Laser satellite weaponry is already here. It wouldn't matter if DARPA undertakes this project or someone else. I think it's still a good idea, if it can deliver energy cheaper than building, maintaining, and running a ground infrastructure. It could potentially lead to greater energy security. I just imagine satellites powering individual city blocks or segments, right along with remote villages. I wonder what the radiation effect is from energy delivered by laser...
How will we know the effects and timing (permanence) of injecting the stratosphere with aerosols that block out solar radiation? Is it localized (how will such gases stay over particular areas such as the poles), because gases expand indefinitely...right? How would we control these aerosols so the earth doesn't get too cold?
I think it seems like a good idea, and I'm sure there are experts that could answer these questions.
I give the Whitehouse kudos for proposing such an initiative, at least through research we will know more about what is possible and the effects of such actions.
The paper provides a great overview of how to achieve a more sustainable earth. Hopefully these actions could be consistent over the long term.
Why don't the stock market traders just use satellite? Shouldn't those transmissions be faster than cable transmission? They are only gaining milliseconds right? I wonder who will be affected. It seems like a lot of wattage, but the stock traders antennas are located in the upper US.
Satellites mean you are eating round trip delay times to orbit and back, encode and decode on both ends, signal strength competition, etc. It's a bad trade. Speed of light limits are a big limiting factor, which is another way of saying you want to minimize your total transmission distance.
Going into orbit increases your total transmission distance. If you can afford to put in the infrastructure, you never want to go into orbit.
It looks like, as the crow flies distance between Chicago and Frankfurt, would take a pulse around 23ms to arrive, at the speed of light. It looks like for a LEO satellite, the round trip time, is around 40ms.
They mention it uses the ionosphere, so curious exactly how long it takes the short-wave pulse to arrive.
HF radio reflects off the ionosphere's F-layer, located about 100-200 miles up. To get from Chicago to Frankfurt requires several hops between the ionosphere and the earth's surface. The hop length is one or two thousand miles.
Satellites such as Starlink operate in low earth orbit at about 350 miles, significantly above the F-layer. Also, they introduce repeater delay when they relay a data packet. To get from Chicago to Frankfurt would require relaying the packet thru multiple satellites. So, greater distance (even if passed by laser between satellites) plus repeater delays.
Also note that satellites in LEO are the only option. Geosynchronous satellites are completely out of the game due to the much greater distances involved.
Microseconds matter to them; even with a satellite in low-earth orbit (~342 mile), you’re looking at a round-trip time of 3.68ms, on top of any packet latency introduced by the satellite itself.
It’s always going to be faster to go point-to-point than pay the light-speed cost of bouncing all the way out to orbit and back.
I suspect reason we are seeing the HF proposal now is the coming Starlink laser links will offer similarly low latency. The HF proposal is to provide an alternative to potential Starlink monopoly. They don't want to get locked out if Starlink is exclusive.
Their latency requirements are such that they want as straight and short a line as possible because a larger round-trip eats up precious nanoseconds. The speed of light is not fast enough for these folks
On that note, Ryan North's book "How to Take Over the World" has a whole chapter about this. He proposes building a tunnel from New York to Chicago, to get the best possible straight-line distance between the two cities, thereby minimizing latency. Leasing this line for HFT is the funding source for most of the later supervillain schemes.
It wasn’t the magnet that was the problem or even the laser but instead the system-level problem of SDI.
It was believed then that the best strategy was to shoot down missiles in the boost phase which is 90 seconds over enemy territory. Trouble is that you have to work very quick to accomplish that and have assets in orbit if the threat is a big country like the USSR.
Before then ABM systems used nuclear tipped interceptors at the terminal phase, the U.S. build one called Safeguard and then shut it down, treaties allowed the Russians to have just one and I think they still have one at Moscow.
Currently the U.S. has missile boats that can intercept many missiles at mid course, the previous two systems rejected this because an ICBM could carry a huge number of decoys that are hard to separate from the warheads. Either this problem is solved, willfully ignored or some combination.
That ground-based FEL would have the problem of being based on friendly territory, thus terminal defense and vulnerable to poor atmospheric conditions such as clouds. An airborne laser seems to be the best option, can be either terminal or boost if you can get close to the enemy (short range missile). It has been proven with a toxic and dangerous COIL laser, and may get revised if and when electrically powered fiber lasers improve sufficiently.
