Vanessa Audi Rhys O'Brien is a British and American mountaineer, sub-orbital spaceflight participant, explorer, author and former business executive. On 4 August 2022, O'Brien became the first woman to complete the Explorers' Extreme Trifecta – reaching extremes on land, sea, and air after she passed the Kármán line as part of Blue Origin NS-22 spaceflight. On 12 June 2020, O'Brien became the first woman to reach Earth's highest and lowest points, receiving a Guinness World Record. She became the first American woman to climb K2 and the first British woman to climb K2 and return safely on 28 July 2017, successfully leading a team of 12 members to the summit and back on her third attempt. She is a Fellow of the Royal Geographical Society (RGS) and an Honorary Advisory Member of The Scientific Exploration Society (SES).

A sub-orbital spaceflight is a spaceflight in which the spacecraft reaches outer space, but its trajectory intersects the surface of the gravitating body from which it was launched. Hence, it will not complete one orbital revolution, will not become an artificial satellite nor will it reach escape velocity.