National Geographic

DEEPSEA CHALLENGE

Sub Facts

• The pilot descended 35,787 feet (6.77 miles/10.90 km), but his ears didn’t pop during the journey; the pressure inside the pilot’s sphere stays constant.
• Crammed with equipment and just 43 inches (109 centimeters) wide, the interior of the pilot sphere is so small that the pilot had to keep his knees bent and could barely move.
• Just like a car, the sub is equipped with “cruise control” so the pilot can hover exactly where he wants to or glide through the water at a constant speed.
• Water vapor from the pilot’s breath and sweat condenses on the cold metal sphere and drains to a space where it’s sucked into a plastic bag. In an emergency, the pilot can drink it.
• The pilot chamber is a sphere because it’s the strongest shape for resisting pressure—if the pilot sat in a cylinder, the walls would need to be three times thicker.
• The sub’s giant beam of syntactic foam shrunk about 2.5 inches (6.4 centimeters) under the immense water pressure at the bottom of Challenger Deep.
• While the sub appears to be one streamlined vessel, the sphere is attached to the foam beam by polyester straps.
• If the sub’s 1,100 pounds (500 kilograms) of ballast weights don’t drop when commanded, a back-up galvanic release will corrode in the seawater within a fixed period of time, freeing the sub to rise to the surface.
• Small “bladders” inside the oil-filled external battery boxes will take in seawater. These “compensation bladders,” made from medical drip bags, are a critical part of the deep-ocean electronics system because the oil compresses at depth.
• The submersible spins slowly as it descends and ascends. It’s engineered to do this so it doesn’t veer off track.
• The sub’s batteries are made up of over a thousand pouch-type lithium-ion cells, bigger versions of the batteries hobbyists use for model airplanes.
• More than 180 systems—from battery packs to sonar—are operating during dives.
• Every circuit board in the sub’s exterior electronics—over 1,500 of them—was designed and built specially for this vehicle.
• The sub’s four external cameras are a tenth the size of previous deep-ocean HD cameras. The housings were designed by the DEEPSEA CHALLENGE team, and the cameras themselves were created from scratch, from the sensor up.

Science Partners

  • Additional major support provided by The Alfred P. Sloan Foundation
  • NASA Jet Propulsion Laboratory
  • Scripps Institution of Oceanography, UC San Diego
  • University of Hawaii at Manoa
  • University of Guam