Other methods of space launch would be nice…. but they really aren’t feasible and many of them probably never will be - for manned flight at least. A rocket gets a good long time to accelerate to orbital velocity and can therefore do so at G loads that won’t turn a human into jelly. A railgun or magnetic launch system would not have that option. You might be able to get a launcher 3 or 4 miles in length - maybe. Acceleration from a standstill to orbital velocity (assuming an orbit alt. of 300km - similar to the Shuttle) in 4 miles would impart a load of about ~580g over about .6 seconds(so sayeth the back o’the napkin). 580G does VERY bad things to the internal organs and skeletal system of humans. In order to have a railgun type launch system that wouldn’t reduce a human to goo and actually allow them to survive the trip (say a 9g load) it would have to be somewhere around 380Km long….

So, not too terribly feasable - and this doesn’t even take into account atmospheric drag and friction heating- which would be a real problem when you accelerate a vehilce to 7.7KM/sec at ground level. I suspect you’d have to go quite a bit faster than 7.7KM per sec to achieve a 300KM orbit due to that drag. I suggest you not roll the window for Fido to stick his head out…

BAd gas! BAd! No star for you!

Ahem.

The system for the shuttle to burn of any ambient hydrogen that might be floating around is not another rocket motor, it’s all those “sparklers” you see in the closeup of the main engines at ME start.

XRayDog Says: “Are you sure the small jet is water deluge? Where is the exhaust from the gas generator? That’s what I thought it was at first glance.”

The exhaust from the pump turbines isn’t always (if ever) a luminescent jet. It also doesn’t appear to have any connections to the engine (i.e. propellant pump inlets and outlets), just some hoses.

I believe that what we’re seeing is a cooling spray to protect the test area from the exhaust heat that’s being illuminated by the exhaust plume. The big NASA and Air Force test sites either hung the test engines way up in the air, or pointed them out over a canyon.

The water deluge under the shuttle is not for cooling, but to absorb the acoustic energy that would otherwise be reflected off of the pad and shake pieces off of the vehicle stack. This is another Hermann Oberth idea that von Braun incorporated into the Saturn V design. If you watch “Die Frau im Mond” you’ll see that the Frede is actually submerged over halfway into a pool at engine start!

- Jack