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Inauguration of mainland Europe's first satellite launch complex

31 points by jcfrei 4y ago

Scoundreller 4y ago
I guess with the big launches now being for LEO satellites, it’s better to optimize for lowest gravity (closest to the poles) rather than closest to the equator (closest to your destination)?
- nottorp 4y ago
  Well, the only EU territory close to the equator is French Guyana and there already is a space port there. I'm curious why Sweden and not, say, the south of Spain, Sicilly, south of Greece...
  - ccakes 4y ago
    Esrange was built back in the 60s, so I guess it makes sense to re-use infrastructure rather than build something brand new
  - Scoundreller 4y ago
    My thought was you only preferred the equator when you’re launching a geosynchronous satellite. If you’re doing Low earth orbit and your satellite it going to regularly cross Europe, it’s best to launch as close to the poles as you can because gravity is weakest there (but air is colder/thicker…)
    - T-A 4y ago
      If you are going to orbit, you need enough kinetic energy to stay in orbit along every point of the orbit. If it's a polar orbit, it covers every latitude, from north pole to equator to south pole. The real advantage of launching from a pole, if you are going to a polar orbit, is that you don't start out with a velocity component due to Earth's rotation, i.e. perpendicular to where want to go. If you do, you'll have to spend part of your fuel budget canceling out that unwanted velocity component. On the other hand, if you're going into an equatorial orbit (e.g. a geosynchronous one) you want to pick up as much of that free contribution from Earth's rotation as possible, so you pick a launch site on the equator, or as close to it as you can go. Polar and equatorial orbits are opposite edge cases. In general, your orbit will be at some angle to the equator, and the closer that angle gets to 90 degrees, the closer to a pole you'll want to go for optimal launch latitude. BTW, surface gravity is lower at the equator (9.78 m/s^2) than at the poles (9.81 m/s^2), exactly because of Earth's rotation.
  - Stevvo 4y ago
    The Mediterranean is quite small and developed along all its coastlines. Sweden is relatively barren with a massive ocean alongside, making it far safer launch site.
- rhn_mk1 4y ago
  > lowest gravity (closest to the poles) Isn't that quite the opposite? https://physics.stackexchange.com/questions/141856/why-is-earths-gravity-stronger-at-the-poles https://physics.stackexchange.com/questions/141856/why-is-ea...
  - Scoundreller 4y ago
    Yes, you’re correct, so now I have no idea why you’d site a spaceport other than on the equator.

31 points by jcfrei 4y ago

I guess with the big launches now being for LEO satellites, it’s better to optimize for lowest gravity (closest to the poles) rather than closest to the equator (closest to your destination)?

nottorp 4y ago
Well, the only EU territory close to the equator is French Guyana and there already is a space port there. I'm curious why Sweden and not, say, the south of Spain, Sicilly, south of Greece...
- ccakes 4y ago
  Esrange was built back in the 60s, so I guess it makes sense to re-use infrastructure rather than build something brand new
- Scoundreller 4y ago
  My thought was you only preferred the equator when you’re launching a geosynchronous satellite. If you’re doing Low earth orbit and your satellite it going to regularly cross Europe, it’s best to launch as close to the poles as you can because gravity is weakest there (but air is colder/thicker…)
  - T-A 4y ago
    If you are going to orbit, you need enough kinetic energy to stay in orbit along every point of the orbit. If it's a polar orbit, it covers every latitude, from north pole to equator to south pole. The real advantage of launching from a pole, if you are going to a polar orbit, is that you don't start out with a velocity component due to Earth's rotation, i.e. perpendicular to where want to go. If you do, you'll have to spend part of your fuel budget canceling out that unwanted velocity component. On the other hand, if you're going into an equatorial orbit (e.g. a geosynchronous one) you want to pick up as much of that free contribution from Earth's rotation as possible, so you pick a launch site on the equator, or as close to it as you can go. Polar and equatorial orbits are opposite edge cases. In general, your orbit will be at some angle to the equator, and the closer that angle gets to 90 degrees, the closer to a pole you'll want to go for optimal launch latitude. BTW, surface gravity is lower at the equator (9.78 m/s^2) than at the poles (9.81 m/s^2), exactly because of Earth's rotation.
- Stevvo 4y ago
  The Mediterranean is quite small and developed along all its coastlines. Sweden is relatively barren with a massive ocean alongside, making it far safer launch site.
rhn_mk1 4y ago
> lowest gravity (closest to the poles) Isn't that quite the opposite? https://physics.stackexchange.com/questions/141856/why-is-earths-gravity-stronger-at-the-poles https://physics.stackexchange.com/questions/141856/why-is-ea...
- Scoundreller 4y ago
  Yes, you’re correct, so now I have no idea why you’d site a spaceport other than on the equator.