Company Aims To Launch Spacecraft On Beams of Microwaves

MarkWhittington writes: The quest for cheap access to space, to make space travel as inexpensive as air travel, has eluded engineers, government policy makers, and business entrepreneurs from before the beginning of the space age. It has become axiomatic, almost to the point of being a cliché, that the true space age will not begin until launch costs come down significantly. Forbes reported about a company called Escape Dynamics that has a unique approach to the problem. The company proposes to launch payloads into low Earth orbit on beams of microwaves.

Comments

What could possible go wrong?

[iamacat]

I hope this is built well away from tall buildings, airplane flight paths and other things that's don't mix well with high power microwaves.

Re:What could possible go wrong?

[Teancum]

I'd like you to point out any launch site for orbital rockets that is anywhere even remotely close to tall buildings or even aircraft flights? The FAA routinely makes a pretty large exclusion zone around any launch activity. With the recent launch disasters from SpaceX and Orbital-ATK, I think such warnings should be well heeded even for ordinary Kerosene fueled rockets, much less something with an exotic propulsion system like this. It sure isn't going to be launched out of Central Park or any other urban center.

Besides, the CEO addressed this specific issue in an interview recorded a few months ago. Not only is the launch going to be far from cities, it will also need to happen in an arid region in part due to the microwave power being absorbed by water in the atmosphere. In other words, it is likely that this won't be launched from KSC in Florida either.

Poorly described

[hackwrench]

I don't think the article described the technology very well. Anybody find a better description elsewhere?

Re:Poorly described

[garyisabusyguy]

There is a whitepaper linked from the company website:
http://escapedynamics.com/wp-c...

The short story

Microwave provides source of energy by targeting heat-absorbing material
Heat exchanger is used to heat and compress Hydrogen to 150 atmospheres
Hydrogen is fed to aerospike nozzle, which provide impulse thrust gt 750 seconds
Claims launcher will be able to provide 8% to 12% of total weight as cargo

Right now most of the website is pretty pictures and videos, time will tell

Re:Poorly described

[weilawei]

So, you don't need to carry an oxidizer. If you wanted to run a turbopump to do the same in order to generate thrust, you'd need to react it with something. Neat idea, nice Isp, no idea if it's actually practical.

IANARS (I Am Not A Rocket Scientist).

Re:Poorly described

[whodunit]

So its a thermal rocket like the NERVA, except it uses ground-based microwave lasers instead of a nuclear reactor to generate the heat. That's actually brilliant!

Re:Poorly described

[HiThere]

It's not a new idea. It's been kicking around for at least 3 decades. Is it a good idea? Maybe. I've no idea how practical it is. Is it brilliant? No. The design, the implementation, may be brilliant, but the idea is a bit long in the tooth.

Like many ideas, the trick is getting a good working implementation, not the idea.

Re:Poorly described

[WindBourne]

kind of surprised that it is only 8-12% for the cargo.
In a normal flight, the LOX is more than 50% of the weight, which is no longer needed.

Re:Poorly described

[Drishmung]

Agreed. it's been around a long time.

Note that the sending array is huge. 1 sq km in the linked article. That means that the energy density of the beam is low, so you don't cook passing birds, but more importantly, don't waste energy heating up the water vapour in the air either. The receiving antenna also needs to be big. The bigger the better, so you can keep the efficient coupling over a long distance. In this case, long enough to get it to orbit.

The interesting thing about this idea is getting the high specific impulse, so you can single stage to orbit.

The coupled microwave idea has been mooted before for a couple of things.

1. Beam solar power back down to earth (1 km array in space, 10 km x 10 km array on earth. Quite efficient.)

2. Ion drive. With a 10km x 10km or even 100km x 100km and 1x1km or 10 x 10km you can power an ion drive over huge distances, enough to send something to nearby stars. With no power source on board, the rocket gets to be extremely efficient. There is of course the inconvenience of the earth both rotating and orbiting, so you really want the transmitter in space.

This latest idea looks quite interesting.

Re:Poorly described

[DanielRavenNest]

IAARS (I am a rocket scientist) (see my wikibook if interested: https://en.wikibooks.org/wiki/... )

Beamed power for space launch has been discussed for decades - I have several ring binders of data on the subject. Practical depends a lot on your power storage. Space launch of anything larger than a teacup takes a lot of power. For example, the three liquid engines on the Space Shuttle put out a combined 21 GigaWatts of power, of which 156 MegaWatts was just to run the turbopumps to shove the propellants into the main combustion chamber (the turbopumps had their own combustion system to power themselves).

So this launch system seems to have batteries between the power grid and the microwave generators. That makes sense, because you can't suck GigaWatts on demand off conventional grids. Batteries have been improving in cost and performance pretty well recently, so that may have put it in a practical range. I wonder, though, if on-demand turbogenerators might not be cheaper.

The other parts of the system: heat exchanger, phased array, high power microwave amplifiers, are relatively straightforward, you just need a lot of them. What I wonder about is traffic model. High power launch systems like this cost a lot to build. If you only use them a few times a year, that investment has to spread over relatively few launches. You really want to use them a lot, like daily or hourly. But where is the traffic going to space to fill that much capacity?

"Tin Foil Hats" is not PC

[smittyoneeach]

The correct phrase is "Lightweight Metal Headwear", and the community are "LMH Aficionados".

Good Idea, and a Possible Modification

[Anonymous Coward]

I have been reading about beamed propulsion for a while, this is an interesting concept. It is very nice to see progress is being made here. The advantage of beamed propulsion is that we can leave the power components on the ground (instead of needing to carry the energy as chemical propellant), which makes it far more efficient and can make spaceflight much more accessible (see rocket equation, most of the energy for a normal rocket is spend moving propellant and other things like propellant tanks up; we usually need to do things like multiple stages, etc. which add complexity and make resuability much harder). I think beamed propulsion is on the right track.

From the article, it seems that the hydrogen propellant (which is heated and blasted out) is used at all altitudes. This ship is then still described by the rocket equation, since it is effectively firing out hydrogen propellant at a given speed (the energy for the firing is external, but still, the propellant must be all on board at the beginning). Is it possible to instead use an air intake as long as feasible, switching to the hydrogen only at very high altitudes? This will greatly reduce the amount of hydrogen propellant needed, which will help a lot (again, refer to the rocket equation). I know this has been considered with usual spacecraft, there the situation is very different as chemical rocket spacecraft have to be using propellant always (even if not oxidizer in the air-breathing phase), here we can have a ship that can initially ascend as slowly as it wants while using air intake (since it is externally powered and isn't using hydrogen propellant yet), can accelerate fastest when air density is optimal (there is air for the intake, but not too much drag), and then switch to hydrogen at the end. Has this been considered?

Good luck Escape Dynamics, you have a very good project.

Re:Good Idea, and a Possible Modification

[Mostly a lurker]

What has surprised me is that there has been no real attempt to move the launch platform up to 80,000 feet or so using gas balloon technology. I would have thought this would be feasible, and could result in a substantial fuel saving.

Re:Good Idea, and a Possible Modification

[ceoyoyo]

I'm sure they've thought of that. This isn't really a new idea, and the use of beamed power engines that switch from using atmosphere to carried fuel isn't new either (you can even use it in Kerbal Space Program with the right mods). The problem is that the molecular mass of air is quite high, and that reduces your specific impulse and thrust for a given power input. So to get the same thrust with air you'd need a bigger transmitter (probably much bigger). With rockets you usually need your highest thrust early on, because you're lifting more fuel, gravity is stronger, and you need to go more or less straight up. Later on you can get by with less thrust. Unfortunately, that's the opposite of what an air/fuel switching beamed power engine provides. You can get around that using a spaceplane design, but you still need to get up to speed and altitude while in range of your ground station... or build more ground stations.

They're probably looking at getting something working first, then building out the infrastructure to do more. That fits in with their plan to make a suborbital ship first: if you go basically straight up you're always in range of a single ground station, but you can't get into orbit.

Re:Good Idea, and a Possible Modification

[fnj]

What has surprised me is that there has been no real attempt to move the launch platform up to 80,000 feet or so using gas balloon technology. I would have thought this would be feasible, and could result in a substantial fuel saving.

Picking a launch vehicle more ar less at random, an Atlas V grosses 334,500 kg (737,400 lb). Now, at 80,000 ft (24,400 m) the lift of helium is 0.0375 kg/m^3. Even if the balloon and suspension massed nothing whatsoever, it would have to have a volume of 8.92 million cubic meters - 44.6 Hindenburgs in size. Counter-intuitively but still most impressively, a sphere 257 m (840 ft) in diameter would do it. But then again, such a balloon and suspension sufficient to lift 334,500 kg would be anything but zero mass. Most high altitude balloons lift only a few hundred kg of payload at most, which is why they do not suffer from scale problems like this.

Hydrogen has a tad more lift, but only a few percent, so the ludicrousness of the scale would not be appreciably affected, plus you'd have to be damn sure you wouldn't have to worry about static buildup in the extremely thin plastic film of the balloon.

Using either helium or hydrogen, you'd have to figure out how to inflate such a colossal structure in the open without it being wrecked by the tiniest zephyr.

Now, since the whole idea is to reduce that 334,500 kg gross weight by saving on fuel mass, it wouldn't be quite that bad, but clearly bad enough to be a spectacular non-starter.

I am thinking an air-breathing ramjet winged first stage would have more potential. It strikes me as spectacularly stupid to use rockets, with a gigantic oxidizer flow rate when the atmosphere is full of oxygen, all the way from zero meters; especially during the first few seconds when the fuel and oxidizer is getting sucked out faster than a cheap hooker could dream of, while the vehicle is barely moving at a snail's pace.

Re:What is this "quest" you speak of?

[Calydor]

Because we finished doing that, we just didn't invite you. For obvious reasons.

Made of Unabtanium

[Required Snark]

I watched their promo video and it shows the airframe structure performing two tasks that seem to be mutually exclusive.

The airframe is a lifting body with a large flat undercarriage. This is the side that absorbs microwave energy, which is somehow transferred to the hydrogen fuel to provides thrust. After achieving orbit and delivering it's payload, the spacecraft deorbits and then the same lifting body surface that absorbed microwave radiation becomes the heat shield for reentry.

So how do you combine the ability to receive a large amount of microwave energy and then turn around and protect the airframe from reentry heat in the same structure? And in addition has the structural integrity to withstand launch and reentry stresses.

Microwaves are not invisible magic. They interact with the matter they encounter. Whatever heat shield material they use, it is going to absorb some of the microwaves that hit the vehicle. Can they keep this amount low enough and also fulfill the other requirements?

At this point there is so little technical detail, and so much marketing hype, that this has to go under the heading of geek fantasy daydreaming. I'm going to ignore this one until they show some real results or publish specific enough information that someone not on their payroll can say that it's feasible.

Popcorn

[fox171171]

The company proposes to launch payloads into low Earth orbit on beams of microwaves.

And fresh popcorn will be served when you get to obit.

Re:What is this "quest" you speak of?

[HiThere]

We haven't finished colonizing the ocean bottoms. We've barely started, and I'm not sure it's such a good idea. (It needs a lot more study than it's had so far before I'll say that. It could be an ecological nightmare. Space, OTOH, is only dangerous to the explorers....well, colonization of space is only dangerous to the explorers.)

So I consider the colonization of space to be a lot better. It's also true, however, that human occupancy of space is going to require a lot of technical development that hasn't happened. As long as the International Space Station reuires more than yearly service missions (including, especially, supplies) that we need more technical development. A permanent occupancy of space cannot be managed until one can derive all the necessities for life (and support of the habitat) by mining asteroids *occasionally*.