For eight years, a tough little sub

For eight years, a tough little submarine worked in the deepest, darkest place on Earth. It explored the ocean floor in terrible conditions. Thepressure there is about 1,000 times greater than at the ocean’s surface. No light from the sun ever reaches so deep. Then at the submarine, Kaiko, suddenly disappeared. What happened? Did the extreme conditions kill Kaiko? Where did Kaiko go?

Researchers in Japan wanted Kaiko to explore the bottom of the Mariana Trench and look for living things deep in the sea. In fact, the name Kaiko mean “trench” in Japanese. The Mariana Trench is a deep opening in the floor of the Pacific Ocean, near the island of Guam. The bottom of the trench is nearly 7 miles (11.27 kilometers) below sea level. Compare this depth to the height of Mount Everest, Earth’s highest mountain. Everest’s elevation is only about 5.5 miles (8.85 kilometers) above sea level.

In 1960, Jacques Piccard of Switzerland and Donald Walsh of the United States traveled to the trench bottom in submarine named Trieste. It went down more than 35,790 feet (10,909 meters) below the surface to the ocean floor. Piccard and Walsh were in constant danger. The deep water put terrible stress on trieste. The ship’s windows started to crack, so Piccard and Walsh had to come to the surface as quickly as possible. They had no time to survey the bottom at these great depths.

Kaiko could stay down longer than Trieste because Kaiko was a robot. No human was inside. The scientists who controlled it floated safely in a research ship on the ocean surface. They monitored the dive through electronic equipment such as television cameras. Kaiko’s trip to the ocean floor was like a Moon landing. A larger “mother ship” went most of the way to the bottom and then released Kaiko. The mother ship stayed nearby, ready to take Kaiko back after its exploration was finished.

Kaiko’s first successful trip to the bottom of the trench was on March 24, 1995. After it made contact with the ocean floor, it planted a simple plaque: “Kaiko 1995.3.24.” The robot took a few samples of bottom sand. Then it rose slightly to take some water samples. After about two hours, Kaiko went back to the mother ship and then went home.

Kaiko brought back amazing information. More than 180 living things were in sample containers. As scientists had expected, the animals and plants Kaiko collected were extremely small. The submarine’s cameras, however, told a surprising story. They sent back pictures of much larger living things like a shrimp, a worm, and a sea cucumber. Scientists had never expected to find such complex life so deep in the ocean.

Over the next eight years, Kaiko continued to explore deep parts of the Pacific Ocean. Then, in 2003, a terrible thing happened. A dangerous storm was approaching. The scientists who controlled Kaiko hurried to pull the submarine back up to the surface, but they were shocked to find only an empty cable . Kaiko was not there.

Kaiko’s disappearance is still a mystery . What broke its cable? Where is it? As late as 2006, a few radio signals from Kaiko reached researchers. This meant it was probably on or near the surface, not on the ocean floor. The Pacific, however, is the world’s biggest ocean. In an area so large, the tough little explorer never be found.