Day One

Building an "airborne Mars Rover" - hopefully it'll be easier than a Mars Rover stuck on the ground. We have black plastic bin bags and sticky tape, so we tried sticking bits together to make a giant cylinder and a giant sphere to compare.

It sounds so simple - the black plastic bodies will absorb the heat from the sun like crazy, get hot and rise. But the wind is a real issue; it always is in ballooning. I live in Bristol, a Mecca for balloonists. There's a world famous Balloon Festival there every year, but balloons can only fly when the wind's not too fierce. The wind whipped the cylindrical balloon to shreds - it looked mad, lashing about all over the place. So we focused on the spherical balloon, which was calmer in the winds.

By the end of day one, we decided we'd build a sphere - but it needed to be bigger.