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Post Info TOPIC: NEAR, 433 Eros


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Asteroid (433) Eros
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Ephemeris

Date       UT      R.A. (J2000) Decl.    Delta     r     El.    Ph.   V 
2011 10 16 000000 06 24 34.1 +46 02 33   0.625   1.315  106.1  46.7  12.0
2011 10 26 000000 07 03 30.2 +46 52 10   0.557   1.284  108.4  47.3  11.7
2011 11 05 000000 07 43 02.6 +46 54 42   0.495   1.255  110.6  47.7  11.4
2011 11 15 000000 08 21 54.7 +46 01 44   0.437   1.227  112.8  48.0  11.1
2011 11 25 000000 08 58 30.7 +44 06 38   0.384   1.202  115.1  48.1  10.8
2011 12 05 000000 09 31 11.4 +41 02 06   0.336   1.180  117.7  47.7  10.4
2011 12 15 000000 09 58 45.2 +36 38 33   0.292   1.162  120.9  46.7  10.1
2011 12 25 000000 10 20 05.7 +30 45 11   0.254   1.148  124.9  44.7   9.7
2012 01 04 000000 10 34 14.5 +23 08 20   0.221   1.138  130.0  41.4   9.3
2012 01 14 000000 10 40 41.3 +13 42 11   0.197   1.134  136.3  36.8   8.9
2012 01 24 000000 10 39 01.8 +02 53 59   0.182   1.134  142.7  31.7   8.7
2012 02 03 000000 10 29 55.7 -07 57 55   0.179   1.140  147.3  27.9   8.5
2012 02 13 000000 10 15 58.1 -17 07 31   0.188   1.151  148.2  26.9   8.6
2012 02 23 000000 10 00 56.6 -23 24 45   0.206   1.166  146.0  28.3   8.9
2012 03 04 000000 09 49 12.4 -26 48 05   0.233   1.185  142.6  30.5   9.3
2012 03 14 000000 09 43 28.4 -28 00 05   0.266   1.208  139.1  32.6   9.6
2012 03 24 000000 09 44 17.8 -27 47 10   0.305   1.234  135.7  34.3  10.0
2012 04 03 000000 09 51 12.9 -26 48 30   0.349   1.262  132.4  35.8  10.4
2012 04 13 000000 10 03 00.5 -25 31 40   0.399   1.292  129.1  37.0  10.8
2012 04 23 000000 10 18 27.5 -24 12 51   0.455   1.324  125.7  38.1  11.1
2012 05 03 000000 10 36 38.3 -23 03 10   0.516   1.356  122.2  39.0  11.5


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RE: NEAR, 433 Eros
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Asteroid (433) Eros is at Opposition on the 1st March, 2012.

Magnitude: 9.2
Distance to Earth: 0.226 AU = 87.8 lunar distances 
Distance to Sun: 1.180 AU 



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Asteroid (433) Eros
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The Regolith of Asteroid Eros

regolith_near_481.jpg
Credit: NEAR Project, JHU APL, NASA

 From fifty kilometres above asteroid Eros, the surface inside one of its largest craters appears covered with an unusual substance: regolith. The thickness and composition of the surface dust that is regolith remains a topic of much research. Much of the regolith on 433 Eros was probably created by numerous small impacts during its long history.

Source 



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RE: NEAR, 433 Eros
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The Near Earth Asteroid Rendezvous - Shoemaker (NEAR Shoemaker), renamed after its launch in honour of planetary scientist Eugene M. Shoemaker, is a robotic space probe designed to study the near-Earth asteroid Eros from close orbit over a period of a year. The primary scientific objective of NEAR was to return data on the bulk properties, composition, mineralogy, morphology, internal mass distribution and magnetic field of Eros. Secondary objectives include studies of regolith properties, interactions with the solar wind, possible current activity as indicated by dust or gas, and the asteroid spin state. This data will be used to help understand the characteristics of asteroids in general, their relationship to meteorites and comets, and the conditions in the early solar system. To accomplish these goals, the spacecraft was equipped with an X-ray/gamma ray spectrometer, a near-infrared imaging spectrograph, a multi-spectral camera fitted with a CCD imaging detector, a laser rangefinder, and a magnetometer. A radio science experiment was also performed using the NEAR tracking system to estimate the gravity field of the asteroid. The total mass of the instruments was 56 kg, and they required 81 W power. 


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The opening ceremony for the Near Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft exhibit at Discovery Station at Hagerstown will be today at 11 a.m.

Discovery Station and Johns Hopkins University's Applied Physics Laboratory (APL) are coordinating the first of a year-round continuing exhibit opening at the museum with a one-quarter scale model of the spacecraft.
The spacecraft was launched Feb. 17, 1996, from Cape Canaveral, Florida, and was programmed to rendezvous Feb. 14, 2000, with asteroid 433 Eros. NEAR was to orbit Eros for a year, conducting scientific studies.



The spacecraft touched down on the 433 Eros asteroid on Feb. 12, 2001, and began sending data from the surface of Eros.
As the first mission launched in NASA's Discovery Program, the NEAR mission set the stage for asteroidal exploration and formed a base of knowledge that will be the framework for future missions.

The spacecraft was designed and built by Johns Hopkins University's Applied Physics Laboratory, which managed the mission for NASA. The NEAR mission was the first comprehensive study of the physical geology, composition and geophysics of an asteroid.
The NEAR Shoemaker was the first solar-powered spacecraft to fly beyond the orbit of Mars - a technical innovation in spacecraft design. It had the capacity to operate as far as 203 million miles from the sun.
The satellite was named NEAR Shoemaker to honour Dr. Eugene M. Shoemaker, the legendary geologist who influenced decades of research on the role of asteroids and comets in shaping the planets.
The Discovery Station spacecraft exhibit includes additional materials and interactive exhibits about space and weather.

Source



The spacecraft impacted at a velocity of about 1.5 to 1.8 meters/second. The spacecraft obtained 69 high-resolution images before touchdown, the final image showing an area 6 meters across. NEAR was not designed as a lander, but survived the low-velocity, low-gravity impact, a signal continued after the "landing" using the omni-directional low-gain antenna as a beacon.
Communications with the NEAR spacecraft on the surface of Eros ended on 28 February 2001.
The last reception of signal was at 7:00 p.m. EST .

The regolith on Eros is nearly 91 meters deep in places. Data indicate the regolith has moved downhill, smoothing over rough areas and spilling into craters. University of Arizona scientists have discovered why the asteroid Eros, has so few small craters. Seismic shaking, resulting when Eros collides with space debris, has obliterated about 90 percent of the asteroid's small impact craters, those less than 100 meters in diameter.

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RE: NEAR, 433 Eros
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An asteroid's external features, when analyzed carefully, can say a lot about its interior. So it was while he was mapping the surface of the asteroid 433 Eros that Peter Thomas, a senior research associate in astronomy at Cornell University, found a simple solution to an earlier puzzle about the asteroid's composition.

Thomas was using images collected by the Near Earth Asteroid Rendezvous mission in 2001 to create a digital map of Eros.



On the asteroid's surface, predictably pock-marked with thousands of craters accumulated from impacts over its lifetime, he saw a feature first noticed by Cornell graduate student Marc Berthoud: that a few particular patches were inexplicably smooth. That observation had led to various theories - but none that seemed completely satisfying.

In a letter appearing in the current issue of the journal Nature (Vol. 436, No. 7049, p. 366), Thomas and North-western University geologist Mark Robinson show that the asteroid's smooth patches can be explained by a seismic disturbance that occurred when the crater, known as the Shoemaker crater, was formed.

The fact that seismic waves were carried through the centre of the asteroid shows that the asteroid's core is cohesive enough to transmit such waves, Thomas says. And the smoothing-out effect within a radius of up to 9 kilometres from the 7.6-kilometer Shoemaker crater (even on the opposite side of the asteroid ) indicates that Eros' surface is loose enough to get shaken down by the impact.
Asteroids are small, planet like bodies that date back to the beginning of the solar system, so studying them can give astronomers insight into the solar system's formation.
And while no asteroids currently threaten Earth, knowing more about their composition could help prepare for a possible future encounter.

Eros, whose surface is a jumble of house-sized boulders and small stones ("what geologists call 'poorly sorted,'" says Thomas), is the most carefully studied asteroid, in part because its orbit brings it close to earth.



Thomas and Robinson considered various theories for the regions of smoothness, including the idea that ejecta from another impact had blanketed the areas. But they rejected the ejecta hypothesis when calculations showed an impact Shoemaker's size wouldn't create enough material to cover the surface indicated. And even if it did, they add, the asteroid's irregular shape and motion would cause the ejecta to be distributed differently.
In contrast, the shaking-down hypothesis fits the evidence neatly. The crater density of small craters increases with the distance from the Shoemaker crater.

"The classic light bulb goes on in your head. Simple geometry says something like a simple seismic wave" - Peter Thomas.



The NEAR mission, in which a NASA spacecraft landed on the asteroid's surface in 2001 after orbiting it for a year, yielded more than 100,000 images of the small asteroid. (Eros is about 33 kilometres long, 13 kilometres wide and 8 kilometres thick). Since the mission's conclusion 16 days after the landing, scientists from institutions around the world have been sorting through the data.

That process is expected to continue for years. "Careful mapping of things on the surface can give you a good clue as to what's inside. And in one sense, we've barely begun" - Peter Thomas.

Source

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On 23 December 1998 the NEAR spacecraft flew within 3824 km of the asteroid 433 Eros (33x33x16 km diameter), and acquired a series of images of about 70% of the asteroid. You can download all the images from the mission here: http://cps.earth.northwestern.edu/near.html



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