Above, the drillers' hero shot. The sign reads, "05.12.12, Vostok Station, Boreshaft 5G,
Lake at depth 3769.3 meters."
The 2012 breakthrough came at 2025 Moscow time on 5 February, when the drill penetrated liquid water and the pressure forced liquid up through the interior of the drill/hole to the surface (more on that later). The day before, the drill had contacted a small water lens at a borehole depth of 3766m/12,356 feet (and this event was prematurely interpreted by some media sources as an actual penetration of the lake.
Project background and history:
The existence of under-ice lakes was first postulated theoretically by Russian scientist Peter Propotkin at the end of the 19th century--he theorized that the extreme pressure of the ice sheet might raise the temperature enough to cause melting at the ice/rock interface. Russian seismic soundings in 1959 and 1964, during the first years of Vostok occupation, suggested the existence of a subglacial lake. British scientists conducted aerial radar surveys in 1973 which also suggested such a lake. Finally, the ERS-1 satellite confirmed the lake's existence in 1991, and it has been further delineated since then; it is about 250km/825 miles long and 50km/165 miles wide (above left; 1997 Canadian Radarsat image from the NSIDC) (information and high resolution image). The lake is named after Vostok Station, which is in turn named after the Vostok, a Russian warship used for Antarctic exploration by Admiral Fabian von Bellingshausen in 1898-21 (the word "Vostok" means "East" in Russian).
The drilling of deep boreholes at Vostok began in 1989 (the 1989-90 summer season), although they were not originally intended to reach a subglacial lake. After the first four holes of varying depths and diameters were completed, later that summer (19 February 1990) the major project, borehole 5G, was begun. It was started using thermal drills; by 27 December 1991 it reached a depth of 2503m/8212 feet. The drill became stuck during recovery and could not be extracted. After study, the borehole was deflected to a new path at a depth of 2243m/7359 feet, so as to avoid the stuck drill. At this point the borehole was called 5G-1.
At the end of the 1992-93 season the borehole 5G-1 had reached 2755m/9039 feet. At that point Vostok Station was temporarily closed due to funding constraints. Drilling resumed in the 1994-95 season using an electromechanical drill, reaching 3109m/10,200 feet. Efforts continued in the ensuing summers until January 1998, when the drilling was halted at a depth of 3623m/11,886 feet. At this point, the hole was determined to be about 100m/330 feet from the lake surface. (At right is a 2001 NOAA aerial photo of Vostok Station showing the drill tower, by Todd Sowers (source and detail)).
A schematic diagram of the Vostok deep borehole as of the end of the 2009-10 season, indicating the various depths, deflections, starts, and stops over the years. This graphic was included in the final CEE approved in late November
2010. Here is another earlier version of the graphic which indicates the borehole diameters, types of drills used, and approximate age of the extracted ice cores.
As indicated in the above graphic, the earlier phase of the drilling project was the Deep Drilling and Ice Core Study, a collaborative program between Russia, France, and the US, and accordingly, each of the collaborators received 1/3 of the core. Thus...
The above 2 photos were taken by Melanie Conner in October 2002 at the NICL in Denver, Colorado (and are from the Antarctic Photo Library). They appeared in two November 2002 Antarctic Sun articles; one titled Seeking life in Vostok's deepest ice, which discussed the Vostok drilling/coring projects; and another titled Frozen to the core which described the NICL and its operations.
Back at Vostok...the drilling stopped for almost eight years, and intense worldwide scientific discussions ensued as to whether and how the effort should be continued. The main issue was contamination--for one thing, the hole had been drilled using diesel fuel/kerosene as an antifreeze drilling fluid [I've been unable to determine the true composition of the drilling fluid...in part because of differing English language definitions of "kerosene" vs "diesel." The "kerosene" was identified as an aviation grade (JP-8, which is similar to AN-8) in the 2003 draft Comprehensive Environmental Evaluation (CEE). Some Freon F-141b was mixed with it. however, at least some of the "antifreeze" introduced in the last years of drilling was ethylene glycol, as mentioned in the 2008-09 report linked below]; and there was concern about contamination of the lake with this liquid and/or various organisms it and the drill equipment might harbor.
[At left is a diagram of a thermal drill used for the earlier drilling efforts above 2755m (diagram from the final/approved CEE). It was proposed but not used for some of the later drilling.]
This issue became a significant discussion item among the scientific community as well as at the annual ATCMs. In January 2005, Russia was granted a permit to resume some drilling at Borehole 5G-1 based on the preliminary CEE reviewed by the Antarctic Treaty nations, but after preparing to resume drilling in December 2005 the Russians decided they needed to make further revisions to the drill design. The drilling did not resume until 26 December 2006, at which time the bottom of the hole was at 3650m/11,975 feet. On 14 January 2007 at a depth of 3658.26m/12,002.16 feet, the drill became stuck after the cable broke. The drill was extracted on 7 February after 200l/53 gal of antifreeze was introduced. Efforts ensued to remove as much of the antifreeze as possible. This accident ended the drilling for the season, and it also necessitated further study which delayed completion of the final CEE. Russia presented this information at the XXX ATCM in March/April 2007; their detailed report is here (this and most of the other ATCM reports provided here are MS Word documents).
Drilling resumed in June 2007, going down to 3666.54m/12029.3 feet, when more problems ensued. The power cables failed; the drill support cable broke again after the drill was stuck in the enlarged hole area created by the previous antifreeze addition. The density and level of the drilling fluid was adjusted by adding Freon F141b to the mix, as well as more kerosene. The plan at this point was to divert the bottom of the hole if the drill could not be extracted, and to switch to a thermal drill (details in the 2008 Russian report presented at the 2008 ATCM in June).
In 2008-09 the efforts resumed; in January the attempts to remove the stuck drill failed, so a new borehole was deflected from the main shaft at 3589m/11,775 feet. This new hole was named 5G-2 as indicated in the above graphic. After further difficulties with the antifreeze solution density, several cores were obtained to a depth of 3598.6m/11,806.4 feet; interestingly they contained 1-2mm inclusions of sedimentary rock (season report presented at the April 2009 ATCM.
In 2009-10 efforts were made to adjust the deflection of of hole 5G-2 from vertical to 1.5º to avoid contamination from the ethylene glycol antifreeze used in the earlier drill extraction attempts. The hole was continued to a depth of 3650m/11,975 feet, and an additional core was obtained. Another layer of mineral inclusions was detected (2009-10 report presented at the May 2010 ATCM). Meanwhile, the final CEE was approved in 2010 and officially disseminated on 30 November, although activity was delayed because of the the mandatory 60-day waiting period following its approval. Here's the final CEE; it includes extensive detail, graphics, drill details, and a copy of Permit No. 67 for the drilling. The permit was issued to the AARI on 23 November 2011.
Despite the delays, the 2010-11 drilling continued until 5 February, to a depth of 3720.45m/12,206.2 feet, with 30 ± 20 meters (!) to go before reaching the top of the lake, according to the June 2011 report. And another 2011 ATCM report includes a discussion of the proposed water sampling mechanism--a multi-sectioned pipe with sealable chambers and an electric heat system.
The drilling rate at the end of the 2010-11 season had been 1.8m per day, so the program felt strongly that the lake could be penetrated during 2011-12. Accordingly, the opening season flight arrived on 28 November 2011, and the passengers included seven drilling specialists. After acclimatization to the altitude, the drilling equipment was reactivated, repaired and upgraded. It was also necessary to carefully measure the hole dimensions as well as the specific gravity of the drilling fluid, so that its level could be adjusted to balance against the pressure expected when the lake was penetrated. A geyser was NOT desired. Drilling finally commenced on 2 January 2012...with the deadline for station closing set for 5 February. By 13 January they reached 3738.5m/12,265.4 feet, when progress slowed due to technical problems. Progress resumed on 20 January at a rate of 1.5-2m per day, by the end of January they reached 3760m/12,335 feet. At this point, new ice temperature measurements predicted the ice melting at about 3766m/12,355.6 feet.
At this point one plan had been to use an organosilicon drilling fluid in conjunction with the thermal drill, but due to the drilling delays this would cause vs the scheduled closing flight, the drilling continued using an electromechanical drill. On 4 February, difficulty was encountered with removing the core from the 3766m depth. When it was examined, the outside of the lower portion of the core was "glazed" as if it had been immersed in water. When the drill was next lowered, it encountered a water lens. Several liters were extracted; this froze in the upper section of the borehole (which was about -55ºC). It had been forced upward through small cracks by the lake pressure, which was about 3 atmospheres higher than that of the drilling fluid. Final drilling resumed, and at 2025 Moscow time on 5 February the 135mm-diameter drill bit came in contact with the main lake water, at a core depth of 3769.3m/12,366.47 feet.
At this point it became urgently necessary to extract the drill assembly as soon as possible, as there was limited clearance in the hole, and the water from the lake, forced up into the hole, would immediately start to freeze in contact with the ice surrounding the borehole. Fortunately this operation was started about 4 seconds after the lake penetration, and the extraction was successful. Fortunately, there was no "geyser" at the surface as the water forced its way up the borehole...about 1500 liters/400 gallons of mixed fluid flooded into collection trays which had been prepared at the surface.
After things were shut down, the borehole was to be monitored by the winterover crew. Meanwhile, calculations indicated that the drill stopped at a depth of 3176m/10,420 feet. Other measurements of pressures, drill fluid density, and the water level rise were made, and this data indicated that hydraulic fracturing had occurred (!)--a significant quantity of pressurized drilling fluid had penetrated into the sides of the borehole. This was not part of the plan, but as the report states, "Such process is quite common in drilling of gas and oil wells."
The report of the 2011-12 drilling season described above came from the report Russia presented at the May 2012 ATCM in Hobart...yes, I find the description of the fracking on the last two pages to be of great interest!
Among the various news reports is this 7 February rt.com story which features the following two videos:
This video features archival footage of the Vostok drilling operation and other views around the station
This TV newscast segment describes and depicts the drilling success as well as some of the potential issues it could create.
This 8 February RiaNovosti article includes several photos of the drilling operation as well as this animated infographic (right) which graphically depicts various aspects of the project and the types of drilling operations. It specifically names the drill type used for each portion of the operation. Here's another rt.com article from 9 February with more information and links. A few days later a sample of liquid (in a metal-and-glass case) recovered from the borehole was presented to Vladimir Putin, then the Russian prime minister (14 February Guardian article with photo). He was asked if he'd taken a drink...and he said no. The liquid, obviously contaminated with drilling fluids, had been taken from the borehole before the final breakthrough.
In October, results were released from testing of ice crystals which had been frozen to the drill bit...this testing indicated no detection of native life. Most of the microbes appeared to match contaminants from the drilling fluids, others were comparable to background contamination levels (19 October article from ouramazingplanet.com).
As of mid-December 2012, no recent news was available. Still, it is expected that 2012-13 operations will obtain clean water samples, which may not be available for testing until May 2013. And future efforts will attempt to sample water from lower water depths, or obtain sediment samples from the lake bottom (18 October Nature blog post). Stay tuned...