NASAStardust Mission - Encounter with Comet Tempel 1 - Live India

Dear Freinds in addition to series of articles below here is information about Spacecraft, target objects etc... along with live video stream of NASA.

Spacecraft : The Stardust spacecraft will have logged more than 5,673,464,575 kilometers (3,525,327,446 miles) and over a dozen years traveling in deep space by the time the Tempel 1 encounter is complete. Back when it launched in 1999, Stardust carried onboard some of the most innovative, state-of-the-art technologies pioneered by other recent missions. It combined this state-of-the-art technology with a combination of off- the-shelf spacecraft components and, in some cases, spare parts and instrumentation left over from previous successful space missions. The Stardust spacecraft is derived from a rectangular deep-space bus called SpaceProbe developed by Lockheed Martin Space Systems, Denver. The main bus is 1.7 meters (5.6 feet) high, 0.66 meter (2.16 feet) wide and 0.66 meter (2.16 feet) deep, about the size of an average office desk. Panels are made of a core of aluminum honeycomb, with outer layers of graphite fibers and polycyanate face sheets. With its two parallel solar panels deployed, the spacecraft takes on the shape of a letter H. There are three dedicated science packages on Stardust -- the two-sided Dust Collector, the Comet and Interstellar Dust Analyzer, and the Dust Flux Monitor. Science data are also being obtained without dedicated hardware. The navigation camera, for example, provides images of its cometary target for both targeting accuracy and scientific analysis.

Dimensions: Main structure 1.7 meters (5.6 feet) high, 0.66 meters (2.16 feet) wide, 0.66 meters (2.16 feet) deep; length of solar arrays 4.8 meters (15.9 feet) tip to tip Weight: 385 kilograms (848 pounds) total at launch, consisting of 254-kilogram (560-pound) spacecraft and 46-kilogram (101-pound) return capsule, and 85 kilograms (187 pounds) of fuel Weight total as of Feb. 3, 2011: 256.6 kg (565.7 lbs) total, consisting of 254-kilogram (560-pound) spacecraft and 2.6 kilograms (5.7 pounds) of fuel. Power: Solar panels providing from 170 to 800 watts, depending on distance from the sun.

Comet Tempel 1 Official designation: 9P/Tempel. It is a periodic comet discovered by Wilhelm Tempel on April 3, 1867. Tempel 1's orbit lies between the orbits of Mars and Jupiter. The comet orbits the sun every 5.5 years. The comet's orbital period has varied in the past and will do so in the future because of close approaches with the planet Jupiter. Nucleus shape: Elongated, irregular. Nucleus size: 7.6 and 4.9 kilometers (4.7 and 3 miles) with an equivalent radius of about 3 kilometers. Nucleus mass: approximately 40 trillion kilograms (88.2 billion tons). Nucleus rotation period: about 41.9 hours.

Tempel 1 was previously visited by NASA's Deep Impact spacecraft on July 4, 2005.

Stardust-NExT mission
Total distance traveled from Earth (since drop off of sample return capsule in 2006) to comet Tempel 1: 1.04 billion kilometers (646 million miles). Total distance Stardust spacecraft has traveled since 1999 launch (Earth to comet Wild 2 to Earth to comet Tempel 1): about 5.7 billion kilometers (3.5 billion miles). Spacecraft speed relative to comet Tempel 1 at time of closest approach: 10.9 kilometers per second (6.77 miles per second/24,300 miles per hour). Distance of spacecraft (and comet) from Earth at time of encounter: 336 million kilometers (209 million miles).

Program : Stardust-NExT (extended mission) costs: $29 million (FY 2010), for operations from 2007 to end of project at the end of fiscal year 2011.

Science Comet Tempel 1 – A History
Even before the Deep Impact and Stardust-NExT mission, comet Tempel 1 was already one of the most analyzed of the Jupiter-family comets. A Jupiter-family comet is one whose orbit has been modified by close passages to Jupiter and has an orbital period less than 20 years. With the completion of the Stardust-NExT flyby, comet Tempel 1 will be by far the most-scrutinized comet in history. Tempel 1's orbit lies between the orbits of Mars and Jupiter. The comet orbits the sun every 5.5 years. The comet's orbital period has varied in the past and will do so in the future because of its close approaches with the planet Jupiter. Tempel 1 is remarkably homogeneous in albedo, or reflectivity, and color. The surface is very dark, reflecting less than five percent of the sunlight that falls on it. Deep Impact identified very few places where water ice is exposed. The comet is oblate and irregular in shape. The nucleus size is 7.6 and 4.9 kilometers (4.7 and 3 miles) with an equivalent radius of about 3 kilometers (1.9 miles). The comet’s period of rotation is about 41.85 hours. Tempel 1 was first seen close up on July 4, 2005, when NASA's Deep Impact mission performed its encounter. The Deep Impact mission consisted of functionally two spacecraft: an impacting spacecraft, and a flyby spacecraft for observing the impact and relaying data from the impactor back to Earth. In reality the mission's impactor was "run over" by the comet at a closing speed of 37,100 kilometers per hour (23,000 miles per hour). Deep Impact's impactor struck the nucleus obliquely and excavated a crater predicted to be in the range of 100 to 300 meters (328 to 984 feet) across. The crater was not directly observed by Deep Impact due to the large amount of fine dust ejected by the impact. The obscuring ejecta were dominated by particles in the diameter range from 1 to 100 micrometers (a single strand of hair usually has a diameter of 20 to 180 micrometers). The resulting ejecta cone appeared to remain attached to the comet’s surface, indicating that formation of the crater was controlled by gravity rather than by material strength. Deep Impact high-resolution images cover about 30 percent of the nucleus at less than 10 meters per pixel (about 33 feet per pixel). A region about 2 kilometers (1.3 miles) across was imaged at slightly better resolution by the impactor camera shortly before it impacted there. The nucleus images reveal several regions of distinct morphology, suggesting considerable variation in exposed materials, geologic processes and ages. Two different areas display several dozen apparently circular features, ranging from 40 to 400 meters (131 to 1,312 feet) in diameter. Although the size distribution of these features is consistent with that of an impact crater population, whether these features are indeed impact craters or sublimation pits remains uncertain.

Two regions of smooth surface were revealed by Deep Impact images. Both smooth areas are in gravitational lows. The smoothness is reminiscent of the plateau seen on comet Borrelly, but the surroundings are different. There is circumstantial evidence that the smooth deposits may be associated with either recent or currently active regions on the nucleus.

Stardust-NExT Science Objectives The purpose of the Stardust-NExT mission is to expand the knowledge of comets by flying a spacecraft through the coma of comet Tempel 1 and imaging its nucleus. It is a low-cost mission that will expand the investigation of comet Tempel 1 initiated by Deep Impact in 2005, and, for the first time, assess the changes in the surface of a comet between two successive orbits around the sun. Stardust-NExT will also provide important new information on how Jupiter-family comets evolve and how they were put together. Stardust-NExT also provides NASA with a unique opportunity to study two entirely different comets with the same instrument. By doing this, scientists will be able to more accurately compare its existing data set.

On February 14, 2011, at a projected distance of 200 kilometers (124 miles), the Stardust-NExT spacecraft will obtain high-resolution images of the coma and nucleus, as well as measurements of the composition, size distribution and density of dust emitted into the coma. Additionally, Stardust-NExT will update the data gathered in 2005 by the Deep Impact mission on the rotational phase of the comet.

The official primary science objectives of the mission are as follows:
• To extend our understanding of the processes that affect the surfaces of comet nuclei by documenting the changes that have occurred on comet Tempel 1 between two successive perihelion passages, or orbits around the sun.
• To extend the geologic mapping of the nucleus of Tempel 1 to elucidate the extent and nature of layering, and help refine models of the formation and structure of comet nuclei.
• To extend the study of smooth flow deposits, active areas and known exposure of water ice.

Other Science Objectives:

• If possible, to characterize the crater produced by Deep Impact in July 2005, to better understand the structure and mechanical properties of cometary nuclei and elucidate crater formation processes on them.
• Measure the density and mass distribution of dust particles within the coma using the Dust Flux Monitor Instrument instrument.
• Analyze the composition of dust particles within the coma using the Comet and Interstellar Dust Analyzer instrument.

The main objective of the experiment is to obtain high-resolution images to address mission goals. At the nominal flyby distance of 200 kilometers (124 miles), high-resolution imaging of the nucleus at scales as fine as 12 meters (39 feet) per pixel will be obtained. Coma and jet imaging may also be obtained on departure.

Many features of interest seen in the Deep Impact images, such as layers, flows, active areas and exposed ice, have details of interest at spatial scales that are equal to or smaller than 200 meters (660 feet) across.

Imaging the Deep Impact Generated Crater
A secondary science objective of the mission is to image, if possible, the Deep Impact crater with sufficient spatial resolution to determine its size, shape, degree of layering and ejecta pattern. Such an achievement would be an added bonus to the huge amount of data that mission scientists expect to obtain. Imaging the crater generated by Deep Impact requires that the comet's face, which includes the crater, be in sunshine and facing the spacecraft during encounter. If this occurs, and the crater is imaged, the observation would be the first ever of a crater created by a human-made impact on a cometary surface.

Imagery obtained of the Deep Impact crater could provide scientists with a better characterization of the surface material that composes comet Tempel 1. The morphology of the crater may provide evidence of surface layering. The form, extent and visibility of the impact ejecta blanket could provide a benchmark for identifying impact craters and ejecta blankets on cometary surfaces, and improve understanding of their material properties. Observations of the crater ejecta would also show what relatively fresh, excavated sub- surface material looks like compared to older surfaces on the comet. To image the Deep Impact-generated crater requires comet Tempel 1 to put its best face forward during time of closest approach. Conversely, if the imagery from the flyby reveals a different face of Tempel 1 -- the side that does not include the crater generated during the Deep Impact mission -- scientists will be able to further extend the geologic mapping of the comet's nucleus and obtain a better understanding of the formation and structure of comet nuclei surface features.

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