Making headlines is never something that has motivated Kathy Sullivan.

Already in the history books as the first US woman to complete a spacewalk in 1984, the 68-year-old found herself in the news again this week after becoming the first woman to travel almost seven miles (11km) to reach the lowest known point in the ocean.

The two missions, total opposites in the minds of some, represent two extremes of a lifelong passion for Dr Sullivan: to understand the world around her as much as possible.

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