr, who helped lead the study. "The strength of GRACE is it sees
all the mass in the system, even though its resolution is not high
enough to allow us to determine separate contributions from each
individual glacier."
About a quarter of the average annual ice loss came from glaciers and
ice caps outside of Greenland and Antarctica (roughly 148 billion
tons, or 39 cubic miles). Ice loss from Greenland and Antarctica and
their peripheral ice caps and glaciers averaged 385 billion tons (100
cubic miles) a year. Results of the study will be published online
Feb. 8 in the journal Nature.
Traditional estimates of Earth's ice caps and glaciers have been made
using ground measurements from relatively few glaciers to infer what
all the world's unmonitored glaciers were doing. Only a few hundred
of the roughly 200,000 glaciers worldwide have been monitored for
longer than a decade.
One unexpected study result from GRACE was the estimated ice loss from
high Asian mountain ranges like the Himalaya, the Pamir and the Tien
Shan was only about 4 billion tons of ice annually. Some previous
ground-based estimates of ice loss in these high Asian mountains have
ranged up to 50 billion tons annually.
"The GRACE results in this region really were a surprise," said Wahr,
who also is a fellow at the University of Colorado-headquartered
Cooperative Institute for Research in Environmental Sciences. "One
possible explanation is that previous estimates were based on
measurements taken primarily from some of the lower, more accessible
glaciers in Asia and extrapolated to infer the behavior of higher
glaciers. But unlike the lower glaciers, most of the high glaciers
are located in very cold environments and require greater amounts of
atmospheric warming before local temperatures rise enough to cause
significant melting. This makes it difficult to use low-elevation,
ground-based measurements to estimate results from the entire system."
"This study finds that the world's small glaciers and ice caps in
places like Alaska, South America and the Himalayas contribute about
.02 inches per year to sea level rise," said Tom Wagner, cryosphere
program scientist at NASA Headquarters in Washington. "While this is
lower than previous estimates, it confirms that ice is being lost
from around the globe, with just a few areas in precarious balance.
The results sharpen our view of land ice melting, which poses the
biggest, most threatening factor in future sea level rise."
The twin GRACE satellites track changes in Earth's gravity field by
noting minute changes in gravitational pull caused by regional
variations in Earth's mass, which for periods of months to years is
typically because of movements of water on Earth's surface. It does
this by measuring changes in the distance between its two identical
spacecraft to one-hundredth the width of a human hair.
The GRACE spacecraft, developed by NASA's Jet Propulsion Laboratory,
Pasadena, Calif., and launched in 2002, are in the same orbit
approximately 137 miles (220 kilometers) apart.
For more on GRACE, visit:
http://www.csr.utexas.edu/
http://grace.jpl.nasa.gov
For more information about NASA and agency programs, visit:
http://www.nasa.gov
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NASA's Chandra Finds Milky Way's Black Hole Grazing on Asteroids
WASHINGTON -- The giant black hole at the center of the Milky Way maybe vaporizing and devouring asteroids, which could explain the
frequent flares observed, according to astronomers using data from
NASA's Chandra X-ray Observatory.
For several years Chandra has detected X-ray flares about once a day
from the supermassive black hole known as Sagittarius A*, or "Sgr A*"
for short. The flares last a few hours with brightness ranging from a
few times to nearly one hundred times that of the black hole's
regular output. The flares also have been seen in infrared data from
ESO's Very Large Telescope in Chile.
"People have had doubts about whether asteroids could form at all in
the harsh environment near a supermassive black hole," said Kastytis
Zubovas of the University of Leicester in the United Kingdom, and
lead author of the report appearing in the Monthly Notices of the
Royal Astronomical Society. "It's exciting because our study suggests
that a huge number of them are needed to produce these flares."
Zubovas and his colleagues suggest there is a cloud around Sgr A*
containing trillions of asteroids and comets, stripped from their
parent stars. Asteroids passing within about 100 million miles of the
black hole, roughly the distance between the Earth and the sun, would
be torn into pieces by the tidal forces from the black hole.
These fragments then would be vaporized by friction as they pass
through the hot, thin gas flowing onto Sgr A*, similar to a meteor
heating up and glowing as it falls through Earth's atmosphere. A
flare is produced and the remains of the asteroid are swallowed
eventually by the black hole.
"An asteroid's orbit can change if it ventures too close to a star or
planet near Sgr A*," said co-author Sergei Nayakshin, also of the
University of Leicester. "If it's thrown toward the black hole, it's doomed."
The authors estimate that it would take asteroids larger than about
six miles in radius to generate the flares observed by Chandra.
Meanwhile, Sgr A* also may be consuming smaller asteroids, but these
would be difficult to spot because the flares they generate would be fainter.
These results reasonably agree with models estimating of how many
asteroids are likely to be in this region, assuming that the number
around stars near Earth is similar to the number surrounding stars
near the center of the Milky Way.
"As a reality check, we worked out that a few trillion asteroids
should have been removed by the black hole over the 10-billion-year
lifetime of the galaxy," said co-author Sera Markoff of the
University of Amsterdam in the Netherlands. "Only a small fraction of
the total would have been consumed, so the supply of asteroids would
hardly be depleted."
Planets thrown into orbits too close to Sgr A* also should be
disrupted by tidal forces, although this would happen much less
frequently than the disruption of asteroids, because planets are not
as common. Such a scenario may have been responsible for a previous
X-ray brightening of Sgr A* by about a factor of a million about a
century ago. While this event happened many decades before X-ray
telescopes existed, Chandra and other X-ray missions have seen
evidence of an X-ray "light echo" reflecting off nearby clouds,
providing a measure of the brightness and timing of the flare.
"This would be a sudden end to the planet's life, a much more dramatic
fate than the planets in our solar system ever will experience,"
Zubovas said.
Very long observations of Sgr A* will be made with Chandra later in
2012 that will give valuable new information about the frequency and
brightness of flares and should help to test the model proposed here
to explain them. This work could improve understanding about the
formation of asteroids and planets in the harsh environment of Sgr A*.
NASA's Marshall Space Flight Center in Huntsville, Ala., manages the
Chandra program for NASA's Science Mission Directorate in Washington.
The Smithsonian Astrophysical Observatory controls Chandra's science
and flight operations from Cambridge, Mass.
For Chandra images, multimedia and related materials, visit:
http://www.nasa.gov/chandra
For an additional interactive image, podcast, and video on the
finding, visit:
http://chandra.si.edu
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