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For the record, these satellites are inserted in groups of 60 at half their orbital height. They have onboard thrusters to boost up to the final operational or

For the record, these satellites are inserted in groups of 60 at half their orbital height. They have onboard thrusters to boost up to the final operational orbit. There is high atmospheric drag at lower altitudes, so they deploy their solar panels horizontally during this boost period, which usually lasts less than a month. These horizontal panels reflect the sun just after sunset and just before dawn. Once they are at their final height they rotate the panels so they are much less reflective. Basically, the constellation's effect on the night sky is proportional to the number of launches in the last month, not the total number in orbit.

amackera 6y ago
Thanks for the info!
- ortusdux 6y ago
  Absolutely! Things will be really interesting when they can use Starships to launch batches. I've seen estimates that they could launch 600 starlink satellites at a time. They could theatrically also launch fewer, but put them all the way into their final orbit, skipping the few weeks of light pollution.
  - grecy 6y ago
    > They could theatrically also launch fewer, but put them all the way into their final orbit I wonder if they might choose to do this so the sats keep more of their onboard fuel, and will be able to keep themselves in orbit a bit longer before the inevitable re-entry burn up.
    - thereisnospork 6y ago
      I'd guess it is more efficient to have them boost themselves, so that they act as an additional rocket stage. (and so not need the delta V to elevate and then de-elevate starship's orbit.)
      - colechristensen 6y ago
        There is certainly someone doing the optimization problem for the orbit insertion and fuel loads and picking the right set of tradeoffs.
        londons_explore 6y ago
        The optimization problem also includes drag losses at the lower altitudes. And those drag losses are a lot lower keeping all the satellites inside the rocket rather than having each experience its own drag. Might be worth putting an ion drive on the f9 2nd stage for that reason...
    - Dylan16807 6y ago
      That's a tradeoff that could be made, but the onboard ion thrusters are about 5x as efficient as the rocket. They'd probably be much better off making the onboard tanks a bit larger and launching to the same low orbit.
    - trothamel 6y ago
      Re-entry is a bit of a feature, though - should a satellite be DOA, it will be in a low orbit and burn up faster.
      - gpm 6y ago
        I wonder if they could use another satellite to sweep a DOA satellite. They all start in almost identical orbits, so unlike most orbital degree cleanup plans there aren't huge relative velocities to deal with or anything... It would mean that 1 DOA satellite means bringing down 2, but that might be worth it if the DOA rate is low.
      - grecy 6y ago
        Absolutely, but for the ones that are not DOA, having more fuel on board means they can re-boot themselves for a longer time, thus staying up for longer and getting a longer service life per sat...
  - m4rtink 6y ago
    Or they could do it theatrically and once in a while make the most sats possible as bright as possible for a pre announced one orbital period with good ground visibility in inhabitted areas. Would be quite a sight! :) They are getting a bit too good at reducing Starlink visibility lately so I could definitely welcome an event like that. :)
    - VortexDream 6y ago
      They could start doing shapes and messages. Throw in some colors. Maybe provide a service where you can get them to show a message of your choice.
  - bruckie 6y ago
    > They could theatrically also launch fewer I'd love to see a theatrical launch. :)
cryptoz 6y ago
> Basically, the constellation's effect on the night sky is proportional to the number of launches in the last month, not the total number in orbit. For the major brightness issues sure, but they are not invisible or undetectable while in operation. Surely the effects are proportional to both the recent launches and the whole size. I think it's a bit early to dismiss the whole sky effect of multiple Starlink-style constellations in operation. Also isn't Starlink intending to do launches for the rest of time? There is always a value for the last month of launches- they'll never stop launching right? Just thinking out loud.
- sneak 6y ago
  There is also the (no help at the moment) fact that the more money that Starlink's parent company makes, the more likely we are to get the world's cheapest heavy lift orbital booster soon, and the more likely we are to soon have multiple large orbital telescopes that far exceed ground-based capabilities. Basically, if SpaceX makes it, we'll probably have a Starship-launched lunar observatory quite soon, in the grand scheme of things. This doesn't help the situation now, although there is so much screaming from the anti-Musk people as well as the pro-Musk people that it's hard to tell what the actual impact of the now-somewhat-albedo-mitigated starlink v.whatever satellites are. All of the coverage is breathless sky-is-falling stuff. In any case, the situation is temporary. Either SpaceX makes it and we get a far side of Luna observatory and LEO/MEO telescopes besides, or they don't and in a few years Starlink all falls down and burns.
  - bruckie 6y ago
    Would cheaper/larger launch vehicles significantly change the economics of deploying space based observatories? The James Webb space telescope has cost about $10 billion, and you can afford even today's largest/most expensive launch vehicle (Delta Heavy) for a relatively small fraction of that ($350M).
    - coryrc 6y ago
      It'd be a lot cheaper if they iterated and could service the machine if needed. Waterfall is the most expensive way of doing something.
Rebelgecko 6y ago
>Basically, the constellation's effect on the night sky is proportional to the number of launches in the last month, not the total number in orbit. For what it's worth, in order for the constellation to reach steady state the number of launches in the last month will need to be proportional to the total # of orbit. So if the constellation has 42,000 satellites and the satellites last 10 years on average (IMO that's an optimistic lifespan), you need to launch around 350/month just to maintain the size of the constellation.
- mlindner 6y ago
  By that time they'll also have a launch vehicle capable of launching around 300 satellites in a single launch. Additionally, 42,000 was a worst case for the number needed and only if things go exceedingly well with the service. I think people quote that number too much when in reality there's likely to be under 5000 (from SpaceX at least).
  - alphaoverlord 6y ago
    I think number of launches was used as a proxy for number of satellites launched in the last month - more satellites/launch shouldn't impact it that much.
    - mlindner 6y ago
      I think it would as the satellites would be closer together with fewer launches so as a percentage of sky the issue would be reduced.
  - greshario 6y ago
    What about when competing services launch, as they will if this is successful? What are the total numbers going to look like if EU, Russia, China, Japan, and India all launch starlink services?
  - Tuna-Fish 6y ago
    > I think people quote that number too much when in reality there's likely to be under 5000 (from SpaceX at least). Why? I think it's much more likely that they either fail, or (eventually) launch every single satellite that their licenses allow. More satellites increases the proportion of the market they can address, and if they can profitably launch a satellite, they can profitably launch a second.

amackera 6y ago

Thanks for the info!

ortusdux 6y ago
Absolutely! Things will be really interesting when they can use Starships to launch batches. I've seen estimates that they could launch 600 starlink satellites at a time. They could theatrically also launch fewer, but put them all the way into their final orbit, skipping the few weeks of light pollution.
- grecy 6y ago
  > They could theatrically also launch fewer, but put them all the way into their final orbit I wonder if they might choose to do this so the sats keep more of their onboard fuel, and will be able to keep themselves in orbit a bit longer before the inevitable re-entry burn up.
  - thereisnospork 6y ago
    I'd guess it is more efficient to have them boost themselves, so that they act as an additional rocket stage. (and so not need the delta V to elevate and then de-elevate starship's orbit.)
    - colechristensen 6y ago
      There is certainly someone doing the optimization problem for the orbit insertion and fuel loads and picking the right set of tradeoffs.
      - londons_explore 6y ago
        The optimization problem also includes drag losses at the lower altitudes. And those drag losses are a lot lower keeping all the satellites inside the rocket rather than having each experience its own drag. Might be worth putting an ion drive on the f9 2nd stage for that reason...
  - Dylan16807 6y ago
    That's a tradeoff that could be made, but the onboard ion thrusters are about 5x as efficient as the rocket. They'd probably be much better off making the onboard tanks a bit larger and launching to the same low orbit.
  - trothamel 6y ago
    Re-entry is a bit of a feature, though - should a satellite be DOA, it will be in a low orbit and burn up faster.
    - gpm 6y ago
      I wonder if they could use another satellite to sweep a DOA satellite. They all start in almost identical orbits, so unlike most orbital degree cleanup plans there aren't huge relative velocities to deal with or anything... It would mean that 1 DOA satellite means bringing down 2, but that might be worth it if the DOA rate is low.
    - grecy 6y ago
      Absolutely, but for the ones that are not DOA, having more fuel on board means they can re-boot themselves for a longer time, thus staying up for longer and getting a longer service life per sat...
- m4rtink 6y ago
  Or they could do it theatrically and once in a while make the most sats possible as bright as possible for a pre announced one orbital period with good ground visibility in inhabitted areas. Would be quite a sight! :) They are getting a bit too good at reducing Starlink visibility lately so I could definitely welcome an event like that. :)
  - VortexDream 6y ago
    They could start doing shapes and messages. Throw in some colors. Maybe provide a service where you can get them to show a message of your choice.
- bruckie 6y ago
  > They could theatrically also launch fewer I'd love to see a theatrical launch. :)

cryptoz 6y ago

> Basically, the constellation's effect on the night sky is proportional to the number of launches in the last month, not the total number in orbit. For the major brightness issues sure, but they are not invisible or undetectable while in operation. Surely the effects are proportional to both the recent launches and the whole size. I think it's a bit early to dismiss the whole sky effect of multiple Starlink-style constellations in operation. Also isn't Starlink intending to do launches for the rest of time? There is always a value for the last month of launches- they'll never stop launching right? Just thinking out loud.

sneak 6y ago
There is also the (no help at the moment) fact that the more money that Starlink's parent company makes, the more likely we are to get the world's cheapest heavy lift orbital booster soon, and the more likely we are to soon have multiple large orbital telescopes that far exceed ground-based capabilities. Basically, if SpaceX makes it, we'll probably have a Starship-launched lunar observatory quite soon, in the grand scheme of things. This doesn't help the situation now, although there is so much screaming from the anti-Musk people as well as the pro-Musk people that it's hard to tell what the actual impact of the now-somewhat-albedo-mitigated starlink v.whatever satellites are. All of the coverage is breathless sky-is-falling stuff. In any case, the situation is temporary. Either SpaceX makes it and we get a far side of Luna observatory and LEO/MEO telescopes besides, or they don't and in a few years Starlink all falls down and burns.
- bruckie 6y ago
  Would cheaper/larger launch vehicles significantly change the economics of deploying space based observatories? The James Webb space telescope has cost about $10 billion, and you can afford even today's largest/most expensive launch vehicle (Delta Heavy) for a relatively small fraction of that ($350M).
  - coryrc 6y ago
    It'd be a lot cheaper if they iterated and could service the machine if needed. Waterfall is the most expensive way of doing something.

Rebelgecko 6y ago

>Basically, the constellation's effect on the night sky is proportional to the number of launches in the last month, not the total number in orbit. For what it's worth, in order for the constellation to reach steady state the number of launches in the last month will need to be proportional to the total # of orbit. So if the constellation has 42,000 satellites and the satellites last 10 years on average (IMO that's an optimistic lifespan), you need to launch around 350/month just to maintain the size of the constellation.

mlindner 6y ago
By that time they'll also have a launch vehicle capable of launching around 300 satellites in a single launch. Additionally, 42,000 was a worst case for the number needed and only if things go exceedingly well with the service. I think people quote that number too much when in reality there's likely to be under 5000 (from SpaceX at least).
- alphaoverlord 6y ago
  I think number of launches was used as a proxy for number of satellites launched in the last month - more satellites/launch shouldn't impact it that much.
  - mlindner 6y ago
    I think it would as the satellites would be closer together with fewer launches so as a percentage of sky the issue would be reduced.
- greshario 6y ago
  What about when competing services launch, as they will if this is successful? What are the total numbers going to look like if EU, Russia, China, Japan, and India all launch starlink services?
- Tuna-Fish 6y ago
  > I think people quote that number too much when in reality there's likely to be under 5000 (from SpaceX at least). Why? I think it's much more likely that they either fail, or (eventually) launch every single satellite that their licenses allow. More satellites increases the proportion of the market they can address, and if they can profitably launch a satellite, they can profitably launch a second.