Can someone with a bit of orbital knowledge ELI5 for me here. Well maybe bit more then 5.
But I cannot help but wonder how pointing a beam in a lab. Prooves the ability to do so at a single point on spinning plannet while while able to see the sun for 24hrs.
I really am no expert or even mildly informed. But surely geostationary is not high enough to have 24hr vision of the sun. If we need to be higher then the complexity of keeping a single satellite pointed at a stationary point on earth. Becomes expensive fuel wise.
Surely any solution would need multiple satellites. Maybe one at an earth sun L point sending the power to a geostationary relay point?
ForgotAboutDre@lemmy.world 2 months ago
The higher up you are the longer it takes for the sun to set so you get a longer day. You can see more of the earth. Or the earth appears smaller, so is less likely to be blocking the sun. The higher you go the easier it is to always be able to point at the sun.
A geostationary orbit has a 42, 000 km radius, the earth has a 6000 km radius. It’s like looking at a 30 cm ball from 2.1 m meters away. Not much will be obscured from your view. It like a ball on the floor at the opposite end of a room, you would expect it to block the view out the window.
There may be times when the sun is eclipsed by the earth, but this will be infrequent. If the satellite isn’t in the same plane as the earth and sun, then this will be unlikely. The UK is relatively far north. So the satellite would be looking ‘over’ the earth during night to see the sun. The satellite would only be a small fraction of it total distance to the sun further away at night. So the power generation impact will be minimal. The elliptical orbit of the earth around the sun would be a bigger factor.
marsokod@lemmy.world 2 months ago
To complete that good answer, basically satellites in GEO will experience eclipses 2x21 days per year (around March and September). The eclipse duration during these period will vary from 0 to 70minutes and then down to 0 again, with one eclipse per day, around midnight.
So your solar plant in space will work 100% of the time 320+ days a year, and will have a small down time that can be up to an hour in the middle of the night otherwise. Not perfect but actually very manageable with a little bit of storage on the ground.
Overall, the main concern with these systems is the total cost, including launch cost. It is hard to tell if it will be competitive with solar + battery on the ground.
HumanPenguin@feddit.uk 2 months ago
Thank you. Fantastic explanation.
Tweak@feddit.uk 2 months ago
This will happen once per day lol. For a geostationary orbit anyway, as the orbital period is 24 hours.
The point, as you mentioned before, is that the nighttime/eclipse part of this period will be very short and the day very long. Our night lasts hours, a geostationary satellite’s night is minutes (maybe a little over 1 hour for the longest ones).
This website calculates eclipse periods for satellites: satellite-calculations.com/…/satellite_eclipse.ht… Apparently it’s a seasonal thing, like 3 months you get daily eclipses, 3 months you get no eclipse, then another 3 months on and another 3 off. The 3 months with eclipses are the around the equinoxes, so Feb-Apr and Aug-Oct.
Wanderer@lemm.ee 2 months ago
The Equator isn’t in line with the angle the earth revolves around the sun.
Tweak@feddit.uk 2 months ago
Yup that’s what I gathered from this. Literally had the “duh” realisation as I was writing that comment.