Author Topic: Starship Ocean Platform; Advantages and Difficulties  (Read 34457 times)

Online steveleach

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #20 on: 12/29/2020 12:38 pm »
People are talking about the environmental issues being potentially no less for sea launch, but I got the impression from Elon's tweets that the primary reason for it was to move the noise away from population centres.

Online DigitalMan

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #21 on: 12/29/2020 04:31 pm »
That sounds like a great reason to me, particularly if the environmental issues are manageable.

Online edzieba

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #22 on: 12/29/2020 05:41 pm »
The benefit of off-shore operations (nearly nobody and nothing around you) is also the biggest hassle.
As we've seen at Boca Chica, operations can be conducted with almost entirely off the shelf equipment. Buy some tanks, truck them in, mount them on concrete. Fill the tanks? Truck the propellant in, commercial suppliers will drive to your door. Need to lift your spaceship? Rent a crane. Crane needs to be bigger? Stop renting it, rent a bigger one. Etc. Startup cost is extraordinarily low, ongoing costs only on-go while you're actually doing something.

Offshore, you need to bring everything you need with you. Tanks? Need ones that don't rust while being blasted with salt water. Not available off the shelf? Whoops, better design bespoke ones ($$$ + lead time) or purchase an LNG tanker. Whaddaya mean nobody builds LOX tanker vessels?! Ugh, more lead-time! Need a crane? Whoops, either build a custom one that can survive being left on the pad next to the rocket, or hire one of the vanishingly few sea-lift cranes with sufficient height (if any exist). Whaddaya mean there's only one it's pre-booked for the next few years! etc.

It's not just the rig(s) themselves that form a big up-front paywall before you can actually start operations, it's all the ancillary infrastructure, equipment and commodities that aren't off the shelf or available for cheap and short notice rental that needs to be bought and paid for up-front and well in advance.

We will probably see a larger drone-ship for down-range landings during testing so they can fly non-RTLS profiles. But it will almost certainly be 'just' a barge that gets hauled back to land for any further operations like the existing ASDSes. Doing any processing - much less actually launching - from off-shore is a whole different ballgame. With the pace SpaceX likes to iterate at, and how averse they are to being locked into a bad design (e.g. CF), I can't see them locking themselves into the large costs and lead-times for a Minimum Viable Product off-shore launch platform until they have been operating Starship & Superheavy for long enough to iron the bugs out.

Online goretexguy

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #23 on: 12/29/2020 06:18 pm »
I can't see them locking themselves into the large costs and lead-times for a Minimum Viable Product off-shore launch platform until they have been operating Starship & Superheavy for long enough to iron the bugs out.

...buuut, when they do get things worked out, SpaceX has a demonstrable tendency to establish a manufacturing process to cheaply make bespoke items. This tendency may extend to offshore launch/landing platforms as seen in the point-to-point Starship video.

So, while I heartily agree that SpaceX will avoid substantial seagoing facilities for as long as possible, at some point they will reach an inflection point in operations which requires them to produce these Off-Shore Launch And Landing Platforms (OSLAPs, or 'oh-slaps', you heard it here first) in significant numbers. If SpaceX is to go to Mars in the numbers that Musk envisions, I don't see any way to achieve these launches without numerous OSLAPs around the world.


Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #24 on: 12/30/2020 05:55 pm »
The benefit of off-shore operations (nearly nobody and nothing around you) is also the biggest hassle.
As we've seen at Boca Chica, operations can be conducted with almost entirely off the shelf equipment. Buy some tanks, truck them in, mount them on concrete. Fill the tanks? Truck the propellant in, commercial suppliers will drive to your door. Need to lift your spaceship? Rent a crane. Crane needs to be bigger? Stop renting it, rent a bigger one. Etc. Startup cost is extraordinarily low, ongoing costs only on-go while you're actually doing something.

Offshore, you need to bring everything you need with you. Tanks? Need ones that don't rust while being blasted with salt water. Not available off the shelf? Whoops, better design bespoke ones ($$$ + lead time) or purchase an LNG tanker. Whaddaya mean nobody builds LOX tanker vessels?! Ugh, more lead-time! Need a crane? Whoops, either build a custom one that can survive being left on the pad next to the rocket, or hire one of the vanishingly few sea-lift cranes with sufficient height (if any exist). Whaddaya mean there's only one it's pre-booked for the next few years! etc.

It's not just the rig(s) themselves that form a big up-front paywall before you can actually start operations, it's all the ancillary infrastructure, equipment and commodities that aren't off the shelf or available for cheap and short notice rental that needs to be bought and paid for up-front and well in advance.

We will probably see a larger drone-ship for down-range landings during testing so they can fly non-RTLS profiles. But it will almost certainly be 'just' a barge that gets hauled back to land for any further operations like the existing ASDSes. Doing any processing - much less actually launching - from off-shore is a whole different ballgame. With the pace SpaceX likes to iterate at, and how averse they are to being locked into a bad design (e.g. CF), I can't see them locking themselves into the large costs and lead-times for a Minimum Viable Product off-shore launch platform until they have been operating Starship & Superheavy for long enough to iron the bugs out.
You paint a dismal picture. Agreed, moving ops off shore is expensive. It seems necessary if P2P becomes a reality (long term projection). It might be forced on SX for environmental and safety reasons (short or medium projection).


There is truth in many of the specifics you point out but some are a bit overblown. At BC SX is building a rocket, building a launch facility and building a manufacturing facility, while figuring out what they need on the fly. Only the launch/landing would move off shore and then it would carry some legacy with it. The longer it's put off, the more developed that legacy.


Starting with landing only, is a beginning where they already have F9 experience. That beautiful swan dive and acrobat flip of SN8 started with a stainless steel plate water tower. If he has to, Elon has the talent to finesse a landing barge into an entire off shore infrastructure at a price point that will drive captains of industry to babbling envy.


Ten years ago who would have thought that the cost of an off shore launch/landing facility would be seen as major issue in a return to the moon or HSF to Mars?
We are on the cusp of revolutionary access to space. One hallmark of a revolution is that there is a disjuncture through which projections do not work. The thread must be picked up anew and the tapestry of history woven with a fresh pattern.

Offline Surfdaddy

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #25 on: 12/31/2020 03:33 am »
Does/will Starship used densified propellants? If so, how does the need to manage huge quantities of propellant affect potential offshore launches?
« Last Edit: 12/31/2020 03:33 am by Surfdaddy »

Offline Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #26 on: 12/31/2020 03:40 am »
Does/will Starship used densified propellants? If so, how does the need to manage huge quantities of propellant affect potential offshore launches?
yes.
the liquid  nitrogen required for subchill is made at the same time as the liquid  oxygen.
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Offline Vanspace

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #27 on: 01/01/2021 04:59 am »
Does/will Starship used densified propellants? If so, how does the need to manage huge quantities of propellant affect potential offshore launches?
yes.
the liquid  nitrogen required for subchill is made at the same time as the liquid  oxygen.

And the boil off can power the bubble curtain.

To be fair, the 5000 tons of propellant Starship uses is not considered a very large amount by marine transport standards. The average LNG tanker carries around 75,000 tons with the big ones around 150K tons.
"p can not equal zero" is the only scientific Truth. I could be wrong (p<0.05)

Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #28 on: 01/03/2021 02:48 am »
Does/will Starship used densified propellants? If so, how does the need to manage huge quantities of propellant affect potential offshore launches?
yes.
the liquid  nitrogen required for subchill is made at the same time as the liquid  oxygen.

And the boil off can power the bubble curtain.

To be fair, the 5000 tons of propellant Starship uses is not considered a very large amount by marine transport standards. The average LNG tanker carries around 75,000 tons with the big ones around 150K tons.
I hope you're talking about LN2 boiloff and not CH4.


I've got a picture in my head of a group of launch platforms, each with small top off GSE tanks and serviced by two of the older and smaller LNG tankers, one converted to LOX to do servicing runs.


Refueling a fleet of mars bound ships will call for ~5 tanker launches for each outbound ship. Four ships, 20 tanker launches. Eight ships, 40 launches. Do a launch, play orbital catch-up for 6 hours, transfer fuel and wait for reentry alignment ~12 hours after launch. One turnaround per day per tanker, SH and pad if everything goes perfect. This assumes an ideal of truly minimal servicing needs. One platform just wouldn't be adequate.


What would be needed to convert an LNG tanker to LOX?

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Offline Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #29 on: 01/03/2021 04:01 am »
They could in principle just do the LOx recovery at the launch site (as well as LN2). If they run a power line.
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Offline OTV Booster

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #30 on: 01/03/2021 07:05 pm »
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.


Alternatives I come up with are wind, solar, tidal and thermal differential. Somehow big wind turbines and rocket exhaust don't seem to mix all that well. Hmm, maybe there is a synergy there.


Solar makes sense and and floating an array of panels both generates power and would keep peak water temps down a bit, reducing energy input to storms. Would the fish mind? Probably.


Don't know much about tidal and thermal differential. ISTM one of those platforms with a very deep draft might be an ideal place to play with this. 
« Last Edit: 01/03/2021 07:08 pm by OTV Booster »
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Online dchenevert

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #31 on: 01/03/2021 10:04 pm »
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/

Online dchenevert

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #32 on: 01/03/2021 10:08 pm »
Enough power for propellant-related chemistry? Yeah that's a lot of power.

If power is only needed to pump propellant around, and keep the cameras and radios running, wouldn't a few tons of grid-battery-storage do the job?

If a lot of power is needed...  All the cool kids are pouring their $-billions into offshore wind. Most of this is fixed-platform but 'floating-platform' is up and coming.

https://www.ge.com/renewableenergy/wind-energy/offshore-wind/haliade-x-offshore-turbine#:~:text=Introducing%20Haliade%2DX%2C%20the%20most,competitive%20source%20of%20clean%20energy.

Purports to provide "13 GWh/year", probably in a high-wind environment.

A few km of separation might be workable; and/or move the windmill or the launch platform away during launches and landings, then move it back.

Or... put the windmill on the same platform, separated by 100 meters or whatever, and lock it down during launches and landings.
« Last Edit: 01/03/2021 10:19 pm by dchenevert »

Offline CameronD

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #33 on: 01/03/2021 10:16 pm »
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.

Whether you (a) manufacture LOX/LNG on land and ship it to the platform or (b) manufacture on-platform is a simple cost equation.  Ignoring tech that doesn't practically exist, given suitably large amounts of $$$ manufacture on-platform can be achieved using off-the-shelf diesel gen-sets, but there are very high real-estate and maintenance costs to be factored in also.

Unless your platform is a really long way off-shore, ISTM it would be significantly cheaper to send all of your supplies - food, water, diesel.. (oh, and LN2, LOX, LNG, Helium, Welding gases also) out on a supply ship every launch or so.
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline clongton

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #34 on: 01/03/2021 10:24 pm »
Unless your platform is a really long way off-shore, ISTM it would be significantly cheaper to send all of your supplies - food, water, diesel.. (oh, and LN2, LOX, LNG, Helium, Welding gases also) out on a supply ship every launch or so.

If this launch facility is to be there long term, it would be worth the expense to run piping along the sea bed for the propellants and other liquid necessities, fed from a shore facility.
« Last Edit: 01/03/2021 10:25 pm by clongton »
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Offline CameronD

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #35 on: 01/03/2021 11:28 pm »
Unless your platform is a really long way off-shore, ISTM it would be significantly cheaper to send all of your supplies - food, water, diesel.. (oh, and LN2, LOX, LNG, Helium, Welding gases also) out on a supply ship every launch or so.

If this launch facility is to be there long term, it would be worth the expense to run piping along the sea bed for the propellants and other liquid necessities, fed from a shore facility.

Maybe.  Remember, undersea pipelines have to start somewhere, and enter the water somewhere, so there is land to be purchased, beach access to be negotiated, HV power provided, trenching (both above and below the high tide mark), permits, notices, signage, on-going maintenance, etc.

Again, it depends exactly how far off-shore we are talking about.. and, if you're talking pipelines, what particular shore also.
« Last Edit: 01/03/2021 11:29 pm by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline Asteroza

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #36 on: 01/04/2021 03:16 am »
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...

Offline Robotbeat

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #37 on: 01/04/2021 04:11 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.
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Online danneely

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #38 on: 01/04/2021 05:08 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.

The development of affordable HVDC hardware has made underwater power cables much more feasible than they used to be.  AC (and data over wires is AC) suffers from capacitive losses that are avoided with DC.

Offline Crispy

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Re: Starship Ocean Platform; Advantages and Difficulties
« Reply #39 on: 01/04/2021 07:49 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).

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