sheeny
05-09-2006, 08:03 AM
I found this from news @ nature this morning,
Al..
Moon mission ends with a bang
Last orbits for triumphant craft produce memorable photo album.
Michael Hopkin (http://www.nature.com/news/about/aboutus.html#Hopkin)
http://www.nature.com/news/images/spacer_pink.gifhttp://www.nature.com/images/spacer.gifThe scientists behind the SMART-1 mission, which ended literally in a blaze of glory at the weekend, have unveiled a series of images taken in the final days of the craft's 3-year voyage.
The pictures show a range of lunar features, including peaks of perpetual sunlight — regions near the lunar north pole that never see shade, and might therefore make promising sites for solar power generators.
The mission team's predictions for the timing and location of the craft's crashdown were almost spot-on, giving them time to instruct SMART-1's cameras to take several valuable shots on the orbits leading up to the crash.
The final stages of flight were at a very shallow angle (it crash-landed at a mere 1º to the lunar surface, similar to the angle at which a commercial aircraft lands), giving the cameras pointing forwards (http://www.esa.int/esaCP/SEMC378ZMRE_index_1.html#subhead1) and downwards (http://www.esa.int/esaCP/SEMC378ZMRE_index_1.html#subhead2) close-up opportunities not known since the Apollo astronauts walked on the Moon.
A sequence of images taken on 29 August also snapped the unique view of the Moon passing between the craft and the Earth (http://www.esa.int/esaCP/SEMC378ZMRE_index_1.html).
Star bright
Astronomers at the ground-based Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, snapped (http://esamultimedia.esa.int/images/smart_1/b_Impact_flash_865170.jpg) the moment of impact on Saturday night.
Scientists have yet to analyse the pictures for any information they might be able to squeeze out about the dust kicked up by the impact. But astronomers have already said that the brightness of the impact was a surprise. It "created a more intense flash than expected", says mission chief Bernard Foing, who watched the impact at the European Space Agency's facility in Darmstadt, Germany. The flash may have been fuelled by the ignition of the handful of hydrazine fuel remaining on board.
Although the impact was not expected to be visible without the aid of binoculars or a telescope, one observer has contacted Nature's newsblog (http://blogs.nature.com/news/blog/2006/08/moon.html) to say that they may have spotted it in the partially cloudy sky from a balcony in Honolulu.
Mission scientists suspect that, because of the craft's shallow run-in, that it will have bounced rather than buried itself. Planetary scientists now plan to examine the furrow, which will have dredged up previously buried lunar rock, to further examine the composition of the Moon.
SMART-1 has a history of geological research. One of its achievements during its 16 months in lunar orbit was to use X-ray images to remotely detect calcium on the Moon — an element also common in Earth's crust. Whereas the geology of Moon rock has been studied in samples brought back to Earth, remote mapping of elements on our satellite is something that researchers are still keen to improve on.
Nature
Published online: 30 August 2006; | doi:10.1038/442969a
Lunar probe ready to bite the dust
SMART-1 prepares to go out with a bang.
Geoff Brumfiel (http://www.nature.com/news/about/aboutus.html#Brumfiel)
After nearly three years in space, Europe's Moon mission is out of fuel. On 3 September the spacecraft SMART-1 will smash into the lunar surface near the Lake of Excellence in the Moon's mid-southern latitudes. Astronomers hope the dust kicked up from the rocky site will provide information about the Moon's composition and impact history.
Researchers at the European Space Agency (ESA) are very happy with what the mission has achieved. The craft was the agency's test-bed for a new type of thruster called an ion engine. SMART-1 is the second such engine to be used in space — the first was on board NASA's comet-chaser Deep Space 1.
Ion engines work by accelerating a stream of ionized atoms through an electric field. The one on SMART-1 provides about as much force as a postcard resting in the palm of your hand. That made its journey painfully slow: it took 14 months and a roundabout trip of 84 million kilometres for it to spiral out of Earth's orbit and reach the Moon. In contrast, Apollo 11's conventional propellants allowed it to travel a roughly 400,000-kilometre line between Earth and the Moon in just over 3 days.
The upside is that SMART-1's journey used around 70 kilograms of fuel, about ten times less than would have been needed with regular propellants. So, although ion engines pick up speed quite slowly, they are extremely effective — and fast — for long-distance trips using light craft.
Learning to drive an ion engine is different from using chemical propellants, according to SMART-1 project scientist Bernard Foing. Chemical propellants are used in short burns lasting seconds or minutes. For those critical periods a craft must be precisely controlled, but otherwise it coasts passively to its destination. But ion drives are always on, so the course of the craft must be constantly monitored and corrected. "It's much more complicated than driving with chemical energy," says Foing.
Using an ion engine is much more complicated than driving with chemical energy. http://www.nature.com/images/spacer.gifhttp://www.nature.com/images/spacer.gif
Despite a few episodes in which the engine spontaneously switched itself off, Foing says that SMART-1 performed well — good news for ESA's upcoming BepiColombo mission to Mercury in 2013. BepiColombo will use conventional propellants to break out of Earth's orbit quickly, then an ion drive to speed towards the Sun. The engine's tiny but continuous thrust over the course of months should cut flight time in half.
Once SMART-1 arrived at its destination, it used a digital camera and two spectrometers to survey the Moon's surface. The craft orbited for 22 months gathering data on the abundances of calcium, aluminium, magnesium and silicon on the lunar surface.
Several teams have been awaiting the release of the full results. For example, Wim van Westrenen, a petrologist at the Free University in Amsterdam, hopes they will help him investigate the Moon's origin. Most lunar researchers believe that the satellite formed when another body crashed into Earth billions of years ago. But it's not clear, for example, which of the two colliding bodies contributed most of the Moon's mass.
"There are dozens of models for where and how and what materials melted in the Moon," says van Westrenen. In a five-year project starting in January 2007, he hopes to work out how the process occurred by crushing various combinations of materials at the high temperatures and pressures that would have been present when the Moon formed, to try to recreate the exact composition detected by SMART-1.
ESA's mission will be followed by a glut of lunar visits. In 2007, Japan is scheduled to launch SELENE, a 3-tonne spacecraft that will survey the Moon's mineralogy, topology and gravity gradients. The same year, India will launch Chandrayaan-1 and China will launch Chang'e 1 — both will be those countries' first missions beyond Earth orbit. In 2008 NASA will launch its Lunar Reconnaissance Orbiter to survey the Moon's surface.
The overlap probably has more to do with national pride than science. But Paul Spudis, a lunar specialist at Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland, says that the data will be welcome nonetheless. In the rush to beat the Soviet Union to the Moon, the Apollo programme did only piecemeal mapping of the satellite's surface. And after astronauts finished their visits, he says it was ignored for decades by planetary researchers. "Mars has better global imaging than the Moon does."
Al..
Moon mission ends with a bang
Last orbits for triumphant craft produce memorable photo album.
Michael Hopkin (http://www.nature.com/news/about/aboutus.html#Hopkin)
http://www.nature.com/news/images/spacer_pink.gifhttp://www.nature.com/images/spacer.gifThe scientists behind the SMART-1 mission, which ended literally in a blaze of glory at the weekend, have unveiled a series of images taken in the final days of the craft's 3-year voyage.
The pictures show a range of lunar features, including peaks of perpetual sunlight — regions near the lunar north pole that never see shade, and might therefore make promising sites for solar power generators.
The mission team's predictions for the timing and location of the craft's crashdown were almost spot-on, giving them time to instruct SMART-1's cameras to take several valuable shots on the orbits leading up to the crash.
The final stages of flight were at a very shallow angle (it crash-landed at a mere 1º to the lunar surface, similar to the angle at which a commercial aircraft lands), giving the cameras pointing forwards (http://www.esa.int/esaCP/SEMC378ZMRE_index_1.html#subhead1) and downwards (http://www.esa.int/esaCP/SEMC378ZMRE_index_1.html#subhead2) close-up opportunities not known since the Apollo astronauts walked on the Moon.
A sequence of images taken on 29 August also snapped the unique view of the Moon passing between the craft and the Earth (http://www.esa.int/esaCP/SEMC378ZMRE_index_1.html).
Star bright
Astronomers at the ground-based Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, snapped (http://esamultimedia.esa.int/images/smart_1/b_Impact_flash_865170.jpg) the moment of impact on Saturday night.
Scientists have yet to analyse the pictures for any information they might be able to squeeze out about the dust kicked up by the impact. But astronomers have already said that the brightness of the impact was a surprise. It "created a more intense flash than expected", says mission chief Bernard Foing, who watched the impact at the European Space Agency's facility in Darmstadt, Germany. The flash may have been fuelled by the ignition of the handful of hydrazine fuel remaining on board.
Although the impact was not expected to be visible without the aid of binoculars or a telescope, one observer has contacted Nature's newsblog (http://blogs.nature.com/news/blog/2006/08/moon.html) to say that they may have spotted it in the partially cloudy sky from a balcony in Honolulu.
Mission scientists suspect that, because of the craft's shallow run-in, that it will have bounced rather than buried itself. Planetary scientists now plan to examine the furrow, which will have dredged up previously buried lunar rock, to further examine the composition of the Moon.
SMART-1 has a history of geological research. One of its achievements during its 16 months in lunar orbit was to use X-ray images to remotely detect calcium on the Moon — an element also common in Earth's crust. Whereas the geology of Moon rock has been studied in samples brought back to Earth, remote mapping of elements on our satellite is something that researchers are still keen to improve on.
Nature
Published online: 30 August 2006; | doi:10.1038/442969a
Lunar probe ready to bite the dust
SMART-1 prepares to go out with a bang.
Geoff Brumfiel (http://www.nature.com/news/about/aboutus.html#Brumfiel)
After nearly three years in space, Europe's Moon mission is out of fuel. On 3 September the spacecraft SMART-1 will smash into the lunar surface near the Lake of Excellence in the Moon's mid-southern latitudes. Astronomers hope the dust kicked up from the rocky site will provide information about the Moon's composition and impact history.
Researchers at the European Space Agency (ESA) are very happy with what the mission has achieved. The craft was the agency's test-bed for a new type of thruster called an ion engine. SMART-1 is the second such engine to be used in space — the first was on board NASA's comet-chaser Deep Space 1.
Ion engines work by accelerating a stream of ionized atoms through an electric field. The one on SMART-1 provides about as much force as a postcard resting in the palm of your hand. That made its journey painfully slow: it took 14 months and a roundabout trip of 84 million kilometres for it to spiral out of Earth's orbit and reach the Moon. In contrast, Apollo 11's conventional propellants allowed it to travel a roughly 400,000-kilometre line between Earth and the Moon in just over 3 days.
The upside is that SMART-1's journey used around 70 kilograms of fuel, about ten times less than would have been needed with regular propellants. So, although ion engines pick up speed quite slowly, they are extremely effective — and fast — for long-distance trips using light craft.
Learning to drive an ion engine is different from using chemical propellants, according to SMART-1 project scientist Bernard Foing. Chemical propellants are used in short burns lasting seconds or minutes. For those critical periods a craft must be precisely controlled, but otherwise it coasts passively to its destination. But ion drives are always on, so the course of the craft must be constantly monitored and corrected. "It's much more complicated than driving with chemical energy," says Foing.
Using an ion engine is much more complicated than driving with chemical energy. http://www.nature.com/images/spacer.gifhttp://www.nature.com/images/spacer.gif
Despite a few episodes in which the engine spontaneously switched itself off, Foing says that SMART-1 performed well — good news for ESA's upcoming BepiColombo mission to Mercury in 2013. BepiColombo will use conventional propellants to break out of Earth's orbit quickly, then an ion drive to speed towards the Sun. The engine's tiny but continuous thrust over the course of months should cut flight time in half.
Once SMART-1 arrived at its destination, it used a digital camera and two spectrometers to survey the Moon's surface. The craft orbited for 22 months gathering data on the abundances of calcium, aluminium, magnesium and silicon on the lunar surface.
Several teams have been awaiting the release of the full results. For example, Wim van Westrenen, a petrologist at the Free University in Amsterdam, hopes they will help him investigate the Moon's origin. Most lunar researchers believe that the satellite formed when another body crashed into Earth billions of years ago. But it's not clear, for example, which of the two colliding bodies contributed most of the Moon's mass.
"There are dozens of models for where and how and what materials melted in the Moon," says van Westrenen. In a five-year project starting in January 2007, he hopes to work out how the process occurred by crushing various combinations of materials at the high temperatures and pressures that would have been present when the Moon formed, to try to recreate the exact composition detected by SMART-1.
ESA's mission will be followed by a glut of lunar visits. In 2007, Japan is scheduled to launch SELENE, a 3-tonne spacecraft that will survey the Moon's mineralogy, topology and gravity gradients. The same year, India will launch Chandrayaan-1 and China will launch Chang'e 1 — both will be those countries' first missions beyond Earth orbit. In 2008 NASA will launch its Lunar Reconnaissance Orbiter to survey the Moon's surface.
The overlap probably has more to do with national pride than science. But Paul Spudis, a lunar specialist at Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland, says that the data will be welcome nonetheless. In the rush to beat the Soviet Union to the Moon, the Apollo programme did only piecemeal mapping of the satellite's surface. And after astronauts finished their visits, he says it was ignored for decades by planetary researchers. "Mars has better global imaging than the Moon does."