Deepsea Challenger

Drawing of the DCV1, based on imagery from the Deepsea Challenger website (not to scale)
History
Australia
Name:	Deepsea Challenger
Builder:	Acheron Project Pty Ltd
Launched:	January 26, 2012
In service:	2012
General characteristics
Type:	Deep-submergence vehicle
Displacement:	11.8 tons
Length:	7.3 m (24 ft)
Installed power:	electric motor
Propulsion:	12 thrusters
Speed:	3 knots (5.6 km/h; 3.5 mph)
Endurance:	56 hours
Test depth:	11,000 m (36,000 ft)
Complement:	1

Deepsea Challenger (DCV 1) is a 7.3-metre (24 ft) deep-diving submersible designed to reach the bottom of Challenger Deep, the deepest-known point on Earth. On March 26, 2012, Canadian film director James Cameron piloted the craft to accomplish this goal in the second manned dive reaching the Challenger Deep.^[1][2][3][4] Built in Sydney, Australia by the research and design company Acheron Project Pty Ltd, Deepsea Challenger includes scientific sampling equipment and high-definition 3-D cameras, and reached the ocean's deepest point after roughly two hours of descent from the surface.^[5]

Development

Deepsea Challenger was secretly built in Australia, in partnership with the National Geographic Society and with support from Rolex, in the Deepsea Challenge program. The construction of the submersible was headed by Australian engineer Ron Allum.^[6] Many of the submersible developer team members hail from Sydney's cave-diving fraternity including Allum himself with many years' cave-diving experience.

Working in a small engineering workshop in Leichhardt, Sydney, Allum created new materials including a specialized structural syntactic foam called Isofloat,^[7] capable of withstanding the huge compressive forces at the 11-kilometre (6.8 mi) depth. The new foam is unique in that it is more homogeneous and possesses greater uniform strength than other commercially available syntactic foam yet, with a specific density of about 0.7, will float in water. The foam is composed of very small hollow glass spheres suspended in an epoxy resin and comprises about 70% of the submarine's volume.^[8]

The foam's strength enabled the Deepsea Challenger design to incorporate thruster motors as part of the infrastructure mounted within the foam but without the aid of a steel skeleton to mount various mechanisms. The foam supersedes gasoline-filled tanks for flotation as used in the historic submarine, Bathyscaphe Trieste.

Allum also built many innovations, necessary to overcome the limitations of existing products (and presently undergoing development for other deep sea vehicles). These include pressure balanced oil filled thrusters;^[9] LED lighting arrays; new types of cameras; and fast reliable penetration communications cables allowing transmissions through the hull of the submersible.^[10] Allum gained much of his experience developing the electronic communication used in Cameron's Titanic dives in filming Ghosts of the Abyss, Bismarck and others.^[10][11]

Power systems for the submarine were supplied by lithium batteries that were housed within the foam and can be clearly seen in publicity photographs of the vessel.^[12] The lithium battery charging systems were designed by Ron Allum.^[13] The submersible contains over 180 onboard systems, including batteries, thrusters, life support, 3D cameras, and LED lighting.^[14] These interconnected systems are monitored and controlled by a programmable automation controller (PAC) from Temecula, California-based controls manufacturer Opto 22.^{[15][16][17][18]} During dives, the control system also recorded depth, heading, temperature, pressure, battery status, and other data, and sent it to the support ship at three-minute intervals^[19] via an underwater acoustic communication system developed by West Australian company L-3 Nautronix.^[20][21]

The crucial structural elements, such as the backbone and pilot sphere that carried Cameron, were engineered by the Tasmanian company Finite Elements.^[22] The design of the interior of the sphere, including fire proofing, condensation management and mounting of control assemblies was undertaken by Sydney-based industrial design consultancy Design + Industry.^[23]

Panorama view of Deepsea Challenger. Left side is the top of the sub.

Specifications

The submersible features a pilot sphere measuring 1.1 metres (43 in) in diameter, large enough for only one occupant.^[24] The sphere, with steel walls 64 mm (2.5 in) thick, was tested for its ability to withstand the required 114 megapascals (16,500 pounds per square inch) of pressure in a pressure chamber at Pennsylvania State University.^[25] The sphere sits at the base of the 11.8-tonne (13.0-short-ton) vehicle. The vehicle operates in a vertical attitude, and carries 500 kg (1,100 lb) of ballast weight that allows it to both sink to the bottom, and when released, rise to the surface. If the ballast weight release system fails, stranding the craft on the seafloor, a backup galvanic release is designed to corrode in salt water in a set period of time, allowing the sub to automatically surface.^[26] Deepsea Challenger is less than one-tenth the weight of its predecessor of fifty years, the Bathyscaphe Trieste; the modern vehicle also carries dramatically more scientific equipment than Trieste, and is capable of more rapid ascent and descent.^[27]

• 
  The top part contains locating and lighting systems
• 
  Battery array
• 
  One of the thrusters
• 
  The bottom part which has the pilot sphere inside. Here is the container that was used to carry ballast weight.
• 
  The life size model of the pilot sphere
• 
  The hatch and viewport
• 
  Interior of the pilot sphere model

Dives

Early dives

In late January 2012, to test systems, Cameron spent three hours in the submersible while submerged just below the surface in Australia's Sydney Naval Yard.^[28] On February 21, 2012, a test dive intended to reach a depth of over 1,000 m (3,300 ft) was aborted after only an hour because of problems with cameras and life support systems.^[29] On February 23, 2012, just off New Britain Island, Cameron successfully took the submersible to the ocean floor at 991 m (3,251 ft), where it made a rendezvous with a yellow remote operated vehicle operated from a ship above.^[30] On February 28, 2012, during a seven-hour dive, Cameron spent six hours in the submersible at a depth of 3,700 m (12,100 ft). Power system fluctuations and unforeseen currents presented unexpected challenges.^[31][32]

On March 4, 2012, a record-setting dive to more than 7,260 m (23,820 ft) stopped short of the bottom of the New Britain Trench when problems with the vertical thrusters led Cameron to return to the surface.^[33] Days later, with the technical problem solved, Cameron successfully took the submersible to the bottom of the New Britain Trench, reaching a maximum depth of 8,221 m (26,972 ft).^[33] There, he found a wide plain of loose sediment, anemones, jellyfish and varying habitats where the plain met the walls of the canyon.^[33]

Challenger Deep

On March 18, 2012, after leaving the testing area in the relatively calm Solomon Sea, the submersible was aboard the surface vessel Mermaid Sapphire, docked in Apra Harbor, Guam, undergoing repairs and upgrades, and waiting for a calm enough ocean to carry out the dive.^[34][35] By March 24, 2012, having left port in Guam days earlier, the submersible was aboard one of two surface vessels that had departed the Ulithi atoll for the Challenger Deep.^[36][37]

On March 26, 2012 local time it was reported that it had reached the bottom of the Mariana Trench.

These two graphs show James Cameron's Deepsea Challenger's descent and ascent during this record-setting dive – times are in UTC, so the dive started on March 25 and ended on March 26 when UTC times are used, but if Guam times are used the entire dive occurred on March 26, 2012. Both graphs are based on Paul Allen's tweets during the time when he was monitoring the progress of the dive from the underwater telephone on his yacht, Octopus.^[38] There were not as many tweets coming up as there were going down, so there is not as much data for the ascent.

Descent, from the beginning of the dive to arrival at the seafloor, took two hours and 37 minutes – almost twice as fast as the descent of Trieste.^[39] A Rolex watch, "worn" on the sub's robotic arm, continued to function normally throughout the dive.^[40][41] Not all systems functioned as planned on the record-breaking dive: bait-carrying landers were not dropped in advance of the dive because the sonar needed to find them on the ocean floor was not working, and hydraulic system problems hampered the use of sampling equipment.^[39] Nevertheless, after roughly three hours on the seafloor and a successful ascent, further exploration of the Challenger Deep with the unique sub was planned for later in the Spring of 2012.^[39]

Records

On March 26, 2012, Cameron reached the bottom of the Challenger Deep, the deepest part of the Mariana Trench. The maximum depth recorded during this record-setting dive was 10,908 metres (35,787 ft).^[42] Measured by Cameron, at the moment of touchdown, the depth was 10,898 m (35,756 ft).^[43] It was the fourth-ever dive to the Challenger Deep and the second manned dive (with a maximum recorded depth slightly less than that of Trieste's 1960 dive). It was the first solo dive and the first to spend a significant amount of time (three hours) exploring the bottom.^[1]

Subsequent events

Deepsea Challenger was donated to Woods Hole Oceanographic Institution for the studies of its technological solutions in order to incorporate some of those solutions into other vehicles to advance deep-sea research.^[44] On July 23, 2015, it was transported from Woods Hole Oceanographic Institution to Baltimore to be shipped to Australia for a temporary loan. While on a flatbed truck on Interstate 95 in Connecticut, the truck caught fire, resulting in damage to the submersible. The likely cause of the fire was from the truck's brake failure which ignited its rear tires. Connecticut fire officials speculated that it was a total loss to the Deepsea Challenger; however, the actual extent of the damage was not reported. The submersible was transported back to Woods Hole Oceanographic Institution after the fire.^[45]

Similar efforts

As of February 2012, several other vehicles are under development to reach the same depths. The groups developing them include:

• 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.^[46]
• Virgin Oceanic, sponsored by Richard Branson's Virgin Group, is developing a submersible designed by Graham Hawkes, DeepFlight Challenger,^[47] with which the solo pilot will take 140 minutes to reach the seabed.^[48]
• DOER Marine,^[49] a San Francisco Bay Area based marine technology company established in 1992, that is developing a vehicle, Deepsearch (and Ocean Explorer HOV Unlimited),^[50] 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.^[50]

See also

• Challenger expedition
• Deep-sea exploration
• Timeline of diving technology

References

External links

Wikimedia Commons has media related to Deepsea Challenger.

• Official website
• NGS video: Cameron's return from Challenger Deep
• Article on usage of Computational Fluid Dynamics during the design process of the Deepsea Challenger