A major problem with using Rocket fuel to launch objects into space is that the majority of the energy spent launching the rocket is consumed just to lift the weight of the rocket fuel itself. Only a small fraction of the energy consumed is actually used to launch the real payload. This is extremely inefficient.
It currently takes about $50,000 per pound to launch a satellite into space using conventional rocket technology. This is a huge barrier to making space travel practical for large scale development. This cost needs to be made dramatically cheaper to enable broader development of space. If we can get this cost down to around a $1,000 per pound or less then space colonization becomes a very interesting very real possibility.
This Wikipedia article has a nice summary of some inspiring out of the box ideas for launching spaceships into orbit without using inefficient rocket fuel technology. There are even some interesting ideas from NASA referenced here.
There is a lot of good info listed above but most of these concepts are still impractical for resource, cost, and/or engineering reasons.
While many of these ideas are interesting and inspiring, let me propose the right way to launch spaceships into space. Are you listening Elon Musk, Richard Branson, and Jeff Bezos ? How about you Russia or China ?
In short divide the work into three incremental phases, and leverage a local mountain range. For the United States let's say the Rocky Mountains.
Phase 1: Micro Satellites
The goal for phase one will be to launch micro satellites using electromagnetic rail gun technology. This will be the base technology for all three phases, but the technology will be scaled up in phase two and three for larger payloads. Meanwhile once phase one is completed it will bring in revenue to fund phase two and then again similarly for phase two to three.
The Navy has already demonstrated rail gun technology capable of launching projectiles 100 miles. The fact that the gun is too expensive to be practical on warships is immaterial for launching satellites. What matters for satellites is that the technology is already proven.
To launch satellites we just need to tilt the gun barrel up a little to get the little buggers into orbit. 😎 OK, maybe we need to harden the satellites for a bit before launching, and make the gun barrel a bit longer for less G forces, but fundamentally most of the technology already exists. It just needs adjustment. Space is defined as 60 miles in altitude.
Micro satellites are small satellites that are only a few inches in diameter and weigh only a couple of pounds. In other words very similar in scale to existing rail gun test projectiles.
Phase 2: Large Satellites
Two major adjustments will need to be made to handle the more traditional larger satellites planned for phase two. The rail gun will need to handle much larger and heavier payloads, and the gun barrel will need to be significantly extended to enable lower G forces exerted on the more fragile payloads. This is where the mountain range comes into play.
A mountain or hillside is suggested for this phase to enable supporting a long track of a mile or two. The longer track will allow for slower acceleration of the payload to reduce G forces as it is brought up to a velocity sufficient to escape the earth's gravity.
An investment in some new machinery to automate building of the barrel tube structure is also recommended. Refer to some existing large tunneling machinery that simultaneously installs tunneling support walls as it digs for inspiration in design. Investing in this technology will also be useful as an incremental learning step toward phase three. As with Phase one, when phase two is complete, it can generate revenue to support the next phase three.
Another consideration in phase two beyond the size and length of the launch tube, is air pressure and air friction. The target payload should be encased in a heat resistant shell to absorb the heat from air friction. To help with air friction heat as well as to improve the efficiency of acceleration vacuum pumps should also be leveraged to reduce air pressure in the tube.
Yet another consideration is managing collisions with birds and similar creatures at the exit of the launch tube. The increased elevation at the tube exit should reduce the bird count. Nonetheless radars could be used to check the flight path at launch, and lasers could also be used as a secondary precaution at launch time, sighted down the path of trajectory.
Phase 3: Manned Spaceships
The target payload for phase three is humans, which will have an even lower tolerance for G forces than large satellites. So for phase three the launch tube length should be in the 30 to 60 mile range. This will require searching terrain maps to find the most suitable site, that contains the desired slope to minimize the required support structure for the launch tube.
The tube should be laser straight and tilted upward as much as the terrain will enable. Making the tube straight will reduce the complexity and risk involved with managing turns in a gun barrel traveling at 50,000 feet per second.
The target payload should be a small spaceship capable of flying in space once propelled out of earth's atmosphere.
The driving strategies behind this proposal are:
- Use mostly static methods to increase reliability and efficiency, verses consuming vast quantities of fuel per launch.
- Use mostly existing technologies instead of relying on the breakthrough invention of radically new materials and/or technologies.
- Leverage the existing natural terrain when building the very large support superstructure of the launch tube, verses other extreme resource intensive designs such as entire man made mountains.