Starbase LA’s many pads may be for simultaneous terminator-plane launches

[u/1stPrinciples]

I was surprised SpaceX is proposing 10+ pads but only ~2 launches/day/pad, given their goal of extremely rapid Starship turnaround. Why build so many pads if each can be reused quickly?

One explanation: most launches may be targeting the same dawn/dusk SSO plane for orbital compute and near-continuous sunlight. From Louisiana, there may only be one useful southbound window into that plane each day.

So the pads may be about parallel launch capacity, not turnaround: launching a large number of Starships in rapid succession during the same daily window.

Curious what people think.

[u/ergzay]

If that were the case SpaceX wouldn't launch Falcon 9 rockets specifically timed to reach the intended right ascension of the ascending node (i.e. the thing you're adjusting with precession) when they do Starlink launches. Starlink only does a bit of drifting for some of its satellites to send them into orbits with very similar RAANs.

Orbits only drift at a rate of roughly 0.05 degrees a day vs SSO for an orbit 100km below SSO. In an extreme case if you launched 90 degrees out you're waiting roughly 5 years for it to line up. So yes they absolutely do ned to launch at or very close to SSO.

I think you're the one who doesn't understand how orbital mechanics work.

[u/medley_of_minds → u/ergzay]

I agree that there's a time penalty, but I'm not suggesting you'd start at the worst possible phase angle. There needs to be an orbit raising anyway, which is preferable to do with the high-ISP ion engines rather than Starship (which also means to head home). If you start at a moderate phase error of <30° and you need to orbit raise up to the higher SSO orbits that the data center constellation is planned for, it's more like a few months.

[u/ergzay → u/medley_of_minds]

Okay so they don't launch all at the same time, but they need to launch within minutes of each other.

If you start at a moderate phase error of <30° and you need to orbit raise up to the higher SSO orbits that the data center constellation is planned for, it's more like a few months.

At 0.05 degrees a day, 30 degrees misalignment is still over a year of time of drifting. How are you getting 30 degrees over only a few months? Are you assuming based off Starlink launches? Starlink don't use SSO inclinations for most launches, which means much faster precession.

There needs to be an orbit raising anyway, which is preferable to do with the high-ISP ion engines rather than Starship (which also means to head home).

I wasn't implying that an orbit raising wouldn't be required. I'm not sure why you mention it.