Editing Trieste (bathyscaphe) (section)

==Design==
{{more citations needed|section|date=January 2011}}
[[File:Trieste nh96807.svg|thumb|upright=1.35|General arrangement, showing the key features]]
''Trieste'' was designed by the Swiss scientist Auguste Piccard, based on his previous experience with the bathyscaphe ''[[FNRS-2]]''. The term [[bathyscaphe]] refers to its capacity to dive and manoeuvre untethered to a ship in contrast to a [[bathysphere]], ''bathys'' being ancient Greek meaning "deep" and ''scaphe'' being a light, bowl-shaped boat.<ref>{{Cite web |title=Bathyscaphe |url=https://education.nationalgeographic.org/resource/bathyscaphe/ |access-date=2023-06-29 |website=education.nationalgeographic.org |language=en}}</ref> Built in Italy and launched on 26 August 1953 near the [[Capri|Isle of Capri]] on the [[Mediterranean Sea]]<ref name=":0">{{Cite web|title=History of the Bathyscaph ''Trieste''|url=http://www.bathyscaphtrieste.org/|access-date=2022-01-28|website=www.bathyscaphtrieste.org}}</ref>  it  was operated in the  Mediterranean by the [[French Navy]] for several years until it was purchased by the [[United States Navy]] in 1958 for US$250,000, equivalent to ${{inflation|US|.25|1958|r=1|fmt=c}} million today.<ref name="9 News">{{Citation| title = A dream and a crack: How the world's first dive to the bottom of the ocean almost killed two men| last = Marsh| first = Stuart | publisher = 9 News| date = 2019-11-03| url = https://www.9news.com.au/world/challenger-deep-first-manned-mission-trieste-jacques-piccard-don-walsh/809e6764-813d-4f63-bad3-e02830611c2f| access-date = 2023-06-28 | archive-date = 2022-07-02| archive-url = https://web.archive.org/web/20220702141207/https://www.9news.com.au/world/challenger-deep-first-manned-mission-trieste-jacques-piccard-don-walsh/809e6764-813d-4f63-bad3-e02830611c2f}}</ref> ''Trieste'' consisted of a heavy crew sphere suspended from a hull containing tanks filled with [[gasoline]] (petrol) for [[buoyancy]], ballast hoppers filled with [[shot (pellet)|iron shot]] and floodable water tanks to sink.<ref name="MH" />  This general configuration remained the same but after modifications to the hull for  [[Project Nekton]], which included the dive to Challenger Deep, ''Trieste'' was more than {{convert|15|m|ft}} long. The hull was built by [[Cantieri Riuniti dell'Adriatico]], in the [[Free Territory of Trieste]] on the border between Italy and Yugoslavia, now in Italy, hence the name. The pressure sphere was built separately and installed on the hull in the Cantiere navale di [[Castellammare di Stabia]], near [[Naples]].<br>
[[File:Bathyscaphe Trieste sphere.jpg|thumb|upright|left|Pressure sphere, with forward ballast hopper, left]]
The pressure sphere was attached to the underside of the hull and accommodated two crew who accessed it via a vertical shaft through the hull; this access shaft was not pressurized and flooded with seawater on descent.  The sphere was completely self-contained, having a closed-circuit [[rebreather]] system with [[oxygen]] provided from [[Diving cylinder|cylinders]] while carbon dioxide was [[Carbon dioxide scrubber|scrubbed]] from the air by being passed through canisters of [[Soda lime|soda-lime]]. Batteries provided electrical power.
Piccard's original pressure sphere was built by Acciaierie Terni of steel [[Forging|forged]] in two hemispheres and welded to form a sphere {{convert|2.4|m|ft}} in diameter and {{convert|89|mm|in}} thick,<ref>{{Citation| title = Science: Voyage of the Trieste| publisher = Time| date = 1953-10-12| url = https://content.time.com/time/subscriber/article/0,33009,860050-1,00.html| access-date = 2023-06-28 | archive-date = 2023-06-29| archive-url = https://web.archive.org/web/20230629032616/https://content.time.com/time/subscriber/article/0,33009,860050-1,00.html}}</ref>  This pressure sphere was replaced in December 1958 with another cast by the [[Krupp]] Steel Works<ref>{{Citation| title = Bathyscaphe Trieste 1958–1963| publisher = United States Navy| date = | year = | url = https://www.history.navy.mil/browse-by-topic/exploration-and-innovation/bathyscaph-trieste.html| access-date = 2023-06-28 | archive-date = 2023-04-08| archive-url = https://web.archive.org/web/20230408213041/https://www.history.navy.mil/browse-by-topic/exploration-and-innovation/bathyscaph-trieste.html}}</ref> of [[Essen, Germany]] in three sections; an equatorial ring and two caps, which were finely machined and joined by the [[Ateliers de Constructions Mécaniques de Vevey]].  The new sphere was also steel, but smaller at {{convert|2.16|m|ft}} diameter and with thicker walls, at {{convert|127|mm|in}},<ref name="9 News" /> calculated to withstand the {{convert|1250|kg/cm2|MPa}} pressure at the bottom of Challenger Deep plus a substantial  [[factor of safety]]. The new sphere weighed {{convert|14.25|MT|lb|abbr=off}} in air and {{convert|8|MT|lb|abbr=off|spell=in}} in water giving it an average specific gravity 2.6 times (or 1.6 times greater than) that of seawater (13÷(13−8)).<ref>{{cite web|title=Bathyscaphe|url=http://education.nationalgeographic.com/media/reference/assets/bathyscaphe-1.pdf |archive-url=https://web.archive.org/web/20140922134506/http://education.nationalgeographic.com/media/reference/assets/bathyscaphe-1.pdf |archive-date=2014-09-22 |url-status=dead|website=National Geographic Education|publisher=2015 National Geographic Society|access-date=27 April 2015}}</ref><ref name=":1">{{Cite web|title=Bathyscaphe ''Trieste''|url=https://www.history.navy.mil/content/history/nhhc/browse-by-topic/exploration-and-innovation/bathyscaph-trieste.html|access-date=2022-01-28|website=NHHC|language=en-US}}</ref>
Outside observations by the crew were made through a porthole made from a single, tapered block of [[acrylic glass]]; the only transparent material available that could withstand the pressure. Outside illumination  was by quartz [[arc lamp|arc-light]] bulbs, which could withstand the pressure without modification.<ref>{{Cite web |date=2012-04-24 |title=Bathyscaphe ''Trieste'' |url=https://www.maritimeprofessional.com/blogs/post/bathyscaphe-trieste-13488 |access-date=2023-01-28 |website=Maritime Logistics Professional |language=en |archive-date=2023-01-28 |archive-url=https://web.archive.org/web/20230128082403/https://2015.maritimeprofessional.com/blogs/post/bathyscaphe-trieste-13488}}</ref>
[[File:Bathyscaphe Trieste Piccard-Walsh.jpg|thumb|upright|Don Walsh and Jacques Piccard aboard ''Trieste'']]
The buoyancy tanks were filled with gasoline, which floats in water and is similarly [[compressibility|incompressible]]. Changes in the volume of the gasoline caused by any slight compression or temperature changes were accommodated by the free flow of seawater into and out of the bottom of the tanks during a dive via valves, equalising the pressure and allowing them to be lightly built.<br>
Ballast was held in two conical hoppers fore and aft of the crew sphere each containing {{convert|9|MT|lb|abbr=off}} of iron shot.  This shot ballast allowed the craft to sink, and its release caused it to ascend. The iron shot was locked in place at the throats of the hoppers by electromagnets thus was released either by switching the electromagnets off or automatically in the event of an electrical failure. Progressive release allowed buoyancy trim. Compressed-air–driven [[variable-buoyancy pressure vessel]]s typically used in submarines are not feasible at extreme pressure.<br>
Water tanks at each end of the hull were pumped out for flotation, lifting, and towing on the surface and fully flooded to allow sinking.<ref>{{Citation | first = Don | last = Walsh | year = 1962 | title = The Bathyscaph ''Trieste'', Technological and Operational Aspects, 1958–1961 | publisher = San Diego, Calif.: U.S. Navy Electronics Laboratory | page = 5 | url = https://archive.org/details/bathyscaphtriest00wals }}</ref><br>
Following its acquisition by the United States Navy, ''Trieste'' was modified extensively by the [[Naval Electronics Laboratory]], [[San Diego]], California, tested in the Pacific Ocean over  the next few years, and culminated in a dive to the bottom of Challenger Deep 23 January 1960.<ref name="MH">{{cite web|title=''Trieste'' Bathyscaphe |url=http://www.machine-history.com/Trieste%20Bathyscaphe |website=Machine-History.Com |publisher=from Time article 12 October 1953 |access-date=27 April 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150906084947/http://www.machine-history.com/Trieste%20Bathyscaphe |archive-date=6 September 2015 }}</ref>