Tuesday, February 27

“It was like descending to another planet”: the expedition to the Atacama Trench, at a depth of 8,000 meters

Like the vast majority of astronomers who probe the universe, scientists Osvaldo Ulloa Y Ruben Escribano they were resigned to the fact that their research was fundamentally based on images and measurements collected remotely, without ever “touching” the object of their studies. They are not dedicated to analyzing the Moon, or Mars, or any of the gas giants in the galaxy. His interest is focused on something much closer, but just as unattainable in practice: the depths remotest of the oceans.

Ulloa and Escribano have been dedicated to getting to know better the Atacama Trench, a gigantic marine trench located in the Pacific Ocean, off the coast of Chile and Peru, about 5,900 kilometers long and more than 8,000 meters deepEnough that the very idea that they could descend to its bottom sounded almost like science fiction.

Until now, of course.

A pioneering expedition

The two Chilean researchers, who hold the positions of director and deputy director, respectively, of the Millennium Institute of Oceanography (IMO) at the University of Concepción, have just become the first scientists to descend to the bottom of the pit. They achieved the feat thanks to Víctor Vescoso, a US explorer who accompanied them in his submersible DVS Limiting Factor, a small ship equipped with a 90 mm thick titanium pressure hull, a 65kWh battery and that allows a wide view forward and through the base.

The characteristics of the ship —baptized in a nod to the fictional novels of Ian Banks— allow you to delve into la zona hadal of the oceans, the deepest oceanic regions of the trenches, located under the abyssal zone, to more than 6,000 meters. The expedition, in fact, which has the support of the Chilean Ministry of Science, was baptized as “Atacama Hadal”.

A couple of years ago, in 2018, Ulloa and Escribano had already looked into the pit during the Atacamex Expedition, although in a quite different and much more conventional way: they used an unmanned submarine that allowed them to take photos, videos, water and DNA samples, in addition to mapping part of the topography of the gigantic depression. What they have done now, however, has little to do with that fascinating experience, yes; but lived at a distance.

Ulloa and Escribano made two trips that lasted a total of ten hours and required special preparation: the day before they had to dehydrate, put on warm clothes and prepare provisions. The first to descend was Ulloa, who, accompanied by Vescovo, took three and a half hours to reach the deepest point of the pit, 8,069 meters deep. The descent, Explain, he spent it chatting with the American explorer about his family and the study of the depths and listening to music by Manuel García and the group The Eagles.

Once at the bottom, Vescovo took control of the submarine and traveled through a terrain criss-crossed with valleys and rock formations that provide valuable information on the geology of the trench.

“Seeing it with my eyes was something extraordinary”

“We were struck by the large number of holothurians, a species of sea cucumber that has been found in other graves, but which were present here in great abundance”, Ulloa explained to the BBC: “But if there is something that I, as a microbiologist, wanted on this expedition, it was to find mats of microbial colonies. And for that reason, seeing them with my own eyes was something extraordinary, the confirmation for the first time of their existence in the Atacama Trench and at more than 8,000 meters”.

vescovo too left on twitter some impressions about what was found during the exploration of the trench, even below the abyssal depths. In his account he highlights, for example, the “extraordinary marine life observed”, with an abundance of holothurians, rocky walls that show chemosynthesis and “bacterial tendrils biggest i have ever seen“. The explorer highlights that they have become the first humans to reach the bottom of the Atacama.

In his account also show a video in which life can be seen thousands of meters deep. “This video shows a ‘paddock’ of sea cucumbers (sea cucumbers) grazing at the bottom of the Atacama Trench at about 8,060 meters. This is the densest collection of sea cucumbers I’ve seen in a Hadal Trench, and it shows the large volume of life in this deep ocean ecosystem.

Escribano’s turn came two days later, although in his case, since he was interested in fauna, the descent was somewhat shorter: up to 7,330 meters. During his mission he focused on exploring the eastern slope for organisms. And he found them, of course. The Limiting Factor allowed him to identify cold-water corals, a starfish, polychaete worms, amphipod crustaceans, and other hadal creatures he spotted. in greater numbers than in other pits.

The experience for him —he explained upon returning to the ship— was similar to a space exploration, as if he were visiting a distant galaxy and traveling through alien landscapes. “It was something magical; how to descend on another planet and see structures built by these beings. I imagined that they were tiny cities made by the worms and crustaceans that make their way through the sediment.”

In addition to providing valuable information and marking a milestone in the exploration of the graves, the expedition “Atacama Hadal” It will also have important practical applications.

Their work has made it possible to draw high-resolution maps of various stretches of the trench, valuable information that will help decide where to install the sensors of another project that aims to fix the first observation system anchored in the deep ocean. Among other things, its data would help to better understand the effects of climate change or the origin of earthquakes and tsunamis.

Cover image | VRID UdeC