Challenger Deep

[7] Detailed sonar mapping of the western, center and eastern basins in June 2020 by the DSSV Pressure Drop combined with manned descents revealed that they undulate with slopes and piles of rocks above a bed of pelagic ooze.

[9] The accuracy of determining geographical location, and the beamwidth of (multibeam) echosounder systems, limits the horizontal and vertical bathymetric sensor resolution that hydrographers can obtain from onsite data.

In 1875, during her transit from the Admiralty Islands in the Bismarck Archipelago to Yokohama in Japan, the three-masted sailing corvette HMS Challenger attempted to make landfall at Spanish Marianas (now Guam), but was set to the west by "baffling winds" preventing her crew from "visiting either the Carolines or the Ladrones.

On her southbound track from Japan to New Zealand (May–July 1951), Challenger II conducted a survey of the Marianas Trench between Guam and Ulithi atoll, using seismic-sized bomb-soundings and recorded a maximum depth of 5,663 fathoms (33,978 ft; 10,356 m).

[11] The Senior Scientist aboard Challenger II, Thomas Gaskell,[12] recalled: [I]t took from ten past five in the evening until twenty to seven, that is an hour and a half, for the iron weight to fall to the sea-bottom.

Using their newly improved echo sounder, they ran survey lines at right angles to the axis of the trench and discovered "a considerable area of a depth greater than 5,900 fathoms (35,400 ft; 10,790 m)" – later identified as the Challenger Deep's western basin.

[21][22] The first definitive verification of both the depth and location of the Challenger Deep (western basin) was determined by Dr. R. L. Fisher from the Scripps Institution of Oceanography, aboard the 325-ton research vessel Stranger.

On Scripps Institution of Oceanography's INDOPAC Expedition Leg 3,[38] the chief scientist, Dr. Joseph L. Reid, and oceanographer Arnold W. Mantyla made a hydrocast of a free vehicle[39] (a special-purpose benthic lander (or "baited camera") for measurements of water temperature and salinity) on 27 May 1976 into the western basin of the Challenger Deep, "Station 21", at 11°19.9′N 142°10.8′E / 11.3317°N 142.1800°E / 11.3317; 142.1800 at about 10,840 metres (35,560 ft) depth.

[40][41] On INDOPAC Expedition Leg 9, under chief scientist A. Aristides Yayanos, Thomas Washington spent nine days from 13–21 January 1977 conducting an extensive and detailed investigation of the Challenger Deep, mainly with biological objectives.

On Mariana Expedition Leg 8, under chief scientist Yayanos, Thomas Washington was again involved, from 12–21 December 1978, with an intensive biological study of the western and central basins of the Challenger Deep.

[51] On Leg 3 of the Hawaii Institute of Geophysics' (HIG) expedition 76010303, the 156-foot (48 m) research vessel Kana Keoki departed Guam primarily for a seismic investigation of the Challenger Deep area, under chief scientist Donald M.

They ran the Deep from east to west, collecting single beam bathymetry, magnetic and gravity measurements, and employed the air guns along the trench axis, and well into the backarc and forearc, from 13 to 15 March 1976.

The Scripps research vessel Thomas Washington's returned to the Challenger Deep in 1986 during the Papatua Expedition, Leg 8, mounting one of the first commercial multi-beam echosounders capable of reaching into the deepest trenches, i.e. the 16-beam Seabeam "Classic".

The results of the 1998–1999 surveys include the first recognition that the Challenger Deep consists of three "right-stepping en echelon individual basins bounded by the 10,500 metres (34,400 ft) depth contour line.

[9] In 2002 Kairei revisited the Challenger Deep 16–25 October 2002, as cruise KR02-13 (a cooperative Japan-US-South Korea research program) with chief scientist Jun Hashimoto in charge; again with Kazuyoshi Hirata managing the ROV Kaikō team.

The Japanese teams made five deployments of their 11,000-meter camera system (three to 6,000 meters – two into the central basin of the Challenger Deep) which returned with 15 sediment cores, video records and 140 scavenging amphipod specimens.

Hideki Kobayashi (Biogeos, JAMSTEC) and the team deployed a benthic lander on 23 November 2013 with eleven baited traps (three bald, five covered by insulating materials, and three automatically sealed after nine hours) into the central basin of the Challenger Deep at 11°21.9082′N 142°25.7606′E / 11.3651367°N 142.4293433°E / 11.3651367; 142.4293433, depth 10,896 metres (35,748 ft).

[98] From 22 June to 12 August 2016 (cruises 2016S1 and 2016S2), the Chinese Academy of Sciences' 6,250-ton submersible support ship Tansuo 1 (meaning: to explore) on her maiden voyage deployed to the Challenger Deep from her home port of Sanya, Hainan Island.

[6] In December 2016, the CAS 3,300-ton research vessel Shiyan 3 deployed 33 broadband seismometers onto both the backarc northwest of the Challenger Deep, and onto the near southern Pacific Plate to the southeast, at depths of up to 8,137 m (26,696 ft).

This cruise was part of a $12 million Chinese-U.S. initiative, led by co-leader Jian Lin of the Woods Hole Oceanographic Institution; a 5-year effort (2017–2021) to image in fine detail the rock layers in and around the Challenger Deep.

[108] Tokyo University of Marine Science and Technology dispatched the research vessel Shinyo Maru to the Mariana Trench from 20 January to 5 February 2017 with baited traps for the capture of fish and other macrobiology near the Challenger and Sirena Deeps.

[115] In 2014, a study was conducted regarding the determination of the depth and location of the Challenger Deep based on data collected previous to and during the 2010 sonar mapping of the Mariana Trench with a Kongsberg Maritime EM 122 multibeam echosounder system aboard USNS Sumner.

Taking uncertainties in depth measurements and position estimation into account, the raw data of the 2010 bathymetry of the Challenger Deep vicinity consisting of 2,051,371 soundings from eight survey lines was analyzed.

[140][141] Due to a technical problem the (uncrewed) ultra-deep-sea lander Skaff used by the Five Deeps Expedition stayed on the bottom for two and half days before it was salvaged by the Limiting Factor (crew: Patrick Lahey, Pilot; Jonathan Struwe, DNV GL Specialist) from an estimated depth of 10,927 m (35,850 ft).

[148] The expedition craft used are the Deep Submersible Support Vessel DSSV Pressure Drop, Deep-Submergence Vehicle DSV Limiting Factor and the ultra-deep-sea landers Closp, Flere and Skaff.

During the first manned dive on 7 June 2020 Victor Vescovo and former US astronaut (and former NOAA Administrator) Kathryn D. Sullivan descended to the "Eastern Pool" of the Challenger Deep in the Deep-Submergence Vehicle Limiting Factor.

[151][152][153][154] On 14 June 2020, Victor Vescovo and John Rost descended to the "Eastern Pool" of the Challenger Deep in the Deep-Submergence Vehicle Limiting Factor spending four hours at depth and transiting the bottom for nearly 2 miles.

[156][157] On 21 June 2020, Victor Vescovo and Woods Hole Oceanographic Institution researcher Ying-Tsong Lin descended to the "Central Pool" of the Challenger Deep in the Deep-Submergence Vehicle Limiting Factor.

On 10 November 2020, the bottom of the Challenger Deep was reached by Fendouzhe with three Chinese scientists (Zhāng Wěi 张伟 [pilot], Zhào Yáng 赵洋, and Wáng Zhìqiáng 王治强) onboard whilst live-streaming the descent to a reported depth of 10,909 m (35,791 ft).

[204][205] Leg 2, under chief scientist Takashi Murashima, operated at the Challenger Deep 8–9 June 2008, testing JAMSTEC's new full ocean depth "Free Fall Mooring System," i.e. a lander.