But when the question of how to explore the lake came up, not long after its discovery, the Vostok scientists faced a serious dilemma. The lake is under immense pressure, and to breach the ice would have devastating consequences.
Roger Federer: Swiss star will play on until at least 2019. Updated 1815 GMT (0215 HKT) February 21, 2017. Chat with us in Facebook Messenger. Find out what's happening in the world as it unfolds.
Sampras and Federer played just once, at Wimbledon in 2001, when Sampras was nearly 30 and declining, and Federer was nearly 20 and ascending. That year Wimbledon changed to a hardier all-rye grass, one that produced a higher bounce and ushered in an era of baseline dominance on Centre Court.