NASA's UARS Re-enters Earth's Atmosphere
NASA’s decommissioned Upper Atmosphere Research Satellite (UARS) fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. Sept. 24, 20 years and nine days after its launch on a 14-year mission that produced some of the first long-term records of chemicals in the atmosphere.
The precise re-entry time and location of debris impacts have not been determined. During the re-entry period, the satellite passed from the east coast of Africa over the Indian Ocean, then the Pacific Ocean, then across northern Canada, then across the northern Atlantic Ocean, to a point over West Africa. The vast majority of the orbital transit was over water, with some flight over northern Canada and West Africa.
Six years after the end of its productive scientific life, UARS broke into pieces during re-entry, and most of it up burned in the atmosphere. Data indicates the satellite likely broke apart and landed in the Pacific Ocean far off the U.S. coast. Twenty-six satellite components, weighing a total of about 1,200 pounds, could have survived the fiery re-entry and reach the surface of Earth. However, NASA is not aware of any reports of injury or property damage.
The Operations Center for JFCC-Space, the Joint Functional Component Command at Vandenberg Air Force Base, Calif., which works around the clock detecting, identifying and tracking all man-made objects in Earth orbit, tracked the movements of UARS through the satellite’s final orbits and provided confirmation of re-entry.
“We extend our appreciation to the Joint Space Operations Center for monitoring UARS not only this past week but also throughout its entire 20 years on orbit,” said Nick Johnson, NASA’s chief scientist for orbital debris, at NASA’s Johnson Space Center in Houston. “This was not an easy re-entry to predict because of the natural forces acting on the satellite as its orbit decayed. Space-faring nations around the world also were monitoring the satellite’s descent in the last two hours and all the predictions were well within the range estimated by JSpOC.”
UARS was launched Sept. 12, 1991, aboard space shuttle mission STS-48 and deployed on Sept. 15, 1991. It was the first multi-instrumented satellite to observe numerous chemical components of the atmosphere for better understanding of photochemistry. UARS data marked the beginning of many long-term records for key chemicals in the atmosphere. The satellite also provided key data on the amount of light that comes from the sun at ultraviolet and visible wavelengths. UARS ceased its scientific life in 2005.
Because of the satellite's orbit, any surviving components of UARS should have landed within a zone between 57 degrees north latitude and 57 degrees south latitude. It is impossible to pinpoint just where in that zone the debris landed, but NASA estimates the debris footprint to be about 500 miles long.
Airplane Plus Heat Plus Ice Equals Mystery
NASA’s decommissioned Upper Atmosphere Research Satellite (UARS) fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. Sept. 24, 20 years and nine days after its launch on a 14-year mission that produced some of the first long-term records of chemicals in the atmosphere.
The precise re-entry time and location of debris impacts have not been determined. During the re-entry period, the satellite passed from the east coast of Africa over the Indian Ocean, then the Pacific Ocean, then across northern Canada, then across the northern Atlantic Ocean, to a point over West Africa. The vast majority of the orbital transit was over water, with some flight over northern Canada and West Africa.
Six years after the end of its productive scientific life, UARS broke into pieces during re-entry, and most of it up burned in the atmosphere. Data indicates the satellite likely broke apart and landed in the Pacific Ocean far off the U.S. coast. Twenty-six satellite components, weighing a total of about 1,200 pounds, could have survived the fiery re-entry and reach the surface of Earth. However, NASA is not aware of any reports of injury or property damage.
The Operations Center for JFCC-Space, the Joint Functional Component Command at Vandenberg Air Force Base, Calif., which works around the clock detecting, identifying and tracking all man-made objects in Earth orbit, tracked the movements of UARS through the satellite’s final orbits and provided confirmation of re-entry.
“We extend our appreciation to the Joint Space Operations Center for monitoring UARS not only this past week but also throughout its entire 20 years on orbit,” said Nick Johnson, NASA’s chief scientist for orbital debris, at NASA’s Johnson Space Center in Houston. “This was not an easy re-entry to predict because of the natural forces acting on the satellite as its orbit decayed. Space-faring nations around the world also were monitoring the satellite’s descent in the last two hours and all the predictions were well within the range estimated by JSpOC.”
UARS was launched Sept. 12, 1991, aboard space shuttle mission STS-48 and deployed on Sept. 15, 1991. It was the first multi-instrumented satellite to observe numerous chemical components of the atmosphere for better understanding of photochemistry. UARS data marked the beginning of many long-term records for key chemicals in the atmosphere. The satellite also provided key data on the amount of light that comes from the sun at ultraviolet and visible wavelengths. UARS ceased its scientific life in 2005.
Because of the satellite's orbit, any surviving components of UARS should have landed within a zone between 57 degrees north latitude and 57 degrees south latitude. It is impossible to pinpoint just where in that zone the debris landed, but NASA estimates the debris footprint to be about 500 miles long.
Airplane Plus Heat Plus Ice Equals Mystery
08.17.11
It's difficult to believe that an airplane flying in the tropics in the summer could have an engine fill up with ice, freeze, and shut down. But the phenomenon, known as engine core ice accretion, has happened more than 150 times since 1988 — frequently enough to attract the attention of NASA aviation safety experts, who are preparing a flight campaign in northern Australia to learn more about this occasional hazard and what can be done to prevent it. "It's not happening in one particular type of engine and it's not happening on one particular type of airframe," said Tom Ratvasky, an icing flight research engineer at NASA's Glenn Research Center in Cleveland. "The problem can be found on aircraft as big as large commercial airliners, all the way down to business-sized jet aircraft." And it has happened at altitudes up to 41,000 feet.
No accident has been attributed to the phenomenon in the 23 years since it was identified, but there have been some harrowing moments in the air. In most of the known cases, pilots have managed to restore engine power and reach their destinations without further problems. According to the Federal Aviation Administration, there have been two forced landings. For example, in 2005, both engines of a Beechcraft business jet failed at 38,000 feet above Jacksonville, Fla. The pilot glided the aircraft to an airport, dodging thunderstorms and ominous clouds on the way down. Engine core ice accretion was to blame.
Little is understood about ice crystal properties at high altitude and how ice accumulates inside engines. The engines may be toasty warm inside at such heights, but the air outside is frosty cold. The prevailing theory holds the trouble occurs around tropical storms in which strong convection currents move moist air from low altitudes to high altitudes where the local temperatures are very cold, creating high concentrations of ice crystals. But the properties of the ice crystals, such as their size and how many of them are in a given volume of air, are a mystery — one that an international research team led by NASA aims to solve.
 This graphic explains what researchers believe might happen to cause engine icing. Credit: NASA/Maria Werries › Link to larger photo |
The FAA has proposed new certification standards for engines that will be operated in atmospheric conditions that generate ice crystals. The rules will take effect next year, just as the NASA team heads to Darwin, Australia, aboard an aircraft specially equipped with instruments to study cloud physics during the Southern Hemisphere summer. Analyses of the Darwin flight tests and additional tests in ground-based facilities in the United States and Canada will provide the FAA the means for ensuring compliance with the new standards.
"We need to understand what that environment is out there and, even though it may be a rare case, be able to fly through those icing conditions unscathed. Or if we can find ways of detecting this condition and keep aircraft out of it, that's something we're interested in doing," Ratvasky said.
Researchers explain the phenomenon this way: Small ice crystals found in storm clouds get sucked into the core of an aircraft engine, where the pressure is high and the temperature is warm. Some of the ice melts and covers the warm engine parts with a thin film of water that traps additional ice crystals. The super-cooled water chills the engine components enough that ice can accumulate on them. If the built-up ice breaks away in chunks it can damage compressor blades, reduce the power level, or snuff out the engine altogether.
This Gulfstream 2 business jet is being outfitted over the next few months with special sensors to probe cloud properties during the High Ice Water Content experiments.For the flight research, NASA is outfitting a Gulfstream 2 business jet with more than 20 meteorological sensors that will be used to probe cloud properties, such as water content and the size and concentration of ice particles, which can lead to engine and air data sensor failures that threaten aviation safety. The data gathered will aid scientists' understanding of cloud growth processes, help them create reliable detection methods and realistic ground-based simulations, and provide a foundation for possible new aircraft design and certification standards. FAA can use what the team learns over the course of its research project to verify the range of atmospheric conditions addressed in the new standards.
The flight campaign has three primary goals:
- Characterize the range of environmental conditions in which internal engine icing can take place, with an emphasis on how much water or ice is present in a given volume of air.
- Determine how to identify geographic regions where such weather threatens and ways to detect the conditions in real time in order to develop guidance that pilots can use to avoid the hazard.
- Collect enough data to enable researchers to simulate the weather conditions for aircraft engine tests in ground facilities such as Glenn’s Propulsion Systems Laboratory.
The Propulsion Systems Laboratory recently underwent upgrades to equip it for ground-based simulations of high-altitude icing conditions. Work to transform the Gulfstream 2 into a working airborne science laboratory is under way at a NASA contractor site, Flight Test Associates in Mojave, Calif., and will be completed early in 2012. Engineers will mount six instruments on each wing and additional instruments on the fuselage to measure cloud particle size and shape and water content, whether the particles are liquid or crystal, and the speed of the updraft as cloud particles form.
The research team – with representatives from FAA, The Boeing Company, the U.S. National Center for Atmospheric Research, Environment Canada, the National Research Council of Canada, Transport Canada, Airbus and the Australian Bureau of Meteorology – will conduct trial runs during the monsoon season in February and March 2012, develop findings and address lessons learned, and then return in January through March 2013 for the primary flight campaign.
The team chose Darwin for several reasons: its ground-based weather observing systems are the best in the tropics, there will be plenty of storms to sample, there is plenty of data from previous atmospheric characterization efforts with which to compare, and the Southeast Asia region has seen a large number of engine power-loss events.
Atlantis and Crew Welcomed Home
Thu, 21 Jul 2011 12:10:31 GMT
The STS-135 astronauts got to take a look at the vehicle that carried them on the final space shuttle mission, and paused for a moment to reflect on the journey.
"Although we got to take the ride," said Commander Chris Ferguson on behalf of his crew, " we sure hope that everybody who has ever worked on, or touched, or looked at, or envied or admired a space shuttle was able to take just a little part of the journey with us."
In the shadow of Atlantis as it sat on the runway at Kennedy Space Center's Shuttle Landing Facility, the crew was welcomed back by senior NASA officials, including NASA Administrator Charles Bolden.
"They have come to be known as the 'final four.' They did an absolutely incredible job," said Bolden. "They made us very proud."
A shuttle program post-landing news conference is set for 10 a.m. EDT, followed by a crew news conference at noon. Both will be carried live on NASA TV and online at www.nasa.gov/ntv. Participants in the 10 a.m. panel will be Bill Gerstenmaier, associate administrator for Space Operations, Bob Cabana, Kennedy center director, Mike Moses, space shuttle launch integration manager, and Mike Leinbach, space shuttle launch director.
Atlantis landed at 5:57 a.m. EDT, after 200 orbits around Earth and a journey of 5,284,862 miles.
The STS-135 crew consisted of Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandra Magnus and Rex Walheim. They delivered more than 9,400 pounds of spare parts, spare equipment and other supplies in the Raffaello multi-purpose logistics module - including 2,677 pounds of food - that will sustain space station operations for the next year. The 21-foot long, 15-foot diameter Raffaello brought back nearly 5,700 pounds of unneeded materials from the station.
A welcome home ceremony for the astronauts will be held Friday, July 22, in Houston. The public is invited to attend the 4 p.m. CDT event at NASA's Hangar 990 at Ellington Field. Gates to Ellington Field will open at 3:30 p.m. The ceremony will be broadcast live on NASA Television.
"Although we got to take the ride," said Commander Chris Ferguson on behalf of his crew, " we sure hope that everybody who has ever worked on, or touched, or looked at, or envied or admired a space shuttle was able to take just a little part of the journey with us."
In the shadow of Atlantis as it sat on the runway at Kennedy Space Center's Shuttle Landing Facility, the crew was welcomed back by senior NASA officials, including NASA Administrator Charles Bolden.
"They have come to be known as the 'final four.' They did an absolutely incredible job," said Bolden. "They made us very proud."
A shuttle program post-landing news conference is set for 10 a.m. EDT, followed by a crew news conference at noon. Both will be carried live on NASA TV and online at www.nasa.gov/ntv. Participants in the 10 a.m. panel will be Bill Gerstenmaier, associate administrator for Space Operations, Bob Cabana, Kennedy center director, Mike Moses, space shuttle launch integration manager, and Mike Leinbach, space shuttle launch director.
Atlantis landed at 5:57 a.m. EDT, after 200 orbits around Earth and a journey of 5,284,862 miles.
The STS-135 crew consisted of Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandra Magnus and Rex Walheim. They delivered more than 9,400 pounds of spare parts, spare equipment and other supplies in the Raffaello multi-purpose logistics module - including 2,677 pounds of food - that will sustain space station operations for the next year. The 21-foot long, 15-foot diameter Raffaello brought back nearly 5,700 pounds of unneeded materials from the station.
A welcome home ceremony for the astronauts will be held Friday, July 22, in Houston. The public is invited to attend the 4 p.m. CDT event at NASA's Hangar 990 at Ellington Field. Gates to Ellington Field will open at 3:30 p.m. The ceremony will be broadcast live on NASA Television.
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