"Salvage" history with technology

——Speaking of the discovery of ancient shipwrecks from the South China Sea under 1,500 meters

【Produced by Deep Hitomi Studio】

Written by: Intern reporter Du Peng

Planner: Liu Li

Deep-sea archaeology has the distinctive characteristics of high technical threshold, and it is precisely because of the breakthrough progress made in China's deep-water technology and equipment that the development of deep-sea archaeology has technical support and finally becomes reality from an idea.

The bottom of the South China Sea, which is 1500,500 meters deep, is dark. In front of the searchlight, a "mountain" made of tens of thousands of pieces of porcelain suddenly appeared. Under the sediment, the glaze of porcelain from <> years ago is still bright and brilliant. This is the picture taken by China's self-developed manned deep submersible "Deep Sea Warrior".

In late May, the State Administration of Cultural Heritage, the Ministry of Science and Technology, the Chinese Academy of Sciences, and the People's Government of Hainan Province jointly released a world-class major archaeological discovery in Sanya, Hainan: two ancient shipwrecks were found in the northwest slope of the South China Sea at a depth of about 5,1500 meters, and the preliminary judgment should belong to the Zhengde and Hongzhi years of the Ming Dynasty, and the number of cultural relics is estimated to exceed <>,<>. A year-long archaeological survey of the shipwreck site of the Ming Dynasty began.

What stories happened on these ships? Where were they supposed to go? Why did it sink to the bottom of the sea here... China's deep-sea archaeological technology, which is moving towards the world's advanced level, will help us uncover the history of shipwrecks.

Chinese underwater archaeology "forced" by stolen salvage

American writer Gary Kinder wrote in his work "In Search of the Golden Ship" about the sinking of the "Central America": "The shipwreck is half of the script written by God, and the end is done by those shipwrecks. ”

However, unlike bizarre legends that seek underwater wealth, the mission of underwater archaeology is to "salvage" history.

"I've always thought that a shipwreck site is equivalent to a time capsule. It preserves the slice of a certain era in its entirety. The shipwreck is both the smallest hierarchical society and a highly concentrated unit of survival. It can reflect not only the cargo on board, but also the time and space information such as the era and shipping routes, as well as the political and social ecology of the time. Cui Yong, former vice president of the Guangdong Institute of Cultural Relics and Archaeology and former leader of the "Nanhai I" archaeological team, believes that compared with a single sacrificial or burial site of a field archaeological object, the shipwreck can bring more diverse and comprehensive historical information.

The South China Sea is such a body of water "written" with history.

Since the Tang Dynasty, the Maritime Silk Road has prospered, and the South China Sea has become an important trade route between China and overseas countries. The prosperity of the history of the South China Sea has left a rich underwater heritage, and the South China Sea has become the birthplace and source of China's underwater archaeology, and it is also a "battleground for archaeologists and poachers".

In fact, China's underwater archaeology began with a fight against poachers.

In 1984, Western sea poacher Mike Hatcher discovered the Goldmarsen, an East India Company merchant ship full of porcelain and gold that had sunk for more than 23 years in the South China Sea, and salvaged more than one million pieces of blue and white porcelain and other cultural relics. However, in order to maximize profits, he left only 9,125 pieces of blue and white porcelain, <> gold ingots, and two bronze cannons engraved with the abbreviation of the Dutch East India Company, and the remaining hundreds of thousands of blue and white porcelain and other cultural relics that had no circulation value but had high historical value were destroyed.

In 1986, Mike Hatcher, who had escaped, obtained permission to auction the underwater artifacts on the grounds that the wreck was unclaimed, and commissioned Christie's in the Netherlands to conduct a public auction of the underwater cultural relics. The Chinese Embassy in the Netherlands sent the news back to China, but when the State Administration of Cultural Heritage tried to prevent the auction, it searched through the law of the sea at the time and could not find an effective legal basis. "Buying it back" was the only feasible way to bring these cultural relics back to China at that time. To this end, the Palace Museum sent two experts, Feng Xianming and Geng Baochang, to the Netherlands with 3,24 US dollars to participate in the auction. But the starting price of this batch of cultural relics was far beyond imagination, and in the auction that lasted for three days, two experts in China did not even get a chance to raise a plaque. In the end, nearly <>,<> treasures were lost overseas.

This underwater fishing incident has greatly stimulated China's cultural protection workers. In this context, in March 1987, the State Administration of Cultural Heritage took the lead in establishing the National Underwater Archaeology Coordination Group, and China's underwater archaeology began its cause. In August of the same year, the Guangzhou Salvage Bureau and the British Commercial Salvage Company unearthed hundreds of Chinese artifacts, including porcelain, pewter and gold belts, in the course of a joint search for the shipwreck of the Rheinburg. Yin Ganhong, the head of the Chinese project at the time, judged: "This is certainly not the 'Rheinburg' that the British are looking for, this is a shipwreck of our China." According to the agreement between the two sides, the Chinese side immediately suspended the salvage cooperation, and the wreck was later known as the Nanhai I.

In November 1987, the Underwater Archaeology Laboratory of the Chinese Museum of History was established, and China's underwater archaeology industry officially started. Under the condition that the relevant talents and technical foundation of underwater archaeology were weak at that time, the State Administration of Cultural Heritage sent personnel to learn diving technology and underwater archaeology from Japan, the Netherlands, Australia and other countries, and initially established an underwater archaeology team of more than ten people. In the following 11 years, China's underwater archaeological power has continued to grow. Finally, in 20, China carried out archaeological salvage of "Nanhai I" in the world's first overall salvage method, which marked a new stage in China's underwater archaeology industry.

The successful salvage of "Nanhai I" has greatly inspired China's underwater archaeologists, and the story of China's underwater archaeology and the South China Sea continues. Deep in the ocean, more shipwreck sites await quietly.

Technological breakthroughs have moved underwater archaeology from shallow to deep sea

Due to the limitation of deep diving technology, in the past, China's underwater archaeology was mostly concentrated in waters within 50 meters of water depth, and the operation mode was mainly scuba diving. For example, in the early archaeological investigation of the Nanhai I, Cui Yong dived more than 20 meters underwater, touched the hull of the ship with his own hands, and took the only clear image of the Nanhai I underwater time.

However, when the water depth exceeds 50 meters or even <> meters, the difficulty of scuba diving operation is greatly increased, and the work efficiency is greatly reduced. To advance to the deep sea, we must rely on the power of deep-sea technology.

"Along the vast ancient maritime Silk Road in the South China Sea, a large number of ancient merchant ships were sunk, and how to enter the deep sea to obtain information about these shipwrecks has become a top priority for China's underwater archaeology." Song Jianzhong, a researcher at the Archaeological Research Center of the State Administration of Cultural Heritage, has also thought about this question. But in the face of the South China Sea, which has an average depth of 1200,200 meters and an area of more than <> million square kilometers, Chinese underwater archaeologists can only "look at the ocean and sigh".

It wasn't until 2009 that the shadow of Chinese finally began to appear in the deep sea. From 2009 to 2012, China's first manned deep submersible "Jiaolong" independently designed successively achieved successful sea trials of 1000 meters, 3000 meters, 5000 meters and 7000 meters. Subsequently, the "Deep Sea Warrior" with a localization rate of 95% pushed China's deep-sea equipment construction to functionalization and genealogy, greatly reducing the cost of deep diving. The "Striver" successfully sat on the Mariana Trench at a depth of 2020,1000 meters in 4500, which not only refreshed China's new record for manned deep diving, but also marked the formation of China's deep diving capacity from 7000 meters, <> meters, <> meters to <>,<> meters.

On January 2018, 1, the Center for the Protection of Underwater Cultural Heritage of the State Administration of Cultural Heritage (now the Archaeological Research Center of the State Administration of Cultural Heritage) and the Institute of Deep Sea Science and Engineering of the Chinese Academy of Sciences (hereinafter referred to as the Institute of Deep Sea Archaeology of the Chinese Academy of Sciences) officially established the Joint Laboratory of Deep Sea Archaeology.

451 meters, 529 meters, 606 meters, 1003 meters... This is a depth that Chinese underwater archaeologists did not dare to imagine in the past. "The depth of the Deep Warrior's one-minute dive surpasses my previous 30-plus year diving record." Sun Jian, deputy director of the Archaeological Research Center of the State Administration of Cultural Heritage and director of the Institute of Underwater Archaeology, is one of the earliest underwater archaeologists in China, who has personally participated in the "Nanhai I" protection and excavation project, and was also surprised by the underwater archaeological breakthroughs brought by deep diving technology.

In April 2018, in the jewel-like blue South China Sea, the Deep Sea Warrior surfaced in the waves, and the deck of the mother ship erupted with applause and cheers. 4 dives, the maximum depth of 7 meters, with the help of the "Deep Sea Warrior", China successfully completed the first deep-sea archaeological survey, filling the gap of China's underwater archaeology.

"Deep-sea archaeology has greatly expanded the scope of work in the traditional sense of underwater archaeology, extending the working tentacles of underwater archaeology to the previously unreachable deep-sea areas, and also enabling the precious heritage that used to sleep in the depths of the ocean to be directly and three-dimensionally presented to us." Jiang Bo, director and distinguished professor of the Marine Archaeology Research Center of Shandong University, believes that deep-sea archaeology has become one of the most valuable frontier research fields in underwater archaeology. He told the Science and Technology Daily reporter that compared with shallow sea shipwrecks, deep-sea shipwrecks can be protected from many human factors and natural factors after sinking, so the preservation status is often better than shallow sea wrecks, thus providing unparalleled historical archaeological information for marine history and marine archaeological research.

"Deep-sea archaeology has the distinctive characteristics of high technical threshold, and it is precisely because of the breakthrough progress made in China's deep-water technology and equipment that the development of deep-sea archaeology has technical support, from idea to reality." Zhu Xuehua, director of the Department of Social Development Science and Technology of the Ministry of Science and Technology, said that after years of research and development accumulation, China has initially possessed the technical equipment and talent team required for deep-sea archaeology, has a genealogical and multi-functional equipment cluster, and has low-cost, high-frequency, normalized and business-oriented operation and maintenance capabilities. Chinese archaeologists have the confidence and strength to advance into the deep sea.

Manned deep diving technology provides a practical platform for underwater archaeology

Compared with underwater archaeology carried out in shallow waters, deep-sea archaeology is very different in equipment technology and operation mode. Searching for clues left by the ancients in the vast deep sea with a depth of more than a thousand meters is tantamount to finding a needle in a haystack. The only thing that can be relied on is the hard power of deep-sea technology.

In April 2018, shortly after the establishment of the Joint Laboratory of Deep Sea Archaeology, the team carried out China's first deep-sea archaeological survey in the waters of the North Reef of the Paracel Islands, and a total of 4 underwater archaeologists followed the "Deep Sea Warrior" into the deep sea.

Before setting off for the dive, Sun Jian deliberately measured his pulse and found that it was faster than usual. "It's also easy to understand that manned deep submersibles like the Deep Sea Warrior were first seen in science fiction when I was in middle school. It's amazing to be able to sit inside and explore the deep sea! "Sun Jian is one of the deepest divemers, at a depth of thousands of meters, through the thick glass porthole of the deep submersible, he constantly sees transparent fish and shrimp swimming by, and he can't help but sigh at the tenacity of life." The seabed is somewhat like the surface of the moon, full of crater-like terrain. "As a master diver, he dived so deep for the first time and was full of curiosity about the underwater world.

On April 2018, 4, in the fourth dive of China's first deep-sea archaeological survey, the first cultural relic specimen, a clay pot, was excavated. When it was discovered, the pot was half-buried in sediment from the seabed at a depth of about 23 meters, and the tank body was intact. Due to the special environmental restrictions, deep-sea archaeology needs to replace the hands of underwater archaeology team members through deep submersible external manipulators to carry out cultural relics extraction, sediment sampling and other related operations.

Compared with the sediments, rocks and other samples usually collected by deep-sea scientific expeditions, the particularity of cultural relics puts forward more refined requirements for the manipulator itself and the operation and extraction process. "The clay pot is large, and I am a little worried about whether it can be smoothly extracted and transported back completely by manipulator." At that time, Li Zhao, who participated in the fourth dive and was the director of the South China Sea Archaeological Research Center of the Hainan Provincial Museum at the time, was worried about the stability of the deep submersible manipulator. Not only the archaeology team members in the deep submersible felt nervous, but when the "Deep Sea Warrior" slowly approached and grabbed the cultural relics with a manipulator, the staff watching the "live broadcast" through the monitor on the mother ship also held their breath, and the cabin was extremely quiet. When the artifacts were finally loaded into the sample basket placed at the front of the submersible, everyone breathed a sigh of relief and cheered. Diving, cruise search, precise positioning, measurement sampling, image recording, extraction and floating... A series of smooth and neat operation movements made the first cultural relic specimen of China's deep-sea archaeology come to everyone intact.

"Practice makes perfect", with the increasing number of dives, China's deep-sea archaeology related technology is also constantly iteratively upgraded. In August 2022, during the deep-sea archaeological survey carried out in the Xisha Trough area in the northern part of the South China Sea, China's underwater archaeological depth exceeded 8,2000 meters for the first time, and 66 cultural relics specimens were found. Moreover, this deep-sea archaeology also introduced unmanned deep diving technology for the first time, and carried out manned-unmanned deep diving collaborative operations. "We analyze the historical record, identify the target area, and then explore in detail with bathymetric side-sweep equipment to confirm the possible target with manned deep diving." Chen Chuanxu, associate researcher of the Institute of Deep Sea of the Chinese Academy of Sciences, introduced that the deep-sea archaeology of the Xisha Trough has also achieved "Double Dragon to the sea", in addition to the "Deep Sea Warrior", which is already a senior "archaeological team", China's <>,<>-meter-class manned deep submersible "Striver" has also joined the ranks of deep-sea archaeology.

In Sun Jian's eyes, the value of diving depth is no longer the most important. With rich diving experience, he believes that many deep-sea archaeological surveys have proved that manned deep diving technology can provide a practical platform for Chinese underwater archaeologists. "For example, if we find that there may be shipwrecks at a coordinate point in the deep sea, we can use it to carry out deep-sea archaeological investigation and excavation work for 8 hours or more every day, which was unimaginable in the past."

A windfall opens a new chapter in China's deep-sea archaeology

The discovery of a large ancient deep-sea shipwreck in the South China Sea actually began with a "accident".

In October 2022, the Institute of Deep Sea of the Chinese Academy of Sciences went to sea on a scientific expedition, and when the "Deep Sea Warrior" divebed for the 10th time and traveled to a depth of about 500,1500 meters on the northwest slope of the South China Sea, the bathymetric side-sweeping equipment on board transmitted unexpected images. The expedition team members followed the trail, and a "hill" 3 meters high made of densely packed porcelain appeared in front of the team. Not far from the wreck, the team also found another shipwreck with a large number of logs scattered around it.

The scientific expedition team immediately reported the news to the relevant national and local units. After comprehensive research and judgment by archaeological experts, it was judged that the first shipwreck should belong to the Zhengde period of the Ming Dynasty (1506-1521), and named it the shipwreck No. 1488 in the northwest slope of the South China Sea, and it is estimated that the number of cultural relics exceeded 1505,<>; The other shipwreck, named Nanhai Northwest Lupo No. <>, is supposed to belong to the Hongzhi period of the Ming Dynasty (<>-<>), and it is judged to be an ancient ship loaded with goods from overseas bound for China. In this way, a major world-class archaeological discovery was accidentally unveiled.

In order to lay a solid foundation for the follow-up deep-sea archaeological survey, on May 5, a joint archaeological team composed of the Archaeological Research Center of the State Administration of Cultural Heritage, the Institute of Deep Sea of the Chinese Academy of Sciences, and the China (Hainan) South China Sea Museum placed a permanent underwater mapping base point made of titanium alloy on the surface of the seabed at a depth of 20,1500 meters. The 60 kg underwater weight and the metal brazing at the bottom ensure that it "sits firmly" on the seabed. Chen Chuanxu introduced that after the base point is placed, with the help of the long baseline positioning system, researchers can accurately calibrate the base point, just like marking the wreck site in the map, and can also be connected with geodetic coordinates and geographic information systems in the later stage to ensure that the surveying and mapping data is scientific, accurate and complete.

Song Jianzhong, leader of the archaeological survey project of the shipwreck site on the northwest slope of the South China Sea, told reporters that the archaeological investigation will take about a year and be implemented in three stages. In the first phase from May 5 to June 20, the team will conduct underwater search and investigation to find out the distribution range of cultural relics of the two shipwrecks, conduct multi-angle and all-round data collection and archaeological records of the wrecks, and extract a suitable amount of representative cultural relics specimens, as well as scientific test samples such as seabed substrate. The second and third phases will be held in August-September this year and March-April next year, respectively.

In order to narrow the distance between the public and deep-sea cultural relics, "we will carry 4K and 8K high-definition camera equipment to shoot underwater cultural relics on site and present a clearer visual feast for everyone." At the same time, we will also use underwater dynamic <>D laser scanning to superimpose optical images, complete <>D scanning and photographic stitching, and generate a plan distribution map of the core area of the No. <> wreck, which will provide basic data for the future application of virtual reality technology to digitize underwater cultural relics. Chen Chuanxu introduced.

At this time, the research ship "Exploration One" was carrying out the first phase of investigation work in the South China Sea with the "Deep Sea Warrior" and the archaeological team. At 5:23 p.m. on May 10, the ship's network signal was intermittent, and after Chen Chuanxu hurriedly answered reporters' questions, he immediately returned to the work of recovering the submersible, which will continue until the end of the first phase of work.

The South China Sea in May is a delightful sight, but the team members have no time to enjoy the scenery, their eyes are firmly fixed on 1500,<> meters underwater, they want to use China's deep-sea technology to "salvage" Chinese history, opening a new chapter in China's deep-sea archaeology.

(Our reporter Zhang Galun also contributed to this article)

(Science and Technology Daily)