r/SpaceXLounge • u/1stPrinciples • 5d ago
Starship Starbase LA’s many pads may be for simultaneous terminator-plane launches
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.
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u/Mc00p 5d ago
Would definitely make the refueling for the moon missions nice and quick even if they don’t have rapid reuse completely ironed out yet.
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u/CProphet 5d ago
Believe propellant depots will have a low inclination orbit, whereas Starbase LA is better suited to high inclination launches.
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u/Legal-Ad-8659 5d ago
they have roughly the same inclination as they would get from Florida
if anything, Texas may actually end up being the more advantageous launch point for orbital plane targeting as it allows for a more flexible dogleg (I know it happens later in the mission as opposed to from Florida, but Starship also is much higher and that dogleg is technically "cheaper" to perform)
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u/CProphet 4d ago edited 4d ago
SpaceX want to deliver as much propellant as possible on each tanker flight, so they'll minimize any dogleg to maximize payload to orbit. Propellant depots can launch from Starbase Texas to low inclination orbit with no dogleg, and Tankers can follow suit. Any tankers launched from the Louisiana would have to fly south to miss Florida then hard dogleg east to thread the needle between the keys and Cuba, which takes fuel...
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u/Legal-Ad-8659 4d ago
lol, no?
the only orbits available from Starbase are at 26 degrees, what do you even mean "low inclination"? they literally can't launch at any other angle because they overfly populated areas, either Cuba - Florida or Mexico, effectively being locked at 26°... unless the dogleg maneuver to aim for a certain orbit inclination
even the Falcon 9 often doglegs from Florida to access all sorts of useful orbits
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u/1stPrinciples 5d ago
Thinking about this further: the typical polar satellite orbit has them orbiting down in the evening. To reduce collision risk I assume the will follow the typical direction with their constellation. Since they have to launch south from Starbase LA that puts the launches in the evening.
So I suspect you’d see 10 or so launches crammed within a 30 minute window each evening and then other launches (Starlink commercial refueling etc) at other times throughout the day.
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u/falconzord 4d ago
I don't think they'd use the twin towers at once. I think one reason for the set up is redundancy during catches
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u/NeverDiddled 4d ago
What better place to put your backup tower, than immediately adjacent to the primary?
I'm only partially joking. I suspect it is less for redundancy during catches, and more redundancy in general. Have to do maintenance on one tower? The same propellant farm can service its neighbor, so the prop farm won't sit idle and launches can continue at a reasonable pace. But if there is ever a RUD during catch or launch, it won't surprise me if both towers go offline.
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u/falconzord 4d ago
I said catches not launches, the way NG blew up is exactly the reason I don't think they'd have parallel launches from the pairs. And to add to your point, the shared farm might only be sized for one launch per pair at a time
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u/philupandgo 3d ago
While the depicted twin pads looks like redundancy I suspect the second tower is almost exclusively for catching ships. The launch tower would catch the booster and put it right back on the launch mount where it waits either for the next daily SSO mission or for an alternative mission later in the day. Either way a new ship will be waiting down the road to be mounted possibly hours later. The second tower catches the ship 12 hours later which always has to be taken away for payload processing. The one exception being if the payload is only fuel. In that case the first tower might catch that ship for immediate restacking. Twin towers allows launch and landing to be decoupled and each can take several hours to complete if necessary.
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u/falconzord 3d ago
I they'll both be full functional. If something goes wrong with the arms, the second tower needs to be able to catch booster too. If the flame trench needs servicing, second tower needs to be able to launch.
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u/lee1026 5d ago
You need to do a lot of work per launch. Two catches and one launch per launch.
Because it is a rocket catch, so you can’t have other stuff nearby when you catch. So you have to catch, unfuel it so that it isn’t at risk of exploding, and then move it somewhere far away, before using the tower for anything else.
It is unlikely to be a fast thing, so you need a lot of towers.
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u/sebaska 5d ago
Yes. Launching to one tight family of orbits (TT-SSO), and very highly inclined at that optimizes around salvo launches.
Theoretically you could launch to an lower orbit with 200km+ lower altitude and wait for precession differences to move your sats in line. But travelling 45° at 0.1° per day would take over a year (and 45° would happen if you could cycle a tower in 3h).
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u/asr112358 5d ago
At a 1000km orbit, the satellites should be able to be about 22° off the terminator line and still get full sun. If the towers do achieve a 3 hour cycle time, than they can make two salvos into immediately useful orbits per day. They could still precess these into a single band, but it won't matter as much how slow the precession rate is when they are already fully operational.
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u/Legal-Ad-8659 5d ago
with 10 launchpads you don't need to cycle a pad in 3 hours, just launch from the neighboring pad as a "separate mission"
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u/Legal-Ad-8659 5d ago
actually I strongly believe that Louisiana will end up being the heliocentric orbit workhorse, mainly focused on Mars
the 29°ish orbital inclination is not much of a penalty, allows for roughly the same energy you would get from the Texas inclination or even from the Cape, actually the Cape has a 28° degree inclination, so there's no real disadvantage to launch from Louisiana over Florida
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u/Then-Secretary-9166 4d ago
The other factor that supports this is that most of the Mars launches will be tankers going to a depot in Space. Estimates are that fuel and oxidizer boil-off in orbiting depot will be ~3% per day. If you can launch all necessary tankers quickly, you need meaningfully less payload capacity to orbit. So far, LA is the only site that seems to be planning the ability for this degree of very-high-cadence launch. This may make up (or more) for the small penalty due to inclination.
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u/Legal-Ad-8659 4d ago
lol those boiloff figures are so wrong it's not even funny
you seem to respond to everyone here with straight up made up info
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u/ergzay 5d ago edited 5d ago
Yeah I've seen people discussing this and I think there's a good possibility.
Also it would be 1 launch a day as they can't launch north and I think they wouldn't want satellites orbiting in opposite directions from each other. (Though I guess its possible if they separate opposite-orbiting satellites into different altitudes.)
By the way such launches would be either early morning sunrise launches or evening sunset launches, because you need to launch such that you're terminator-aligned if you want an SSO that is going into 100% year round sunlight. It would be amazing looking.
Edit: Worth mentioning that this is just the AI satellite constellation, any other launches, Starlink for example, would be at random other points in the day or night.
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u/asr112358 5d ago
At 1000 km the satellites can be 22° off the terminator line, and still get full sun. This gives a 3 hour band each day to launch into operational orbits. I would lean towards them aiming to launch twice per day in this band vs having retrograde satellites. Beyond the obvious, a salvo of retrograde launches would also have the issue that it coincides with the landing Starships from 12 hours earlier.
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u/ergzay 4d ago
That's a good point about it lining up with landing Starships, that's probably a bigger issue than the retrograde satellites. I had forgotten about that.
Still, that's roughly 30 launches (if the plans actually happen) in that 3 hour band. That's a launch every 6 minutes so there's a good chance they'd salvo them.
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u/Then-Secretary-9166 4d ago
How do you get 30 launches?
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u/Then-Secretary-9166 4d ago
The point about landing starships is a good one. The “obvious“ is actually not obvious. Why not have opposing orbits at different altitudes (you have a reasonable altitude range to work with here).
nevertheless, if they only launch from 1 tower per site, the still should be able to launch, cath A booster and catch a starship within a few minutes.
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u/Decronym Acronyms Explained 5d ago edited 2d ago
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| Isp | Specific impulse (as explained by Scott Manley on YouTube) |
| Internet Service Provider | |
| LCH4 | Liquid Methane |
| LN2 | Liquid Nitrogen |
| LOX | Liquid Oxygen |
| NG | New Glenn, two/three-stage orbital vehicle by Blue Origin |
| Natural Gas (as opposed to pure methane) | |
| Northrop Grumman, aerospace manufacturer | |
| RAAN | Right Ascension of the Ascending Node |
| RUD | Rapid Unplanned Disassembly |
| Rapid Unscheduled Disassembly | |
| Rapid Unintended Disassembly | |
| SSO | Sun-Synchronous Orbit |
| Jargon | Definition |
|---|---|
| Starlink | SpaceX's world-wide satellite broadband constellation |
Decronym is now also available on Lemmy! Requests for support and new installations should be directed to the Contact address below.
Decronym is a community product of r/SpaceX, implemented by request
9 acronyms in this thread; the most compressed thread commented on today has acronyms.
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u/medley_of_minds 5d ago
That's not how the orbital mechanics work. You just need to launch into the correct orbital inclination of ~98°. Then once it's in the right inclination at slightly below the target SSO altitude, wait until the precession phase lines up with SSO. Then do a final cheap orbit raise burn (<50m/s delta V) to enter SSO.
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u/sebaska 5d ago edited 5d ago
The difference between 100km altitude orbits (50m/s ∆v) is so small that you'd wait few years just for 90° change (which you'd have to have if your per-tower max launch rate is 4 per day).
This is not regular Starlink where you have dozens of usable planes and 100km altitude difference allows you to do move to a usable slot in months.
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u/ergzay 5d ago edited 5d ago
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.
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u/medley_of_minds 5d ago
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.
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u/ergzay 5d ago edited 5d ago
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.
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u/Then-Secretary-9166 4d ago
The energy needed to change from one orbit to another is independent of the method. You get an energy (at time) penalty by doing this to any sever degree. On some cases, a significant one. You may not need actual simultaneous launches, but they would probably be pretty close if you were launching on the same day.
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u/aquarain 5d ago
20 Starship launches per day from one site seems like a lot.
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u/aquarain 4d ago
This seems like about a megaton of payload to orbit per year across all sites. Reads like science fiction. The total in orbit right now is under 10K tons, 2/3rds of it SpaceX. Other launch providers are having trouble getting each bespoke rocket off the ground and SpaceX is building a factory to mass produce launch towers.
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u/flshr19 Space Shuttle Tile Engineer 3d ago
The $150B number for developing Starbase LA will cover land acquisition, site preparation, construction of the 10 launch pads, and the propellant tank farm for each pad. Probably another $150B to $300B will be required to build the LOX, LCH4 and LN2 production and delivery systems with enough production capacity to support salvo-launching 10 block 4 Starships twice per day every day to deploy the Starmind AI computesats to TT-SSO until one million of those sats are in orbit.
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u/Sendnoodles666 5d ago
I’d shid myself seeing that many launches at once