Before the summit survey of Everest, someone chased the stars at an altitude of 6000 meters

 Before the summit survey of Everest, someone chased the stars at an altitude of 6000 meters

The team of professional mountaineers and surveyors has been training intensively for several months. Next, they will take GNSS (global satellite navigation system) receivers, gravimeters, snow depth radars, meteorological measuring instruments and targets and other measuring equipment to the top of Mount Everest to measure the height of Mount Everest.

Although the height of 8848.43 meters has been widely recognized, because the Qinghai Tibet Plateau is one of the most violent regions in the global plate movement, the height of Everest is still changing, people try to use new technology to find more accurate height of Everest. After 1975 and 2005, the height survey of Everest began again in 2020.

Measuring the height of Everest is a complex, precise and multi department system engineering. Before surveying the final climbing survey of the mountaineering team, it is necessary for the surveying and mapping personnel to find a suitable position at the foot of the Everest, i.e. the intersection point, so as to coordinate the survey after the mountaineers climb the summit; the leveling survey of the zero point of the height of the Everest, as the basis of the height of the Everest; the calibration of the location coordinates of the intersection point, so as to improve the final measurement accuracy; the meteorological and climbing guide are also required , equipment supply, data processing, etc.

On May 8, affected by the weather, the mountaineering team postponed the summit plan, which was scheduled to take place around May 12. When the weather is fine and the wind is right, they will attack the top of Everest again. At that time, the surveyors who stay at the foot of Everest will also wait at the intersection point in advance to cooperate with the climbing team members to complete the final measurement work. The final height data of Everest will be obtained in a few months, which will be helpful for the study of earth movement and geological activities.

The surveying and mapping team carries the moisture-proof mat, climbs the steep slope, goes to the surveying and mapping site. Picture provided by interviewee

General survey of intersection points: looking for Dongrong 2

Their cooperation with the mountaineers is as follows: when the mountaineers finally reach the top of Everest, they will set up a target more than 2 meters high at the top. The target looks like a cage with a length of 40 cm and a width of 40 cm on top of an aluminum alloy stick. There are multiple sets of prisms in the box, which are used to reflect the laser beam from the rangefinder. Because the top of Everest is not a point, but a small platform of several square meters, so in the actual measurement process, the cage at the top of the target will become the symbol of the top of Everest, which is convenient for various instruments aiming measurement.

In this process, the location of Surveying and mapping personnel such as Li Ke is very critical, which is called intersection point. In this Everest survey, six intersection points will work at the same time.

Distribution diagram of intersection points of Everest survey. Picture provided by interviewee

These intersection points do not exist on ordinary maps, and ordinary people can hardly walk on them. They are only used for Everest measurement. Take Dongrong 2 intersection as an example, this is a platform located in the middle of the small mountain, with gentle slope, suitable for people to stay for a long time and machine erection. At the time of Everest survey in 2005, surveyors left the mark of survey point here - a small red cross.

However, due to the time interval of 15 years, the traces left by time to the Everest area are particularly deep enough to change some of the terrain and geomorphic features, and the location of the intersection point may also have changed. Therefore, surveying and mapping personnel, such as Li Ke, need to first carry out a census of intersection points, that is to find these intersection points according to the location information left in 2005.

The oxygen on the plateau is thin, and people will be panting even if they walk slowly, let alone hiking. On April 11, Li feizhan and his colleagues set out with hand-held satellite navigation equipment and maps. From the second camp to another camp, which is 5800 meters above sea level, it is expected to be three hours journey, and they walked seven hours to get there.

According to the description of Everest surveying and Mapping Team in 2005, there is a small river near the camp where they are going. But now, the small river has become a deep ditch with a depth of more than 7 meters and a width of nearly 20 meters. The team members need to pull a rope to get up and down.

Near 5 p.m., the weather suddenly changed, the wind and snow mixed, and the strong wind made people almost unable to breathe. The team exploring the road ahead found that the original road to Dongrong 2 had collapsed and was unable to pass. Looking for new roads in such an environment is extremely dangerous. They can only set up tents and rest on the spot. That night, they hurriedly ate some compressed biscuits and drank cold water. Li feizhan wrote in his work diary: there is too much snow outside, the stove is too small, and the water cant be boiled.

In the first ten days of April, the surveying and mapping team participating in the general survey of intersection points cooked noodles during the field work rest period. Picture provided by interviewee

The next morning, they set out again to look for Dongrong 2. Due to the plateau reaction, Li feizhan had to take three steps to rest. Teammates have turned over the mountain ridge in front of him before he reaches the valley in front of him. When he climbs up the River Ridge, teammates have been waiting for him at the next mountain ridge.

Liu zhanke said that the main points of five of the six intersection points have been found, and only Zhongrong point cant find its main point and secondary point because of glacier change, so it can only re select the point. It used to be on a big rock, but now its gone. I cant find it.

Surveying team member Li feizhan and his teammates are on their way to the intersection of Dongrong 2. Picture provided by interviewee

Leveling and intersection position calibration: find the reference point

While Li feizhan is conducting a census of the intersection points, Huo Shenshen and his teammates are re measuring the height of the surrounding areas and the intersection points of Everest. Huo Shenshen is a member of the 2020 Everest leveling group. Their work is the basis of the work of Everest leveling - only when the origin is found as the benchmark, can the Everest elevation be meaningful; only when the height of each intersection point is determined, can the accuracy of Everest elevation measurement be guaranteed.

Leveling is equivalent to determining the height from the yellow sea level of Qingdao to the intersection point, i.e. 1-25 floors. However, leveling does not need to be measured all the way from Qingdao to the foot of Everest, as long as a small-scale retest is carried out on the basis of existing data to obtain the latest data. That is to say, the surveying and mapping personnel can directly call the height of the 1-20 floors measured in 2015, and only need to re measure the height of the 20-25 floors. An expert in the field of Geodesy explained to the reporter of the new Beijing News.

The process of leveling is simple and complicated. Huo Shenshen and his teammates should take equipment, hike to each predetermined point, set up a ruler and level, keep horizontal and vertical, measure and record. Then repeat the process.

Huo Shenshens work photo. Picture provided by interviewee

Its too windy here. Huo Shenshen told the Beijing news that in normal times, only four people are needed for leveling, with three people holding two rulers and level gauge respectively and one for assistance. But in this survey of Everest, there are 8 people in the leveling group. At least two people can make sure that the 3-meter-long aluminum alloy ruler is vertical in strong wind, and even three people can keep the level. I cant walk with my ruler when the wind is strong.

Most of the roads passed by the survey team were difficult to walk and few people were seen, often no one was seen in a day, and occasionally local people drove yaks by. Huo Shenshen still remembered that when they found Basong village, the nearest village to Everest, they were invited to have a cup of buttered tea at the local villagers home during the break time.

If you can pass through mountains and rivers, you can pass through anyway. Huoshenshen said. According to the data provided by the first national survey team, the team has completed nearly 800 kilometers of leveling since March 2.

The surveying and mapping team of the first national survey team carried out leveling at the foot of Everest. Picture provided by interviewee

In addition to leveling, surveyors also use GNSS (global satellite navigation system) satellites to measure the location coordinates of rendezvous points. In order to ensure the accuracy of the position, the team chose to use the oldest measurement method - observation of stars, to verify the measurement.

On May 11, Dongrong 2, Li feizhan finally waited for his sunny night. Breeze, cloudless, dark night, bright stars. Mount Everest is not far away and seems to be within reach.

The survey ended at 4 a.m. on this night, they tracked hundreds of stars in total. The collected data will be used to improve the coordinate accuracy of Dongrong 2, which will directly affect the accuracy of the elevation survey of Everest.

It was a rare night sky. I was very happy at that time. However, the altitude of nearly 6000 meters and the temperature of more than 20 degrees below zero make them happy and miserable. During the measurement, Li feizhan and his colleagues could hardly stand in the same place. In order to operate the instrument, they had to wear gloves to show their fingers, their fingers are stiff..

In the past month or so, surveying and mapping team members have carried out surveying work between the second battalion and Dongrong 2. Workers who help transport equipment and supplies need to go back and forth more frequently. Now, a new road has been built between the second battalion and Dongrong 2.

Meteorological observation, mountaineering service, equipment and data processing support: waiting for the final climb

Now, more than 30 survey climbers are heading for the top of Everest. They plan to climb on May 22. Weather is the most variable factor in the process of height measurement of Everest. According to the original plan, the team members should have reached the summit around May 12. However, due to the impact of snow, the climbing Road was blocked, and the climbing team had to postpone the climbing plan.

The weather is fine and the wind is suitable is the basic requirement of climbing time, but the actual judgment depends on the experience of senior climbers. According to several experts interviewed, the window period for climbing Mount Everest in the right weather is mainly in May and October. If the climbing cant be completed in May, it may take October to have another chance.

During the waiting period, at 7:15 a.m. in the morning and evening of each day, the members of the meteorological service support group and the Tibetans from the Xigaze Meteorological Bureau, Zisang, need to carry out high-altitude meteorological observation. The balloon with a diameter of more than 2 meters is equipped with a detection device to quickly rise to the sky and measure the air temperature, wind direction and wind speed at 6000 meters, 7000 meters, 8000 meters and 9000 meters above sea level around Everest. These data will provide reference for the survey team to choose the time of climbing.

The closer the balloon is to Everest, the more accurate the prediction will be. In many ways, the location of the release of the weather balloon was located in Dingri County, which is more than 100 kilometers away from the base camp of Everest.

Because of the rapid change of the weather, the large temperature difference between day and night, the great influence of the terrain, the lack of historical data and the sparse monitoring stations in the Everest area, it is more difficult to forecast the weather. Sometimes its sunny in the morning, cloudy at noon, and snowing in the afternoon. Said tisan.

On the day the survey team reaches the summit, the frequency of high altitude weather detection will be increased to 10 times a day. Clouds and air currents are flowing, and the survey command requires us to detect them every two hours.

Li feizhan is preparing for the astronomical survey in Everest base camp. Picture provided by interviewee

There are also a group of professional guides to form a road repair team and a transportation team, who are standing in front of the survey climbers.

At 9:00 on May 12, seven road menders from the Himalayan mountain climbing guide school in Lhasa, Tibet, set out from the 8300 meter high assault camp. Six hours later, they arrived at the first step of the 8600 meter high altitude and repaired the climbing route here, vice leader of the 2020 Everest survey and mountaineering team tserensangzhu said in an interview with the China Mountaineering Association.

On May 11 and 12, a total of 37 transport team members successively sent materials to the assault camp to prepare materials for climbing team members.

In addition, there are also equipment providers. The requirement of equipment is very high when measuring on Everest. Ordinary rangefinders can not meet the measurement requirements of Everest, so it is necessary to customize ultra long distance rangefinders. The larger the distance is, the greater the error is, which puts forward higher requirements for equipment and measurement methods. Liu said.

At the same time, the atmospheric pressure in the plateau area is low, which also poses a problem for the manufacturing of measuring equipment. Bringing instant noodles and mineral water in bags to the plateau will cause bags or bottles to swell, and the same will happen to the equipment. Designers should work hard on design and material selection.

According to the plan, the survey climbing team will climb Everest from the traditional route on the north slope, passing through the ice wall of Beiao, Dafengkou and the second step. If all goes well, it will take at least three days for the team to reach the summit from the 6500 meter camp. When the survey and mountaineering team launches a sprint to the top of Everest, surveying and mapping team members such as Li Ke will also start from the camp with an altitude of 5200 meters, go to each intersection point and wait for the final cooperation to measure the height of Everest.

This may be the most expensive measurement value, a geodetic expert told the new Beijing news that Everest measurement costs a lot of manpower and material resources, but it also has incomparable social and scientific significance, which will provide rich data for the study of earth movement and geological activities.

Li Ke and other team members took a group photo after completing the mapping work. Picture provided by interviewee