If future satellites have fold out antennas that are 45 meters diameter, spot sizes of half a mile are possible. With that, service will make sense everywhere except urban areas.
45 meter fold out antennas are very possible. Imagine you screen print antenna wires onto a mylar sheet, then double up the sheet and seal the edges to make it like a large airbed. Then, when in space, inflate it.
I think regulators would be much more hesitant to allow thousands of 45 meter diameter antennae in low orbit.
That's a significantly increased collision risk, as well as increasing interference with astronomy and potentially increased brightness mitigation challenges.
Practicality wise, such a large antenna would add a lot of drag, such as to meaningfully shorten how long a satellite can stay in operation (which would cause an entire bunch of tradeoffs in terms of mass budget to need to be reevaluated).
That's true - although the antenna can be oriented to be perfectly parallel to the direction of travel - therefore only experiencing drag from the edge cross sectional area.
> increasing interference with astronomy
The antenna could be painted matt black. It can also consist of ~95% holes without much loss in functionality.
> increased collision risk,
I don't think it will matter while the number of uncontrollable satellites remains low. If I were a regulator, I would put a cap on the number of uncontrollable satellites that may be in orbit at any given time, and if that cap is exceeded prevent all new launches and require active de-orbiting of existing ones.
Inflating is such a cool idea, it'd work for any 3D shape I can think of.
If keeping air pressure is an issue, that might be resolved by making the sheet rigid once deployed. Are there UV curing resins that won't cure at all before being exposed to UV?
Speaking of sunlight, heating from the sun could be used to create the pressure for inflation. Or off-gassing from UV induced reactions.
It’s more likely you choose a higher frequency to narrow down your spot size vs growing your antenna comically large. Increased frequency also allows for increased bandwidth.
Gravity is effectively nil on a satellite - the satellite is within the gravity well, yes, but is constantly falling in a parabolic path, so doesn't feel any gravity. The total forces experienced due to gravity and related forces will be nano-newtons, so irrelevant. They are dwarfed by the drag force.
Thrusters are ion drive thrusters, so have typical forces of 2 milliNewtons (0.2 grams-force). I don't think 2 millinewtons will be sufficient to fold an airbed-like structure, even with 0 internal pressure. (imagine a fly lands on a plastic bag... the fly isn't heavy enough to flatten the bag, even though the bag has no internal structure - a fly is about 0.2 grams).
45 meter fold out antennas are very possible. Imagine you screen print antenna wires onto a mylar sheet, then double up the sheet and seal the edges to make it like a large airbed. Then, when in space, inflate it.