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Article:Challenger Deep
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[[Image:Marianatrenchmap.png|right|300px|thumb|Location of Challenger Deep within the [[Mariana Trench]] and Western Pacific Ocean]]
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The '''Challenger Deep''' is the deepest known point on the [[Earth]], with a depth of 10,898 metres (35,756 feet) to 10,916 metres (35,814 ft) by direct measurement from submersibles, and slightly more by sonar bathymetry (see below). It is located in the Pacific Ocean, at the southern end of the [[Mariana Trench]] near the [[Mariana Islands]] group. The Challenger Deep is a relatively small slot-shaped depression in the bottom of a considerably larger crescent-shaped trench, which itself is an unusually deep feature in the ocean floor.{{citation needed|date = March 2012}} Its bottom is 11.3&nbsp;km (7 miles) long and 1.6&nbsp;km (1 mile) wide, with gently sloping sides.<ref>{{cite web|author=All Things Considered |url=http://www.npr.org/2012/03/09/148317355/film-director-to-travel-to-bottom-of-mariana-trench |title=Diving Back To The Bottom Of The Mariana Trench |publisher=NPR |date=9 March 2012 |accessdate=26 March 2012}}</ref> The closest land to the Challenger Deep is [[Fais Island]] (one of the outer islands of [[Yap]]), {{convert|289|km|0|abbr=on}} southwest, and [[Guam]], 500 km (311 mi) to the northeast. The depression is named after the British [[Royal Navy]] survey ship [[HMS Challenger (1858)|HMS ''Challenger'']], whose [[Challenger expedition|expedition of 1872–1876]] made the first recordings of its depth. According to the August 2011 version of the GEBCO Gazetteer of Undersea Feature Names, the location of the Challenger Deep is given as 11° 22.4'N, 142° 35.5'E.<ref name="GEBCO Gazetteer of Undersea Feature Names">{{Cite news|url=http://www.gebco.net/data_and_products/undersea_feature_names/#feature_links4|title=IHO-IOC GEBCO Gazetteer of Undersea Feature Names, August 2011 version|date=August 2011|publisher=GEBCO|accessdate=20 March 2012}}</ref>
 
 
Recent (1 June 2009) sonar mapping of the Challenger Deep by the Simrad EM120 (sonar multibeam bathymetry system for 300–11,000&nbsp;m deep water mapping) aboard the [[RV Kilo Moana|RV ''Kilo Moana'']] indicated a depth of 10,971 metres (35,994 ft&nbsp;— 6.82 miles). The sonar system uses phase and amplitude bottom detection, with a precision of better than 0.2% of water depth; this is an error of about 22 metres (72 ft) at this depth.<ref name="Daily Reports for R/V KILO MOANA">{{Cite news|url=http://www.soest.hawaii.edu/UMC/Reports/Archives/KMreportJuneJuly2009.html|title=Daily Reports for R/V KILO MOANA June and July 2009|date=4 June 2009|publisher=University of Hawaii Marine Center|accessdate=4 June 2009}}</ref><ref name="Scientic Equipment aboard the R/V KILO MOANA">{{Cite news|url=http://www.soest.hawaii.edu/UMC/KM/scienceequipment.htm|title=Inventory of Scientific Equipment aboard the R/V KILO MOANA|date=4 June 2009|publisher=University of Hawaii Marine Center|accessdate=4 June 2009}}</ref> Further soundings made by the US [[Center for Coastal & Ocean Mapping]] in 2011 are in agreement with this figure, placing the deepest part of the Challenger Deep at 10,994 m (36,070 ft), with a vertical precision of approximately 40 m (130 ft).<ref name=BBC_CCOM>{{cite news|last= Amos |first= Jonathan |title= Oceans' deepest depth re-measured |url= http://www.bbc.co.uk/news/science-environment-15845550 |date= 7 December 2011 |publisher=BBC News |accessdate=7 December 2011 }}</ref>
 
 
Only four descents have ever been achieved. The first manned descent was by [[Bathyscaphe Trieste|''Trieste'']] in 1960. This was followed by the unmanned [[Remotely operated underwater vehicle|ROVs]] ''[[Kaikō]]'' in 1995 and [[Nereus (underwater vehicle)|''Nereus'']] in 2009. These expeditions measured very similar depths of 10,902 to 10,916 metres. On 26 March 2012, filmmaker [[James Cameron]] reached the bottom of the trench with a depth on arrival of 10,898 metres in the ''[[Deepsea Challenger]]'' submersible.<ref name="NGS-20120325">{{cite web |last=Than|first=Ker |title=James Cameron Completes Record-Breaking Mariana Trench Dive|url=http://news.nationalgeographic.com/news/2012/03/120325-james-cameron-mariana-trench-challenger-deepest-returns-science-sub/|date=25 March 2012 |publisher=[[National Geographic Society]]|accessdate=25 March 2012 }}</ref><ref name="NYT-20120325">{{cite news |last=Broad|first=William J. |title=Filmmaker in Submarine Voyages to Bottom of Sea|url=http://www.nytimes.com/2012/03/26/science/james-camerons-submarine-trip-to-challenger-deep.html|date=25 March 2012 |work=New York Times |accessdate=25 March 2012 }}</ref><ref name="MSNBC-20120325">{{cite web |author=AP Staff |title=James Cameron has reached deepest spot on Earth |url=http://www.msnbc.msn.com/id/46850002/ns/technology_and_science-science |date=25 March 2012 |publisher=[[MSNBC]] |accessdate=25 March 2012 }}</ref>
 
 
==History of depth mapping from the surface==
 
*The [[Challenger expedition|HMS ''Challenger'' expedition]] (December 1872 – May 1876) first [[Sounding line|sounded]] the depths now known as the Challenger Deep. This first sounding was made on 23 March 1875 at station 225.<ref>{{cite web|url=http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1895-Summary/htm/doc877.html |title=Report on the scientific results of the voyage of H.M.S. Challenger during the years of 1872-76 (page 877) |publisher=19thcenturyscience.org |accessdate=26 March 2012}}</ref> The reported depth was 4,475 [[fathom]]s (26,850&nbsp;ft, 8,184 m), based on two separate soundings.
 
 
*A 1912 book, ''The Depths of the Ocean'' by [[John Murray (oceanographer)|Sir John Murray]], records the depth of the Challenger Deep as {{convert|31614|ft|0|abbr=on}}, reporting the sounding taken by the converted navy collier, [[USS Nero (AC-17)|USS Nero]], in 1899.<ref name="Theberge">{{cite web|url=http://www.hydro-international.com/issues/articles/id1049-Thirty_Years_of_Discovering_the_Mariana_Trench.html|title=Thirty Years of Discovering the Mariana Trench|last=Theberge|first=A.|date=24 March 2009|work=Hydro International|accessdate=31 July 2010}}</ref> Murray was one of the expedition<!--which expedition, the British (he's "Sir" John) or the more recent US one?--> scientists, a young man at the time.<ref>[http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1912-Murray/htm/doc131.html Page 131] of Murray's book refers to the Challenger Deep.</ref>
 
 
*In 1951, about 75 years after its original discovery, the entire Mariana Trench was surveyed by a second [[Royal Navy]] vessel, captained by [[George Stephen Ritchie]] (later [[Rear admiral|Rear Admiral]] Ritchie); this vessel was also named [[HMS Challenger (1931)|HMS ''Challenger'']], after the original expedition ship. This survey recorded the deepest part of the trench using [[echo sounding]], a more precise and easier way to measure depth than the sounding equipment and drag lines used in the original expedition. A depth of 5,960 [[fathom]]s (10,900 m, 35,761&nbsp;ft) was measured at {{Coord|11|19|N|142|15|E}}.
 
 
*The maximum surveyed depth of the Challenger Deep was reported in 1957 by the Soviet vessel Vityaz recording a spot 11,034 m (36,201&nbsp;ft) deep. It was dubbed the ''Mariana Hollow'' and is listed in many reference sources, including the ''Encyclopædia Britannica'',<ref>{{cite encyclopedia | title = Mariana Trench | encyclopedia = Encyclopædia Britannica | publisher = Encyclopædia Britannica | id = }}</ref> articles in ''[[National Geographic Society|National Geographic]]''<ref name="ngnews">[http://news.nationalgeographic.com/news/2005/02/0203_050203_deepest.html "Life Is Found Thriving at Ocean's Deepest Point"], National Geographic News, 3 February 2005</ref> and on maps. It equals 6.86 miles. The pressure at this depth is approximately 1,099 times that at the surface, or 111 [[Pascal (pressure)|MPa]], roughly 16,155 [[Pounds per square inch|psi]].<ref name="Akimoto">{{Cite journal| author=Akimoto et al. | title=The deepest living foraminifera, Challenger Deep, Mariana Trench | journal=Marine Micropaleontology | volume=42 | year=2001 | page=95 | doi=10.1016/S0377-8398(01)00012-3}}</ref> The depth figure has not been confirmed by any later expedition. Considering that even in the early 21st century, the error margin for sounding out depressions in the sea floor at these depths is about 20 m, it is, however, reasonably close to a recent (2009, see below) measurement.
 
 
*In 1984, a Japanese survey vessel used a narrow, multi-beam [[echo sounder]] to take a measurement of {{convert|10924|m|0|abbr=on}}.<ref name="deepestdepth">{{cite web|url=http://www.noc.soton.ac.uk/OTHERS/CSMS/OCHAL/deep.htm|title=The deepest depths|last=Ritchie|first=Steve|accessdate=4 July 2007 |archiveurl = http://web.archive.org/web/20071027092319/http://www.noc.soton.ac.uk/OTHERS/CSMS/OCHAL/deep.htm <!-- Bot retrieved archive --> |archivedate = 27 October 2007}}</ref>
 
 
*On 1 June 2009 sonar mapping of the Challenger Deep by the Simrad EM120 sonar multibeam bathymetry system for deep water (300 – 11,000 meters) mapping aboard the ''[[RV Kilo Moana]]'' (mothership of the Nereus vehicle) indicated a depth of {{convert|10971|m|0|abbr=on}}. The sonar system uses phase and amplitude bottom detection, with an accuracy of better than 0.2% of water depth across the entire swath.<ref name="Daily Reports for R/V KILO MOANA"/><ref name="Scientic Equipment aboard the R/V KILO MOANA"/>
 
 
*Further sonar mapping of the Mariana Trench, conducted by the US [[Center for Coastal & Ocean Mapping]], was reported in December 2011 at the annual [[American Geophysical Union]] fall meeting. Using a similar multibeam echo sounder system, from over 400 individual soundings the CCOM team determined that the Challenger Deep has a maximum depth of {{convert|10994|m|ft|abbr=on}}, with vertical accuracy of plus or minus {{convert|40|m|ft|abbr=on}}.<ref name=BBC_CCOM />
 
 
The latter maximal depths were not confirmed by the series of dives ''[[Nereus (underwater vehicle)|Nereus]]'' made to the bottom during the [[Challenger Deep Nereus May/June 2009 Expedition]]. The direct descent measurements by the three expeditions which have reported from the bottom, have fixed depths in a narrow range from 10,916 m ([[Bathyscaphe Trieste|''Trieste'']]) to 10,911 m (''[[Kaikō]]''), to 10,902 m ([[Nereus (underwater vehicle)|''Nereus'']]) to 10,898 m (''[[Deepsea Challenger]]''). However, although an attempt was made to correlate locations, it could not be absolutely certain that Nereus (or the other two previous descents) reached exactly the same points found to be maximally deep by the sonar/echo sounders of previous mapping expeditions, even though one of these echo soundings was made by the Nereus mothership.
 
 
==Descents==
 
===Manned descents===
 
====''Trieste''====
 
{{Main|Bathyscaphe Trieste}}
 
On 23 January 1960, the Swiss-designed [[bathyscaphe]] ''Trieste'', originally built in Italy and acquired by the [[United States Navy|U.S. Navy]], descended to the ocean floor in the trench manned by [[Jacques Piccard]] (who co-designed the submersible along with his father, [[Auguste Piccard]]) and USN Lieutenant [[Don Walsh]]. Their crew compartment was inside a spherical pressure vessel, which was a heavy-duty replacement (of the Italian original) built by [[Krupp]] Steel Works of [[Essen]], Germany. Their descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the three-hour-and-fifteen-minute ascent. Their early departure from the ocean floor was due to their concern over a crack in the window caused by the intense pressure of their descent, and also because their landing on the sea bed had stirred up a cloud of [[silt]] which reduced visibility to zero and showed no sign of settling. The measured depth at the bottom was {{convert|10916|m|0|abbr=on}}.<ref name=usn1960>{{cite web
 
|author=Press Release, Office of Naval Research
 
|date=1 February 1960
 
|url=http://www.onr.navy.mil/focus/ocean/vessels/submersibles11.htm
 
|title=Research Vessels: Submersibles – ''Trieste''
 
|publisher=United States Navy
 
|accessdate=16 May 2010}}</ref>
 
 
==== ''Deepsea Challenger'' ====
 
{{main|Deepsea Challenger}}
 
 
On 26 March 2012, Canadian film director [[James Cameron]] made a solo manned descent in the [[deep submergence vehicle|DSV]] ''Deepsea Challenger'' to the bottom of Challenger Deep.
 
<ref name="NGS-20120325">{{cite web |last=Than|first=Ker |title=James Cameron Completes Record-Breaking Mariana Trench Dive|url=http://news.nationalgeographic.com/news/2012/03/120325-james-cameron-mariana-trench-challenger-deepest-returns-science-sub/|date=25 March 2012 |publisher=[[National Geographic Society]]|accessdate=25 March 2012 }}</ref><ref name="NYT-20120325">{{cite news |last=Broad|first=William J. |title=Filmmaker in Submarine Voyages to Bottom of Sea|url=http://www.nytimes.com/2012/03/26/science/james-camerons-submarine-trip-to-challenger-deep.html|date=25 March 2012 |work=New York Times |accessdate=25 March 2012 }}</ref><ref name="MSNBC-20120325">{{cite web |author=AP Staff |title=James Cameron has reached deepest spot on Earth |url=http://www.msnbc.msn.com/id/46850002/ns/technology_and_science-science |date=25 March 2012 |publisher=[[MSNBC]] |accessdate=25 March 2012 }}</ref><ref>{{cite web|last=Prince |first=Rosa |url=http://www.telegraph.co.uk/news/worldnews/australiaandthepacific/guam/9166425/James-Cameron-becomes-first-solo-diver-to-visit-Earths-deepest-point.html |title=James Cameron becomes first solo diver to visit Earth's deepest point |publisher=The Telegraph |date=25 March 2012 |accessdate=26 March 2012}}</ref>
 
At approximately 05:15 [[ChST]] on 26 March (19:15 UTC on 25 March), the ''Deepsea Challenger'' began descending to the Challenger Deep.<ref name="James Cameron Begins Descent to Ocean's Deepest Point">{{cite web |author=National Geographic |title=James Cameron Begins Descent to Ocean's Deepest Point |url=http://news.nationalgeographic.com/news/2012/03/120325-james-cameron-mariana-trench-dive-deepest-science-sub-descent/ |date=25 March 2012 |publisher=National Geographic Society |accessdate=25 March 2012 }}</ref>
 
At 07:52 ChST (21:52 UTC), the ''Deepsea Challenger'' arrived at bottom of the Challenger Deep. The descent lasted 2 hours and 36 minutes and the recorded depth was {{convert|10898.4|m|ft}} when the ''Deepsea Challenger'' touched down.<ref name="James Cameron Now at Ocean's Deepest Point">{{cite web |author=National Geographic |title=James Cameron Now at Ocean's Deepest Point |url=http://news.nationalgeographic.com/news/2012/03/120325-james-cameron-mariana-trench-challenger-deep-deepest-science-sub/ |date=25 March 2012 |publisher=National Geographic Society |accessdate=25 March 2012 }}</ref>
 
Cameron planned to spend about six hours near the ocean floor but, due to a hydraulic fluid leak in the lines controlling the manipulator arm which obscured the visibility out the only viewing port in the DSV and the loss of the submersible's starboard or right side thrusters<ref name="Problems at the bottom">{{cite web |author=National Geographic |title=Cameron's Historic Dive Cut Short by Leak; Few Signs of Life Seen |url=http://news.nationalgeographic.com/news/2012/03/120326-james-cameron-mariana-trench-fluid-leak-fish-science-sub/ |date=28 March 2012 |publisher=National Geographic Society |accessdate=28 March 2012 }}</ref>, decided to start the ascent to the surface after 2 hours and 34 minutes exploring the ocean floor.<ref name="Cameron's Historic Dive Cut Short by Leak; Few Signs of Life Seen">{{cite web |author=National Geographic |title=Cameron's Historic Dive Cut Short by Leak; Few Signs of Life Seen |url=http://news.nationalgeographic.com/news/2012/03/120326-james-cameron-mariana-trench-fluid-leak-fish-science-sub/ |date=26 March 2012 |publisher=National Geographic Society |accessdate=26 March 2012 }}</ref>
 
At around 12:00 ChST (02:00 UTC on 26 March), the Deepsea Challenge website says the sub resurfaced after a 90-minute ascent,<ref name="We Just Did the Impossible">{{cite web |author=www.deepseachallenge.com |title=We Just Did the Impossible |url=http://deepseachallenge.com/expedition-journal/we-just-did-the-impossible/ |date=25 March 2012 |publisher=www.deepseachallenge.com |accessdate=26 March 2012 }}</ref> although Paul Allen's tweets indicate the ascent took only about 67 minutes.<ref name="Paul Allen Tweets from Challenger Deep">{{cite web |author=https://twitter.com/#!/PaulGAllen |title=Paul Allen Tweets from Challenger Deep |url=https://twitter.com/#!/PaulGAllen/ |date=27 March 2012 |publisher=https://twitter.com/#!/PaulGAllen |accessdate=27 March 2012 }}</ref>
 
During a post-dive press conference Cameron said: "I landed on a very soft, almost gelatinous flat plain. Once I got my bearings, I drove across it for quite a distance ... and finally worked my way up the slope." The whole time, Cameron said, he didn't see any fish, or any living creatures more than an inch (2.5 centimeters) long: "The only free swimmers I saw were small [[amphipods]]"—shrimplike bottom-feeders.
 
<ref name="James Cameron on Earth's Deepest Spot: Desolate, Lunar-Like">{{cite web |author=National Geographic |title=James Cameron on Earth's Deepest Spot: Desolate, Lunar-Like |url=http://news.nationalgeographic.com/news/2012/03/120326-james-cameron-mariana-trench-challenger-deepest-lunar-sub-science/ |date=27 March 2012 |publisher=National Geographic Society |accessdate=27 March 2012 }}</ref>
 
 
====Planned manned descents====
 
 
Several other manned expeditions are planned for 2012. These include:<ref> {{cite web |publisher= BBC News |url= http://www.bbc.co.uk/news/science-environment-17041435 |title= Race to the bottom of the ocean |date= 22 February 2012 |accessdate= 22 March 2012 }} </ref>
 
*[[Triton Submarines]], a Florida based company that designs and manufactures private submarines, whose vehicle, [[Triton 36000/3]], will carry a crew of three to the seabed in 120 minutes;<ref>{{cite web |url= http://tritonsubs.com/submersibles/triton-360003/ |title= Triton 36,000 Full Ocean Depth Submersible |publisher=Triton Sumarines |accessdate=25 March 2012 }}</ref>
 
*[[Virgin Oceanic]], sponsored by [[Richard Branson]]'s [[Virgin Group]], is developing a submersible designed by [[Graham Hawkes]], [[DeepFlight Challenger]],<ref name=VOteam> Virgin Oceanic, [http://www.virginoceanic.com/team/operations-team/ Operations Team] (accessed 25 March 2012) </ref> with which the solo pilot will take 140 minutes to reach the seabed;<ref>{{cite web|url=http://www.virginoceanic.com |title=Virgin Oceanic |publisher=Virgin Oceanic |accessdate=1 March 2012}}</ref>
 
* [[DOER Marine]]<!-- Deep Ocean Exploration and Research -->, a San Francisco based marine technology company established in 1992, that is developing a vehicle, [[Deepsearch]] (and [[Ocean Explorer HOV Unlimited]]), with some support from [[Google]]'s [[Eric Schmidt]] with which a crew of two or three will take 90 minutes to reach the seabed, as the program [[Deep Search]].<ref> {{cite web |url= http://www.doermarine.com/?page_id=704 |title= Deep Search |publisher= DOER Marine |accessdate=25 March 2012 }} </ref>
 
 
===Unmanned descents===
 
====''Kaikō''====
 
{{Main|Kaikō}}
 
On 24 March 1995, the Japanese robotic deep-sea probe ''Kaikō'' broke the depth record for unmanned probes when it reached close to the surveyed bottom of the Challenger Deep. Created by the Japan Marine Science and Technology Center [http://www.jamstec.go.jp/jamstec-e/index-e.html (JAMSTEC)], it was one of the few unmanned deep-sea probes in operation that could dive deeper than {{convert|6000|m}}. Its recorded depth of {{convert|10911|m|0|abbr=on}}<ref>{{cite web|url=http://www.jamstec.go.jp/e/about/equipment/ships/kaiko7000.html |title=Kaiko 7000II |publisher=Japan Agency for Marine-Earth Science and Technology |accessdate=26 March 2012}}</ref> for the Challenger Deep is believed to be the most accurate measurement taken yet. ''Kaikō'' also collected sediment cores containing marine organisms from the bottom of the deep.<ref name="ngnews"/><ref name="Akimoto"/> ''Kaikō'' made many unmanned descents to the Mariana Trench during three expeditions between 1995 and 1998.
 
 
====''Nereus''====
 
{{Main|Nereus (underwater vehicle)}}
 
On 31 May 2009 the United States sent the ''Nereus'' hybrid remotely operated vehicle (HROV) to the Challenger Deep.<ref name="Robot sub reaches deepest ocean">{{Cite news|url=http://news.bbc.co.uk/2/hi/science/nature/8080324.stm|title=Robot sub reaches deepest ocean|date=3 June 2009|accessdate=3 June 2009|publisher=BBC News}}</ref> Nereus thus became the first vehicle to reach the Mariana Trench since 1998 and the deepest-diving vehicle currently in operation.<ref name="Robot sub reaches deepest ocean"/> Project manager and developer Andy Bowen heralded the achievement as "the start of a new era in ocean exploration".<ref name="Robot sub reaches deepest ocean"/> ''Nereus'', unlike ''Kaikō'', did not need to be powered or controlled by a cable connected to a ship on the ocean surface.<ref name='Nereus' reaches deepest part of the ocean>{{cite web|url=http://www.physorg.com/news163167519.html|title='Nereus' reaches deepest part of the ocean|date=2 June 2009|accessdate=2 June 2009|publisher=physorg.com}}</ref>
 
 
''Nereus'' spent over 10 hours at the bottom of the Challenger Deep and measured a depth of {{convert|10902|m|0|abbr=on}}, while sending live video and data back to its mothership ''[[RV Kilo Moana (T-AGOR-26)|RV Kilo Moana]]'' at the surface and collecting geological and biological samples from the Challenger Deep bottom with its manipulator arm for further scientific analysis.<ref name="Daily Reports for R/V KILO MOANA">{{Cite news|url=http://www.soest.hawaii.edu/UMC/Reports/KMreport.htm|title=Daily Reports for R/V KILO MOANA|date=4 June 2009|publisher=University of Hawaii Marine Center|accessdate=4 June 2009}}</ref><ref name="Robot sub reaches deepest ocean"/><ref name="Nereus Mission">{{Cite news|url=http://www.whoi.edu/page.do?pid=7545&tid=282&cid=57586&ct=162 |title=Hybrid Remotely Operated Vehicle "Nereus" Reaches Deepest Part of the Ocean|date=2 June 2009|publisher= Woods Hole Oceanographic Institution|accessdate=2 June 2009}}</ref><ref name="Daily Reports for R/V KILO MOANA April and May 2009">{{Cite news|url=http://www.soest.hawaii.edu/UMC/Reports/Archives/KMreportAprilMay2009.html|title=Daily Reports for R/V KILO MOANA April and May 2009|date=31 May 2009|publisher=University of Hawaii Marine Center|accessdate=31 May 2009}}</ref>
 
 
The ''Nereus'' is operated by the [[Woods Hole Oceanographic Institution]].
 
 
==Lifeforms==
 
The Summary Report of the HMS ''Challenger'' expedition lists [[radiolaria]] from the two dredged samples taken when the Challenger Deep was first discovered.<ref>[http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1895-Summary/htm/doc878.html], entry on 23 March 1875.</ref> These (Nassellaria and Spumellaria) were reported in the Report on Radiolaria (1887)<ref>[http://www.19thcenturyscience.org/HMSC/HMSC-Reports/Zool-40/README.htm], Report on the Radiolaria collected by H.M.S. Challenger
 
by Ernst Haeckel.</ref> written by [[Ernst Haeckel]].
 
 
On their 1960 descent, the crew of the ''Trieste'' noted that the floor consisted of [[diatom]]aceous ooze and reported observing "some type of flatfish, resembling a [[Sole (fish)|sole]], about 1 foot long and 6 inches across" lying on the seabed.<ref>[http://www.americanheritage.com/articles/magazine/it/1992/1/1992_1_28.shtml "To the bottom of the sea"], T. A. Heppenheimer, AmericanHeritage.com</ref>
 
 
{{quote |"...&nbsp;And as we were settling this final fathom, I saw a wonderful thing. Lying on the bottom just beneath us was some type of flatfish, resembling a sole, about 1 foot long and 6 inches across. Even as I saw him, his two round eyes on top of his head spied us&nbsp;— a monster of steel&nbsp;— invading his silent realm. Eyes? Why should he have eyes? Merely to see phosphorescence? The floodlight that bathed him was the first real light ever to enter this hadal realm. Here, in an instant, was the answer that biologists had asked for the decades. Could life exist in the greatest depths of the ocean? It could! And not only that, here apparently, was a true, bony teleost fish, not a primitive ray or elasmobranch. Yes, a highly evolved vertebrate, in time's arrow very close to man himself. Slowly, extremely slowly, this flatfish swam away. Moving along the bottom, partly in the ooze and partly in the water, he disappeared into his night. Slowly too&nbsp;— perhaps everything is slow at the bottom of the sea&nbsp;— Walsh and I shook hands.<ref>Seven Miles Down: The Story of the Bathyscaph Trieste (1961) by J. Piccard and R. S. Dietz. pp. 172–174. Published by the Putnam, New York.</ref>}}
 
 
The report has since been questioned, with suggestions that it may have been a [[Holothuroidea|sea cucumber]].{{citation needed|date = March 2012}} The video camera on board the ''Kaiko'' probe spotted a sea cucumber, a [[Polynoidae|scale worm]] and a [[shrimp]] at the bottom.<ref>[http://space.newscientist.com/article/mg15220548.100-mission-to-marianas--if-mount-everest-was-dropped-into-the-worlds-deepest-trench-it-woulddrown-kaiko-hit-bottom----and-came-back-to-tell-the-tale.html "Mission to Marianas"], ''New Scientist'', 2 November 1996</ref><ref>[http://www.time.com/time/magazine/article/0,9171,983295-6,00.html "The last frontier"], ''Time'', 14 August 1995</ref> At the bottom of the Challenger deep, the ''Nereus'' probe spotted one [[polychaete]] worm (a multi-legged predator) about an inch long.<ref>[http://ns.gov.gu/geography.html Accessed 8 Oct. 2009] Geography of the ocean floor near Guam with some notes on exploration of the Challenger Deep.</ref>
 
 
An analysis of the sediment samples collected by ''Kaiko'' found large numbers of simple organisms at {{convert|10900|m|ft|abbr=on}}.<ref>{{Cite journal|last=Todo |first=Yuko |coauthors=''et al.'' |year=2005 |title=Simple Foraminifera Flourish at the Ocean's Deepest Point |journal=[[Science (journal)|Science]] |volume=307 |issue=5710 |page=689 |doi=10.1126/science.1105407 |url= |quote= |pmid=15692042 }}</ref> While similar lifeforms have been known to exist in shallower ocean trenches (> 7,000 m) and on the [[abyssal plain]], the lifeforms discovered in the Challenger Deep possibly represent [[taxon|taxa]] distinct from those in shallower ecosystems.
 
 
Most of the organisms collected were simple, soft-shelled [[foraminifera]] (432 species according to National Geographic<ref>{{Cite news|first=John |last=Roach |title=Life Is Found Thriving at Ocean's Deepest Point |url=http://news.nationalgeographic.com/news/2005/02/0203_050203_deepest.html |work=National Geographic News |date=3 February 2005 }}</ref>), with four of the others representing species of the complex, multi-chambered genera ''[[Leptohalysis]]'' and ''[[Reophax]]''. Eighty-five percent of the specimens were organic, soft-shelled [[allogromiid]]s, which is unusual compared to samples of [[sediment-dwelling organisms]] from other deep-sea environments, where the percentage of [[Foraminifera#Organic-walled|organic-walled foraminifera]] ranges from 5% to 20%. As small organisms with hard, calcareous shells have trouble growing at extreme depths because of the high solubility of [[calcium carbonate]] in the pressurized water, scientists theorize that the preponderance of soft-shelled organisms in the Challenger Deep may have resulted from the typical [[biosphere]] present when the Challenger Deep was shallower than it is now. Over the course of six to nine million years, as the Challenger Deep grew to its present depth, many of the species present in the sediment died out or were unable to adapt to the increasing water pressure and changing environment.{{Citation needed|date=May 2009}} The species that survived the change in depth were the ancestors of the Challenger Deep's current denizens.{{citation needed|date = January 2012}}
 
 
==See also==
 
* [[HMRG Deep]]
 
* [[Philippine Trench]]
 
 
==Notes==
 
{{Reflist|30em}}
 
 
==External links==
 
* [http://www.onr.navy.mil/focus/ocean/vessels/submersibles11.htm Official press release regarding Challenger Deep operation].
 
* [http://www.marianatrench.com/default.htm Mariana Trench]
 
 
{{Coord|11|22.4|N|142|35.5|E|display=title}}
 
 
[[Category:Geology of the Pacific Ocean]]
 
[[Category:Landforms of Oceania]]
 
[[Category:Extreme points of Earth]]
 
 
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