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Escape Dynamics Aims to Eliminate Single-Use Rockets in Space Flight

space, commercial space exploration, space travel, escape dynamics, external propulsion
Right there in the grainy films of the first successful guided missile launches — achieved, alas, by the Nazis at the height of World War II — you see it: The million-dollar first-stage launch rocket falls back to ground just as the missile takes off. The massive expense of single-use equipment was written into the history of space flight even before we reached space.

NASA’s 1980s space shuttle represented an historic accomplishment as the first spacecraft to land from one mission and go out on another, but its launches also relied on one-use rocket launchers that fell away just as they had decades before.

Recently, SpaceX has gained enormous renown by promising to reuse the rockets as well. “If we become the biggest launch company in the world, making money hand over fist, but we’re still not reusable, I will consider us to have failed,” CEO Elon Musk has said in typical bombastic fashion.

commercial space exploration, space travel, escape dynamics, external propulsionThere’s a lesser-known company quietly at work at a private airport in Broomfield, Colorado, with an even bolder aspiration. Escape Dynamics is proposing that we do away with fiery rockets altogether in order to make a much more dramatic attack on the exorbitant cost of space flight.

“We want to look at a next-gen technology, not an improvement on chemical combustion, to drive a 10x change in the way we access Earth’s orbit,” said Dmitriy Tseliakhovich, reflecting some of the language he picked up as an admirer of Peter Diamandis and an alum of Singularity University’s Graduate Studies Program.

“Chemical propulsion simply does not allow for a small and simple launch vehicle. There is a fundamental physical limit on how efficient chemical rockets can become,” Tseliakhovich had concluded by 2010, when he launched Escape Dynamics. About 2 percent of the weight of a vehicle launched today is payload, Tseliakhovich says.

Escape Dynamics would propel spacecraft with energy transmitted in a microwave beam that tracks the vehicle’s ascent trajectory. The energy, caught with an antenna, would run through a heat exchanger before being pushed out of a thruster. Tseliakhovich first sketched out the method as part of the Ph.D. in astrophysics he received from Caltech in 2010.

The company has tested its ability to heat an engine remotely with a microwave and to send microwave energy with a narrow focus. To improve its ability to keep the microwave energy focused (and safe), Escape Dynamics is developing “side lobe” suppression system. The team is also embracing big data simulations to prune development costs.

If it all works out, it would mean that spacecraft themselves would be far simpler vehicles, within the budgets, perhaps, of private companies. Takeoff costs would also be much lower without the extra weight of first-stage rockets and the fuel to power them. Space travel would lighten its carbon footprint substantially, just as people gear up to do more of it.

But it’s an ambitious undertaking, something even its optimistic founder has to admit.

“We believe on the basis of our in-house technology development that we can make it more affordable, but with any new technology it is a long, expensive and complicated business proposition,” said Tseliakhovich.

commercial space travel, space exploration, NASA, escape dynamics, technologyStill, we asked Tseliakhovich what dramatically cheaper space travel could accomplish.

He had us imagine an “airport-like operation,” with Escape Dynamics’ sleek shuttles busily coming and going. The shuttles could also help other companies deploy swarms of telecommunications satellites to launch their smaller payloads.

“But what really excites me,” Tseliakhovich said, “is building a low-earth orbiter station where companies and individuals would be able to access and work on developing businesses that utilize zero-gravity to develop new ideas.” Materials science and medicine could benefit from a zero-gravity research environment, he said.

This summer, the company plans will emerge from the 30,000 square-foot hangar where it has done most of its work to date to start testing its propulsion methods over long distances.

Images: Escape Dynamics

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22 comments

  • Quantium says:

    Wouldn’t this rocket still have to take reaction mass with it even if the energy comes from broadcast microwaves?

    • Jim Gravelyn says:

      You would think. But the guy apparently wrote a doctoral thesis about this so he must know what he’s doing. Doesn’t seem like simply re-directing the energy out the back would be enough to make the mass of the vehicle achieve escape velocity.

      • Quantium says:

        I suppose if Ve in the equation here
        http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
        is extremely large then M0-M1 (ie the total reaction mass) can be smaller.

        But the article doesn’t make it clear how this is achieved. Clearly “the energy” alone cannot propel the ship, ie if M0=M1 then the deltaV is zero. (log of 1 = 0).

        Maybe the idea is to run it as a jet when in the atmosphere (ie take in air and heat it to expand) and then as an ion engine where indeed the reaction mass is small. But there always has to be some mass.

        • EscapeDynamics
          EscapeDynamics says:

          @Quantium
          The hybrid approach, where part of the working fluid is coming from the air during the initial portions of the ascent is possible, however, this approach is more complex than carrying the working fluid on-board and heating it with the external microwave energy. One of the key advantages of external propulsion is that vehicle can be very simple. There is no combustion on-board and so the design of the launch vehicle can be simplified compared to chemical rockets. The complexity of the system is left on the ground where energy is generated.

        • Andrew Atkin
          Andrew Atkin says:

          Yep – it’s either using the air, or functioning as an additional heat source to make the rocket exhaust ultra hot beyond just the chemical reaction (or both). Ion engines are not realistic because of the low mass output…except for interstellar stuff of course. Personally I think the technology won’t go anywhere….what we need are the ram-jets and rail guns, for now.

    • andy_spoo says:

      This is only a guess, but using a rail isn’t very flexible in that once you’ve built it, that’s aleays going to be your trajectory.

      Plus, to go fast enought to get into space means a massive initial amount of G-force, compared to rockets gradual push.

      • Jim Gravelyn says:

        I think you can control the g-force by making the run longer, but you have a point: a rough calculation says at 3 gs you would need more than 2,000 miles of rail to reach escape velocity. (Did I get my decimal point in the wrong place? That seems extreme.) Obviously not feasible. So maybe just use the rail to replace the booster stages and use normal rocket propellant to finish the job. Or increase the gs. Not sure if humans could take much time at 4 gs even with those special suits the F-22 pilots wear, so maybe use the rail at very high gs to shoot building material up and use normal rockets to get the people up there.

        The trajectory issue… well, that’s just unsolvable. You can’t turn a 2,000-mile rail to point it in a new direction, can you? Oh well. Sounded good in the science fiction novels.

        • Andrew Atkin
          Andrew Atkin says:

          Of course the energy required to go 2x as fast is 4x, but for rockets it must be so much more in practice due to the vast inefficiency of the rocket propulsion system at slower speeds.

          But taking out the first 2,000 mph with a rail gun is then like accelerating your craft from 0 to 15,000 mph rather than 0 to 17,000 mph, which must come with huge efficiency gains on its own. But yes, you’re gonna need rockets at some final point of the game…unless you have a scramjet that scoops off the top of the atmosphere at 17,000 mph. Hmmm…good luck trying not to melt the craft; it will take a long time to accelerate it due to the thin mass of the upper atmosphere. Again rockets are gonna be the only realistic final-stage option.

    • EscapeDynamics
      EscapeDynamics says:

      @Quantium, Thanks for your comment!
      Yes, the launch vehicle still requires reaction mass. In externally powered launch systems energy for propulsion is coming from the electric grid on the ground and is delivered to the vehicle via a carefully controlled microwave beam. The beam from a ground-based phased array of microwave emitters is absorbed in a heat exchanger on the bottom of the launch vehicle and transferred to a propellant flowing through the heat exchanger. Propellant heated inside the heat exchanger is expelled through a nozzle creating thrust. This approach is significantly more efficient than combustion in providing energy necessary for acceleration.

  • Jim Gravelyn says:

    I have never understood why these companies aren’t embracing a long magnetic rail launch ramp to replace the chemical rocket launchers. Build it on the Nevada side of the Sierras going uphill, use geothermal to produce the electricity. Is it the sound barrier that prevents this from being feasible?

    • Andrew Atkin
      Andrew Atkin says:

      I’ve never got it either. Use an electromagnetic rail gun for the first 1 or 2 stages, then maybe use a ramjet (no problem if the rail gun gets you to mach 2) then a small chemical rocket, reusable, to finish the job. Also launch them at the equator.

      Having a winged craft in space is (and was) just bloody stupid. Bring your cone down with parachutes – like the old days.

      …It’s almost like a conspiracy to keep the cost of space travel at ridiculous heights (no pun intended). That electromagnetic gun should have been one of our first development priorities.

    • EscapeDynamics
      EscapeDynamics says:

      @Jim Gravelyn and @Andrew Atkin Thanks for the discussion and many interesting points. These questions were all considered in the design process and we look forward to sharing some of the details in the coming month.
      A few quick comments:
      The rail gun is an exciting technology that does well during initial acceleration. The challenge is that in the air the drag force goes as the velocity squared and acceleration close to the ground is economical only to velocities very small compared to the velocity needed to reach orbit. Rail gun indeed can be used to take-off and accelerate and from there any propulsion system can take over. The primary trade-off is cost and complexity of a combined system.
      Regarding the winged airframe, Escape Dynamics is designing and building a single state to orbit, reusable system. The vehicle is optimized to launch, deploy the satellite and return to the launch site as a light-weight glider. The goal is, in the long run, to enable operation similar to the operation of airplanes today, where we don’t need to deal with parachutes and rocket recovery.

      • Jim Gravelyn says:

        Ah ha, so air pressure close to the ground wrecks the idea of shooting spaceships into orbit. I should’ve known there had to be something simple like that standing in the way. And lord knows what the BLM would say about building a long rail gun in the desert. But still… seems like using electricity from a power plant for the first few hundred mph would be the cheapest way of adding velocity and reducing weight. (I’m an accountant by trade, can you tell?)

  • Andrew Atkin
    Andrew Atkin says:

    Trajectory: For most applications I don’t think this would be a problem?? If it’s destined to leave earth’s orbit, then it can ‘release’ from any point in the circumference, and the rocket stages can ‘correct’ from the primary trajectory created by the rail gun and ram-jets, etc. Usually there should be no waste – each stage of propulsion just specialises to a given vector.

  • dobermanmacleod says:

    http://en.wikipedia.org/wiki/SABRE_(rocket_engine)

    This is exactly what the article describes.

    “The design comprises a single combined cycle rocket engine with two modes of operation. The air breathing mode combines a turbo-compressor with a lightweight air precooler positioned just behind the inlet cone. At high speeds this precooler cools the hot, ram-compressed air leading to an unusually high pressure ratio within the engine. The compressed air is subsequently fed into the rocket combustion chamber where it is ignited with stored liquid hydrogen. The high pressure ratio allows the engine to continue to provide high thrust at very high speeds and altitudes. The low temperature of the air permits light alloy construction to be employed which gives a very lightweight engine—essential for reaching orbit.”

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