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While I share the community's concern for preserving the dark skies wherever possible, is it not premature considering _none_ of the 60 satellites launched have

While I share the community's concern for preserving the dark skies wherever possible, is it not premature considering _none_ of the 60 satellites launched have yet to reach their destination altitude?

gnode 7y ago
Why would this be significant? The separation altitude in the launch was around 450km, according to the numbers in the livestream. The orbital shell being targeted is 550km. This doesn't constitute a large difference in visibility.
- Robotbeat 7y ago
  Due to the inverse square law, it constitutes half an (astronomical) order of magnitude in visibility. For satellites that are already dim, that's a significant difference. ...especially when combined with proper orientation of the satellites.
- gpm 7y ago
  Since it likely also affects satellite orientation and possibly configuration. Also since brightness obeys a square law so they should ignoring effects other than distance be 1.5 times their final level still.
  - gnode 7y ago
    A factor of 1.5 doesn't strike me as being enough to suggest the problem will go away (the satellites become too small a part of images to matter). Additionally, the satellites are not two-dimensional, so there is no orientation in which they would not occlude the view. It appears that the objections are not to the size of the satellites (they are relatively small compared to other satellites in LEO), but that they are to be highly numerous. The planned size of the constellation is 11927 satellites. The frequency with which these satellites photobomb astronomical images is the concern, rather than how much area they affect. In fact, their being smaller makes them more of a menace, as they will be more challenging to spot, or easier to confuse with an astronomical entity. This said, I don't think this is a strong argument against putting such satellites in orbit, and progress will and should continue. Astronomers will have to be careful to avoid contamination.
    - w8vY7ER 7y ago
      For my part, I wouldn't put it past the minds that land orbital class, first stage rockets on the regular to come up with something that surprises us. Not suggesting that's a meaningful strategy for ensuring dark skies, just pointing out they've surprised us more than once!
bsmith 7y ago
Interesting, what is your source on that? Do they have substantial onboard fuel to boost into higher orbits at a later date? Even if they do, they are already in LEO so I'd think must be quite close to their destination orbits.
- Obi_Juan_Kenobi 7y ago
  They use Krypton-fueled Ion thrusters; they're much like Xenon thrusters, but Krypton is cheaper. Being a LEO constellation, they require propulsion to maintain their orbit. Their destination orbit is 550km, and were launched around 400km IIRC.

gnode 7y ago

Why would this be significant? The separation altitude in the launch was around 450km, according to the numbers in the livestream. The orbital shell being targeted is 550km. This doesn't constitute a large difference in visibility.

Robotbeat 7y ago
Due to the inverse square law, it constitutes half an (astronomical) order of magnitude in visibility. For satellites that are already dim, that's a significant difference. ...especially when combined with proper orientation of the satellites.
gpm 7y ago
Since it likely also affects satellite orientation and possibly configuration. Also since brightness obeys a square law so they should ignoring effects other than distance be 1.5 times their final level still.
- gnode 7y ago
  A factor of 1.5 doesn't strike me as being enough to suggest the problem will go away (the satellites become too small a part of images to matter). Additionally, the satellites are not two-dimensional, so there is no orientation in which they would not occlude the view. It appears that the objections are not to the size of the satellites (they are relatively small compared to other satellites in LEO), but that they are to be highly numerous. The planned size of the constellation is 11927 satellites. The frequency with which these satellites photobomb astronomical images is the concern, rather than how much area they affect. In fact, their being smaller makes them more of a menace, as they will be more challenging to spot, or easier to confuse with an astronomical entity. This said, I don't think this is a strong argument against putting such satellites in orbit, and progress will and should continue. Astronomers will have to be careful to avoid contamination.
  - w8vY7ER 7y ago
    For my part, I wouldn't put it past the minds that land orbital class, first stage rockets on the regular to come up with something that surprises us. Not suggesting that's a meaningful strategy for ensuring dark skies, just pointing out they've surprised us more than once!

bsmith 7y ago

Interesting, what is your source on that? Do they have substantial onboard fuel to boost into higher orbits at a later date? Even if they do, they are already in LEO so I'd think must be quite close to their destination orbits.

Obi_Juan_Kenobi 7y ago
They use Krypton-fueled Ion thrusters; they're much like Xenon thrusters, but Krypton is cheaper. Being a LEO constellation, they require propulsion to maintain their orbit. Their destination orbit is 550km, and were launched around 400km IIRC.