what concerns me is that it's wild laser beam in potentially public space. anyone that would accidentally cross that potentially invisible line could get killed or severely hurt.
imagine something reflective entering this beam, it could blind people in a very large radius.
for me it means that thus would still need some pipe/fiber that would protect world from this laser.
IMO there's two safe ways to implement this:
- Ground-satellite-ground relaying, with at least one geostationary satellite between the ground stations. The satellites being geostationary means that the path of the beam through the atmosphere is constant, and air traffic can be routed around them in a reasonable way. (You could do this with lower orbits, but it'd be a hassle with current aviation industry technology).
- Beaming by tunnel! Can't get hit by a laser if it's under your feet. Obviously, this negates the benefits of the technology, and just turns into fibre lines without the fibre, over shorter distances, with all the pain in the ass of laying underground cable.
In the first approach, there'd have to be an effective exclusion zone around the receiving station (how big, I don't know), and it'd be nice to have satellites fail safe, so that if they end up pitching or rolling off axis, the beam will be shut off before becoming an accidental weapon.
Geostationary orbit is way way too far and tunnels? Really?
They tested that thing at the White Sands Missile Range where the public is excluded.
A friend of mine was looking for a stargazing spot between WSMR and the Rio Grande River a fair bit south of San Antonio, NM and got her Chevy Blazy stuck and figured her best bet was to walk across the security perimeter and get caught by the security force and they caught her pretty quickly.
The eventual goal is to use it at extremely high altitude with drones so that that isn't much of a risk.
The laser would ricochet from disintegrating drones (think of the props) and cause collateral damage to people on the ground.
Also see this (with remaining eye): https://www.funraniumlabs.com/2024/07/how-i-got-my-laser-eye...
There's danger and risk in everything worth doing.
The dams could burst and drown millions.
The highrise you live in could topple over or burn.
The bridge carrying the train could crash into the valley.
The passenger plane could lose lift and crash into a residential building.
The power source in your car could catch fire.
We engineer around it.
That will be quite a sight -- seeing the videos of people on the ground, filming future drone laser battles
“It’s a lot easier to send a power beam directly up or down relative to the ground because there is so much less atmosphere to fight through,” Jaffe explains. “For PRAD, we wanted to test under the maximum impact of atmospheric effects.”
Super impressive! My only complain is that this was done at the White Sounds desert in New Mexico, at over 1200 meters of elevation. For maximum impact they should have done it in Florida on a hot humid day
＂maximum impact of atmospheric effects＂ would be simply a foggy day...
Both your example and theirs would be better tests than a desert.
The US is always geared up and ready to fight the previous war.
The desert is bad enough. On a hot day you get convection which will vary the refractive index of light and spread out the beam. I wonder if they have active optics on the transmitter to fight this.
There’s no range in Florida large enough for this test otherwise I’m sure they would have.
Even Eglin wouldn’t be large enough.
Humidity would most likely attenuate the beam from 20% end to end to less than 1% - water vapour absorbs energy like nobody’s business.
This is a tech for arid environments - which seem to be where the US does most of its deployments these days.
The application to drones seems most clear: beam drones some extra power as needed. Or continually!
I wonder how big that receiving apparatus is. Whether the receiver is gimballed, or whether the drone itself has to fly a heading to aim at the sender: TBD.
Seems like that has a high chance of frying sensors on sats flying behind the drone though
And have a great opportunity to drill some holes in birds heads.
Sorry I really fail to recognise how beaming 1kw of excited particles is a safe thing to do just like this…
if you are the military and you are using drones to win a war, I don't think birds are your primary concern tho
It must not be safe to be out in the sun then.
It’s not, for an extended period of time. Now imagine it was collimated rather than diffuse.
That's the thing, sunlight is collimated. It only gets diffuse once it reflects of a diffuse surface.
Fair enough, poor choice of words on my part. What I meant was concentrated further (in terms of energy per area) than the typical concentration received at the surface of the Earth.
Density (and wavelength), rather than total power, is important.
Sun's 1kW/m^2, and even then you shouldn't look directly at it, and being out in it all day without protection leads to sunburn.
Last time I forgot sunscreen at a UV index of 10 my skin started peeling of after half an hour so...
Why not just beam power down the optical fiber? Optical fiber is exceptionally clear and works in fog and rain
Fiber transmits light, not rf. To get power out of fiber optics you have to have a photovoltaic cell on the other side and there's a limit for how much those can produce with such a collaminated light source.
Using fiber optics for power is like trying to make a solar panel generate electricity from a laser beam.
"trying to make a solar panel generate electricity from a laser beam" is literally what the article is about.
> Using fiber optics for power is like trying to make a solar panel generate electricity from a laser beam.
Isn't that exactly what power beaming is, except typically with frequency range in microwaves instead of visible light?
> except typically with frequency range in microwaves instead of visible light
That's a big freaking deal.
just have a tiny steam turbine equivalent...? (some thermoelectric generator) You don't really need to be efficient. You have fans to blow air and dissipate heat on the other end after all
You should do the first round of engineering calculations on this.
I have no idea why this might be limited by the light source being collimated?
I mean, you can get electricity from PV illuminated by a laser, and everything I've heard so far says it's easier than with sunlight because you can match the frequency of the laser to the band gap of the PV.
Sure, you absolutely can do it. But material science quickly becomes a major limit.
For something 15% efficient like a high quality PV cell, for every 100 watts you want to be usable on the receiving side, the receiver has to bleed off 566 watts of heat. And that's 566 watts of waste heat that is highly concentrated.
Consider a single residental power circuit. 12A maximum, 120v, that's 1440 watts at delivery. For PV power delivery via laser, that PV would need to dissipate 8 kilowatts of waste heat. One a very small surface
If you were to go that way, why not a wire?
How about drones with a solar panel case? Would require a sunny day to work at all though.
Tiny nuclear reactor?
On the scale that useful nuclear reactors operate, a "tiny nuclear reactor" is the size of a shipping container.
Even a tiny RTG is in the same range as a dumbbell.
While not reactors, how about nuclear batteries without heavy shielding?
Nuclear batteries are a superset of RTGs.
There are other kinds of nuclear battery, but the ones I've heard of outside labs, are extremely low power betavoltaics.
"reflects onto dozens of photovoltaic cells arranged around the inside of the device which convert the energy back to usable power."
This is no different that what we were considering two decades ago for the space elevator competition. One of the problems with this approach is that as the photovoltaic cells heat up their overall efficiency decreases.
They'll only get so hot, and you can just spread the energy across more cells, right?
You end up with a thermal runaway situation where the hotter the photovoltaics get, the more energy they convert to heat (instead of reflecting or converting to electricity).
Is it possible to steer the weather by heating the atmosphere with power beaming microwaves?
Is it possible to cancel the vortical formation of a tornado or a hurricane with microwave power beam(s)?
Does heating the atmosphere with microwaves change the weather, or the jet stream, or the cloud cover?
What sort of a fluidic weather simulator could answer this question?
Is there a fluid simulation device that allows for precise wireless heating of certain points in the fluid?
If so, there could be international space law to study and control for the known and presumed risks of space-based microwave power beaming.
Nuking a hurricane would not break it because nukes are not big enough https://edition.cnn.com/2019/08/26/weather/hurricane-nuclear...
I think it's possible to nuke a tornado, but if someone does it to try to save a city, I expect even more destruction.
I don't expect the beam to be energetic enough to change anything. The closest method I can think of is https://en.wikipedia.org/wiki/Cloud_seeding but it doesn't distribute energy, just tiny crystals to condense oversaturated vapor.
Could this also be a viable alternative to HVDC lines for civilian applications?
No. 800 watts (vs megawatts for HVDC). 5 miles vs thousands of miles. 20% efficiency optical to electrical - so electrical vs electrical is much worse - vs 90%+.
This is so much worse in every aspect it's not really compareable.
It's great if you hate birds, though.
The key thing they aren't saying is how much power it took to "send" 800 watts 5.3 miles...
They mentioned that it was 20% efficient at a closer distance.
So likely much lower than that.
20% efficiency in terms of light -> electricity. A 50% laser efficiency (electricity -> light) is really good, possible for some diode lasers, if you pump a fiber laser with diodes to get a high quality beam for cutting materials or weapons purposes maybe you get 25%.
That demo would require about 45 kW of laser power with good beam quality which would be totally possible with a fiber laser
Wow that's a long way from the proposals for sending GW of microwave power from satellites.
But pretty close to powering drones from ground stations
Those sat to ground power sources use gallium arsenide switched FETs = synchronous rectification, avoiding the voltage drop of diodes has been tested on a small scale, the 10GW orbital 35% efficient solar arrays, maybe next week... Solar boilers, end to end, are more efficient than solar cells, but mechanical complexity(leaks, corrosion, worker avarice) made one US plan in the South West non viable. As we sit silicon-perovskite tandem solar cells will top out around 42-45% - unless Schockley is end runned? Ternary -??. A good lecture = https://www.youtube.com/watch?v=Ft0VJX0_Td0&t=2s&ab_channel=...
Solar thermal as well as solar-chemical systems have the problem of start-up.
PVs do not have any problem starting up, they produce less than full power with less than full illumination but they produce something and once the illumination is full they produce full power immediately.
Many solar thermal power plants are fired with natural gas in the morning to get them spun up to the point where they can take advantage of the solar energy. Without that they'd probably lose a few hours of production.
Laser power beaming from space could be useful at lower power levels than that, for example for powering aircraft.
I was thinking of"how much is enough" so they can power 'instruments'. I am also thinking of 'how can we use this tech to revive space-instruments (the next generation of 'Voyagers' may be equipped with such receivers?)
I also wonder how difficult/impossible would it be, and the 'throughput'. Assuming that you want to recharge a recon drone (or the 'next generation of Voyagers flying in space) that flies over XYZ area/country/etc. Would it take 1sec or 10seconds 'of beam', and the accuracy/waste/total amount one would have to 'dispense' in order to give that drone the X seconds of 'juice' to keep it running for 1000x X seconds of flight duration. And what about clouds/mist/rain/snow/birds/etc.
'Infinite energy' for a drone (I mean no dependency to come down to refuel) is a game changer.
Would that work with 'instruments buried underground? And at what depth? ('War of the worlds' scenario). Could someone bury a device, with only the receiver protruding from the ground, with a battery to keep it alive, and waiting to be activated by a satellite passing by giving it the "10 seconds beam" to fully charge it and.. (I am thinking of the recent drone-related incidents/attacks within Russia and Iran)(if you park a drone for 10 months, its battery will deplete, right?)(I don't have a drone, but batteries are batteries).
A second thought on the matter, can one 'program' the light to be also transferring data? Park the drones in <insert foreign territory>. No programming. In the middle of nowhere (no 4G-5G). You fly a satellite over it, beam down the 'juice' (together with the instructions - no interception of the transfer is possible). Someone finds it 'before', they only get the hardware but no info/intel.
"The possibilities are endless" (and so are the nightmares)
This can only be used where efficiency doesn't matter, like military applications for powering a drone. The overall efficiency i.e. grid -> laser -> pv -> grid would be atrocious.
> New Mexico
Great stuff.
Do Seattle, next.
The popcorn is a very nice touch
This seems very silly. It's either a death ray project in a fake mustache or somebody had earmarked a bunch of money that they had to spend before it expired.
This is kinda surprising to read. I’ve never known anyone who isn’t incredibly excited at least at the prospect of wireless energy transfers. If you can do 800 watts over 8 km, surely we can do 150 watts across 3 feet in the household, and MANY of our most important discoveries come from DARPA essentially being a black budget skunkworks team.
But much of the stuff DARPA does seems weird. It’s not about ideas with solid foundation and thorough engineering, it’s about crapshoots that might work and would pay off in some way - often any financially feasible way.
They once put “cats” on guns in hopes it would surprise opponents even just for a quarter second, giving your spec ops dudes the advantage. They tried to create angled guns that could shoot around corners like 20 years ago. All kinds of crazy stuff! It would be a lot of fun to work there, I think.
The problem with wireless energy is that the efficiency losses are mostly because of physics, not because of technology just needing to scale up a bit more.
A future with having wireless energy transfer everywhere is one where energy is so abundant that we don't mind throwing out 80% of it powering wireless things.
> They tried to create angled guns that could shoot around corners like 20 years ago
The IDF got a gun that does this[0] into service in 2003.
Reminded me of "Wanted" (2008)[0]
The actual work is usually done by private companies under contract
The germans tried the curved gun with an attachment called Krummlauf during ww2. It would break after just a couple of magazines being fired. https://en.wikipedia.org/wiki/Krummlauf
Not sure how you would build one of those without the stress of the bullet during firing would not damage the barrel.
I'm amazed that worked for even one shot. Presumably gp was referring to cornershot or something similar, which seems like a much more reasonable approach.