[coenhyde]

Some more context. If I understand correctly this gas plant is need to power a desalination plant which is need to produce massive amounts of water which will be used to implement a sound suppression deluge system that is required by the FAA. Salt water will corrode everything and there isn't existing water and gas infrastructure in place to lean on. ie they have to build the stack from scratch.

[phkahler]

Or they want a gas well because super heavy and starship engines burn METHANE for fuel.

[cma]

If it is for desalination why aren't they using solar, which wouldn't even need storage in that application.

[ericcumbee]

Because you also get Methane as a by-product of natural gas production and that is the fuel for starship.

[cma]

Methane is typically the vast majority of the gas, I figured they were burning it for desalination too, but it makes sense if they are burning just the other fraction.

[wolverine876]

Perhaps there's a more efficient place to build the facility, perhaps someplace with abundant water so that you don't have to spend all this energy to create it?

[gpm]

I don't think there is.

You need water to your east (because you can't fly over people for safety reasons), for a really long way. As in launches from texas have to dodge Florida, Cuba and all the other islands over there.

You need very low population density (because rocket launches and landings require large exclusion zones).

You need to be in the US, because of export restrictions.

You want to be as far south as possible, for efficiency reasons (to get as much kinetic energy from the earths rotation as possible).

You are looking at this launch site, attempting to acquire a lot of land on Florida's coast (not really feasible anymore, it's all occupied), or launching from tiny islands/ocean platforms which will have the exact same fresh water issues.

[sbierwagen]

>You want to be as far south as possible, for efficiency reasons

It is absolutely true that a rocket launched at the equator gets the biggest boost from the Earth's rotation, but stuff isn't put into orbit just for fun, it's often because you want it pass over a specified part of the Earth's surface. To pass over CONUS you need some inclination, and the more inclined an orbit is the less assist you get from the planet's rotation. A polar orbit (inclination 90 degrees) has no assist, and a sun-synchronous orbit is slightly retrograde, where you then want to launch as far north as possible, so you don't have to cancel out as much rotation velocity!

The Soviets put their launch site at 45.9 degrees north not because they're bizarrely stupid, but because they'd like their orbits to pass over Russia. Similarly, no Starlink satellite has had an inclination lower than 42 degrees: https://en.wikipedia.org/wiki/Starlink#Constellation_design_...

Going forward, depending on how much interplanetary traffic there will be, you can imagine Guiana Space Centre (Which is currently hosting JWST, destined for a Lagrange point) will see more traffic, but right now almost everything has some amount of inclination.

[gpm]

For normal moderately inclined orbits the boost is still greatest at the equator, just always less than for non inclined orbits (until you start launching retrograde).

The soviet launch site was indeed chosen for other reasons than maximizing payload... in particular I think I recall that it was largely motivated by avoiding launching over China, and being in an empty enough part of the world that it's unlikely to kill to many people (despite launching over land).

[bell-cot]

> or launching from tiny islands/ocean platforms which will have the exact same fresh water issues.

If launching from an ocean platform, then fresh water seems pretty easy to bring in via tanker. That's less workable at Boca Chica, or on most tiny islands - where ports for decent-sized tankers are scarce.

[wolverine876]

Thank you! Now I'm thinking of course ... Puerto Rico? I don't know how much fresh water there is, or if there's available and suitable land on the east coast. Are Georgia or South Carolina too far north?

[gpm]

Hmm, no I don't think Georgia or South Carolina are too far north, I'd be more worried that their coasts look pretty populated - and generally I'd expect that to be doubly the case around river mouths.

To put some numbers on the "north"ness.

Boca chica is at 26 degrees north, which gives you 416 m/s free velocity (1500 km/h) [1]. The southernmost point of Georgia's coast is at 30 degrees or 401 m/s, the southernmost point of South Carolina's coast is at 32 degrees or 393 m/s.

Actually calculating payload to orbit is more work that I don't really want to do, but you can find someone else who put in the work on this stack overflow question [2], just for different latitudes and a different rocket. 28 to 30 degrees is roughly a .3% change in payload capacity in their model.

You're definitely not the first to suggest Peurto Rico, but I think you have the same problem of there not being enough empty land [3].

[1] https://www.google.com/search?q=%28%282+*+pi+*+6378.14+km+%2...

[2] https://space.stackexchange.com/questions/998/how-much-of-an...

[3] https://www.quora.com/Why-don-t-we-build-a-rocket-launch-sit...

[ep_jhu]

The Puerto Rico Ports Authority is actually currently evaluating proposals received in response to an RFI for developing a spaceport in the site of the old Roosevelt Roads US Naval Air Base in Ceiba, on the eastern tip of the island.

https://newsismybusiness.com/11-firms-interested-in-developi...

[justahuman74]

Because the rocket is so huge, they need to build it either next to a waterway for barge transport, or right next to the launch pad which has to be on the coast

[wolverine876]

Thanks. Next question: Inland waterways are fresh water, and generally they carry the largest volume of water near the coast, so why not build next to a river?

[speedybird]

I guess you're alluding to KSC or Cape Canaveral? As far as I know they pipe their water in from a neighboring town. Do they actually have enough fresh water to support the launch cadence SpaceX is planning for?