SMART-1: Difference between revisions
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===Going out with a bang=== |
===Going out with a bang=== |
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3 September 2006 at 05:42:22 UT today, the SMART-1 spacecraft impacted the Moon's surface as planned, ending ESA's first solar-powered mission to another celestial body and Europe's first mission to the Moon. ESA estimates that impact ocurred at 46.2º West, 34.4º South. |
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SMART-1 |
SMART-1 impacted the Moon's surface as planned, on [[September 3]], [[2006]] at 05:42:22 [[Universal Coordinated Time|UTC]], ending its mission. Moving at approximately 2000 m/s, SMART-1 created an impact visible with ground telescopes from Earth. It is hoped that not only will this provide some data simulating a meteor impact, but also that it might expose materials in the ground, like water ice, to spectroscopic analysis. |
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ESA estimates that impact ocurred at {{coor dm|34|24|S|46|12|W|globe:Moon}}. These numbers can be entered into NASA's [[World Wind]], to see where on the Moon it crashed. At the time of impact, the Moon will be visible in North and South America, and places in the Pacific Ocean, but not Europe, Africa, or western Asia. |
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==Important events and discoveries== |
==Important events and discoveries== |
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Revision as of 06:05, 3 September 2006
 | This article documents a current event. Information may change rapidly as the event progresses, and initial news reports may be unreliable. The latest updates to this article may not reflect the most current information. |
Smart 1 or SMART-1 is a European Space Agency satellite that orbits around Earth's Moon. "SMART" stands for Small Missions for Advanced Research in Technology.
On September 3, 2006, SMART-1 is programmed to crash into the Moon's surface, ending its mission. If the impact raises enough dust, it may be visible with binoculars or small telescopes.
Spacecraft Design
SMART-1 is about one metre (approximately 3 feet) across, and lightweight as probes go. Its launch mass was 367 kg or 815 pounds, of which 287 kg was non-propellant.
It is powered by a solar-powered Hall effect thruster using xenon propellant, of which there was 60 litres at launch (this amounts to 80 kg). The thrusters use an electrostatic field to ionize the xenon and accelerate the ions to a high velocity. This ion engine setup achieves a specific impulse of 16.1 kN·s/kg (1640 seconds), more than three times the maximum for chemical rockets. Therefore 1 kg of propellant (1/350 to 1/300 of the total mass of the spacecraft) produces a delta-v of about 45 m/s.
The solar arrays make 1190 W available for powering the thruster, giving a nominal thrust of 68 mN, hence an acceleration of 0.2 mm/s² or 0.7 m/s per hour. As for all ion-engine powered craft, orbital maneuvers are not carried out in short bursts but very gradually. The particular trajectory taken by SMART-1 to the Moon requires thrusting for about one third to one half of every orbit. When spiralling away from the Earth thrusting is done on the perigee part of the orbit. The total delta-v expected over the thrusting lifetime of 5,000 hours is about 4 km/s, corresponding to a total impulse of 1.5 MN·s.
As part of the European Space Agency's strategy to build very inexpensive and relatively small spaceships, the total cost of SMART-1 was a relatively small 110 million euros (about 126 million U.S. dollars).
SMART-1 was developed by the Swedish Space Corporation[1] and built by Saab Ericsson Space in Linköping[2] on behalf of ESA.
Mission
As a part of Small Missions for Advanced Research in Technology, SMART-1 will test new spacecraft technologies. The primary objective of SMART-1 is to test the solar-powered ion thruster. It will also be testing the miniaturized scientific instruments, which are thought to be more efficient. If successful, these technologies will be used on future ESA missions.
A secondary objective is to learn more information about the Moon, such as how it was created. SMART-1 will map the lunar surface by way of X-ray and infrared imaging, taking images from several different angles so that the Moon's surface can be mapped in three dimensions. It will also determine the Moon's chemical composition using X-ray spectroscopy. A specific goal is to use infrared light to search for frozen water at the Moon's south pole, where some areas of the surface are never exposed to direct sunlight. It is also mapping the Moon's Peaks of Eternal Light (PELs), eerie mountaintops which are permanently bathed in sunlight and surrounded by craters shaded in eternal darkness.
Flight
SMART-1 was launched September 27, 2003 together with Insat 3E and eBird 1, by an Ariane 5 rocket from the Guiana Space Center in French Guiana. After 42 minutes it was released into a geostationary transfer orbit of 7035 × 42 223 km. From there it used its Solar Electric Primary Propulsion (SEPP) to gradually spiral out during thirteen months.
You can see the orbit up to October 26, 2004 at moontoday.net, when the orbit was 179 718 × 305 214 km. On that date, after the 289th engine pulse, the SEPP had accumulated a total on-time of nearly 3648 hours out of a total flight time of 8000 hours, hence a little less than half of its total mission. It consumed about 58.8 kg of xenon and produced a delta-v of 2737 m/s (46.5 m/s per kg xenon, 0.75 m/s per hour on-time). It was powered on again on November 15 for a planned burn of 4.5 days to enter fully into lunar orbit. It took until February 2005 using the electric thruster to decelerate into the final orbit 300-3000 km above the Moon's surface.
| Summary of osculating geocentric orbital elements | |||||
|---|---|---|---|---|---|
| Epoch (UTC) | Perigee (km) | Apogee (km) | Eccentricity | Inclination (deg) (to Earth equator) |
Period (h) |
| September 27, 2003 | ~7 035 | ~42 223 | ~0,714 | ~6.9 | ~10.6833 |
| October 26, 2003, 21:20:00.0 | 8 687.994 | 44 178.401 | 0.671323 | 6.914596 | 11.880450 |
| November 16, 2003, 04:29:48.4 | 10 843.910 | 46 582.165 | 0.622335 | 6.861354 | 13.450152 |
| December 8, 2003, 06:41:47.6 | 13 390.351 | 49 369.049 | 0.573280 | 6.825455 | 15.366738 |
| December 29, 2003, 05:21:47.8 | 17 235.509 | 54 102.642 | 0.516794 | 6.847919 | 18.622855 |
| February 1, 2004, 22:46:08.6 | 20 690.564 | 65 869.222 | 0.521936 | 6.906311 | 24.890737 |
| March 1, 2004, 00:40:52.7 | 20 683.545 | 66 915.919 | 0.527770 | 6.979793 | 25.340528 |
| August 25, 2004, 00:00:00 | 37 791.261 | 240 824.363 | 0.728721 | 6.939815 | 143.738051 |
| October 1, 2004, 21:30:45.9 | 69 959.278 | 292 632.424 | 0.614115 | 12.477919 | 213.397970 |
| October 26, 2004, 06:12:40.9 | 179 717.894 | 305 214.126 | 0.258791 | 20.591807 | 330.053834 |
After its last perigee on November 2,[3] on November 11, 2004 it passed through the L1 Lagrangian Point and into the area dominated by the Moon's gravitational influence, and at 1748 UT on November 15 passed the first periselene of its lunar orbit. The osculating orbit on that date was 6704 × 53 208 km,[4] with an orbital period of 129 hours, although the actual orbit was accomplished in only 89 hours. This illustrates the significant impact that the engine burns have on the orbit and marks the meaning of the osculating orbit, which is the orbit that would be travelled by the spacecraft if at that instant all perturbations, including thrust, would cease.
| Summary of osculating selenocentric orbital elements | |||||
|---|---|---|---|---|---|
| Epoch (UTC) | Periselene (km) | Aposelene (km) | Eccentricity | Inclination (deg) (to Moon equator) |
Period (h) |
| November 15, 2004, 17:47:12.1 | 6 700.720 | 53 215.151 | 0.776329 | 81.085 | 129.247777 |
| December 4, 2004 10:37:47.3 | 5 454.925 | 20 713.095 | 0.583085 | 83.035 | 37.304959 |
| January 9, 2005, 15:24:55.0 | 2 751.511 | 6 941.359 | 0.432261 | 87.892 | 8.409861 |
| February 28, 2005, 05:18:39.9 | 2 208.659 | 4 618.220 | 0.352952 | 90.063603 | 4.970998 |
| April 25, 2005, 08:19:05.4 | 2 283.738 | 4 523.111 | 0.328988 | 90.141407 | 4.949137 |
| May 16, 2005, 09:08:52.9 | 2 291.250 | 4 515.857 | 0.326807 | 89.734929 | 4.949919 |
| June 20, 2005, 10:21:37.1 | 2 256.090 | 4 549.196 | 0.336960 | 90.232619 | 4.947432 |
| July 18, 2005, 11:14:28.0 | 2 204.645 | 4 600.376 | 0.352054 | 90.263741 | 4.947143 |
ESA announced on February 15, 2005, the endorsement of a proposal to extend the mission of SMART-1 by one year until August 2006. This date was later shifted to September 3, 2006, to "favour scientific observations from Earth".[5]
Going out with a bang
3 September 2006 at 05:42:22 UT today, the SMART-1 spacecraft impacted the Moon's surface as planned, ending ESA's first solar-powered mission to another celestial body and Europe's first mission to the Moon. ESA estimates that impact ocurred at 46.2º West, 34.4º South.
SMART-1 impacted the Moon's surface as planned, on September 3, 2006 at 05:42:22 UTC, ending its mission. Moving at approximately 2000 m/s, SMART-1 created an impact visible with ground telescopes from Earth. It is hoped that not only will this provide some data simulating a meteor impact, but also that it might expose materials in the ground, like water ice, to spectroscopic analysis.
ESA estimates that impact ocurred at 34°24′S 46°12′W / 34.400°S 46.200°W. These numbers can be entered into NASA's World Wind, to see where on the Moon it crashed. At the time of impact, the Moon will be visible in North and South America, and places in the Pacific Ocean, but not Europe, Africa, or western Asia.
Important events and discoveries
- June 17, 2004: SMART-1 took a test image of Earth with the camera that will be used for Moon closeup pictures. It shows parts of Europe and Africa. It was taken on May 21 with the AMIE camera, a compact imaging device with a weight of 450 grams.
- November 2, 2004: Last perigee of Earth orbit.
- November 15, 2004: First perilune of lunar orbit.
- January 15, 2005: Calcium detected in Mare Crisium.
- January 26, 2005: First close up pictures of the lunar surface sent back.
- February 27, 2005: Reached final orbit around the Moon with an orbital period of about 5 hours.
- April 15, 2005: The search for PELs begins.
- June 8, 2005: ESA announces that calcium was detected on the Moon.