Exploration

Out of the whole ocean, there is one place that scientists want to discover dearly: The Mariana's Trench. Being the deepest place in the ocean, it's one of the most mysterious places in the sea. Exploration of this trench started around 1875, by a British ship called the H.M.S Challenger. The scientists on board tried to measure the depth of the trench using a weighted sounding rope. This technology works by having a weight weighing in at about 450 lbs attached to the end of a twine rope. The weight was detachable so that it wouldn't hinder off it's track, and so that the measurements would be more accurate. The made sure to bring around 232 km of rope so they had enough to properly measure and more than 19 km of piano wire for sampling. Down the rope, they marked every 25 fathoms (one fathom equals six feet, or around 2 meters) with flags. Then they lowered they weight in the water and waited for 40 minuets, and when it hit the bottom, they measured 4,475 fathoms (eight kilometers).

But then, in 1951, the British ship, the H.M.S. Challenger II returned to the same spot with an echo-sounder. Echo-sounding is done by using the sonar method. This method is done by sending sound waves into the  ocean and recording how much time it takes for the sound to bounce off the sea floor and return to the boat as an echo. There is a sound source on the ship that sends the sound and a receiver that receives it. Sound waves travel at around 1,500 meters per second in the ocean water, so you then take how many seconds it takes to travel from the boat, down to the floor, and back, and multiply it by 1,500. But, since the total time is how long it takes to get to the floor, and back, you have to divide that number in half. That's your total depth. The ship travels in a line to cover an area.The crew of  the H.M.S. Challenger did this and found that  it took 7.3 seconds one way, so the deepest point was 11,000 meters, or 11 km.

In 1960, Jacques Piccard and Don Walsh were the first humans to dive to the Challenger Deep. They dove down in a bathyscaphe called the Trieste, a self-propelled vehicle that can dive deeper than a submarine. It's float has air tanks and gas tanks which allow the vehicle to propel and maneuver itself, and also move up and down. 

The Triest on display at the National Museum of the U.S. Navy.

The two scientists went down for a scarce 20 minutes compared to a 5 hour descent. They couldn't take any pictures because the water was very murky and hard to see through. But, the flash light of the Trieste flashed over what Piccard thought to have been a flatfish, and he got very excited. He wrote in his journal, "Here, in an instant, was the answer that biologists had asked for decades: Could life exist in the greatest depths of the ocean? It could!"

The most recent expedition to the great depths of the Mariana Trench was done by James Cameron, a national geographic explorer. On March 26, 2012, he made a descent all the way down to the Challenger Deep in the Deepsea Challenger, a 24 foot long craft made of highly specialized glass foam. But out of all this room inside the submersible, he was inside a tiny pilot sphere. It is so small, it has a diameter of 43 inches, and with all of the equipment needed to survive and explore in this environment, the Cameron's legs were tightly bent, and he could barely move his arms. 

The hull is made of 6.4 centimeter thick steel, designed to withstand the pressures of the deep sea. There are also layers foam that allow it to float it's way back to the surface. And on the inside of this ball, it has all the equipment needed to explore and survive this environment. First of all, there are joysticks to control the thrusters and move the vehicle horizontally and vertically. It has emergency batteries located underneath the pilot's seat, and on the right of the pilot are tanks that absorb carbon dioxide and release oxygen. To the pilot's left is an array of controls and buttons that control everything from power to communications. There is also a screen in front of the pilot that show him the surroundings captured by a  Red Epic 5K camera, giving the pilot a wide-angle view, much better than what he can see out of the tiny window he has. There is also a touch screen controlling everything from battery power to oxygen levels, food, and water.

Survival is a big part of exploration, as anyone would think. The engineers who built it (including James Cameron himself) had to study Cameron's exact needs to build this sphere. The oxygen tanks contain enough oxygen to keep the pilot breathing for 56 hours. The sphere even makes use of water vapour that the pilot breathes out. When the pilot breathes out carbon dioxide, the tanks absorb it. The water vapour that he breathes out and the sweat he produces condensed on the sides of the sphere trickle down the side and collect in a bag so that if the pilot needs emergency water, he can drink that.

The pilot's clothes and the tape used inside the sphere are fire-proof. He also has a change of clothes, a vacuum packed electronically heated suit, plus a sleeping bag and even more layers to keep him warm. Sitting at the bottom of the Mariana's Trench can be a very cold experience, as the temperatures drop below freezing.