A former chief scientist at NASA and a well-known TV presenter have been appointed as guest directors of a major event in Gloucestershire.

De Ellen Stofan and Dallas Campbell will be sharing their expertise as key figures at the 2017 Cheltenham Science Festival in June.

Dr Stofan served for three years as principal advisor to the NASA administrator on the agency's science-related strategic planning and programmes.

She is an Honorary Professor in the Department of Earth Sciences at University College London and co-chair of the World Economic Forum Space Council.

Dr Stofan will be using her guest directorship at Cheltenham to talk about the solar system and the search for extra-terrestrial life, as well as the intersection of science and politics.

"I'm looking forward to sharing the excitement of space exploration with everyone at the Cheltenham Science Festival," she said.

"A generation of kids currently aged under 16 will one day walk on the surface of Mars. I want to inspire those future Mars astronauts."

Mr Campbell (pictured) is one of the best known factual television presenters working in the UK.

He has worked across a wide range of subjects, including magazine programmes such as The Gadget Show, Bang Goes the Theory and Stargazing Live, as well as documentary series Supersized Earth, City in the Sky, and Britain Beneath Your Feet.

He will be asking big questions about the planet and human society, from climate change to the future of work, food and travel.

Mr Campbell said: "It's a huge honour to be guest director of the Cheltenham Science Festival. It's everyone's favourite science festival and always brings together the best of the best - the familiar faces, as well as the next generation of rising stars."