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.
Pete Sampras on Roger Federer: 'I don't know how he maintains the level'. 'As long as heâs healthy and enjoying it, I can see Roger playing for another two, three, four more years,' says Pete Sampras of the ageless Federer, who beat him on their only meeting in 2001.