The traveling-public gripes at the lack of direct Earth-to-Moon service, but it takes three types of rocket ships and two space-station changes to make a fiddling quarter-million-mile jump for a good reason: Money. Marshall Savage calls this a "Bifrost Bridge", that is, a bridge to space composed of colored light), launching loops, space fountains These might take the form of rockets climbing rails set up the side of a mountain, a laser thermal launching facility (in THE MILLENNIAL PROJECT, There are other ways besides rocket boosters and space shuttles to get payloads into orbit. So any ship that can handle a Brachistochrone is not going to even notice the delta V cost for lift-off.īut even with torchships, the real bottle-neck restricting developing space resources remains the cost to boost payloads into Earth orbit.įor some cold hard reality read When Rocket Science Meets The Dismal Science. Brachistochrones typically require delta Vs that are hundreds of times more than the equivalent Hohmann. Of course, once you have torchships you can stop all this child's play with wimpy Hohmann transfers and start doing some big muscular Brachistochrone trajectories. Space transport system from the game FTL: 2448 by Tri Tac Games.
The trouble is that entering an orbit takes a freaking lot of delta V, about 8 kilometers per second around Terra. An orbit is a clever way to constantly fall but never hit the ground. You can't use a helicopter blade because there is no air.īut what you can do is put the rocket in an "orbit". You can't build rocket legs that are hundreds of kilometers long. How do you support the sad little rocket? If it uses propellant it will eventually run out, sooner more than later.
Then the propellant runs out, and the poor little rocket finds itself unsupported hundreds of kilometers up. It is making sure you stay in space that takes a freaking lot of delta V.Ī little sounding rocket can easily rise from 50 to 1,500 kilometers above Terra's surface, where outer space starts about 150 kilometers up. Getting into orbit takes just a little bit of delta V. Rob Davidoff suggests that in a rocketpunk future, people will no longer use the expression "worth its weight in gold." Instead they will say "worth its weight in upmass", referring to the outrageous cost of shipping any payload from Terra's surface into Low Terra Orbit.īut the delta V cost breakdown is interesting. How much delta V does it take to go from the surface of Terra to Low Terra Orbit? 7.6 Freaking kilometers per second, that's what! In other words it takes more delta V to travel the pathetic 360 kilometers up to Low Terra Orbit as it does to travel the 228,000,000 kilometers to Mars!įrom Low Terra Orbit, where can you travel to with 7.6 km/s? Oh, only to the Planet Saturn, 1,433,000,000 kilometers towards the edge of the entire solar system. How much delta V does it take to go from Low Terra Orbit to Mars orbit? About 5.6 kilometers per second. From A STEP FARTHER OUT by Jerry Pournelle (1979)
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