9P / Temple 1
| 9P / Temple 1 [i] | |
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Core of Comet 9P / Temple 1
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| Properties of the orbit ( animation ) | |
| Orbit type | short-term |
| Numerical eccentricity | 0.512 |
| Perihelion | 1.53 AU |
| Aphelion | 4.75 AU |
| Major semi-axis | 3.14 AU |
| Sidereal period | 5.56 a |
| Inclination of the orbit plane | 10.5 ° |
| Perihelion | 2nd August 2016 |
| Orbital velocity in the perihelion | 29.6 km / s |
| Physical properties of the core | |
| Medium diameter | 6 km (7.6 km × 4.9 km) |
| Dimensions | 7.2 x 10 13 kg |
| Medium density | 0.62 g / cm³ |
| Albedo | 0.04 |
| history | |
| Explorer | Ernst Wilhelm Leberecht Temple |
| Date of discovery | April 3, 1867 |
| Older name | 1867 II, 1873 I, 1879 III, 1966 VII, 1972 V, 1978 II, 1983 XI, 1989 I, 1994 XIX, 1873a, 1879b, 1972a, 1977i, 1982j, 1987e1, 1993c |
| Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles . | |
9P / Tempel 1 is a short- period comet that was examined by NASA's Deep Impact space probe in the summer of 2005 .
discovery
The comet Tempel 1 was discovered on April 3, 1867 in the observatory in Marseille by the Saxon astronomer and lithographer Ernst Wilhelm Leberecht Tempel . Later calculations showed that it was then 0.71 astronomical units (AU) from the earth and 1.64 AU from the sun. Tempel described at the time that the comet had an apparent diameter of 4 to 5 minutes of arc .
Orbit
At the time of its discovery, the comet had an orbital period of around 5.7 years. In 1881 the comet approached the planet Jupiter to within 0.55 AU , whereby the orbit of the comet was changed by the gravitational effect of the planet so that the orbit period was extended to 6.5 years. Due to this change in orbit, the comet was initially lost. When its orbit could be calculated in the 1960s, taking into account the orbital disturbance caused by the planets , it was found that the comet had in the meantime approached Jupiter twice (1941 to 0.41 AU and 1953 to 0.77 AU), so that its orbital period had been shortened to roughly its current value of 5.5 years. According to these new orbital determinations , the comet was subsequently found in December 1968 on a photo plate from June 1967. The recovery was finally confirmed when the comet returned in 1972. Currently it is 1.53 AU in perihelion and 4.758 AU in aphelion from the Sun and its orbit inclination to the ecliptic is 10.5 °.
Deep Impact spacecraft
During its appearance in the summer of 2005, Comet Tempel 1 was not only examined by telescopes, but also by the Deep Impact space probe . NASA's spacecraft released a 372 kg, refrigerator-sized projectile, which hit the comet's core at a relative speed of 10.3 km / s (37,080 km / h) and observed the impact of this so-called impactor from a distance of around 8,600 km . Around 4500 pictures were taken. The space probe then passed the comet at a distance of about 500 km, but was unable to carry out any observations because its instruments had to be turned away from the comet to protect against the ejected particles. The event was also observed by several telescopes stationed in space and on Earth.
Results
The size of the comet could be determined by the space probe's recordings at 7.6 × 4.9 km and its albedo at 0.04.
Before the impact of the impactor, the scientists were unsure whether it would create a classic impact crater , penetrate the comet without a trace, or even destroy the entire comet.
The outcome of the mission turned out to be rather conventional. Shortly after the impact of the impactor, a thermal flash was observed, in which the projectile was explosively destroyed. As a result of the explosion , a fountain of about 3,500 ° C hot, molten core material with a total mass of around 4 tons and a speed of 5 to 8 km / s rose. While an impact crater with an estimated diameter of about 100 (−50 / + 100) meters and a depth of about 30 meters formed on the comet's core, another 10,000 to 20,000 tons of material were ejected, of which 3,000 to 6,000 tons were dust . According to this, temple 1 does not have a hard crust, but is surrounded by a soft layer of dust.
The released gas spread at 1 km / s and more, while the dust particles were significantly slower at speeds between 10 and 400 m / s. The majority of the dust (around 80%) therefore fell back onto the nucleus, the remaining dust and the gas were released into the comet's coma and subsequently into interplanetary space. Unexpectedly, so much powdery material was thrown out that the view of the resulting crater was completely blocked. Therefore, the size of the crater could only be estimated from the mass of the material released. Images from the Stardust-NExT mission show the crater, which is around 150 m in diameter and has a central mountain.
From the trajectory of the ejected dust particles, the density of the comet's nucleus was determined to be 0.62 (+ 0.47 / -0.33) g / cm³ - about two thirds the density of water ice. The comet's nucleus appears to be made of porous and fragile material; between 50% and 70% of the comet's nucleus is empty space. On the surface of the core, the surface temperature of which was between +56 ° C and −13 ° C, traces of water ice could be detected in some isolated regions . In the spectrum of the ejected material, however, water could be found as well as carbon dioxide , carbonates , complex organic compounds (such as polycyclic aromatic hydrocarbons ), silicates (such as the mineral olivine ) and clay minerals . In any case, the solid components in relation to the volatile elements seem to prevail, so that the comet, which until then often called dirty snowballs ( dirty snowballs ) were designated, rather than snowy dirtballs ( icy dirt balls ) are to be considered.
The composition and amount of the ejected material is reminiscent of some comets of the Oort cloud that have already been investigated . It is therefore possible that some comets originated in the Kuiper Belt , including Temple 1, near the gas giant region of the protoplanetary disk . This would suggest a common origin for comets far from the Sun today.
It was a surprise that the surface of the comet's core has not only been marked by impact craters - which were observed here for the first time in a comet - and bumps due to the loss of ice and solar warming. Different geological layers could also be observed, which are reminiscent of those of the comet-like Saturn moon Phoebe . Accordingly, comets could have been subjected to certain geological processes, or Temple 1 could have arisen from the merging of two different bodies.
Stardust spacecraft
Another space probe explored the comet on February 14, 2011. The Stardust probe , which has been on the move since 1999, came extremely close to the comet. It passed Temple 1 just 181 kilometers away. The recordings made by the probe are to be compared with those of Deep Impact to see what and how much has changed. The aim is to begin unraveling the history of a comet's surface. In addition to the photos, the space probe provides information on the composition and quantity of the dust particles released by comet Tempel 1. In this way, the researchers want to find out how the celestial body came into being millions of years ago.
See also
swell
- ^ Richard A. Kerr: Comet Crackup Will Spur Science, Whatever the Result. In: Science. Vol. 308, May 27, 2005, AAAS, p. 1247.
- ↑ Stardust-NExT Date with a Comet. Press briefing. At: youtube.com. Retrieved February 16, 2011.
- ↑ Michael J. Mumma et al: Parent Volatiles in Comet 9P / Temple 1: Before and After Impact. In: Science. Vol. 310, October 14, 2005, AAAS, pp. 270-274.
- ^ Richard A. Kerr: Deep Impact Finds a Flying Snowbank of a Comet. In: Science. Vol. 309, September 9, 2005, AAAS, p. 1667.
- ↑ Florian Freistetter: With mathematics to the comet. At: ScienceBlogs.de. February 18, 2011.
- ↑ NASA probe passes comet "Tempel". At: orf.at. February 14, 2011, accessed February 15, 2011.
literature
- Thorsten Dambeck: The new picture of comets. Bild der Wissenschaft , December 2007, pages 38-43, ISSN 0006-2375 .
