Using Wireless transmission of Power to deliver power to Adastra module?

[ptolemy1977]

I recently viewed an article that describes photonic propulsion as a means of taking us to the stars, search for "Mars in Three Days" on foxnews.com.  I am sure that this will someday be true.  But, it also brought to mind that we currently do not have a viable power source for the Adastra rocket engine.  The Adastra rocket engine is foreseen as a source of propulsion for use in deep space missions.  It is apparent that beaming microwaves to an Adastra engine propelled rocket might overcome NASA's reluctance to use it in the upcoming Mars mission because of a lack of a viable power source?  This method of sending energy is commonly known as wireless transmission of power.  It is touted as a means of addressing future power requirements here on earth.  This methodology requires that solar collectors are setup in space and power is then beamed to earth from the the collectors via microwaves.  This method could of course be utilized to beam power to deep space vehicles in flight, Adastra would probably require not more than about 5MW of power for a mission to mars.  It might make more sense to build such a transmitter on the surface of the moon because of the ready availability of resources there, I believe that the moon would make a fantastic jumping off point for all other deep space missions.  It would possibly also make sense to setup an orbital relay satellite to address logistical challenges of sending power to a moving rocket.

What do you think?  I am sure that most on this sight know more about this than I do.

[Jim]

What is going to supply the power to be transmitted?

Also,

https://en.wikipedia.org/wiki/Inverse-square_law

[ptolemy1977]

Thanks for the reply Jim, as I said this would still use solar collectors just not solar cells.  The idea is to build a solar furnace or similar device on the moon using moon based resources to lower cost.  That would of course incur the cost of the initial development of manufacturing on the moon, but I think that said manufacturing ability on the moon would be enabling to many other deep space objectives thus helping to spread the cost of initial development.  For example, deep space exploration using resources produced on the moon, deep space astronomy, asteroid deflection using either lasers i.e. a heat source or by using rail guns to shoot bags of moon dust at threatening solar bodies which may impact the earth to deflect them.  There are many other possibilities, building small self contained manufacturing units that could be modularized  then trucked to the moon  by a carrier like Spacex to produce metals, mirrors, textiles, and complex products made from these could be accomplished over time of course the issue is price.  However, if we consider examples from earth modular manufacturing has enabled great cost reductions in steel production for instance we may be able to leverage these ideas for manufacturing in space, specifically on the moon using moon based raw materials.  Also, lets not forget that 3d printing technology has become advanced enough to allow Spacex to print a 3d rocket engine, over the next decade these technologies may quite easily have advanced far enough to make moon based manufacturing feasible.

[Jim]

Thanks for the reply Jim, as I said this would still use solar collectors just not solar cells.  The idea is to build a solar furnace or similar device on the moon using moon based resources to lower cost.  T

Better off just using the sun on the spacecraft.  There is no real advantage beaming the power from the moon to a spacecraft.

[ptolemy1977]

I don't think that I agree with that.  It is possible to provide large amounts of power to a space craft by having the generation system off the vessel.  Of course to get high power, which is why NASA is again researching the development of nuclear reactors and nuclear batteries for space, you will need something like a nuclear reactor even large solar arrays could not supply a vessel with a couple of Adastra engines with sufficient power, current reference designs require 250KW or more for the engines and crew compartments.  The problem is of course the weight requirement of placing the generator on the rocket ship, and the unavailability of sufficiently large generating sources for space use, that is the rationale behind using wireless power transmission it would completely supply the power requirements while keeping the receive mechanism simple and possibly highly reusable.

[Nilof]

you will need something like a nuclear reactor even large solar arrays could not supply a vessel with a couple of Adastra engines with sufficient power,

Wrong, large solar arrays are better for the job and much more reliable. Nuclear reactors need radiators. Just because Nuclear "sounds more powerful" doesn't mean it actually is when it'd be based around a heat engine that has to operate in a vacuum.

current reference designs require 250KW or more for the engines and crew compartments

...for manned Mars missions it'd definitely be more than that. 250 KW is the bare minimum for a good cargo tug.

The problem is of course the weight requirement of placing the generator on the rocket ship, and the unavailability of sufficiently large generating sources for space use,

For nuclear, yes. For solar power, specific power is already quite high with state of the art blanket arrays, and there should be room for two orders of magnitude of improvements in specific power or more as time goes on.

that is the rationale behind using wireless power transmission it would completely supply the power requirements while keeping the receive mechanism simple and possibly highly reusable.

The reciever mechanism will never be simple if you beam the power over distances on the order of 1 AU. Now, using a ground based laser installation to give a ~2x boost to a regular solar-electric vehicle while it is spiraling out from Earth does make a lot of sense, since the spiraling phase takes up a big portion of the time and delta-v of most SEP missions. It allows it to spiral out faster, and depending on design it can help conserve fuel. Long term colonization of Mars may include having something similar at the destination, also to improve spiraling times.

[A_M_Swallow]

Can the solar power satellite be put into orbits that allow the transmission of power to the night side of the planet? Possibly from an orbit behind the planet.

[ptolemy1977]

Yes, I agree that solar has its uses, even the data on the Adastra site acknowledges this.  They do however limit the usefulness of solar with their engines to near earth feasibility, they tout nuclear as the solution for deep space exploration, which is the point of my suggestion that beaming power to spacecraft might make sense at least up to the orbit of Mars and maybe Jupiter.  See Adastra's marketing statements at http://www.adastrarocket.com/aarc/VASIMR for their blubs on solar and nuclear power sources.  As for the power requirements of the VASIMR these are 100kwh engines there is expected to be two engines used in a mission to Mars, the crew compartment of a crew cabin isn't expected to be much more that 20kwh power demand.  However, this is probably a moot point because I am not actually arguing about some specific power capability but in general that using this method of power delivery can be an efficient alternative to solar or nuclear while capable of the higher power requirements of large fast spacecraft.

That said, probably the best way to answer this query to determine feasibility might be to simply simulate the process in matlab or some similar program.

[whitelancer64]

See Jim's first post. Beaming power over such large distances is not practical, it's very inefficient due to the inverse-square law.

[ChrisWilson68]

I recently viewed an article that describes photonic propulsion as a means of taking us to the stars, search for "Mars in Three Days" on foxnews.com.  I am sure that this will someday be true.  But, it also brought to mind that we currently do not have a viable power source for the Adastra rocket engine.

Please note that the Ad Astra engine is a plasma engine, which is not photonic propulsion.  Photonic propulsion has much higher Isp but much, much lower thrust and requires much higher power levels for the same thrust.

[AegeanBlue]

I am a great fan of VASIMR. Power generation is indeed a stumbling block. It is far from the only block. There is a document flying around in the Lunar Prospector thread from September 2015 about the goals and current projects of HEOMD. According to the document the funding that NASA has given to Ad Astra is so that at the end of the program in a couple years VASIMR reaches TRL 5. HEOMD is also hedging its bets with more traditional electric propulsion, there are several threads on this forum on how upscaling Hall effect thrusters is less risky. VASIMR's main stumbling block towards space implementation is that it cannot be downscaled to levels compatible with a robotic mission so as to fly sooner. There was a plan to fly it for testing on the ISS, which apparently has fallen through because developing VASIMR has taken longer than expected. If we do have a TRL 6 VASIMR in 5 years, and that is a big if, the ISS is currently approved only to 2024. There have been concepts about a free flying VASIMR demonstrator, but only concepts, nothing more.

In respect to beamed power, TRL is probably even lower. Beamed power concepts date to the 1970s and the oil crises, create a photovoltaic power station on earth orbit and beam power down to earth. 40+ years later we have yet to demonstrate microwave power beaming from orbit to earth. The ISS is the most powerful electric generation system in space, with a theoretical maximum of around 120 kW. The robotic part of the asteroid redirect mission talks about a 40 kW power system. As mentioned in the thread, the VASIMR prototype currently require 100 kW * 2 thrusters = 200 kW. NASA is funding high power solar electric panels, so the VASIMR's requirements are along the realm of the possible, at earth distance. This is more mature technologically than beamed power