Comet Temple 1 is a Periodic comet (formerly 9P/Tempel 1). At the time of discovery, Comet Temple 1 approached the perihelion once every 5.68 years. In the subsequent observations from 1873 to 1879, it was found that the orbit of Comet Temple 1 was sometimes very close to Jupiter, so that its orbital period changed due to the influence of gravity. This happened once in 1881, and the orbital period was extended to 6.5 years. At the same time, the perihelion has also changed, and the distance has increased by 50 million kilometers, which makes this comet more difficult to see from the Earth's perspective. Even astronomers at that time claimed that it had disintegrated because they could no longer track its orbit. Comet Temple 1 was not "discovered" again until the 1960s by American astronomer Brian G. Marsden with the help of accurate comet orbit calculation after considering the disturbance of Jupiter. Its orbital period is 5.5 years. 
Tempel 1 
Tempel 1 Details of the crater formed by the impact have not been reported in detail. It is believed that the crater may be 200 meters in diameter and 30-50 meters in depth, but according to the structure of Comet Temple 1 Material composition The crater may be much smaller. The purpose of this mission is to study the internal components of the cometary nucleus. 
Tempel 1 Michael Hern, the chief scientist of the Deep Impact project, said that the particles of these debris were smaller than fine sand and only equivalent to talcum powder, which showed that the comet nucleus was not a "big ice lump" as people had originally thought. Project scientist Peter Schultz said, Cometary nucleus The surface material is so small, indicating that it has not been greatly disturbed during the long space journey. These fine powders contain water 、 carbon dioxide And simple organic matter, in which the composition of water is much less than the original guess. 
Tempel 1 Scientists also said that the "deep impact" probe took about 4500 photos before and after the impact, becoming an important source of scientific information. One of the best photos resolving power Up to 4 meters, 10 times better than the previous comet detection project. The "deep impact" aircraft carried out a state detection after impact, and the results showed that everything was normal. 
Tempel 1 Surprise 1: The nucleus of Tempel 1 is layered. The surface of the nucleus is covered with fine powdery material more than 10 meters deep, and below it is a hard "nucleus of the nucleus". The average density of the comet nucleus is only 0.6 grams per cubic centimeter, which is lighter than water. The fine powder on the surface of the comet nucleus existed many years ago or accumulated year by year, which also proves that the inner part of the comet nucleus contains the original material of the early solar system.
Surprise 2: The comet nucleus will Eruption , especially the part of the surface of the comet nucleus facing the sun, there will often be small-scale eruptions. Cometary nucleus It is porous, the thermal inertia of the surface material is small, and it will be heated quickly by the sun, but the heat of solar radiation will not affect the material inside the comet nucleus, which indicates that the material inside the comet nucleus is unlikely to be affected by the outside. Surprise 3: Although the comet nucleus of Tempel 1 is very small, it has a variety of landforms, including smooth and flat parts and craters similar to craters, which indicates that before the "deep impact", the comet nucleus was often hit by smaller objects in space.
Surprise 4: There are a lot of carbon and nitrogen in the comet nucleus Organic molecule , the material ejected from the comet nucleus after the "deep impact" contains Hydrocyanic acid （HCN）、 acetonitrile , ice and carbon dioxide However, there are no such substances in the powder on the surface of the comet nucleus, which indicates that they exist in the shallow part below the surface and only erupt when impacted or affected by heat. It also shows that comets may bring the earliest organic matter to the earth in the early stage of the earth when comets and asteroids collide frequently. Xinhua News Agency, Washington, February 14 (Reporter Ren Haijun) On the Valentine's Day night in the Americas, more than 300 million kilometers away from the earth, the US "Stardust" probe and Comet Temple 1 staged a "space dating" - when they were most "intimate", the distance between the two was about 200 kilometers, which was enough to make "Stardust" The spacecraft took high-resolution pictures of Comet Temple 1.
NASA TV reported that, US Eastern Time At 23:41 on the 14th (12:41 on the 15th Beijing time), in the space about 338 million kilometers away from the earth, the "Stardust" probe realized "close" contact with Comet Tempel 1. At that time, the distance between the two sides was 203 kilometers, which was far from the earth, but very close in astronomy. Before the "intimate" contact, Stardust took pictures for Temple 1 every 6 seconds and sent them back to Earth successively. When the flight control team confirmed that the "Space Dating" had been successful and received all the required photos, the flight control room in Denver, Colorado burst into applause. Joseph Weiverka, the chief scientist of the project, said excitedly: "The date is perfect. No one is happier than me."
Perhaps to add a romantic atmosphere to the "space date", two researchers participating in the "Stardust" spacecraft observation project announced their engagement hours before the "space date". When NASA announced the news through Twitter, it said: "These two project researchers have just got engaged, which has pushed the 'comet dating' of Valentine's Day to a new level. Let's cheer."
This "space date" enabled NASA to send two probes to the same comet for the first time. The US Deep Impact spacecraft once released its impactor in July 2005, hitting Comet Temple 1. Although Temple 1 was hit by a hole at that time, the large amount of dust and debris rising from its surface made Deep Impact unable to observe the impact location in detail.
Tempel 1 looks like a potato, but the Stardust detector has been "attracted" to it for a long time. Stardust was launched in February 1999 and flew near Comet Wilder 2 in January 2004, making scientists collect comet particles in space for the first time. In view of its sufficient fuel after completing this mission, NASA assigned a new mission to Stardust in July 2007 - to advance toward Comet Temple 1. Stardust's "wish" of more than three years has finally been realized on Valentine's Day night. NASA also hopes to take advantage of this "appointment" to see the current "true face" of Comet Temple 1.
However, the reality after the "date" is also cruel - the remaining fuel of Stardust can no longer support its next goal. The total cost of this $300 million probe will eventually be annihilated in the vast space.
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<b>Comet 9P/Temple 1</b> |
find | |
Discovered by: | |
Date of discovery: | April 3, 1867 |
Temporary number ： | 9P/1867 G1; 1867 II; 9P/1873 G1; 1873 I; 1873a 1879 III; 1879b 9P/1967 L1; 1966 VII 9P/1972 A1; 1972 V; 1972a 1978 II; 1977i 1983 XI; 1982j 1989 I; 1987e1 1994 XIX; 1993c |
Track characteristics | |
Epoch: | March 6, 2006 |
Aphelion distance ： | 4.737AU |
Perihelion distance ： | 1.506AU |
Semi major diameter of track ： | 3.122AU |
Eccentricity: | zero point five one seven five |
Orbital period: | five point five one five a |
Rail inclination: | 10.5301° |
Last perihelion passing date: | July 5, 2005 |
Next perihelion passing date (forecast): | January 12, 2011 |
Chasing Comet Temple 1
NASA's comet chasing spacecraft, Stardust, is on its way to the Valentine's Day with Comet Temple-1. Six years ago, the comet was visited by Deep Space Impact for the first time. This plan is to monitor the changes of the comet after it has circled the sun once.
Comet is the oldest and most primitive celestial body in the solar system, which retains the basic module for building the life of the sun, planets and even the earth. They are also used to transport water and organic matter to the Earth and other planets, so understanding their composition is the key to studying the formation and evolution history of the solar system [2] 。
