This week's picture is from a series of unique pictures from the Flight International spaceflight archive, which goes back to the very beginning of the space age.
Thanks to Brett Davidson, in Wellington, and Kim E.Keller, Florida for correctly guessing last weeks image. Thanks to all of the other readers who suggested an explanation.
Last week’s image shows the British Aerospace HOTOL (HOrizontal Take Off Landing) on it’s way to orbit. HOTOL was a single-stage-to-orbit concept that would have used a ground-based trolley to accelerate to take-off speed.