and a lot of that, most of all of that, we can be able to test on the ground, because those are the things that we want to make sure are healthy in orbit. what's the height of it? is it pretty muchjust a horizontal flame? it doesn't go too high? now, we've brought along a friend to film the test. remember gav? he is one half of the slow mo guys, who helped me to get egg all over my face a couple of weeks ago, and he's going to be capturing the action at 2,000 frames per second. that's 80 times slower than real life. the only thing is, he, like the rest of us, has to be hundreds of metres away when the rocket ignites, so i'm going to leave him to set the remote triggers and work out how his camera's not going to be incinerated. and we will come back later in the programme to watch a rocket ignite like you've never seen before. nasa has been putting rockets into space since the �*50s and, increasingly, it's been working with companies like firefly