From Lake Vostok to Europa Tractors and satellites

A fool always wants to shorten space and time; a wise man wants to lengthen both.

Words of J. Ruskin in Modern Painters, which Dr. E. A. Wilson, a member of Captain R. F. Scott's Antarctic expedition, wrote in his diary on "Thursday 11 December 1902'' on their way to the South Pole (Wilson, 1982)

It is a long story, more than 40 years old, of a scientific (and a human) struggle where "Murphy's Law'' and just plain good luck were competing against one another, with the sequence of events however moving in the right direction.

Let us start with the journal Nature, 20 June 1996, which illustrated a large map of Antarctica on the cover. A feature in red appeared at the center of the map, and below the map, in big letters, were the words "Giant lake beneath the Antarctic Ice'' (Figure 1.1).

There was a description of the picture within the magazine on the contents page, stating that some traces of the giant lake were discovered below the East Antarctic Ice Sheet 20 years ago, and now new laser altimetry and radio-echo sounding data proved that the largest of all known subglacial lakes was discovered. The size of the lake approached that of one of the Great Lakes of North America, and was only a few times smaller than Lake Baikal. Its length was estimated at about 200 km, its width about 50 km, and its depth about 500 m. Picturesque details on the front cover figure of Nature (Bamber, 1994) showed the Antarctic Ice Sheet surface, developed at the Millard Space Science Laboratory of the University College of London on the basis of altimetry data obtained from ERS-1, the first European satellite designed to study the Earth (Ridley et al, 1993; Bamber, 1994).

The data, when combined with known ice sheet elevations, produced surface features accurate to within a few meters, showing the lake's presence at several thousand meters below the surface. The lake was named Vostok, after the name of the Russian Antarctic research station located above it.

About 40 years before the article in Nature was published, the International Geophysical Year (IGY, 1957-1958) was in its planning stages, and major

Volume 381 No. 6534 20 June 1996 £4.00 FFr44 DM17.5 Lirel3000 A$12

Volume 381 No. 6534 20 June 1996 £4.00 FFr44 DM17.5 Lirel3000 A$12

Figure 1.1. Lake Vostok on the front page of Nature, June 1996.

Giant lake beneath the Antarctic ic

Figure 1.1. Lake Vostok on the front page of Nature, June 1996.

developed countries of the time were involved in finding locations for their research stations in Antarctica. Most countries agreed on coastal sites in order to reduce logistical problems, but both the U.S.A. and the Soviet Union also planned to position stations in the middle of the Antarctic Ice Sheet.

At the start of these preparations, the Soviet Union had shown no interest in the continent since Bellingshausen's circumnavigation in the early nineteenth century. As delegates of the eleven nations assembled in Paris in July 1955 to plan their cooperative effort, it was not known whether a Soviet representative would join them. "I know that he [the Soviet] was waiting for permission to go abroad, which was difficult to get at this time. He got it too late and arrived with delay.'' (Quigg, 1983). It became clear that the Soviet Union planned a major program - at least three bases (soon to be six), including one at the South Pole. Since the U.S.A. had already expressed a prior interest in the site, there was considerable relief when the Soviet delegate deferred without argument and chose instead the Pole of Relative

Inaccessibility (the spot in the middle of Antarctica, which is located at the longest distance from any shore) and the Geomagnetic Pole (Quigg, 1983).

As a result, a close connection of Russian scientists to Lake Vostok was established because of this delay in July 1955. The history behind the events at Lake Vostok is worth relating - one reader of the first draft of this manuscript wrote "Being published in one of the high-ranking scientific journals does not mean that this picture (and previous work) was the beginning, the pinnacle, or the end of work on Lake Vostok. In my opinion, it is an excellent idea to remind people, scientists or not, that events did not start when interest was shown by NASA in relatively recent years, but had in fact been going for half a century."

According to the agreement in Paris the Soviet Antarctic Expedition (SAE) constructed its main scientific station in 1956 at Davis Coast in East Antarctica, the closest coastal location (about 1,300 km) from the Geomagnetic Pole in the interior. The station was named Mirny, which means "peaceful", after the name of one of the two ships of the first Russian Antarctic Expedition of 1820. In the next year, ten large Kharkovchanka tractors left Mirny Station, towing insulated huts on sledges and more than 100 tons of diesel oil. About 90 days and nights later, after a non-stop struggle, 30 tons of diesel fuel and 3 tons of food provisions were brought to the interior site, enough to establish an overwinter station for four people.

The huts, on sledges, were moved close together, forming a compact four room house. A generator station, kitchen, and a meteorological laboratory were erected, as well as radio masts and a pole for the station flag. An airstrip on snow, capable of accommodating twin-engine Russian Ilyuchin-2 aircraft in an Antarctic summer, was constructed and a new year-round station began operation.

This station was named Vostok, which means "east" in Russian. It was also named after the second ship of the First Russian Antarctic Expedition of 1820. Located at 3,500 m above sea level, it became the coldest place on the Earth's surface to be occupied by human beings - the lowest temperature registered was -89°C (Atlas of Antarctica, 1966).

No one knew at this time that there were about 4 kilometers of glacier ice below the station, and that this ice sat above the surface of a large subglacial lake, with water some half a kilometer deep. There was only one such lake of this size in the ten million square kilometers of the surface of Antarctica, and only two interior stations. Of these two stations, one just happened to be located precisely above the lake. The likelihood of such an occurrence is remarkable. Figure 1.2 shows the position of Vostok Station.

Kapitsa et al. (1996) published what the Nature issue called the discovery of a large, deep freshwater lake beneath the ice sheet, while others (Ellis-Evans and Wynn-Williams, 1996; Bentley, 1996), explained a mechanism for the water formation and reasons for its existence. The mechanism was simple - the water formed as a result of the entrapment of the geothermal heat flow. The possibility of some forms of life in the lake was also discussed. The Times newspaper devoted a special article to this event on the same day that the Nature issue was printed (Nuttal, 1996). The author of this article reviewed the new details of the lake with a freshwater source deep below the ice, commenting that it reminded him of a famous Jules

Figure 1.2. Schematic map of the East Antarctic Ice Sheet, plan view (A), showing Lake Vostok and Vostok and Mirny Stations and a cross section along I-I (B). In (A) note the following: (1) outer contours of the ice sheet; (2) ice shelves (floating parts of the ice sheet); (3) isolines of the elevation of the ice sheet surface above sea level; (4) upper surface of the ice sheet along the line I-I; (5) directions of ice movement; and (6) ice sheet-bedrock interface along line I-I (adapted from Zotikov, 1986). An enlargement of the map in the vicinity of Vostok Station is shown in (C). Surface elevation contours for the enlargement are from Ridley et al. (1993). A flat nearly horizontal surface of ice marks Lake Vostok surrounded by the relatively steep slopes of the ice sheet. Arrows show the direction of ice flow from a nearby ice divide.

Figure 1.2. Schematic map of the East Antarctic Ice Sheet, plan view (A), showing Lake Vostok and Vostok and Mirny Stations and a cross section along I-I (B). In (A) note the following: (1) outer contours of the ice sheet; (2) ice shelves (floating parts of the ice sheet); (3) isolines of the elevation of the ice sheet surface above sea level; (4) upper surface of the ice sheet along the line I-I; (5) directions of ice movement; and (6) ice sheet-bedrock interface along line I-I (adapted from Zotikov, 1986). An enlargement of the map in the vicinity of Vostok Station is shown in (C). Surface elevation contours for the enlargement are from Ridley et al. (1993). A flat nearly horizontal surface of ice marks Lake Vostok surrounded by the relatively steep slopes of the ice sheet. Arrows show the direction of ice flow from a nearby ice divide.

Figure 1.3. A large, hidden subglacial lake is mindful of Jules Verne's lake in Journey to the Centre of the Earth, where underground travelers find a lake containing sea monsters. The Times published this picture from Verne's novel the same day that the Nature issue about Lake Vostok was published (Nuttall, 1996).

Figure 1.3. A large, hidden subglacial lake is mindful of Jules Verne's lake in Journey to the Centre of the Earth, where underground travelers find a lake containing sea monsters. The Times published this picture from Verne's novel the same day that the Nature issue about Lake Vostok was published (Nuttall, 1996).

Verne science fiction novel, in which individuals discovered a huge lake deep underground, and in the water of this lake they found sea monsters, which existed only there, remaining unknown to science (Figure 1.3). Contrary to Verne's lake, Lake Vostok looks like a cup, with the top cap being a thick ice cover. This cover keeps the lake separated from the rest of the world.

Biologists suggested that Lake Vostok might be a location for living microbes, and because they have had no contact with life in the rest of the world for a lengthy time period, they would be different from anything that lives now. It is possible that they could be used as genetic material for new developments in the medical treatment of humans and animals, as well as for other industrial applications.

Other newspapers and magazines in the U.K. also published articles about Lake Vostok on 20 June 1966, repeating the concept of "The Lost World'' (Ratford, 1996) and "The Time Machine Capsule''. New Scientist magazine projected into the future, and mentioned that recovery of uncontaminated live micro-organisms from the lake was comparable with that of bringing biological samples from Mars to the Earth (Muir, 1996).

Galileo Europa mission

Figure 1.4. Subglacial Lake Vostok as an analog of a sub-ice ocean on the Jovian moon Europa (Carsey and Horvath, 1996).

Europa Lake Vostok, Antarctica

Figure 1.4. Subglacial Lake Vostok as an analog of a sub-ice ocean on the Jovian moon Europa (Carsey and Horvath, 1996).

Publicity about the discovery of a giant lake, separated from the rest of the world by many kilometers of ice "armor", raised excitement and interest for many scientists and engineers involved in the study of Solar System planets, especially Europa, one of the Jovian moons.

The publication in Nature in 1996 on the discovery of Lake Vostok appeared at the time when information from the Galileo spaceship was arriving back on Earth (workshop at the end of 1996), proving that the surface of Europa (with its diameter of more than 3,000 km) is covered with a sheet of ice (Carsey and Horvath, 1996) (Figure 1.4).

The thickness of this ice sheet is estimated at this time to be several kilometers to hundreds of kilometers, and it appears to be a system of large subglacial lakes or a sea of liquid water below ice, similar to Lake Vostok on Earth. The existence of liquid water below Europa's ice sheet is still not certain, but has been inferred from measurements of gravity, moments of inertia, and study of images of the moon's surface. But the probable cause of sub-ice water is the same as for Lake Vostok -heat flow from beneath the ice sheet. However, the source of heat in the case of Europa is different. Gravity effects due to Jupiter itself and its moons Io and Ganymede produce considerable heat deep within the interior of the moon, and the thermal insolation of a thick ice layer is substantial. Liquid water below the ice sheet should exist, in spite of the temperature at the surface of the moon, estimated at about — 170°C. A logical assumption is that if there is life in Lake Vostok, perhaps there is also life in the sub-ice ocean of Europa, at least in its simplest forms.

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