4 ms·

It's nice, but remember that Russia launches from 45N, so it isn't that critical. The boost is 880mph for KSC, vs. 790mph for Denver vs. 710 mph for Baikonur. T

by dalke 11y ago

It's nice, but remember that Russia launches from 45N, so it isn't that critical. The boost is 880mph for KSC, vs. 790mph for Denver vs. 710 mph for Baikonur. The deltas are only 100-200 mph, vs. the 17,500 mph needed for orbit. The worst case is Israel, which for geographic and geopolitical reasons has to launch to the west instead of east. Even that's only about a 30% penalty in payload. https://en.wikipedia.org/wiki/Israel_Space_Agency#Palmachim_Spaceport https://en.wikipedia.org/wiki/Israel_Space_Agency#Palmachim_...

brownbat 11y ago
And is this counteracted at all by the mile head-start out of the gravity well? Also, for spent stages, the population density of Kansas isn't that much higher than the Atlantic, they're basically identical after rounding. /s
- dalke 11y ago
  No, not really. It's only 1/250th of the way up, and the hard part is to go sideways real fast, not up. https://what-if.xkcd.com/58/ https://what-if.xkcd.com/58/ . The lawsuits are $0, after rounding to the nearest trillion.
  - brownbat 11y ago
    > The lawsuits are $0, after rounding to the nearest trillion. Exactly so! Wait, you caught the sarcasm tag right?
    - dalke 11y ago
      Yes, I did. It was marred, however, by the image of my Kansas relatives being killed by falling rocket debris.
      - brownbat 11y ago
        As a Kansan myself, I like to think most of my relatives can handle a modicum of dark humor.
        dalke 11y ago
        Ahh, but I am not a Kansan.
mikeash 11y ago
It depends on what orbit you're trying to reach. Looking at the raw speed needed doesn't tell the whole story, because now that the space race is over and most launches actually try to do something besides set a record, you can't just launch into whatever orbit is convenient. If you're going for something highly inclined then it doesn't matter at all. Launching to the ISS from Baikonur is no more costly than launching to the ISS from Canaveral or Guiana. Launching into a high equatorial orbit, like for a comsat, is far more costly because you can't naturally achieve an inclination lower than the latitude of the launch site, so you need an expensive plane change. If you wanted to launch into a low equatorial orbit for some reason then it would be even worse, and the high-latitude launch sites would become impractical. And actually, Israel is far from the worst case. The worst case would be something like launching into an equatorial orbit from a site at one of the poles. This would require something like 25-30% more delta-v, which because of the rocket equation means vastly more rocket for the same payload. But for a polar orbit, launching from the poles would be fine, actually very slightly better than an equatorial launch site because you wouldn't have to cancel out the speed you get from the Earth's rotation.
- dalke 11y ago
  You make valid objections to my objections of the simplified model of the g'parent poster. We were indeed only talking about putting something into orbit, not putting something into useful orbit. That said, I pointed out that Israel has geographical and geopolitical difficulties, which force them to launch to the west rather than east. Would it be harder for Israel to place something in GEO from Palmachim, which must first travel west over the Mediterranean before going east, or for Sweden to place something in GEO from Esrange, which requires a plane change? (I'm trying to be somewhat realistic. I think Esrange is the most poleward launch facility, though they only do suborbital. Otherwise, consider a possible Norwegian launch facility on Svalbard.)
  - mikeash 11y ago
    Thinking about it more, once you get to the point where a bi-elliptic transfer is the most efficient way to do a plane change, the launch site doesn't make a lot of difference. That's basically Baikonur and up, counting Israel as effectively having a ~150-degree latitude. Anyway, the penalties can be pretty big, but they're often tolerable. For GEO you want minimal latitude, for others latitude may not matter at all. But other considerations (like Israel having land to the east) can easily override the penalties. For the particular example discussed here, if you could ignore the problems with squishing people and buildings downrange, Colorado would make a decent launch site. KSC's latitude is better, but it wouldn't be a huge deal. You'd even get at least a little bit of it back because you'd be launching from higher altitude.

by dalke 11y ago

brownbat 11y ago

And is this counteracted at all by the mile head-start out of the gravity well? Also, for spent stages, the population density of Kansas isn't that much higher than the Atlantic, they're basically identical after rounding. /s

dalke 11y ago
No, not really. It's only 1/250th of the way up, and the hard part is to go sideways real fast, not up. https://what-if.xkcd.com/58/ https://what-if.xkcd.com/58/ . The lawsuits are $0, after rounding to the nearest trillion.
- brownbat 11y ago
  > The lawsuits are $0, after rounding to the nearest trillion. Exactly so! Wait, you caught the sarcasm tag right?
  - dalke 11y ago
    Yes, I did. It was marred, however, by the image of my Kansas relatives being killed by falling rocket debris.
    - brownbat 11y ago
      As a Kansan myself, I like to think most of my relatives can handle a modicum of dark humor.
      - dalke 11y ago
        Ahh, but I am not a Kansan.

mikeash 11y ago

It depends on what orbit you're trying to reach. Looking at the raw speed needed doesn't tell the whole story, because now that the space race is over and most launches actually try to do something besides set a record, you can't just launch into whatever orbit is convenient. If you're going for something highly inclined then it doesn't matter at all. Launching to the ISS from Baikonur is no more costly than launching to the ISS from Canaveral or Guiana. Launching into a high equatorial orbit, like for a comsat, is far more costly because you can't naturally achieve an inclination lower than the latitude of the launch site, so you need an expensive plane change. If you wanted to launch into a low equatorial orbit for some reason then it would be even worse, and the high-latitude launch sites would become impractical. And actually, Israel is far from the worst case. The worst case would be something like launching into an equatorial orbit from a site at one of the poles. This would require something like 25-30% more delta-v, which because of the rocket equation means vastly more rocket for the same payload. But for a polar orbit, launching from the poles would be fine, actually very slightly better than an equatorial launch site because you wouldn't have to cancel out the speed you get from the Earth's rotation.

dalke 11y ago
You make valid objections to my objections of the simplified model of the g'parent poster. We were indeed only talking about putting something into orbit, not putting something into useful orbit. That said, I pointed out that Israel has geographical and geopolitical difficulties, which force them to launch to the west rather than east. Would it be harder for Israel to place something in GEO from Palmachim, which must first travel west over the Mediterranean before going east, or for Sweden to place something in GEO from Esrange, which requires a plane change? (I'm trying to be somewhat realistic. I think Esrange is the most poleward launch facility, though they only do suborbital. Otherwise, consider a possible Norwegian launch facility on Svalbard.)
- mikeash 11y ago
  Thinking about it more, once you get to the point where a bi-elliptic transfer is the most efficient way to do a plane change, the launch site doesn't make a lot of difference. That's basically Baikonur and up, counting Israel as effectively having a ~150-degree latitude. Anyway, the penalties can be pretty big, but they're often tolerable. For GEO you want minimal latitude, for others latitude may not matter at all. But other considerations (like Israel having land to the east) can easily override the penalties. For the particular example discussed here, if you could ignore the problems with squishing people and buildings downrange, Colorado would make a decent launch site. KSC's latitude is better, but it wouldn't be a huge deal. You'd even get at least a little bit of it back because you'd be launching from higher altitude.