It is doubtful that anyone in China with any kind of influence would take this project seriously.
Why?
Many years ago I read that the Defense Dept was investigating the possibility of a giant reflective mirror to light up the combat areas of Vietnam about the same as the full moon. It was cancelled when studies also suggested the illumination would create 10% more jungle growth.
The actual illumination would be a giant Mylar mirror very light (ha ha) that sat in geostationary orbit at an angle that kept it in sunlight.
Alternatively for northern climates the Soviet communication satellites had a 12 hour very oblong orbit so it would hang over the northern town at apogee. Put several of these with apogee distributed evenly abound the earth and get round the clock coverage.
I also wonder if reflectors of the size required wouldn’t need constant fuel to counteract the light pressure that would be applied to them. The thing is designed to intercept as much sunlight as possible and reflect it at an angle down to the Earth. That would essentially turn the things into light sails.
All in all, this sounds like an absolutely hairbrained idea. However, I’m not blaming the Chinese for promoting some speculative project as if it’s real - my real beef is with the godawful state of science ‘journalism’. This is just one in an endless series of bogus stories that shouldn’t have passed the smell test by anyone even remotely competent to be reporting on science and tech.
Is this just the result of terrible science education? Or media hiring ‘science’ reporters based on criteria other than that they know anything at all about science? I just don’t get it.
Hats off to ‘NextBigFuture’ - they’re the only ones I’ve seen who applied a modicum of rigor to the story.
Science journalists have to write about everything from deep space to the bottom of the ocean floor. Even if they took science classes in college, there’s no way they learned about EVERYTHING. The best science reporters are intelligent people who try to understand the stories they cover, but what with deadline pressure and economic pressure, even the best intentioned will screw up.
Compare with police reporting, politics reporting, or sports reporting. Not that journalists always get those stories right, but the scope of what needs to be understood is much narrower.
If you have a good general science education, you should know how to find basic information, and you should have a sense for what is utter bullshit and what isn’t. If a press release about a perpetual motion machine crosses your desk, you should know enough to know it’s bullshit. And if you don’t, as a responsible journalist you should have some people you can reach out to, who can tell you what’s bogus and what isn’t. There are plenty of people in colleges and industry who would love to get a mention in a newspaper for vetting something.
What isn’t acceptable is to take that press release, say to yourself, “Jeez, I have no clue about this subject”, then go ahead and post it as a news article anyway.
I mean, there are some REALLY egegious examples out there. Look up the ‘PlayPump’. It’s gotten tens of millions of dollars in funding, and destroyed water access for more than one African village, based on credulous articles about it being printed in prestigious magazines. It should have taken no more than five or ten minutes for anyone who understands basic science to see major problems with the concept and to at the very least ask hard questions about the concept before writing some glowing news story about it. Instead, it took years and a lot of failures before people started to look at the concept critically.
Sounds to me like Chairman Mao would have loved this. Remember his plan to kill the sparrows that ate the rice? The insects the dead sparrows didn’t eat ate the rice and millions of people died of starvation – more people than sparrows were killed by unintended consequences.
One thing that jumps out at me is that some plants (tomatoes, for instance) require a certain length of darkness to trigger flowering and fruiting. Shine a flashlight around your tomato plants and they stop flowering and go back to vegetative growth. I suspect there is a good chance that five times brighter than moonlight may be enough to disrupt the growth cycles of some crops.
Yes it’s a light sail - which means it can maneuver without using any fuel, just by adjusting the sail.
I still haven’t seen any definitive reason it wouldn’t work, if we assume the 500km altitude is just for a proof-of-concept experiment.
It doesn’t just need to work. It needs to work cheaper than the existing solutions to the problem. What’s the lifetime of one of these satellites? How much light could it provide over that lifetime? How much does the construction and launch of each cost? How much electric lighting could you provide for that same price?
Not necessarily. It’s not a business. It’s a public works project. It may have other goals than just providing illumination - national prestige, technology development/test, stimulating the city economy, justifying the development of heavy lift vehicles, etc.
That’s a lot of material. Even if they make a structure with multiple mirrors that pivot versus one large sail/mirror contraption.
And, a lot of rocket fuel to get it all up there, unless they plan to build it on a lower orbit and then use the “sail” to push it out into final orbit.
It mostly doesn’t matter what orbit they build it in-- Most of the energy is going to be used in just getting it up into orbit at all. As the old science fiction writers were fond of saying, LEO is halfway to anywhere.
No, it means it’s GOING to manoever, whether you want it to or not. Assuming this thing is in geostationary orbit (nothing else makes a whole lot of sense), you want it to remain fixed over its position on Earth. But when you expose a 300m diameter mirror to the sun, you are going to be pushed by the photons. It will take energy to counteract that.
Solar power satllites also ‘work’, if we don’t consider the cost. So do space colonies and lots of other things.
The problem is that the articles presented this not as some speculative, maybe-one-day kind of thing, but as something that is about to happen:
That’s the lead graf of the story. It isn’t remotely close to being true. If they had said, “Chinese scientists are planning to launch an experimental, proof of concept satellite that will test out the possibility of one day beaming light down to earth to light up cities” I wouldn’t have had nearly as much problem with it. But the article seriously implies that this is a production thing - it says that it will soon begin to light up the city, and if all goes well it will be joined by three more in 2022, and cumulatively they will provide the light necessary.
That is not factual. It’s fake news. It’s essentially a Chinese press release being passed off as fact because Time is apparently unable to understand the problems that multiple people on a messageboard could instantly spot.
There are lots of other orbits that would work. Geostationary is too far.
A solar sail can be controlled by adjusting the tilt or shifting the center of mass, neither of which requires propellant. And what makes you thin it’s impossible to find an orbit that’s stable with the photon pressure factored in? Especially since the photon pressure won’t always be in one particular direction relative to orbital motion.
That’s how I read the article. The article makes it clear the 2020 launch is an experimental satellite.
And I’m not saying the idea is feasible. I just don’t see any evidence to dismiss it as a hoax or conspiracy.
I would imagine that most journalists don’t know much about physics; or chemistry, or aeronautics, biology or many other thing they write about.
And that’s the problem with modern journalism. Too many people ‘reporting’ on issues they don’t understand.
It seems to me that to be a science and technology reporter you should have an education in science. J school is not the right qualification. Some science journalists do have backgrounds in science or engineering, but the majority do not. And it shows.
Fast. Cheap. Accurate. Choose 2.
The New York Times does fine science reporting. So does the Economist. The first section of Science magazine is terrific.
AP? Not so much.
Can you elaborate on some of the other orbits?
The only one I can think of is the terminator-riding orbit mentioned upthread. But asRiemann points out, this orbit only provides for a brief period of extended illumination before dawn and after dusk. And even having 36000 satellites one-kilometer intervals following this orbit wouldn’t change that, would it?
You could also just use any old orbit, accept that most of the orbit is going to be useless, and launch enough that you still get good coverage anyway. In principle, at least.