Difference between revisions of "Gusev Crater"
(correct link) |
|||
| (19 intermediate revisions by 3 users not shown) | |||
| Line 1: | Line 1: | ||
| − | The '''Gusev Crater''' was named in 1876 after Russian astronomer Matvei Gusev (1826–1866).<ref>[http://en.wikipedia.org/wiki/Matvei_Gusev Matvey Matveyevich Gusev on Wikipedia]</ref> The crater (created by a large [[meteorite]] impact approximately 3.9 billion years ago during the | + | {{Mars atlas}} |
| + | [[Image: MOLA spiritcontext.jpg|thumb|200px|left|MOLA map with star showing landing site for Spirit Rover]] | ||
| + | |||
| + | |||
| + | [[Image:GusevCrater.gif|thumb|200px|right|Image of the Gusev Crater]] | ||
| + | |||
| + | The '''Gusev Crater''' was named in 1876 after Russian astronomer Matvei Gusev (1826–1866).<ref>[http://en.wikipedia.org/wiki/Matvei_Gusev Matvey Matveyevich Gusev on Wikipedia]</ref> The crater (created by a large [[meteorite]] impact approximately 3.9 billion years ago during the Late Heavy Bombardment) is located 14.6°S and 175.4°E (184.6 W) just south of the equator. Gusev Crater is in the Aeolis quadrangle. It is 144 km (90 mi) in diameter and provided an ideal landing zone for one of the [[:category:Mars Exploration Rover Mission|MER]] rovers, [[Spirit]]. Spirit Rover landed at 14.5718 S and 175.4785 E (184.5215 W) on January 4, 2004. | ||
| + | |||
| + | == ''Spirit'' rover discoveries == | ||
| + | |||
| + | Spirit found the rocks on the plains of Gusev to be a type of basalt. They contain the minerals plagioclase, olivine, pyroxene, and magnetite. The rocks look like fine-grained basalt with irregular holes (geologists would say they have vesicles and vugs).<ref>McSween, etal. 2004. "Basaltic Rocks Analyzed by the Spirit Rover in Gusev Crater". Science : 305. 842–845</ref> <ref>Arvidson R. E.; et al. (2004). "Localization and Physical Properties Experiments Conducted by Spirit at Gusev Crater". Science. 305: 821–824."Arvidson, R. E. 2004"</ref> | ||
| + | |||
| + | Much of the soil on the plains came from the breakdown of the local rocks. Fairly high levels of nickel were found in some soils; probably from meteorites.<ref>{{cite journal | author = Gelbert R. ''et al.'' | year = 2006 | title = The Alpha Particle X-ray Spectrometer (APXS): results from Gusev crater and calibration report | url = | journal = J. Geophys. Res. Planets | volume = 111 | issue = | page = }}</ref> | ||
| + | |||
| + | There is evidence that the rocks have been slightly altered by tiny amounts of water. Outside coatings and cracks inside the rocks suggest water deposited minerals, maybe bromine compounds. All the rocks are covered with a fine coating of dust. One type can be brushed off, while another needed to be ground off by the Rock Abrasion Tool (RAT).<ref>{{cite journal | author = Christensen P | year = | title = Initial Results from the Mini-TES Experiment in Gusev Crater from the Spirit Rover | url = | journal = Science | volume = 305 | issue = | pages = 837–842 | doi=10.1126/science.1100564 | pmid=15297667 | date=August 2004| </ref> | ||
| + | |||
| + | The dust in Gusev Crater is the same as dust all around the planet. All the dust was found to be magnetic. In addition, ''Spirit'' found the magnetism was due to the mineral magnetite, especially magnetite that contained the element titanium. One magnet was able to completely divert all dust hence all Martian dust is thought to be magnetic.<ref>Bertelsen, P., et al. 2004. "Magnetic Properties on the Mars Exploration Rover Spirit at Gusev Crater". ''Science'': 305. 827–829</ref> The spectra of the dust was similar to spectra of bright, low thermal inertia regions like Tharsis and Arabia that have been detected by orbiting satellites. A thin layer of dust, maybe less than one millimeter thick covers all surfaces.<ref name="Bell, J 2008">Bell, J (ed.) ''The Martian Surface''. 2008. Cambridge University Press. ISBN|978-0-521-86698-9</ref> <ref>Gelbert, R. et al. "Chemistry of Rocks and Soils in Gusev Crater from the Alpha Particle X-ray Spectrometer". ''Science'': 305. 829-305</ref> | ||
| + | |||
| + | [[Image: Rockgusevdiagram.jpg |thumb|200px|right|Labeled diagram showing a cross section of a typical rock from Gusev plains]] | ||
| + | |||
| + | Scientists found a variety of rock types in the Columbia Hills The rocks were put into six different categories. The six are: Clovis, Wishbone, Peace, Watchtower, Backstay, and Independence. They are named after a prominent rock in each group. Their chemical compositions are significantly different from each other.<ref>Squyres, S., et al. 2006 Rocks of the Columbia Hills. J. Geophys. Res. Planets. 111</ref> Most importantly, all of the rocks in Columbia Hills show various stages of alteration due water.<ref>Ming,D., et al. 2006 Geochemical and mineralogical indicators for aqueous processes in the Columbia Hills of Gusev crater, Mars. J. Geophys: Res.111</ref> | ||
| + | They are enriched in the elements phosphorus, sulfur, chlorine, and bromine—all of which can be transported in water solutions. The Columbia Hills’ rocks contain basaltic glass, along with varying amounts of olivine and sulfates.<ref name="Schroder, C. 2005">Schroder, C., et al. (2005) European Geosciences Union, General Assembly, Geophysical Research abstr., Vol. 7, 10254, 2005</ref> <ref>Christensen, P.R. (2005) Mineral Composition and Abundance of the Rocks and Soils at Gusev and Meridiani from the Mars Exploration Rover Mini-TES Instruments AGU Joint Assembly, 23–27 May 2005 </ref> <ref>http://www.agu.org/meetings/sm05/waissm05.html</ref> | ||
| + | The olivine abundance varies inversely with the amount of sulfates. This is exactly what is expected because water destroys olivine but helps to produce sulfates. | ||
| + | |||
| + | |||
| + | [[File: Spirit's First Color Photograph Mars.jpg|thumb|200px|left|First image from Spirit at Gusev Crater]] | ||
==An ancient lake?== | ==An ancient lake?== | ||
The crater exhibits evidence that it once contained substantial quantities of liquid [[water]]. A channel enters the south of the crater. Known as [[Ma'adim Vallis]], this was almost certainly a means for which the crater was supplied with water. On January 9th, 2004, the [[Spirit]] rover landed in the crater and began to analyse the surrounding rock. Expecting to find overwhelming evidence of an ancient lake, mission scientists were disappointed to find very little indication of water. | The crater exhibits evidence that it once contained substantial quantities of liquid [[water]]. A channel enters the south of the crater. Known as [[Ma'adim Vallis]], this was almost certainly a means for which the crater was supplied with water. On January 9th, 2004, the [[Spirit]] rover landed in the crater and began to analyse the surrounding rock. Expecting to find overwhelming evidence of an ancient lake, mission scientists were disappointed to find very little indication of water. | ||
| − | Although this was unexpected, during the trip to the | + | Although this was unexpected, during the trip to the Columbia Hills, Spirit eventually found evidence that the area had once held a quantity of saltwater.<ref>[http://en.wikipedia.org/wiki/Gusev_Crater Gusev Crater on Wikipedia]</ref><ref>[http://marsrovers.nasa.gov/newsroom/pressreleases/20070521a.html NASA press release, May 21, 2007. Evidence for water in Gusev Crater]</ref> |
===References=== | ===References=== | ||
<references/> | <references/> | ||
| − | [[category: | + | [[category:Geologic Processes]] |
| − | |||
Latest revision as of 18:04, 8 January 2020
The Gusev Crater was named in 1876 after Russian astronomer Matvei Gusev (1826–1866).[1] The crater (created by a large meteorite impact approximately 3.9 billion years ago during the Late Heavy Bombardment) is located 14.6°S and 175.4°E (184.6 W) just south of the equator. Gusev Crater is in the Aeolis quadrangle. It is 144 km (90 mi) in diameter and provided an ideal landing zone for one of the MER rovers, Spirit. Spirit Rover landed at 14.5718 S and 175.4785 E (184.5215 W) on January 4, 2004.
Spirit rover discoveries
Spirit found the rocks on the plains of Gusev to be a type of basalt. They contain the minerals plagioclase, olivine, pyroxene, and magnetite. The rocks look like fine-grained basalt with irregular holes (geologists would say they have vesicles and vugs).[2] [3]
Much of the soil on the plains came from the breakdown of the local rocks. Fairly high levels of nickel were found in some soils; probably from meteorites.[4]
There is evidence that the rocks have been slightly altered by tiny amounts of water. Outside coatings and cracks inside the rocks suggest water deposited minerals, maybe bromine compounds. All the rocks are covered with a fine coating of dust. One type can be brushed off, while another needed to be ground off by the Rock Abrasion Tool (RAT).[5]
The dust in Gusev Crater is the same as dust all around the planet. All the dust was found to be magnetic. In addition, Spirit found the magnetism was due to the mineral magnetite, especially magnetite that contained the element titanium. One magnet was able to completely divert all dust hence all Martian dust is thought to be magnetic.[6] The spectra of the dust was similar to spectra of bright, low thermal inertia regions like Tharsis and Arabia that have been detected by orbiting satellites. A thin layer of dust, maybe less than one millimeter thick covers all surfaces.[7] [8]
Scientists found a variety of rock types in the Columbia Hills The rocks were put into six different categories. The six are: Clovis, Wishbone, Peace, Watchtower, Backstay, and Independence. They are named after a prominent rock in each group. Their chemical compositions are significantly different from each other.[9] Most importantly, all of the rocks in Columbia Hills show various stages of alteration due water.[10] They are enriched in the elements phosphorus, sulfur, chlorine, and bromine—all of which can be transported in water solutions. The Columbia Hills’ rocks contain basaltic glass, along with varying amounts of olivine and sulfates.[11] [12] [13] The olivine abundance varies inversely with the amount of sulfates. This is exactly what is expected because water destroys olivine but helps to produce sulfates.
An ancient lake?
The crater exhibits evidence that it once contained substantial quantities of liquid water. A channel enters the south of the crater. Known as Ma'adim Vallis, this was almost certainly a means for which the crater was supplied with water. On January 9th, 2004, the Spirit rover landed in the crater and began to analyse the surrounding rock. Expecting to find overwhelming evidence of an ancient lake, mission scientists were disappointed to find very little indication of water.
Although this was unexpected, during the trip to the Columbia Hills, Spirit eventually found evidence that the area had once held a quantity of saltwater.[14][15]
References
- ↑ Matvey Matveyevich Gusev on Wikipedia
- ↑ McSween, etal. 2004. "Basaltic Rocks Analyzed by the Spirit Rover in Gusev Crater". Science : 305. 842–845
- ↑ Arvidson R. E.; et al. (2004). "Localization and Physical Properties Experiments Conducted by Spirit at Gusev Crater". Science. 305: 821–824."Arvidson, R. E. 2004"
- ↑ Gelbert R. et al. (2006). "The Alpha Particle X-ray Spectrometer (APXS): results from Gusev crater and calibration report". J. Geophys. Res. Planets 111.
- ↑ {{cite journal | author = Christensen P | year = | title = Initial Results from the Mini-TES Experiment in Gusev Crater from the Spirit Rover | url = | journal = Science | volume = 305 | issue = | pages = 837–842 | doi=10.1126/science.1100564 | pmid=15297667 | date=August 2004|
- ↑ Bertelsen, P., et al. 2004. "Magnetic Properties on the Mars Exploration Rover Spirit at Gusev Crater". Science: 305. 827–829
- ↑ Bell, J (ed.) The Martian Surface. 2008. Cambridge University Press. ISBN|978-0-521-86698-9
- ↑ Gelbert, R. et al. "Chemistry of Rocks and Soils in Gusev Crater from the Alpha Particle X-ray Spectrometer". Science: 305. 829-305
- ↑ Squyres, S., et al. 2006 Rocks of the Columbia Hills. J. Geophys. Res. Planets. 111
- ↑ Ming,D., et al. 2006 Geochemical and mineralogical indicators for aqueous processes in the Columbia Hills of Gusev crater, Mars. J. Geophys: Res.111
- ↑ Schroder, C., et al. (2005) European Geosciences Union, General Assembly, Geophysical Research abstr., Vol. 7, 10254, 2005
- ↑ Christensen, P.R. (2005) Mineral Composition and Abundance of the Rocks and Soils at Gusev and Meridiani from the Mars Exploration Rover Mini-TES Instruments AGU Joint Assembly, 23–27 May 2005
- ↑ http://www.agu.org/meetings/sm05/waissm05.html
- ↑ Gusev Crater on Wikipedia
- ↑ NASA press release, May 21, 2007. Evidence for water in Gusev Crater
