Vostok Station is located directly above Lake Vostok, with access to the lake via a hole drilled from the surface of the ice sheet to 3,663 m depth, leaving a further 130 m of ice remaining before reaching the lake. A review of the station and history of drilling at Vostok Station will aid in explaining the present situation.
Vostok Station is located at a Pole of Cold on our planet. It is called a Pole of Cold because it is the coldest registered place on Earth - with a mean August temperature of —68°C and a minimum temperature in 1974, which is also the world's record low temperature, of —89.4°C. The station is located in the middle of the East Antarctic Ice Sheet. The elevation of the station is about 3,500 m and the thickness of the ice below the station is about 3,750m. This means that the bedrock elevation is thus below sea level, and the station's elevation is due to the ice thickness only. Rate of precipitation at Vostok is about 2.4cmyr—1. The area could in fact be called a polar desert because of this low precipitation rate. The temperature of the upper hundred meters increases slightly from —57.13°C at a depth of 48 m. It has a temperature of —53.7°C at a depth of 507 m. The temperature increases slowly at deeper horizons until it reaches the ice melting temperature of —2.4°C for a pressure of about 300 bars at the bottom of the ice sheet. The station has been occupied continuously from 1957 to the present-day (2005), with one exception being the interruption for the polar winter of 1962/1963 when it was closed due to budget constraints. It was re-opened the next summer under pressure from the scientific community, and has been occupied since that time. From 1957 to 1995 tractor trains from Mirny Station provided the main means of food and fuel supply each year. The distance from Mirny to Vostok Station is more than 800 km and it takes more than a month for the train to cover this distance. Russian planes from Mirny Station exchange scientists and station personnel, but cannot bring large amounts of cargo.
From 1996 to around 2000 the Russian Antarctic Expedition (RAE) was unable to supply the station in the traditional way due to financial difficulties associated with the disintegration of the Soviet Union, and the U.S.A. assisted to maintain the station without interruption. A special agreement was signed between Russia and the U.S.A. for a cooperative drilling program and shared use of the ice core for scientific study, with supplies being delivered to the station by American LC-130 Hercules aircraft.
The main purpose of drilling through the ice sheet at Vostok Station up until 1996 was to procure an ice core from different depths to provide a climatic record of Antarctic Ice Sheet temperatures and other data versus time in order to trace climatic changes. The idea was based on two postulates. The first is based on the existence of continuous snow accumulation at the surface of the Antarctic Ice Sheet. Each snow particle does not stay at the surface very long, instead it is buried by other snow particles, which cover it according to the accumulation rate. Snow converts to firn, and firn to ice, and it is possible to determine the time that has passed since the particle was at the surface. This time period depends on the rate of snow accumulation and the depth at which the particle is located. There is a strong correlation between the depth from which the core is taken and the time that has passed since the ice was at the surface of the ice sheet in the form of snow (Nye, 1959; Dansgaard, 1964). The second postulate is based on the correlation between the ratio of stable isotopes Oxygen 16 and Oxygen 18 in the snow at the surface of the ice sheet and the temperature at the surface (Dansgaard, 1964; Dansgaard et al., 1973), as well as the assumption that each particle of ice at any horizon retains the Oxygen 16/Oxygen 18 ratio it had at the surface of the ice sheet.
The first attempt to drill the ice sheet at Vostok Station was made by Station leader Dr. Ignatov in the middle of the 1958 winter (Ignatov, 1960). He attached a weight to electrically heated elements and placed the device on the ice sheet surface. The device penetrated the upper 40 m of the ice sheet, making a borehole, which was dry. Apparently the water escaped from the borehole through permeable walls, but the thermal drill did not penetrate further because meltwater was not removed from the hole at deeper horizons. The heat produced by the drill made the hole larger, increasing its diameter.
It became clear that the meltwater would have to be removed from the hole to maintain downward progress of the thermal drilling device. Under the direction of Dr. Kapitsa, several 40 m deep holes were produced at Vostok Station at the end of 1959 with a rotating device. The author made an attempt in late 1959 to drill a hole at Vostok Station with a thermo-electrical drilling device equipped with a pump to remove meltwater from the bottom of the hole using a special water container in the upper part of the device. However, the pump failed at a depth of about 50 m and drilling was stopped.
Was this article helpful?