“NASA thruster test aids future robotic lander's ability to land safely - PhysOrg”

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NASA thruster test aids future robotic lander's ability to land safely - PhysOrg Posted: 08 Oct 2010 07:35 AM PDT NASA's Marshall Space Flight Center in Huntsville, Ala., collaborated with NASA's White Sands Test Facility in Las Cruces, N.M., and Pratt & Whitney Rocketdyne in Canoga Park, Calif., to successfully complete a series of thruster tests at the White Sands test facility. The test will aid in maneuvering and landing the next generation of robotic lunar landers that could be used to explore the moon's surface and other airless celestial bodies. The Robotic Lunar Lander Development Project at the Marshall Center performed a series of hot-fire tests on two high thrust-to-weight thrusters – a 100-pound-class for lunar descent and a 5-pound-class for attitude control. The team used a lunar mission profile during the test of the miniaturized thrusters to assess the capability of these thruster technologies for possible use on future NASA spacecraft. The test program fully accomplished its objectives, including evaluation of combustion stability, engine efficiency, and the ability of the thruster to perform the mission profile and a long-duration, steady-state burn at full power. The test results will allow the Robotic Lander Project to move forward with robotic lander designs using advanced propulsion technology. You need Flash installed to watch this video NASA's Marshall Space Flight Center in Huntsville, Ala., has successfully completed tests on two thrusters at NASA's White Sands Test Facility in Las Cruces, N.M., to aid in manuevering and landing the next generation of robotic lunar landers that could be used to explore the moon's surface and other airless celestial bodies. The test articles are part of the Divert Attitude Control System, or DACS, developed by the U.S. Missile Defense Agency of the Department of Defense. The control system provides two kinds of propulsion -- one for control and the other for maneuvering. The Attitude Control System thrusters provide roll, pitch and yaw control. These small thruster types were chosen to meet the golf-cart-size lander's requirement for light-weight, compact propulsion components to aid in reducing overall spacecraft mass and mission cost by leveraging an existing government resource. "The Missile Defense Agency heritage thrusters were originally used for short-duration flights and had not been qualified for space missions, so our engineers tested them to assess their capability for long-duration burns and to evaluate their performance and combustion behavior," said Monica Hammond, lander propulsion task manager for the Robotic Lunar Lander Development Project at the Marshall Center. "The thrusters are a first step in reducing propulsion technology risks for a lander mission. The results will be instrumental in developing future plans associated with the lander's propulsion system design." During tests of the 100-pound thruster, the Divert Attitude Control System thruster fired under vacuum conditions to simulate operation in a space environment. The tests mimicked the lander mission profile and operation scenarios. The test included several trajectory correction maneuvers during the cruise phase; nutation control burns to maintain spacecraft orientation; thruster vector correction during the solid motor braking burn; and a terminal descent burn on approach to the lunar surface. The objective for the 5-pound-class thruster test was similar to the 100-pound thruster test with an additional emphasis on the thruster heating assessment due to the long-duration mission profile and operation with MMH/MON-25 -- monomethylhydrazine (MMH) fuel and a nitrogen tetroxide (75 percent)/nitrogen oxide (25 percent) (MON-25) oxidizer. A standard propellant system for spacecraft is the MMH/MON-3 propellant system -- containing 3 percent nitric oxide. An alternate propellant system, MMH/MON-25, contains 25 percent nitric oxide. With its chemical composition, it has a much lower freezing point than MON-3, making it an attractive alternative for spacecraft with its thermal benefits and resulting savings in heater power. Because the MMH/MON-25 propellant system has never been used in space, these tests allowed engineers to benchmark the test against the MMH/MON-3 propellant system. "The lower freezing point could save considerable heater power for the spacecraft and increase thermal margin for the entire propulsion system," said Huu Trinh, lead propulsion engineer for the Robotic Lunar Lander Development Project at the Marshall Center. "These tests showed stable combustion in all scenarios and favorable temperature results." This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

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“Green comet expected to bring meteor shower to UK - New York Post”

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Green comet expected to bring meteor shower to UK - New York Post Posted: 28 Oct 2010 05:31 AM PDT A green comet that is passing close to Earth this month could produce an impressive meteor shower over Britain and Ireland next week, astronomers predicted. Two fireballs have already been observed over the U.S. and Canada. NASA experts said that another shower may be visible in Britain next Tuesday and Wednesday, Nov. 2 and 3, as Comet Hartley 2 makes one of the closest approaches to Earth by a comet in centuries. Just 11 million miles away, it was closest last Wednesday and appeared as a fuzzy glow through small telescopes. Warmed by the sun, it revealed a green gaseous shell and a tail of ejected dust -- the material that burns up as meteors or shooting stars. The comet was discovered by British-born professional astronomer Malcolm Hartley from Siding Spring, Australia. NASA's Deep Impact probe will fly past Hartley 2 next Thursday and is expected to send back dramatic photos of its rocky nucleus. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

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“Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com” plus 2 more

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• Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com
• Lackluster Meteor Shower Sets Stage for Big Show in 2011 - msnbc.com
• Green comet expected to bring meteor shower to UK - New York Post

Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com Posted: 20 Oct 2010 07:20 AM PDT A junior version of the famous Perseid meteor shower thought to have originated from the remains of Halley's Comet will hit its peak over the next week, but the light of the moon may intrude on the sky show. This upcoming meteor display is known as the Orionids because the meteors seem to fan out from a region to the north of the Orion constellation's second brightest star, ruddy Betelgeuse. The annual event peaks before sunrise on Thursday (Oct. 21) but several viewing opportunities arise before then for skywatchers in North America. [ Where to look to see the Orionids ] The shooting stars are created by small bits of space dust — most no larger than sand grains — thought to be left over from the famed Halley's Comet, which orbits the sun once every 76 years. Currently, Orion appears ahead of us in our journey around the sun, and has not completely risen above the eastern horizon until after 11 p.m. local daylight time. The constellation is at its best several hours later. At around 5 a.m. – Orion will be highest in the sky toward the south – Orionids typically produce around 20 to 30 meteors per hour under a clear, dark sky. But skywatchers beware: You will be facing a major obstacle in your attempt to observe this year's Orionid performance. As bad luck would have it, the moon will turn full on Oct. 23. Bright moonlight outshines fainter meteors, seriously reducing the number anyone can see. The gradual build up to the full moon will hamper – if not outright prevent – dark-sky observing during the Orionid meteor shower's peak on Oct. 21. The Orionids are actually already underway, having been active only in a very weak and scattered form since about Oct. 2. But a noticeable upswing in activity is expected to begin around Oct. 17, leading up to their peak night.  "Orionid meteors are normally dim and not well seen from urban locations," notes meteor expert, Robert Lunsford, adding that "it is highly suggested that you find a safe rural location to see the best Orionid activity." Damage control for 2010 With all this as a background, perhaps the best times to look this year will be during the predawn hours several mornings before the night of full moon. That's when the constellation Orion (from where the meteors get their name) will stand high in the northeast sky.  In fact, three "windows" of dark skies will be available between moonset and the first light of dawn on the mornings of Oct. 18, 19 and 20. Generally speaking, there will be about 150 minutes of completely dark skies available on the morning of the 18th.This shrinks to about 100 minutes on the 19th, and to about 50 minutes by the morning of the 20th. This skywatching table shows prime Orionid meteor shower viewing times for some select U.S. cities. In the table, all times are a.m. and are local daylight times. "Dawn" is the time when morning (astronomical) twilight begins. A "Window" is the number of minutes between the time of moonset and the start of twilight. For example: When will the sky be dark and moonless for Orionid viewing on the morning of Oct. 20 from Houston?  Answer: There will be a 50-minute period of dark skies beginning at moonset (5:16 a.m.) and continuing until dawn breaks (6:06 a.m.). Perhaps up to a dozen forerunners of the main Orionid display might appear to steak by within an hour's watch on these mornings, particularly on the 20th, the morning before the peak. It might even be worthwhile to try on Thursday morning, Oct. 21, although for most places, the moon will not set until just after the first light of dawn.  Halley's legacy In studying the orbits of many meteor swarms, astronomers have found that they correspond closely to the orbits of known comets. The Orionids are thought to result from the orbit of Halley's Comet, as some of the dust that has been shed by this famous object intersect earth's orbit around the sun during October. There are actually two points along Halley's path, where it comes relatively near to our orbit. Another one of these points occurs in early May causing a meteor display from the constellation Aquarius, the Water Carrier. The tiny particles that are responsible for the Orionid and Aquarid meteors are – like Halley itself – moving through space in a direction opposite to that the earth. This results in meteors that ram through our atmosphere very swiftly at 41 miles (66 km) per second. Of all the meteor displays, only the November Leonids move faster. Orionid postmortem After the peak, activity will begin to slowly descend, although most of the meteors will be squelched by the light of the moon. Rates drop back to around five per hour around Oct. 26. The last stragglers usually appear sometime around Nov. 7. It is indeed unfortunate that the Moon will likely obliterate most of the Orionids in the nights following the peak, but the viewing odds will be much better before the break of dawn on those mornings leading up to the peak. Almost certainly, you should sight at least a few of these offspring of Halley's Comet as they streak across the sky. In the absence of moonlight a single observer might see at least a couple of dozen meteors per hour on the morning of the peak, a number that sadly can not be hoped to be approached in 2010. In fact, it appears that this year, fans of the Orionids will be uttering the same lament that the old Dodger fans in Brooklyn used to: "Wait till next year!"  © 2010 Space.com. All rights reserved. More from Space.com. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

Lackluster Meteor Shower Sets Stage for Big Show in 2011 - msnbc.com Posted: 10 Oct 2010 09:20 AM PDT The Earth will pass through the cast-off remnants of an ancient comet Friday (Oct. 8), but the resulting meteor shower will be lackluster at best, experts say. Yet the event sets the stage for a truly remarkable shooting star display in 2011. The source of this annual October meteor display, called the Draconid meteor shower, is dust and debris leftover from Comet Giacobini-Zinner. The Draconid meteor shower has a reputation for disappointing skywatchers with lackluster displays, unlike the spectacular sky shows that sometimes accompany the annual Perseid meteor shower in August and the Leonid shower in November. [ Best Leonid Meteor Shower Photos ] This year, according to skwatching experts, will be no different. But by all accounts, 2011 will be a year to remember for the Draconids. "This year, forecasters expect Earth to narrowly miss several of the debris streams, resulting in no appreciable display for 2010," reported Spaceweather.com, a website dedicated to monitoring space weather and sky events. "Next year, however, could be different. On Oct. 8, 2011, Earth will have a near head-on collision with a tendril of dust, setting off a strong outburst of as many as 750 meteors per hour." In fact, the 2011 Draconid meteor shower is expected to be so astounding that NASA has already begun preparing for the risk to satellites orbiting Earth such as the International Space Station or Hubble Space Telescope. "We're already working with NASA programs to deal with spacecraft risk," said William Cooke, a scientist with the Meteoroid Environment Office at NASA's Marshall Space Flight Center in Huntsville, Ala., during an interview with SPACE.com in June. "I imagine when the word gets out there will be a Draconid outburst, I'll get the usual calls from Comsat companies as well as government space programs." In addition to the chance of dings, there is the possibility of electrostatic discharges associated with the collision between a meteoroid and a satellite, Cooke said. Such discharges can account for a significant fraction of spacecraft anomalies during meteor showers, he added. While this year's Draconid meteor shower will likely be a bust, the 2011 Draconids should be a sight to behold, forecasters said.  The best vantage points will be Europe, Africa and the Middle East, Spaceweather.com reported. The 2011 Draconids could possibly be the most powerful meteor shower since the dazzling Leonids display 10 years ago, the website added. © 2010 Space.com. All rights reserved. More from Space.com. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

Green comet expected to bring meteor shower to UK - New York Post Posted: 28 Oct 2010 05:31 AM PDT A green comet that is passing close to Earth this month could produce an impressive meteor shower over Britain and Ireland next week, astronomers predicted. Two fireballs have already been observed over the U.S. and Canada. NASA experts said that another shower may be visible in Britain next Tuesday and Wednesday, Nov. 2 and 3, as Comet Hartley 2 makes one of the closest approaches to Earth by a comet in centuries. Just 11 million miles away, it was closest last Wednesday and appeared as a fuzzy glow through small telescopes. Warmed by the sun, it revealed a green gaseous shell and a tail of ejected dust -- the material that burns up as meteors or shooting stars. The comet was discovered by British-born professional astronomer Malcolm Hartley from Siding Spring, Australia. NASA's Deep Impact probe will fly past Hartley 2 next Thursday and is expected to send back dramatic photos of its rocky nucleus. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

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“Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com” plus 2 more

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• Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com
• Lackluster Meteor Shower Sets Stage for Big Show in 2011 - msnbc.com
• NASA thruster test aids future robotic lander's ability to land safely - PhysOrg

Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com Posted: 20 Oct 2010 07:20 AM PDT A junior version of the famous Perseid meteor shower thought to have originated from the remains of Halley's Comet will hit its peak over the next week, but the light of the moon may intrude on the sky show. This upcoming meteor display is known as the Orionids because the meteors seem to fan out from a region to the north of the Orion constellation's second brightest star, ruddy Betelgeuse. The annual event peaks before sunrise on Thursday (Oct. 21) but several viewing opportunities arise before then for skywatchers in North America. [ Where to look to see the Orionids ] The shooting stars are created by small bits of space dust — most no larger than sand grains — thought to be left over from the famed Halley's Comet, which orbits the sun once every 76 years. Currently, Orion appears ahead of us in our journey around the sun, and has not completely risen above the eastern horizon until after 11 p.m. local daylight time. The constellation is at its best several hours later. At around 5 a.m. – Orion will be highest in the sky toward the south – Orionids typically produce around 20 to 30 meteors per hour under a clear, dark sky. But skywatchers beware: You will be facing a major obstacle in your attempt to observe this year's Orionid performance. As bad luck would have it, the moon will turn full on Oct. 23. Bright moonlight outshines fainter meteors, seriously reducing the number anyone can see. The gradual build up to the full moon will hamper – if not outright prevent – dark-sky observing during the Orionid meteor shower's peak on Oct. 21. The Orionids are actually already underway, having been active only in a very weak and scattered form since about Oct. 2. But a noticeable upswing in activity is expected to begin around Oct. 17, leading up to their peak night.  "Orionid meteors are normally dim and not well seen from urban locations," notes meteor expert, Robert Lunsford, adding that "it is highly suggested that you find a safe rural location to see the best Orionid activity." Damage control for 2010 With all this as a background, perhaps the best times to look this year will be during the predawn hours several mornings before the night of full moon. That's when the constellation Orion (from where the meteors get their name) will stand high in the northeast sky.  In fact, three "windows" of dark skies will be available between moonset and the first light of dawn on the mornings of Oct. 18, 19 and 20. Generally speaking, there will be about 150 minutes of completely dark skies available on the morning of the 18th.This shrinks to about 100 minutes on the 19th, and to about 50 minutes by the morning of the 20th. This skywatching table shows prime Orionid meteor shower viewing times for some select U.S. cities. In the table, all times are a.m. and are local daylight times. "Dawn" is the time when morning (astronomical) twilight begins. A "Window" is the number of minutes between the time of moonset and the start of twilight. For example: When will the sky be dark and moonless for Orionid viewing on the morning of Oct. 20 from Houston?  Answer: There will be a 50-minute period of dark skies beginning at moonset (5:16 a.m.) and continuing until dawn breaks (6:06 a.m.). Perhaps up to a dozen forerunners of the main Orionid display might appear to steak by within an hour's watch on these mornings, particularly on the 20th, the morning before the peak. It might even be worthwhile to try on Thursday morning, Oct. 21, although for most places, the moon will not set until just after the first light of dawn.  Halley's legacy In studying the orbits of many meteor swarms, astronomers have found that they correspond closely to the orbits of known comets. The Orionids are thought to result from the orbit of Halley's Comet, as some of the dust that has been shed by this famous object intersect earth's orbit around the sun during October. There are actually two points along Halley's path, where it comes relatively near to our orbit. Another one of these points occurs in early May causing a meteor display from the constellation Aquarius, the Water Carrier. The tiny particles that are responsible for the Orionid and Aquarid meteors are – like Halley itself – moving through space in a direction opposite to that the earth. This results in meteors that ram through our atmosphere very swiftly at 41 miles (66 km) per second. Of all the meteor displays, only the November Leonids move faster. Orionid postmortem After the peak, activity will begin to slowly descend, although most of the meteors will be squelched by the light of the moon. Rates drop back to around five per hour around Oct. 26. The last stragglers usually appear sometime around Nov. 7. It is indeed unfortunate that the Moon will likely obliterate most of the Orionids in the nights following the peak, but the viewing odds will be much better before the break of dawn on those mornings leading up to the peak. Almost certainly, you should sight at least a few of these offspring of Halley's Comet as they streak across the sky. In the absence of moonlight a single observer might see at least a couple of dozen meteors per hour on the morning of the peak, a number that sadly can not be hoped to be approached in 2010. In fact, it appears that this year, fans of the Orionids will be uttering the same lament that the old Dodger fans in Brooklyn used to: "Wait till next year!"  © 2010 Space.com. All rights reserved. More from Space.com. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

Lackluster Meteor Shower Sets Stage for Big Show in 2011 - msnbc.com Posted: 10 Oct 2010 09:20 AM PDT The Earth will pass through the cast-off remnants of an ancient comet Friday (Oct. 8), but the resulting meteor shower will be lackluster at best, experts say. Yet the event sets the stage for a truly remarkable shooting star display in 2011. The source of this annual October meteor display, called the Draconid meteor shower, is dust and debris leftover from Comet Giacobini-Zinner. The Draconid meteor shower has a reputation for disappointing skywatchers with lackluster displays, unlike the spectacular sky shows that sometimes accompany the annual Perseid meteor shower in August and the Leonid shower in November. [ Best Leonid Meteor Shower Photos ] This year, according to skwatching experts, will be no different. But by all accounts, 2011 will be a year to remember for the Draconids. "This year, forecasters expect Earth to narrowly miss several of the debris streams, resulting in no appreciable display for 2010," reported Spaceweather.com, a website dedicated to monitoring space weather and sky events. "Next year, however, could be different. On Oct. 8, 2011, Earth will have a near head-on collision with a tendril of dust, setting off a strong outburst of as many as 750 meteors per hour." In fact, the 2011 Draconid meteor shower is expected to be so astounding that NASA has already begun preparing for the risk to satellites orbiting Earth such as the International Space Station or Hubble Space Telescope. "We're already working with NASA programs to deal with spacecraft risk," said William Cooke, a scientist with the Meteoroid Environment Office at NASA's Marshall Space Flight Center in Huntsville, Ala., during an interview with SPACE.com in June. "I imagine when the word gets out there will be a Draconid outburst, I'll get the usual calls from Comsat companies as well as government space programs." In addition to the chance of dings, there is the possibility of electrostatic discharges associated with the collision between a meteoroid and a satellite, Cooke said. Such discharges can account for a significant fraction of spacecraft anomalies during meteor showers, he added. While this year's Draconid meteor shower will likely be a bust, the 2011 Draconids should be a sight to behold, forecasters said.  The best vantage points will be Europe, Africa and the Middle East, Spaceweather.com reported. The 2011 Draconids could possibly be the most powerful meteor shower since the dazzling Leonids display 10 years ago, the website added. © 2010 Space.com. All rights reserved. More from Space.com. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

NASA thruster test aids future robotic lander's ability to land safely - PhysOrg Posted: 08 Oct 2010 07:35 AM PDT NASA's Marshall Space Flight Center in Huntsville, Ala., collaborated with NASA's White Sands Test Facility in Las Cruces, N.M., and Pratt & Whitney Rocketdyne in Canoga Park, Calif., to successfully complete a series of thruster tests at the White Sands test facility. The test will aid in maneuvering and landing the next generation of robotic lunar landers that could be used to explore the moon's surface and other airless celestial bodies. The Robotic Lunar Lander Development Project at the Marshall Center performed a series of hot-fire tests on two high thrust-to-weight thrusters – a 100-pound-class for lunar descent and a 5-pound-class for attitude control. The team used a lunar mission profile during the test of the miniaturized thrusters to assess the capability of these thruster technologies for possible use on future NASA spacecraft. The test program fully accomplished its objectives, including evaluation of combustion stability, engine efficiency, and the ability of the thruster to perform the mission profile and a long-duration, steady-state burn at full power. The test results will allow the Robotic Lander Project to move forward with robotic lander designs using advanced propulsion technology. You need Flash installed to watch this video NASA's Marshall Space Flight Center in Huntsville, Ala., has successfully completed tests on two thrusters at NASA's White Sands Test Facility in Las Cruces, N.M., to aid in manuevering and landing the next generation of robotic lunar landers that could be used to explore the moon's surface and other airless celestial bodies. The test articles are part of the Divert Attitude Control System, or DACS, developed by the U.S. Missile Defense Agency of the Department of Defense. The control system provides two kinds of propulsion -- one for control and the other for maneuvering. The Attitude Control System thrusters provide roll, pitch and yaw control. These small thruster types were chosen to meet the golf-cart-size lander's requirement for light-weight, compact propulsion components to aid in reducing overall spacecraft mass and mission cost by leveraging an existing government resource. "The Missile Defense Agency heritage thrusters were originally used for short-duration flights and had not been qualified for space missions, so our engineers tested them to assess their capability for long-duration burns and to evaluate their performance and combustion behavior," said Monica Hammond, lander propulsion task manager for the Robotic Lunar Lander Development Project at the Marshall Center. "The thrusters are a first step in reducing propulsion technology risks for a lander mission. The results will be instrumental in developing future plans associated with the lander's propulsion system design." During tests of the 100-pound thruster, the Divert Attitude Control System thruster fired under vacuum conditions to simulate operation in a space environment. The tests mimicked the lander mission profile and operation scenarios. The test included several trajectory correction maneuvers during the cruise phase; nutation control burns to maintain spacecraft orientation; thruster vector correction during the solid motor braking burn; and a terminal descent burn on approach to the lunar surface. The objective for the 5-pound-class thruster test was similar to the 100-pound thruster test with an additional emphasis on the thruster heating assessment due to the long-duration mission profile and operation with MMH/MON-25 -- monomethylhydrazine (MMH) fuel and a nitrogen tetroxide (75 percent)/nitrogen oxide (25 percent) (MON-25) oxidizer. A standard propellant system for spacecraft is the MMH/MON-3 propellant system -- containing 3 percent nitric oxide. An alternate propellant system, MMH/MON-25, contains 25 percent nitric oxide. With its chemical composition, it has a much lower freezing point than MON-3, making it an attractive alternative for spacecraft with its thermal benefits and resulting savings in heater power. Because the MMH/MON-25 propellant system has never been used in space, these tests allowed engineers to benchmark the test against the MMH/MON-3 propellant system. "The lower freezing point could save considerable heater power for the spacecraft and increase thermal margin for the entire propulsion system," said Huu Trinh, lead propulsion engineer for the Robotic Lunar Lander Development Project at the Marshall Center. "These tests showed stable combustion in all scenarios and favorable temperature results." This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

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“NASA thruster test aids future robotic lander's ability to land safely - PhysOrg”

---

NASA thruster test aids future robotic lander's ability to land safely - PhysOrg Posted: 08 Oct 2010 07:35 AM PDT NASA's Marshall Space Flight Center in Huntsville, Ala., collaborated with NASA's White Sands Test Facility in Las Cruces, N.M., and Pratt & Whitney Rocketdyne in Canoga Park, Calif., to successfully complete a series of thruster tests at the White Sands test facility. The test will aid in maneuvering and landing the next generation of robotic lunar landers that could be used to explore the moon's surface and other airless celestial bodies. The Robotic Lunar Lander Development Project at the Marshall Center performed a series of hot-fire tests on two high thrust-to-weight thrusters – a 100-pound-class for lunar descent and a 5-pound-class for attitude control. The team used a lunar mission profile during the test of the miniaturized thrusters to assess the capability of these thruster technologies for possible use on future NASA spacecraft. The test program fully accomplished its objectives, including evaluation of combustion stability, engine efficiency, and the ability of the thruster to perform the mission profile and a long-duration, steady-state burn at full power. The test results will allow the Robotic Lander Project to move forward with robotic lander designs using advanced propulsion technology. You need Flash installed to watch this video NASA's Marshall Space Flight Center in Huntsville, Ala., has successfully completed tests on two thrusters at NASA's White Sands Test Facility in Las Cruces, N.M., to aid in manuevering and landing the next generation of robotic lunar landers that could be used to explore the moon's surface and other airless celestial bodies. The test articles are part of the Divert Attitude Control System, or DACS, developed by the U.S. Missile Defense Agency of the Department of Defense. The control system provides two kinds of propulsion -- one for control and the other for maneuvering. The Attitude Control System thrusters provide roll, pitch and yaw control. These small thruster types were chosen to meet the golf-cart-size lander's requirement for light-weight, compact propulsion components to aid in reducing overall spacecraft mass and mission cost by leveraging an existing government resource. "The Missile Defense Agency heritage thrusters were originally used for short-duration flights and had not been qualified for space missions, so our engineers tested them to assess their capability for long-duration burns and to evaluate their performance and combustion behavior," said Monica Hammond, lander propulsion task manager for the Robotic Lunar Lander Development Project at the Marshall Center. "The thrusters are a first step in reducing propulsion technology risks for a lander mission. The results will be instrumental in developing future plans associated with the lander's propulsion system design." During tests of the 100-pound thruster, the Divert Attitude Control System thruster fired under vacuum conditions to simulate operation in a space environment. The tests mimicked the lander mission profile and operation scenarios. The test included several trajectory correction maneuvers during the cruise phase; nutation control burns to maintain spacecraft orientation; thruster vector correction during the solid motor braking burn; and a terminal descent burn on approach to the lunar surface. The objective for the 5-pound-class thruster test was similar to the 100-pound thruster test with an additional emphasis on the thruster heating assessment due to the long-duration mission profile and operation with MMH/MON-25 -- monomethylhydrazine (MMH) fuel and a nitrogen tetroxide (75 percent)/nitrogen oxide (25 percent) (MON-25) oxidizer. A standard propellant system for spacecraft is the MMH/MON-3 propellant system -- containing 3 percent nitric oxide. An alternate propellant system, MMH/MON-25, contains 25 percent nitric oxide. With its chemical composition, it has a much lower freezing point than MON-3, making it an attractive alternative for spacecraft with its thermal benefits and resulting savings in heater power. Because the MMH/MON-25 propellant system has never been used in space, these tests allowed engineers to benchmark the test against the MMH/MON-3 propellant system. "The lower freezing point could save considerable heater power for the spacecraft and increase thermal margin for the entire propulsion system," said Huu Trinh, lead propulsion engineer for the Robotic Lunar Lander Development Project at the Marshall Center. "These tests showed stable combustion in all scenarios and favorable temperature results." This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

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“Meteor Shower From Halley´s Comet Can Be Seen This Week - Short News”

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Meteor Shower From Halley´s Comet Can Be Seen This Week - Short News Posted: 21 Oct 2010 12:48 PM PDT In May and in mid-October, the orbit of Halley´s Comet is extraordinary close to the Earth. Then the small conglomerates of ice and dust the comet leaves behind collide with the Earth. The meteor shower that appears in May is called Eta Aquarids, the October-shower is called Orionids, as the meteors appear to come from Orion the Hunter. These Orionids move at a speed of 147,300 mph. The peak is today, on Oct. 21st. Halley´s Comet passes near Earth only once in 76 years (next time in 2061). This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe. This posting includes an audio/video/photo media file: Download Now

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“Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com”

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Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com Posted: 20 Oct 2010 07:20 AM PDT A junior version of the famous Perseid meteor shower thought to have originated from the remains of Halley's Comet will hit its peak over the next week, but the light of the moon may intrude on the sky show. This upcoming meteor display is known as the Orionids because the meteors seem to fan out from a region to the north of the Orion constellation's second brightest star, ruddy Betelgeuse. The annual event peaks before sunrise on Thursday (Oct. 21) but several viewing opportunities arise before then for skywatchers in North America. [ Where to look to see the Orionids ] The shooting stars are created by small bits of space dust — most no larger than sand grains — thought to be left over from the famed Halley's Comet, which orbits the sun once every 76 years. Currently, Orion appears ahead of us in our journey around the sun, and has not completely risen above the eastern horizon until after 11 p.m. local daylight time. The constellation is at its best several hours later. At around 5 a.m. – Orion will be highest in the sky toward the south – Orionids typically produce around 20 to 30 meteors per hour under a clear, dark sky. But skywatchers beware: You will be facing a major obstacle in your attempt to observe this year's Orionid performance. As bad luck would have it, the moon will turn full on Oct. 23. Bright moonlight outshines fainter meteors, seriously reducing the number anyone can see. The gradual build up to the full moon will hamper – if not outright prevent – dark-sky observing during the Orionid meteor shower's peak on Oct. 21. The Orionids are actually already underway, having been active only in a very weak and scattered form since about Oct. 2. But a noticeable upswing in activity is expected to begin around Oct. 17, leading up to their peak night.  "Orionid meteors are normally dim and not well seen from urban locations," notes meteor expert, Robert Lunsford, adding that "it is highly suggested that you find a safe rural location to see the best Orionid activity." Damage control for 2010 With all this as a background, perhaps the best times to look this year will be during the predawn hours several mornings before the night of full moon. That's when the constellation Orion (from where the meteors get their name) will stand high in the northeast sky.  In fact, three "windows" of dark skies will be available between moonset and the first light of dawn on the mornings of Oct. 18, 19 and 20. Generally speaking, there will be about 150 minutes of completely dark skies available on the morning of the 18th.This shrinks to about 100 minutes on the 19th, and to about 50 minutes by the morning of the 20th. This skywatching table shows prime Orionid meteor shower viewing times for some select U.S. cities. In the table, all times are a.m. and are local daylight times. "Dawn" is the time when morning (astronomical) twilight begins. A "Window" is the number of minutes between the time of moonset and the start of twilight. For example: When will the sky be dark and moonless for Orionid viewing on the morning of Oct. 20 from Houston?  Answer: There will be a 50-minute period of dark skies beginning at moonset (5:16 a.m.) and continuing until dawn breaks (6:06 a.m.). Perhaps up to a dozen forerunners of the main Orionid display might appear to steak by within an hour's watch on these mornings, particularly on the 20th, the morning before the peak. It might even be worthwhile to try on Thursday morning, Oct. 21, although for most places, the moon will not set until just after the first light of dawn.  Halley's legacy In studying the orbits of many meteor swarms, astronomers have found that they correspond closely to the orbits of known comets. The Orionids are thought to result from the orbit of Halley's Comet, as some of the dust that has been shed by this famous object intersect earth's orbit around the sun during October. There are actually two points along Halley's path, where it comes relatively near to our orbit. Another one of these points occurs in early May causing a meteor display from the constellation Aquarius, the Water Carrier. The tiny particles that are responsible for the Orionid and Aquarid meteors are – like Halley itself – moving through space in a direction opposite to that the earth. This results in meteors that ram through our atmosphere very swiftly at 41 miles (66 km) per second. Of all the meteor displays, only the November Leonids move faster. Orionid postmortem After the peak, activity will begin to slowly descend, although most of the meteors will be squelched by the light of the moon. Rates drop back to around five per hour around Oct. 26. The last stragglers usually appear sometime around Nov. 7. It is indeed unfortunate that the Moon will likely obliterate most of the Orionids in the nights following the peak, but the viewing odds will be much better before the break of dawn on those mornings leading up to the peak. Almost certainly, you should sight at least a few of these offspring of Halley's Comet as they streak across the sky. In the absence of moonlight a single observer might see at least a couple of dozen meteors per hour on the morning of the peak, a number that sadly can not be hoped to be approached in 2010. In fact, it appears that this year, fans of the Orionids will be uttering the same lament that the old Dodger fans in Brooklyn used to: "Wait till next year!"  © 2010 Space.com. All rights reserved. More from Space.com. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe.

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“NASA Cameras Spot Meteor From Obscure Shower - The Future of Things”

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NASA Cameras Spot Meteor From Obscure Shower - The Future of Things Posted: 11 Oct 2010 04:06 PM PDT It's a strange-sounding name for a constellation, coming from the Greco-Roman word for giraffe, or "camel leopard". The October Camelopardalids are a collection of faint stars that have no mythology associated with them -- in fact, they didn't begin to appear on star charts until the 17th century. Even experienced amateur astronomers are hard-pressed to find the constellation in the night sky. (source: nasa.gov) No comments have been posted for this item. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe.

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“Moonlight meteor shower spawned by Halley's Comet - msnbc.com”

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Moonlight meteor shower spawned by Halley's Comet - msnbc.com Posted: 18 Oct 2010 08:06 AM PDT A junior version of the famous Perseid meteor shower thought to have originated from the remains of Halley's Comet will hit its peak over the next week, but the light of the moon may intrude on the sky show. This upcoming meteor display is known as the Orionids because the meteors seem to fan out from a region to the north of the Orion constellation's second brightest star, ruddy Betelgeuse. The annual event peaks before sunrise on Thursday (Oct. 21) but several viewing opportunities arise before then for skywatchers in North America. [ Where to look to see the Orionids ] The shooting stars are created by small bits of space dust — most no larger than sand grains — thought to be left over from the famed Halley's Comet, which orbits the sun once every 76 years. Currently, Orion appears ahead of us in our journey around the sun, and has not completely risen above the eastern horizon until after 11 p.m. local daylight time. The constellation is at its best several hours later. At around 5 a.m. — Orion will be highest in the sky toward the south – Orionids typically produce around 20 to 30 meteors per hour under a clear, dark sky. But skywatchers beware: You will be facing a major obstacle in your attempt to observe this year's Orionid performance. As bad luck would have it, the moon will turn full on Oct. 23. Bright moonlight outshines fainter meteors, seriously reducing the number anyone can see. The gradual build up to the full moonwill hamper — if not outright prevent — dark-sky observing during the Orionid meteor shower's peak on Oct. 21. The Orionids are actually already underway, having been active only in a very weak and scattered form since about Oct. 2. But a noticeable upswing in activity is expected to begin around Oct. 17, leading up to their peak night.  "Orionid meteors are normally dim and not well seen from urban locations," notes meteor expert, Robert Lunsford, adding that "it is highly suggested that you find a safe rural location to see the best Orionid activity." Damage control for 2010 With all this as a background, perhaps the best times to look this year will be during the predawn hours several mornings before the night of full moon. That's when the constellation Orion (from where the meteors get their name) will stand high in the northeast sky.  In fact, three "windows" of dark skies will be available between moonset and the first light of dawn on the mornings of Oct. 18, 19 and 20. Generally speaking, there will be about 150 minutes of completely dark skies available on the morning of the 18th.This shrinks to about 100 minutes on the 19th, and to about 50 minutes by the morning of the 20th. This skywatching table shows prime Orionid meteor shower viewing times for some select U.S. cities. In the table, all times are a.m. and are local daylight times. "Dawn" is the time when morning (astronomical) twilight begins. A "Window" is the number of minutes between the time of moonset and the start of twilight. For example: When will the sky be dark and moonless for Orionid viewing on the morning of Oct. 20 from Houston?  Answer: There will be a 50-minute period of dark skies beginning at moonset (5:16 a.m.) and continuing until dawn breaks (6:06 a.m.). Perhaps up to a dozen forerunners of the main Orionid display might appear to steak by within an hour's watch on these mornings, particularly on the 20th, the morning before the peak. It might even be worthwhile to try on Thursday morning, Oct. 21, although for most places, the moon will not set until just after the first light of dawn.  Halley's legacy In studying the orbits of many meteor swarms, astronomers have found that they correspond closely to the orbits of known comets. The Orionids are thought to result from the orbit of Halley's Comet, as some of the dust that has been shed by this famous object intersect earth's orbit around the sun during October. There are actually two points along Halley's path, where it comes relatively near to our orbit. Another one of these points occurs in early May causing a meteor display from the constellation Aquarius, the Water Carrier. The tiny particles that are responsible for the Orionid and Aquarid meteors are — like Halley itself — moving through space in a direction opposite to that the earth. This results in meteors that ram through our atmosphere very swiftly at 41 miles (66 km) per second. Of all the meteor displays, only the November Leonids move faster. Orionid postmortem After the peak, activity will begin to slowly descend, although most of the meteors will be squelched by the light of the moon. Rates drop back to around five per hour around Oct. 26. The last stragglers usually appear sometime around Nov. 7. It is indeed unfortunate that the Moon will likely obliterate most of the Orionids in the nights following the peak, but the viewing odds will be much better before the break of dawn on those mornings leading up to the peak. Almost certainly, you should sight at least a few of these offspring of Halley's Comet as they streak across the sky. In the absence of moonlight a single observer might see at least a couple of dozen meteors per hour on the morning of the peak, a number that sadly can not be hoped to be approached in 2010. In fact, it appears that this year, fans of the Orionids will be uttering the same lament that the old Dodger fans in Brooklyn used to: "Wait till next year!"  © 2010 Space.com. All rights reserved. More from Space.com. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php Five Filters featured article: Beyond Hiroshima - The Non-Reporting of Falluja's Cancer Catastrophe.

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