Other projects planning penetration into Lake Vostok

Up to now there is no other project planned for penetration into Lake Vostok that is sufficiently developed from a contamination point of view.

There are projects planned for the penetration of the Lake from some other locations on the ice sheet. The Lake Vostok workshop in Washington D.C. in 1998 began with a question: ''Lake Vostok: A Curiosity or a Focus for Interdisciplinary Study'' and ended with the timetable of events, connected with observatory sites, which should be erected at the surface of the ice above Lake Vostok over a 6-year period beginning in 2000 (Bell and Karl, 1998). The timeline proposed was:

• 2000 (2000-2001 field season). Year 1 for preliminary identification of observatory sites.

• 2001 (2001-2002). Year 2 for site identification and site survey, to include ground-based site surveys and testing of access/contamination control technologies at a site somewhere on the Ross Ice Shelf.

• 2002 (2002-2003). In situ measurement year. A long-term observatory will be installed at a chosen site above the lake and an access hole will be drilled into the lake for in situ measurements. Attempts for in situ detection of microbial life, vertical profiling of the water characteristics, micro-scale profiles within the bottom surface sediments, and ice-water and water-sediment interface surveys will be undertaken. An international planning workshop and data exchange will be held.

• 2003 (2003-2004). Vostok Lake sample return year. Retrieval of basal ice samples, samples of water and gas hydrates, and samples of lake bottom sediments will be undertaken. A search for a second observatory site will be performed. An international planning workshop and data exchange will be held.

• 2004 (2004-2005). The year of installation of the second long-term observatory. "Analyses of data. Build new models'' - inform authors of the timeline for this year.

Presently (at the begining of 2006) not one of the timeline bullet points has been realized. Why is the gap between reality and the timeline so large?

No one from the RAE or from the cadre of Russian scientists involved in many years of study of Lake Vostok were present at the 1998 workshop on "Vostok Lake: Curiosity or a Focus of Interdisciplinary Study'' and not a single word about the possibility of using Vostok Station's deep hole for international interdisciplinary study of the lake was published in its final report (Bell and Karl, 1998). This discrepancy occurred because, for the first time in the history of multi-international scientific exploration of Antarctica, scientists from different countries did not move toward assisting each other to proceed expeditiously, but instead were motivated by their own agenda to retard progress in order to achieve a time advantage toward being the first to penetrate the lake. This explains why the SALEGOS group of specialists failed to authorize permission (contamination clearance) from SCAR to drill an additional 50 m at Vostok Station. The clearance was received from SCAR after 4 years of discussions, amounting to the time allocated for the main part of the timeline program.

Deep ice core drilling of the kind performed at Vostok Station would not be a feasible option at a newly planned observatory. It takes years of drilling plus years of preliminary preparation. One available technique is deep drilling (actual penetration) of the ice sheet using hot water. This concept is as old as thermal drilling of the ice by a solid hot point or an electrically heated ring. Technical difficulties connected with this method, however, presented major problems, so that for a long time hot water drilling was used only for making small-diameter shallow holes.

The technology changed in 1978, when J. Browning, an engineer and inventor from Hanover, New Hampshire, U.S.A., applied the technique of flame-drilling through the Ross Ice Shelf at the site known as J-9. The equipment included a large, industrial-size, full output 250-horsepower water boiler heated by burning 300 kg of diesel oil per hour (Browning, 1978). This heated about 280 kg of water per minute from about 2°C to plus 98°C. Hoses brought the hot water to the bottom of the hole in the ice and made a hole with a diameter of 0.90 meters at a speed of about 40 mh_1. Less than a day was required to produce a hole through the 416 m thick ice shelf and enter the sea below.

This technique, used to produce large, deep holes, was also developed for drilling more than 1,000 m to the bottom of the ice sheet of West Antarctica to reach the bottom of ice streams, as well as for the approximately 1,000 m hole at the U.S. Amundsen-Scott South Pole Station for use in the Antarctic Muon and Neutrino Detector Array (AMANDA) project. More than 10 deep holes, each more than 1,000 m deep and about 1m diameter were drilled (Koci, 1999).

As a result of these successes, it appeared that rapid hot water penetration to the bottom of the 3,700-3,500 m thick ice cover of Lake Vostok could be achieved easily using this kind of drill, considered applicable for operating at the planned observatory sites.

However, a study performed recently by experts on hot water deep drilling through the Antarctic Ice Sheet showed that a hot water drill can provide rapid access holes to depths of 1.5 km. However, if the hot water drill is scaled to drill deeper, the energy requirements are such that they become enormous if depths below 1.5 km are desired (Clow and Koci, 2002). The same specialists showed that the new type of hot water drills required for penetration of Lake Vostok's ice cover would weigh about 200 tons and require about 50 tons of fuel, an unacceptable amount. The drilling itself would take only 10-12 days, but the hole of about 0.3 m diameter could only be used for study purposes for 2-3 days before it would close due to the surrounding pressure.

(Clow and Koci, 2002) recommend that only the use of so-called coil tubing drilling technologies (Gaddy, 2000), developed recently by commercial firms in the U.S.A. can be used for this kind of task (Figure 11.4).

The principle of this technology is the use of bendable, advanced composite spoolable tubing (Fowler et al., 1999) that is capable of transporting a large amount of liquid, pumped into the hole by a high-pressure pump located at the surface. There is no drill housing or mast, as such, but an "injector" is used instead. The injector provides control for the drill string of bendable tubing. A fluid passing through the tube under pressure drives a downhole hydraulic "mud motor'', which drives the drilling head. Core barrels, or special kinds of instruments can be attached to the drill head. The chips and fluid return to the surface outside the bendable tube using the annular space between the tube and the hole wall. The hole should be sealed through the firn layer to prevent drilling fluid leaking into the permeable firn. The chips are separated from the drilling fluid at the surface, and the drilling fluid is then pumped back down the hole (Fowler et al., 1999).

The use of this type of technology for deep and rapid Antarctic ice drilling will need considerable field testing and additional studies. This technology was used in the Arctic for temperatures as low as —40°C at the surface and — 15°C within the hole. The mean annual surface temperature of the ice overlying Lake Vostok is — 56°C, being about the same for the upper 500 m of the hole, so it is impossible to predict the consequences of these temperature differences. Nevertheless, it might still be possible that advanced composite spoolable tubing technology of deep ice drilling may provide the required holes for new observatories above Lake Vostok, as suggested by the timeline of the "Curiosity or a Focus for Study?" workshop.

Casing or gel-pack — Firn-ice transition

; Bottom hole assembly

Drill bit, coring head, or other tool

Figure 11.4. Coil tubing drilling technology proposed for fast access to Lake Vostok (after Clow and Koci, 2002). The main idea of this technology is the use of bendable, advanced composite spoolable tubing that is capable of transporting a large amount of liquid pumped into the hole by a high-pressure pump located at the surface.

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