I think it's a big mistake by the X-Prize foundation to become involved in this proposed prize.First of all, it's choosing a technology instead of leaving it open to any technology. It's specifically saying it's for an "EM Drive". That would be like having the original X-Prize specify a liquid-engine rocket, which would have excluded SpaceShipOne.Prizes like the X-Prize work best when they specify only the end result that has to be achieved and leave the means to do so as open as possible.Secondly, it's associating the X-Prize brand with a highly controversial specific technology. Part of the whole point of the X-Prize is to bring respectability to New Space. By associating its brand with a specific technology that the vast majority of professional scientists consider to be a crackpot idea, they are diminishing the X-Prize brand. It gives ammunition to those in the aerospace establishment to belittle anything associated with the X-Prize, and that hurts all the companies trying to raise money for lunar rovers, space launch, and anything else the X-Prize offers a prize for.
Being able to generate at least 10g / 0.1N of thrust EVERY time it is powered on, do that for 1,000 cycles, do it in a vacuum, generate thrust that you can feel with your hand in air, in a portable rig that can be easily transported to any test lab on the planet, tests and data captures streamed live over the net with open comments and discussion as the tests are happening, will be enough to cause an avalanche of further research. That is my replication goal.
Once you've definitively proven the effect real, you don't need a puny few million dollar prize to stimulate development, you'll have the entire aerospace industry pushing it (even if its limited to millinewtons it would revolutionise space travel.)What I can't see is how you could define a test, in a way that would satisfy the lawyers, at any level of thrust that hasn't already unequivocally proven the effect is real. Either you open yourself to ambiguous results (and lawsuits), fraud (and lawsuits), or the demonstration will need to be 100pts on a scale where 10pts is enough to have already convinced people with real money. The prize becomes pointless, either being soft and therefore ambiguous, or only being claimable when it no longer matters. It seems to be a Catch-22 situation.To use an analogy: It's like proposing the Orteig Prize (Atlantic crossing) as the level of demonstration necessary to "prove" the claims of the Wright Bros. By the time anyone is able to claim the prize, the basic claim "powered flight is real" is long, long proven beyond a shadow of a doubt; and probably already in commercial use. So what is the point of the prize?Or another analogy: It's like the original X-Prize (flight to 100km) was offered before chemical-rockets were proven to exist. By the time someone could meet the terms of the prize, the idea of rockets will have been long since proven to everyone's satisfaction. The prize doesn't actually add anything.
I also believe that a cubesat is the best way to go for an X-prize. Prove constant mass and constant thrust of at least x.xxx N over minimum t length of time (starting from LEO). Thrust benchmark would have to be an order of magnitude above known effects such as the best-case photon rocket. Time and trajectory goals should be selected to indirectly and conclusively rule out all other known propellantless thrusting techniques.
I can see future development that includes optical cavities that span many kilometers achieved with precise mirror alignment to enable maneuvering spacecraft many kilometers apart, and propellant-free propulsion of satellites in formations.
{snip}It seems (*) that the X-Prize needs to state not just a propellant-less means of space propulsion, but in addition that the propulsion has to be effected entirely by internal power and fields, without the need of any external forces or power from external fields (thus eliminating solar sails, electromagnetic tethers, Photonic Laser Thrusters, etc.)
...A practical thruster will take its power from solar arrays because batteries will not carry sufficient power to last the trip.
The just announced successful Photonic Laser Thruster experiment by NASA which accelerated a 450 gram (~1 lb., ~4.4 Newtons) spacecraft simulator: http://www.spaceref.com/news/viewpr.html?pid=45847is an example of competing propellant-less means of space propulsion that should be taken into account in formulating this X-Prize as a propellant-less prize in general. Would the Photonic Laser Thruster, for example, be able to compete for the X-Prize ? (if so, the Photonic Laser Thruster is already ahead of the EM Drive in highest achieved thrust).
Quote from: Rodal on 05/15/2015 07:19 pmThe just announced successful Photonic Laser Thruster experiment by NASA which accelerated a 450 gram (~1 lb., ~4.4 Newtons) spacecraft simulator: http://www.spaceref.com/news/viewpr.html?pid=45847is an example of competing propellant-less means of space propulsion that should be taken into account in formulating this X-Prize as a propellant-less prize in general. Would the Photonic Laser Thruster, for example, be able to compete for the X-Prize ? (if so, the Photonic Laser Thruster is already ahead of the EM Drive in highest achieved thrust).This is an *excellent* point.As Dr. Rodal points out, there are other effective ways to generate various forms of thrust for specific applications. What prevents those being of interest to an X-Prize is that they all are part of reasonably well understood physics and have been the subject of engineering consideration for a long time. They live well along the technology improvement s-curve and, consequently, are "relatively" unlikely to deliver a breakthrough in capability.By contrast, if the EM Drive is real at all, this represents a major anomaly and novelty. Precisely because it is highly novel, it represents at least a *potential* breakthrough. To put it bluntly, we don't really have any idea what the upside could be. It could be quite significant (i.e., satellite applications are the low end of the potential). And this is what makes it interesting for an X-Prize. Accordingly, the challenge design should rule out approaches that deliver "propellant free" thrust via well understood physics.
If the EM Drive emits tachyons then it does not meet this definition.
Quote from: A_M_Swallow on 05/16/2015 02:35 amIf the EM Drive emits tachyons then it does not meet this definition.If the EM Drive would emit tachyons (a hypothetical, fictional, particle that has never been found in nature) then the EM Drive could be used for communication with the past, which would involve a time paradox.(Tachyons are fictional particles that can travel faster than the speed of light. Sending signals faster than light, leads to to violations of causality. For example, somebody from the future could send Shawyer, using tachyons, a message with the design for an EM Drive for Shawyer to get the X-Prize )See: http://en.wikipedia.org/wiki/Tachyonic_antitelephone
Why vacuum? Obviously it will be important for space operations that one be able to operate this thing in a vacuum - but for the purposes of proving that we have a "something new result," what does a vacuum add? If thrust is > X, don't all of the things that a vacuum would help eliminate already drop away?
c) Keeping in mind the above also don't worry too much about the X-prize and their association with risky endeavours. That is their raison d'etre. They know that this has a small chance of success and are delighted by the prospect. They are all about high risk / high reward innovation.