Reflect Orbital: Sunlight after dark using a constellation of spatial reflectors
reflectorbital.com
reflectorbital.com
TL;DW: not practical in it's current design.
1. On of the big tradeoffs is the sun sync orbit altitude chosen. The higher up you are, the slower you have to tilt to track, the longer time possible on a given customer, and bigger range of possible customers you have as the sat goes around. But, as you are higher, the size of sunlight you send gets bigger and bigger. A 5km by 5km circle is going to waste a lot of energy on not-solar panels all but the largest solar installations. If you double the light radius, you quarter the intensity.
2. Most of the earth is water. Of that land left, most of the land is quite uninhabited. This means that most of your time orbiting is going to be over areas with no paying customers.
3. I think the EEVBLog video overestimates the cost per sat, but I still didn't get the economics to work out to something profitable.
Of course they don't reveal their neat trick now because from a strategic point of view it would be bad, because other people would copy them, and probably outpace them.
Once it's only a physics problem, it becomes quite easy. Here are two potential solutions to the physics problem : Liquid mirrors, and plasma mirrors. The easiest being the liquid mirrors so let's explain this one. In fact it's so easy, it's child play.
Have your kids ever played with soap bubble : It's the same thing but in space. You make a big ring (roughly of the same area of the spot you are trying to make on the ground) (thin circular wire that you fold so that it will unfold itself like these tents) and you flow liquid metal (like mercury) on top to form a thin layer, hold by surface tension (and eventually electric field to have finer control of the shape or the surface).
The mirror will be a few atoms thick, a design that must be fabricated in space directly. It's just that we are not used to thinking with low force zero gravity environment. You don't use motors to move your mirror, you use fields spawned from precisely positioned points (and you have to compensate for solar winds).
Of course there are still technological problems due to the harsh conditions of space, but it's not something unheard of : https://engr.ncsu.edu/news/2024/03/06/reflecting-the-future-...
Unfortunately, this is not how the size of the spot on the ground is decided. Sunlight, even if reflected by a perfectly shaped mirror, spreads by approx 1 meter every hundred meters. At the "edge of space" at 100km, your spot already has a 1km diameter, in reality with a higher orbit and imperfect mirror & tracking it will be much larger. The size of your (ideal) mirror decides the brightness of the spot, not the size of the spot.
Liquid mirrors in space seem like a cool concept though!
To focus light, the ideal shape is a parabola, and it's a shape that occur naturally when you spin liquid in gravity. (Their are process to build big telescopes which only point up). Of course you don't have gravity anymore, but you can pull on your surface with fields, or you can have concentric rings that you align more or less along the axis to deform the surface. We don't need perfect focus just a rough spot.
One important thing to note is that the climate change is not caused by the heat we released into the atmosphere. It's due to the change in the power equilibrium of the Earth caused by the greenhouse gases we released.
The satellites are dumb and would have a negligible effect. But if you want to offset the heat just to be on the right side, some mirrors or simply white surfaces on the ground could do the job.
It evolved from the fake HTML tag "</sarcasm>" to "</s>" [1] (not referring to the actual <s> strikeout tag), to "/s".
[1] https://www.urbandictionary.com/define.php?term=%3C%2Fs%3E
A few comments here claim to have run the numbers. With negative results. How do seed rounds with name-brand VC work? Please tell me an independent party would have been paid to do due diligence on the feasibility of the approach. Or is this perhaps an investment in the team with an openness to pivot.
Let's say you go to one of the illuminated areas that paid for reflectorbital-light and look up. What would you see? You would see a tiny bright spot flying past, with an angular size of about 10^-10 steradians [1].
This tiny spot has the same "brightness" (radiance) as the sun, because a mirror preserves radiance. However the mirror looks about 10 000 times smaller than the sun from your perspective (the sun has an angular size of about 10^-5 steradians). This means that the satellite would only give you 0.01% of the light compared to the real sun.
If you could somehow take 10k satellites and use them to illuminate the same spot, you could technically get it to resemble real sunlight. But imagine what this would look like: These satellite would need to be many enough / huge enough to cover a very significant portion of our sky, on the order of the apparent size our actual sun. They would be spread out in a sun-synchronous orbit, so they would be visible at dusk with this size, from all points on the earth. Would we really want that?
The founder has been thinking about using mirrors to collimate the sunlight to get around this problem, but it won't work. The collimator design he showed in a 2022 article [2] would decrease the focal spot from a 5km diameter to some smaller diameter as intended, but it would do so by throwing away light, not by increasing the brightness in this smaller spot. This is given by conservation of ètendue, one of the fundamental laws of nonimaging optics (where I do research).
[1] They are planning a 100sqm mirror at 600km altitude, which gives a solid angle of (100 m^2)/(600e3 m)^2
[2] https://www.vice.com/en/article/this-man-is-trying-to-put-mi...
Sounds like an eco disaster to me.
Some things only happen when it's dark...
I'm amazed I almost never read about a much more viable alternative: inter-continental power transmission cables.
There are a few projects: UK buying electricity from Morocco, Singapore buying electricity from Australia. Both implemented using undersea power transmission cables.
If this could be implemented on a global scale, it would also massively reduce the requirements of storage for transient solar and wind power.
That's like saying "what we need is to improve mass public transit" -- no Vulture Capitalist would bite at that!
You have to pitch a solo-vehicle-in-a-tunnel or some such crazy idea, so that everybody knows you're a "visionary".
https://en.wikipedia.org/wiki/Submarine_power_cable#Operatio...
Is that too old school?
Becasue, of course, the cables would have AI, duh...
Who do I complain to when a nearby golf course orders some nightshine and now my sky looks like I'm under a fucking police helicopter?
A key thing that would make this easier than it'd naively seem, is that human perception of ambient light levels (like many kinds of human sense) is sort-of logarithmic. Twilight is just 10^{-5} – 10^{-4} the illumination level of sunlight,
https://www.engineeringtoolbox.com/light-level-rooms-d_708.h...
(That is, to my naive first take: a 100 x 100-meter collector in orbit intercepts enough sunlight to bring a 10km x 10km city to bright twilit level).