FIGURE 1. The technique of airborne radio-echo sounding, and its application to identifying Lake Vostok and other subglacial lakes.

In the 1970s, airborne RES surveys were undertaken with a C130 Hercules transporter aircraft, with the wings mounted with the radar transmitter and receiver. Aircraft navigation was accurate to around 5 km in the centre of Antarctica. Today, most RES surveys use smaller aircraft and the global positioning system (GPS) to navigate. Subglacial lakes are easily identified on airborne RES records owing to their uniformly strong and flat appearance². Bedrock perturbations are recorded as hyperbolae in radar data. The geographical location of known subglacial lakes (shown as triangles) is also provided¹.