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Curious to see what those “sunshades” are going to look like...
dwolvin
Member
dhanson865
Well-Known Member
Higher orbits make sense if F9 is your launch vehicle. Less sats at higher orbit means less launches per year to maintain or grow network.
Lower orbits make sense if Starship is your launch vehicle. More sats in the same amount of launches or less launches for the same number of sats means Starship won't be pushing as hectic a launch schedule to keep Starlink maintained and they can grow at will.
So I'd say that they moved to lower orbits shows confidence in Starship even though it hasn't made it to orbit yet.
Is that assuming the higher sats can handle more simulations ground connections?
dhanson865
Well-Known Member
no, that's purely based on orbital decay rates. The lower orbits require replacing sats more often and launching more sats per year even ignoring quality of connections and quantity of connections.
You might have advantages other than that but I'm saying ignoring all other advantages the orbit height choice is noticeably affected by your available launch vehicles.
There is much discussion in r/spacex about how many launches a year F9 could do and how much of that would be required just for replacing starlink satellites that deorbit on a yearly basis + how much would be required to expand the network.
Starship would change that equation and make it a non issue, if it fails (if Starship was a dead end project that never got to orbit) Starlink wouldn't have the same launch capability from F9 alone.
Its actually has very little to do with decay rate. 550km is pretty easy to maintain with very minimal delta V. Pretty much a no-brainer for any current technology electric propulsion. We're talking probably a few kg at most for station keeping vs 1100, which would be well offset by the extra propellant required to get a sat up from insertion orbit to 1100km (or whatever it was) and back down again. You probably actually get a little longer average useful life at the lower orbit with the same sat because the radiation environment is a little easier to manage. So, fewer upsets/events, fewer hard failures.
When you go lower you get better link margin at the expense of ground coverage (assuming of course the array half-angles don't change); that coverage can then be made up with more satellites...which end up improving overall network capacity so its a double win. So that's the big upside here.
Starship is a double edged sword as the exercise of orbital phasing and plane precession gets complicated and time consuming. With F9 there's pretty much no need to precess as all the sats can go into one plane. Certainly the lifts-more-*sugar*-for-less-money aspect is Starship's upside and once its operational that will certainly be the deciding factor.
Anyway, while many of the above speculations in this thread (mine included) are valid to some degree or another, its become clear in the past few weeks that the proposed new orbital debris mitigation rules are really what's driving SpaceX's change. In short, the rules would basically restrict the number of satellites in any given NGSO shell by way of regulating collision probability, and that's effectively going to commoditize LEO orbits in the same way that GEO slots have been for decades. So there's a couple plays here by SpaceX:
1. Certainly they're making a go at securing what are otherwise pretty ideal altitudes. 550 is really idea for minimal orbit decay, reasonable ground coverage, and manageable radiation and AO environments (like the SAA), not to mention is pretty solid for imaging, and one could imagine two downstream benefits of 'owning' shells in that altitude. First, there's certainly going to be what is essentially orbital slot hoarding and trading that you get with GEO, and you might as well get in on the ground floor for that. Second, it sets SpaceX up for re-purposing those oribits for constellation-as-a-service. Maybe its a reduced Starlink payload and someone else's gizmo, but maybe its truly a complete re-purpose where they basically end up with a constellation in a constellation. As an aside 550 is also ideal for the old rules of "deorbit within 25 years", since pretty much anything will easily come down from 550 in that timeframe passively, BUT...
2. The new rules would require controlled deorbiting. Gone are the days of set-and-forget, its-someone-else's-problem-now deorbiting. One needs to be able to perform collision avoidance maneuvers while coming down--which BTW is A Good Thing. While we can assume that's a non-issue for nominal operations as SpaceX has always planned (to my knowledge) to deorbit by re-entry from 1100 as opposed to deorbit up to a LEO graveyard (and that high up absolutely requires propulsion to re-enter), if there are uncontrollable satellites in the constellation--which is a statistical certainty--the thing needs to be pulled out of the sky. That's WAY easier the lower you are especially if there's a ton of dead sats to be removed.
Aside, look for coroner sats to become big business...
FCC Doc:
https://docs.fcc.gov/public/attachments/FCC-20-54A1.pdf
I suspect (and will bet) none of the satellites have propulsion, but might have little wings to INCREASE drag to control descent.
TLCTimFL
Member
On a side note, I live in Florida and last week at just the right time we could see the train of Starlink Satellites in the night sky just after dark. A local station was inundated with calls asking what it was.
I'll take that bet.
The cliff's notes from the proposed rules is that they all but demand propulsion on most satellites. Pretty much the only things that would get away without propulsion will be cubesats below ISS.
The flip side is that pretty much any satellite that has any real value--and certainly any satellite in a large constellation--is going to have propulsion on it anyway. So the new rules really manifest as a) more delta V for the existing prop system (= a bigger tank) and b) potentially more robust bus electronics (because they to last through deorbit).
e-FTW
New electron smell
Good stuff from Wyler on the reality of satellite internet, if you can get past the typical billionaire narcissism.
In the Eye of the Storm: Greg Wyler Breaks Cover to Talk OneWeb
Certainly Starlink roots in fundamental change from legacy space whereas OneWeb's foundation is in agressive evolution of legacy space; time will tell whether Starlink's next-level approach is enough to drive them toward long term commercial stability.
In the Eye of the Storm: Greg Wyler Breaks Cover to Talk OneWeb
Certainly Starlink roots in fundamental change from legacy space whereas OneWeb's foundation is in agressive evolution of legacy space; time will tell whether Starlink's next-level approach is enough to drive them toward long term commercial stability.
It would have been better if the journalist asked about Starlink. Also Wyler kept talking about how expensive satellite broadband is and how it can't compete in dense urban environments. One would have hoped that this is not new information for Wyler!
Buckminster
Well-Known Member
From another thread:
Here's a bit of odd/interesting news. A massive tower was built in the span of a few days at the London, Ontario Supercharger: T Ξ S L A London HW3.0 on Twitter
Is it just me, or does it look like the square mount on the tower could be used to hold something like a Starlink receiver box? Elon did say they would shortly begin testing in Northern latitudes.
I doubt this has anything to do with SpaceX or Tesla. It's a 5G cell tower.
https://www.landmarkdividend.com/our-services/flexgrid/the-flexgrid-ecosystem-portfolio/
