Energy Beams to Launch Rockets?

That sound like another idea with the decimal point two or three places off.

The concept seems valid, but if you are to transmit the amount of energy that a major launch would need in a short interval at a high enough efficiency at each stage to they would not be destroyed by the losses and the receiving mechanism would have to absorb the microwave energy and make heat and be cooled by the reaction mass they were going to use in the rocket in the same manner that liquid hydrogen and oxygen are circulated through the rock engines to stop the heat of combustion from burning them to destruction.

So this microwave energy must heat the reaction mass, with little loss and use the cold reaction mass to save itself and then the mass is accelerated to get that level of specific impulse ~~600. The mass equation and the impulse are somewhat better, so the higher SI would allow about 50% of the launch mass - all else equal.

Now, at this stage, I do not believe they have this now, they have an idea to expand and develop to see if they can overcome the inherent inefficiencies that I can see in this idea. So let them research and see if it will work.

If you calculate the energy it takes to lift an object to orbital altitude (potential energy) and accelerate it to orbital velocity (kinetic energy), it works out to 9.1 KWHrs per kg or about 11 cents worth of electricity per kg.

Ref: http://www.wired.com/2011/07/space-shuttle-launch-equator-vs-mountains/

Rockets are a very inefficient means to orbit ($1000 per kg), but unfortunately it's all we have. A lot of the cost is needing multiple stages. Beaming energy is an interesting approach to the problem of SSTO (single stage to orbit), which has been the dream of rocket engineers for decades. (I'm not sure I want to be an astronaut on the receiving end of the microwave beam! )

Studies have shown that SSTO is possible, but barely possible, with current technology. Operating near the limits of technology results in not only high costs but limited liability. Here is an interesting article about SSTO:

https://en.wikipedia.org/wiki/Single-stage-to-orbit

the graphic looks cool

Seems like a reasonable premise, but the article glosses over a few items:

1. Ship/Beam tracking system is going to have to be exceptional. The test they performed was stationary, using helium (for safety). I think this one can be solved, but they are going to need redundant beam sources for safety.

2. 1/D^2. The beam strength reaching the ship is going to get weaker as it ascends. Since the thrust required is less as they ascend, this might not be such a problem.

3. As it ascends, the beam is going to spread, not only delivering less energy to the collectors on the ship, but also showering microwave energy beyond the collectors (ie. on the cargo/crew). For an unmanned (payload only) mission, that might be fine, but "I'm not hitching a ride" on the thing!

A laser is generated in a resonant cavity, the length of the cavity coupled with the exit aperture determines the beam spread. What this means in practical terms is is you want a laser beam to reach, say 500 miles in height and impinge on a 6 foot target it must have a quite long resonant cavity to exit from, say a 2 foot exit.

Microwave energy has such a large wavelength that it would present unaccptable losse at 500 miles. Even at millimeter wavelengths, the dispersion would be too much. There is a formular for microwave dish spot diameter

In addition, the power limit in air must be respected, lest you develop transit losses while in air. In a vacuum, these losses go to zero, but I believe there is also a masimum energy density in a vacuum as well. I do not know enough to nail these down. One method might be to make the ground to ship path part of the resonant feedback loop to not amplify beam portions that exit the impact zone. Dielectric mirros can be used to protect the super structure from any beam wobble

Not sure where a laser entered the discussion. The article states microwave, with helping satellites into low earth orbit. Even if you take the lower boundary that is ~99 miles. I don't think they can use microwaves (in any significant amount) to be useable for even a fraction of that distance. Might be able to give it a boost for a time, and therefore use less fuel. But it just won't go the distance.

Yes, that microwave idea has been around for a while. Not suitable, since beam spread would waste too much energy under 10 Ghz. let alone making megawatts Higher frequencies, 50-100 ghz microwave to make spot focus smaller might not find suitable RF to thermal conversion efficient, and again hiow do we make megawatts?. That is why I mentioned lasers, frequency is high enough that focus to a small spot can be done

They might worry it into viability some day

It looks like the entire rocket is one big giant hydrogen tank!

Where is the payload?