Author Topic: Starship Ocean Platform; Advantages and Difficulties  (Read 34220 times)

Offline DistantTemple

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #40 on: 01/04/2021 10:25 am »
Has Sea Launch (the company) already been raked over in this forum?

They launched rockets and caught helicopters back in the day. Not that SpaceX should buy this old hulk--but it is an existence proof of ??? something similar.

https://www.spaceflightinsider.com/space-flight-news/sea-launch-reduces-staff-due-lull-launches/
Yes, extensively. Well documented: https://forum.nasaspaceflight.com/index.php?topic=34112.280#lastPost etc

Its not considered a hulk by its proud new guardians, and looks quite pristine on a walk-through video.
« Last Edit: 01/04/2021 10:27 am by DistantTemple »
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Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #41 on: 01/04/2021 11:16 am »
I remember this being discussed some years back, but it's hard to search for:

What are the tradeoffs for building a causeway out to an ocean platform?

You gain the convenience of road access for spacecraft and equipment, and can run all power, coms, lox/ch4 pipes alongside, out of the water. The only downside I can see is cost (both capital and ongoing maintenance).
Unless there are very expensive high bridges (overpasses? I'm not sure of the word) to allow ship traffic there will be some mighty frakked people out there. Not a deal killer but the expense has to be part of the equation.


We can only guess what launch tempo would justify this.
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Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #42 on: 01/04/2021 11:32 am »
They could in principle just do the LOx recovery at the launch site (as well as LN2). If they run a power line.
That brings up another issue with platforms. Power. A cable can be run. That's not only big time expensive but can be damaged by drag netting. There's a lot of shrimping down that way. And underwater telecom cables have a lot of loss. Can't see power being much different.
...
Offshore wind turbines run power cables just fine.
The whole point of an offshore wind farm is the cable. It has to be there. Cable installation and maintenance costs are part of the business case. The case for a launch platform doesn't have to include a cable although that can be a factor in choice of location. Wasn't saying it couldn't be done but think that alternatives are a consideration.
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Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #43 on: 01/04/2021 11:32 am »
The only downside I can see is cost (both capital and ongoing maintenance).
And pissing off everyone else wanting to use the waterway you've just dragged an effective wall across. For Boca Chica as an example, anyone wanting to head south from Brownsville or South Padre Island would need to detour around your however-many-miles-long pier.

Plus there's hurricanes. The Mulberries at Omaha & Arromanches only survived with the aid of large additional breakwaters, and even they had trouble in the relatively mild summertime Channel environment. If you want to put something out at sea, it either needs to be extraordinarily sturdy, or it won't be there for long.

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #44 on: 01/04/2021 04:41 pm »
Having been on a submarine launching a couple SLBM’s I can say they are quite loud even a hundred + feet under water.

Elon mentioned no legs on SH, maybe caught with a derrick while hovering next to the platform. No need barge or transfer crane. I suggested this in jest many years ago on Selenian Boondocks

Hrm, Saipem 7000 is getting a little long in the tooth, wonder if she's coming up for sale...
Whoo, that is one impressive piece of hardware. [size=78%]https://en.m.wikipedia.org/wiki/Saipem_7000[/size]


And it can lay pipe up to 24".

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Offline Bananas_on_Mars

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #45 on: 01/04/2021 06:15 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Offline Asteroza

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #46 on: 01/05/2021 06:46 am »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...

Offline Bananas_on_Mars

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Starship Ocean Platform; Advantages and Difficulties
« Reply #47 on: 01/05/2021 05:21 pm »
Someone at another site concern-trolled the idea of “marine noise pollution.” Assuming the exhaust goes straight into the water, offshore SH launches would inject enormous amounts of acoustic energy into the ocean, on a regular schedule.

Not sure what to think about that.

Curtain wall bubbles was what I heard suggested.

A ring of seabed emplaced pipes/valves/nozzles that can inject large quantities of air into the seawater. They start doing this just before ignition, with sufficient time for the bubbles to rise to the surface from the seafloor. Tne nozzles are close enough together that there is little or no pure water between bubbles

This supposedly forms a curtain wall that will attenuate soundwaves a lot.

I can't remember where I heard this or whether it's ever been done at this scale. It would take a LOT of compressed air, that's for sure!

OK NVM:
This came up in another thread some time ago and bubble curtains look like something that may work.
https://canadianpond.ca/air-bubble-curtains-bubble-tubing/?gclid=Cj0KCQiAoab_BRCxARIsANMx4S69fEEKqsHe-TrqYN1TYomIJXgiVHAZoXrtWGmVJO3suaPcEW57lTkaAht0EALw_wcB

Ninja'ed again :)
Also have a look at the Prairie-Masker System on warships.

https://en.wikipedia.org/wiki/Prairie-Masker

Bubble curtains attenuate sound by making water somewhat „compressible“. It doesn’t have to be a continuous wall of gas. I think it might be advantageous to have multiple rings.

The other objection i have is that they might build a platform with a flame diverter so that the exhaust gases are redirected parallel to the surface. And they can use huge amounts of sea water to take energy out of the exhaust gases.

Problem with a bubble curtain is that it makes the local water less able to support a floating ship due to change in density. There are suspicions that sudden gas boiloffs have led to unexplained sinkings, though that is at a larger scale than just one bubble curtain...
You‘re not putting the bubble curtain directly under the platform, but with some horizontal separation.

And bubbles are not necessarily a problem. It becomes a problem if the average density under the ship is so reduced that the ship isn’t buoyant any more. A bubble curtain can‘t do that. Huge gas releases of methane or so can do that. It‘s been one of the proposed explanations for the bermuda triangle (though AFAIK there‘s no statistical increase of ships disappearing in that region, and not even a clear definition of what the bermuda triangle is).

And this is why you don‘t want to drop in the bubble bath part of a wastewater treatment facility. In that bath you can‘t swim because the average density is so reduced, but you can drown there...
« Last Edit: 01/05/2021 05:24 pm by Bananas_on_Mars »

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #48 on: 01/05/2021 07:35 pm »
The only downside I can see is cost (both capital and ongoing maintenance).
And pissing off everyone else wanting to use the waterway you've just dragged an effective wall across. For Boca Chica as an example, anyone wanting to head south from Brownsville or South Padre Island would need to detour around your however-many-miles-long pier.

Plus there's hurricanes. The Mulberries at Omaha & Arromanches only survived with the aid of large additional breakwaters, and even they had trouble in the relatively mild summertime Channel environment. If you want to put something out at sea, it either needs to be extraordinarily sturdy, or it won't be there for long.
If memory serves, the storm that took out the British mulberry and damaged the American was unprecedented for that time of the year, which doesn't minimize the rack and ruin a hurricane can unleash. Has a semi submersable rig ever been taken out by storm?

Here's an overview of semi submersible platforms. https://en.m.wikipedia.org/wiki/Semi-submersible_platform

"The operating deck can be located high above the sea level owing to the good ship stability of the design, and therefore is kept well away from the waves."
« Last Edit: 01/05/2021 07:36 pm by OTV Booster »
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Offline Bananas_on_Mars

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #49 on: 01/05/2021 08:28 pm »
Has a semi submersable rig ever been taken out by storm?

Alexander L. Kielland, capsized in north sea, 1980

Ocean Ranger, sank in a storm, 1982

Offline Garrett

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #50 on: 01/06/2021 09:19 am »
For this discussion, I think some data on seafloor depth would be useful. As far as I can find, the seafloor has a very small slope and is still only about 50 meters deep 50 km out to sea from Boca Chica.
https://woodshole.er.usgs.gov/project-pages/mobility/images/gmex.png
https://charts.noaa.gov/PDFs/11301.pdf

Would this not make tunnels a viable option, particularly given Elon being a fan of them. Either a Boring Company tunnel, or a prefabricated tunnel laid down on the seabed (like the Transbay Tube for the BART).

Bridges are possible, but I would assume much more troublesome to build. An example that springs to mind is the Øresund Bridge, linking Denmark and Sweden:
https://en.wikipedia.org/wiki/%C3%98resund_Bridge

Also, given such small depths, why would any platform be floating, rather than directly fixed on the seafloor?

Edit: spelling
« Last Edit: 01/07/2021 12:05 pm by Garrett »
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Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #51 on: 01/06/2021 10:52 am »
Seabed-laid tunnels (or any seabed-laid infrastructure like cables or pipes) are vulnerable to damage from anchor dragging and other hazards. Boca Chica is immediately next to a major port, and large vessels anchored just offshore is a very common sight (and visible in many local photos and videos of SpaceX sites). A lot of underwater infrastructure is now buried on install in coastal regions for this reason.

Offline philw1776

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #52 on: 01/06/2021 04:40 pm »
For this discussion, I think some data on seafloor depth would be useful. As far as I can find, the seafloor has a very small slope and is still only about 50 meters deep 50 km out to sea from Boca Chica.
https://woodshole.er.usgs.gov/project-pages/mobility/images/gmex.png
https://charts.noaa.gov/PDFs/11301.pdf

Would this not make tunnels a viable option, particularly given Elon being a fan of them. Either a Boring Company tunnel, or a prefabricated tunnel laid down on the seabed (like the Tansbay Tube for the BART).

Bridges are possible, but I would assume much more troublesome to build. An example that springs to mind is the Øresund Bridge, linking Denmark and Sweden:
https://en.wikipedia.org/wiki/%C3%98resund_Bridge

Also, given such small depths, why would any platform be floating, rather than directly fixed on the seafloor?

Agree heartily. At these shallow depths fixed seafloor platforms are the simpler solution.
Long bridges block access and environmental political review would take ages and most likely fail review.
Anyone know what the feature ~12 miles offshore on the noaa chart near he Mexican ocean border labeled (2) is? 
Could is be a shallow seamount? Size?
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Offline rsdavis9

« Last Edit: 01/06/2021 05:02 pm by rsdavis9 »
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Offline Garrett

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #54 on: 01/07/2021 12:37 pm »
Just for context for this thread, Elon previously mentioned that platforms would need ~30km / 18 miles clear area for noise.
https://twitter.com/elonmusk/status/1298019842356703232?s=20

So offshore from Boca Chica that would mean a depth of 50 m max, and maybe even only 30 m.

I would feel pretty confident in betting that they will build a Boring Company tunnel (or tunnels more likely) for access to an offshore platform and also for piping propellant and transporting electricity.

At current prices and tunneling speeds, they could probably build an initial service tunnel for a few $100 million, over 2 years. Short term that is a massive waste of money, but I think in the long term it would be cost effective.
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Offline sghill

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #55 on: 01/07/2021 01:47 pm »
Don't fall for the fallacy that the Gulf Coast is a pristine marine environment, that the seafloor bed is uncluttered, or that a platform at any location or in any condition is difficult to obtain.

The Gulf may be a big place, but it has thousands of active platforms, thousands of inactive platforms, and thousands of miles of undersea servicing pipes and pipelines. 

You can literally pick your preferred spot and make an offer.

https://skytruth-org.carto.com/tables/offshore_platforms_not_removed/public

As I posted in another thread, I think the active orbital launch facilities will be right off-shore from Galveston because it has better on-shore support and transfer facilities.
« Last Edit: 01/07/2021 01:48 pm by sghill »
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Offline philw1776

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #56 on: 01/07/2021 07:00 pm »
Offshore Galveston would overfly too many crewed oil platforms. 
They would also overfly too many ships for near daily flight cadence.
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Offline sghill

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #57 on: 01/08/2021 04:11 pm »
Offshore Galveston would overfly too many crewed oil platforms. 
They would also overfly too many ships for near daily flight cadence.

I've thought about that.  If this thing is going to be a crew rated point-to-point spacecraft, it's going to need to have the reliability and corresponding FAA clearances approaching if not equal to airliners. We need to stop thinking about this spacecraft in terms of one-off launches.

Daily launches means daily refueling, passenger processing, and cargo operations; as well as the means, reliability, and clearances to fly over stuff.

First Principles tell us it can't be so remote as to preclude the former in order to accommodate an absence of the later. The business case (daily or hourly flights) won't support it.

Besides, there is a HUGE empty space southeast of Galveston where there is nothing for hundreds of miles before you get to the next line of platforms (which are not anywhere near each other for the most part even though the map makes it look like they are). Perfect for a launch area.
« Last Edit: 01/08/2021 04:24 pm by sghill »
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Offline edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #58 on: 01/08/2021 04:26 pm »
And what inclinations can you actually launch to from Galveston without one hell of a dogleg?

Offline danneely

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #59 on: 01/08/2021 05:08 pm »
And what inclinations can you actually launch to from Galveston without one hell of a dogleg?

Not sure what inclinations they'd correspond to, but this is roughly the allowable launch vectors.  The black lines show the gap between Mexico and Cuba, the red line appears to thread its way between all the islands.  The orange lines overfly the Bahamas and the Dominican Republic; if it's going fast enough at that point to safely overfly populated areas is more than I can say, it's farther downrange than Cuba in the dogleg SSO corridor from the Cape; but I'm not sure what the relative population densities are (and those matter as much as how fast it's going for the risk assessment).

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