Author Topic: Space Truck: Orbital Construction Requirements - Speculation  (Read 10074 times)

Offline Space Ghost 1962

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What is currently being discussed is non traditional payloads, of the kind used for HSF/exploration.

The scope is large LV that way exceed the traditional payloads. The issues relate to how to encapsulate/deliver the payloads for the mission.

Large, infrequent payloads may require fairing's of unusual size that are a considerable cost to develop qualify. Or, like BFS/ITS/Dragon, have same as part of SC. Likewise, GNC/props for prox ops.

Using a tug is not for free. Having integral props/GNC to a SC means you don't have to endure significant risk of the tug not being available/on-orbit/phased/oriented, able to dock/insert/KOS/handoff/exit, plus the costs of maintaining the tug as an independent mission/ops/replenishment. It complicates the picture w/o possibly improving the missions that depend on it.

(Where tugs (and depots) begin to get useful is when you have a mature situation, like possibly a DSG. But even for the life of the ISS, the desirability of such has been minimal.

Your best model for a trucking service would be exploration logistical support for DSG near Moon/Mars/etc, and looking at alternatives to build DSG/etc as currently in plan.

(There are still significant political "sacred cows" - obviously the stupid anemic (GTOW) solids on SLS, SLS primes, t and the need for HSF assembly where robotic/automated is far more mass efficient/safer. Will skip these.)

Lets suppose we have 10+ assembly payloads to deliver cislunar to the same place with a tug. And we have a tug that does this 2-3 times before replenishment. Instead of the 10 FH "direct delivery" missions, you'd have  1 FH + 13-15 F9 missions plus the development of a tug, which will likely be the cost of 5+ FH missions. Easier to do the 10 FH missions.

Now, what if we needed 100+ assembly payloads to the same place with say 5-6 before replenishment? Different story.

Don't build a trucking line until you have something for it to do. Duh.
Anyone know how many assembly payloads for ISS (not logistics!)?

Offline CuddlyRocket

I think it probably depends on what the purpose of the station is.

This is the fundamental issue. First decide the reason you want a space station.

Offline savuporo

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For Ariane 5 and Falcon 9/H they can carry payloads up to 4.5m in diameter within their fairings, and at least 6.7m in length, but to make sure more international launchers can be used it would be better to assume a slightly small diameter (JAXA H-IIB is likely 4.4M diameter capable).

(somewhat dated) Reference on fairing diameters

Angara is 2.9m. Proton will supposedly get a 5m fairing in 2020.

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Online Norm38

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People seem to be missing the question I'm asking.  SpaceX is going to build ITS / ITSy.  It will be crew rated, it will carry people and carry cargo.  The plan is for it to be fully reusable.  Sending up cargo on ITS(y) and crew up on Dragon2 with an expendable second stage seems to be more expensive and wasteful.
If crew and cargo on the same vehicle is a bad idea (or unnecessary), then send up two ITS(y).  The crewed version can be the construction shack that supports the initial assembly, spacewalks, etc.  While the cargo version brings up the modules. 

It doesn't matter if it's the most optimal solution by performance if it's the lowest cost to orbit.  SpaceX is going to build it, and they want to fly it a lot to drive down cost.  And I don't see how it makes sense to design a custom launcher around a space station. Unique one-use vehicles are not low cost.

So assuming this is built, it's flying and hauling cargo, how do people want to use it? If you can give input now on a cargo bay, what are the requirements?
Or is the answer really "No thanks, we'll keep flying on expendable or only partly reusable EELVs"??

Offline savuporo

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Or is the answer really "No thanks, we'll keep flying on expendable or only partly reusable EELVs"??

The answer is, learn the right lessons from past mistakes, and learn from the successes as well.

Commercial comsat market has decent flexibility in delivering payloads ( yeah, a bit late sometimes, but sometimes ahead of the schedule too ) partly because there is some commonality between payload fairings and interfaces. In other words, you can have a redundancy plan for delivering your very valuable asset on multiple providers

Whereas a project like ISS construction was severely screwed by having its only launcher grounded - and immediately retired after the project was cut down to bare minimum viable configuration.
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Offline Cherokee43v6

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People seem to be missing the question I'm asking.  SpaceX is going to build ITS / ITSy.  It will be crew rated, it will carry people and carry cargo.  The plan is for it to be fully reusable.  Sending up cargo on ITS(y) and crew up on Dragon2 with an expendable second stage seems to be more expensive and wasteful.
If crew and cargo on the same vehicle is a bad idea (or unnecessary), then send up two ITS(y).  The crewed version can be the construction shack that supports the initial assembly, spacewalks, etc.  While the cargo version brings up the modules. 

It doesn't matter if it's the most optimal solution by performance if it's the lowest cost to orbit.  SpaceX is going to build it, and they want to fly it a lot to drive down cost.  And I don't see how it makes sense to design a custom launcher around a space station. Unique one-use vehicles are not low cost.

So assuming this is built, it's flying and hauling cargo, how do people want to use it? If you can give input now on a cargo bay, what are the requirements?
Or is the answer really "No thanks, we'll keep flying on expendable or only partly reusable EELVs"??

Lets start by defining 'cargo'.

There is a difference between what a 'truck' hauls and what a specialized heavy-hauler carries.  For FedEx/UPS, sure, use up the extra space in the manned rocket.  But when SpaceX moves an F9 from Hawthorne to Kennedy, they don't use a 53' box or flatbed.

When you start talking Space Station Modules and other big ticket items that will spend their entire lives exposed to space anyway, why create the extra risk modalities involved in putting them in a crew-carrier?  As said, if crew is needed, send them up on the dedicated crew vehicle to meet up with the modules on-site.
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Online Norm38

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When you start talking Space Station Modules and other big ticket items that will spend their entire lives exposed to space anyway, why create the extra risk modalities involved in putting them in a crew-carrier?  As said, if crew is needed, send them up on the dedicated crew vehicle to meet up with the modules on-site.

The cargo version can be unmanned if that's best.  But as the image in the first post shows, crew and cargo versions will probably have identical mold lines, so that the launch and re-entry profiles are identical.
Modules designed for space need protection through Max Q.  There are either massive fairings with their issues, or a cargo bay. I think the cargo bay wins out.

So the consensus is that SpaceX and Blue Origin need to work together to define an industry standard for cargo and get two ships flying before anyone will use it for anything but comsats?

I guess SpaceX could use it to build their own fuel depot and not be concerned they're reliant on only their own hardware.
« Last Edit: 08/30/2017 07:05 PM by Norm38 »

Online BobHk

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Why bother using anything but ITS/ITSy S1 Booster when you can have an expandable Bigelow made to order fit on top and launched into orbit?  You get larger modules into orbit that way.  Dont need human crew for the mission. 

Offline philw1776

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Why bother using anything but ITS/ITSy S1 Booster when you can have an expandable Bigelow made to order fit on top and launched into orbit?  You get larger modules into orbit that way.  Dont need human crew for the mission.

If I understand your proposal correctly, S1 going to LEO, it won't work even if S1 could get there because S1 is not designed for anything even close to LEO re-entry velocities.  Throw away an expensive S1 per launch.
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Online BobHk

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Why bother using anything but ITS/ITSy S1 Booster when you can have an expandable Bigelow made to order fit on top and launched into orbit?  You get larger modules into orbit that way.  Dont need human crew for the mission.

If I understand your proposal correctly, S1 going to LEO, it won't work even if S1 could get there because S1 is not designed for anything even close to LEO re-entry velocities.  Throw away an expensive S1 per launch.

That really depends on the module doesnt it?  Max weight with no engine of its own wouldn't work.  Expendable second stage booster for the module would, depending on orbit you want. 

Using the 2nd stage fuelling ship concept or people transport (converted to carry up cargo) for this kind of mission seems to be another Shuttle rabbit hole... a special kind of waste of resources all its own.

Offline Cherokee43v6

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Okay, let's look from a different angle then.

What is a 'payload bay' actually good for as a 'primary resource'?

The primary purpose of the payload bay is to streamline a large vehicle that goes both up and down through the atmosphere.  Primarlily down.  Thus the purpose of a payload bay is to bring cargo FROM orbit to the ground.

What are you bringing down that requires that scale of downmass capability?

If you have no downmass to bring down, why waste resources on a 'payload bay' when the same base vehicle can lift multiple tens of tons more mass up in a more traditional configuration.

As an example, the Space Shuttle was an approximately 120 tons to LEO system... capable of delivering a mere 20 tons of cargo.  So with this example, you're wasting 100 potential usable on-orbit tons for unnecessary structure.

Now, I will admit that if you have a large scale product coming down from orbit, then a payload bay is very desirable.  However I think in 40 years of flight, the shuttle was used that way twice.  Two mis-deployed satellites, and the LDEF.  Otherwise, it was bringing back what it took up on the same flight.
« Last Edit: 09/02/2017 03:54 PM by Cherokee43v6 »
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Offline AncientU

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Okay, let's look from a different angle then.

What is a 'payload bay' actually good for as a 'primary resource'?

The primary purpose of the payload bay is to streamline a large vehicle that goes both up and down through the atmosphere.  Primarlily downThus the purpose of a payload bay is to bring cargo FROM orbit to the ground.

What are you bringing down that requires that scale of downmass capability?

If you have no downmass to bring down, why waste resources on a 'payload bay' when the same base vehicle can lift multiple tens of tons more mass up in a more traditional configuration.

As an example, the Space Shuttle was an approximately 120 tons to LEO system... capable of delivering a mere 20 tons of cargo.  So with this example, you're wasting 100 potential usable on-orbit tons for unnecessary structure.

Now, I will admit that if you have a large scale product coming down from orbit, then a payload bay is very desirable.  However I think in 40 years of flight, the shuttle was used that way twice.  Two mis-deployed satellites, and the LDEF.  Otherwise, it was bringing back what it took up on the same flight.

Don't agree.  The payload bay needs to ensure structural integrity of the ship as it enters atmosphere and descends.  Bring stuff down is an extra benefit.
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Offline Cherokee43v6

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Okay, let's look from a different angle then.

What is a 'payload bay' actually good for as a 'primary resource'?

The primary purpose of the payload bay is to streamline a large vehicle that goes both up and down through the atmosphere.  Primarlily downThus the purpose of a payload bay is to bring cargo FROM orbit to the ground.

What are you bringing down that requires that scale of downmass capability?

If you have no downmass to bring down, why waste resources on a 'payload bay' when the same base vehicle can lift multiple tens of tons more mass up in a more traditional configuration.

As an example, the Space Shuttle was an approximately 120 tons to LEO system... capable of delivering a mere 20 tons of cargo.  So with this example, you're wasting 100 potential usable on-orbit tons for unnecessary structure.

Now, I will admit that if you have a large scale product coming down from orbit, then a payload bay is very desirable.  However I think in 40 years of flight, the shuttle was used that way twice.  Two mis-deployed satellites, and the LDEF.  Otherwise, it was bringing back what it took up on the same flight.

Don't agree.  The payload bay needs to ensure structural integrity of the ship as it enters atmosphere and descends.  Bring stuff down is an extra benefit.

I'd point at the F9 stage one and argue otherwise.  Lack of a 'payload bay' doesn't affect it's structure.

Also, I'll add, that if you don't need a payload bay to bring stuff back then there is no need for all that structure.
« Last Edit: 09/02/2017 05:06 PM by Cherokee43v6 »
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Offline savuporo

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...With Shuttle retired, the next orbital station will be built by something else..

Coming back to thread opening, the next orbital station program is already underway and yes, it will be launched by EELV-sized launchers.
Larger core module than ever before though, at around 22 tons, reportedly.

Quote
Length of the module is 18.1m, it is cylindrical with a maximum diameter of 4.2m and an on orbit mass between 20 and 22 thousand kilograms.
« Last Edit: 09/02/2017 05:55 PM by savuporo »
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Offline oldAtlas_Eguy

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Ok lets review SpaceX policies and how they impact how things are designed from a systems standpoint.

SpaceX does not create designs that incur additional costs if not absolutely required.

This then impacts the ground handling, GSE hardware and software, and the launch and processing procedures. Each of which if you have to have major differences incurs actually a very significant development cost prior to even the first launch. Plus incurring even more costs for making these changes compatible with systems that must be there for the Mars goals and vehicle designs is also a  nonstarter. So mold lines, lift points, shapes, sizes, weights, props, umbilical and ground software should be the same for the Space Truck as for the Mars vehicles (tanker and Mars ITSy). Proposing something else just will not happen.

Within these constraints is a fairly wide range of possibilities. The Space Truck would be more kin to the tanker ITSy version than the Mars ship ITSy version. If you need personnel and personnel supplies or other equipment that fits in the ITSy Mars ship and needs personnel to help in its installation then use the existing ITSy Mars ship design. A new design for personnel carrier is not needed.

Now as to a secondary vehicle for 100mt large contiguous payloads look to BO and the New Armstrong to provide this. It will likely also be a lifting body US fully reusable vehicle of about the same size. But it may have widely different versions such as a 3 stage one where a much smaller Lunar Vehicle is the 3rd stage on top of a reusable second stage. And then also a different version of that second stage for delivery of very large payloads to LEO. So if a significant payload size is defined with a significant amount of launch activity (more than 1 every other year) like 5-10 times per year, then additional commercial launchers will emerge to handle it possibly at even cheaper prices than the ITSy Space Truck.

Online Norm38

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What is a 'payload bay' actually good for as a 'primary resource'?

The primary purpose of the payload bay is to streamline a large vehicle that goes both up and down through the atmosphere.  Primarlily down.  Thus the purpose of a payload bay is to bring cargo FROM orbit to the ground.

The primary purpose is to keep the second stage in one piece, to not shed parts on the way to orbit, and to give the cargo version the same re-entry profile as the crewed version. If you're talking about dropping fairings, then the second stage is a completely different craft. Why do you want that?

This is going to be a fully reusable vehicle and it's not optimized on performance, but cost. 
The SLS system will be able to put 100MT into LEO in one launch. But it's expendable and very expensive.  If a cargo ITSy can put 20MT into LEO per launch, and 5 ITSy launches cost less than one SLS launch, then what is gained by going expendable? Unless there is some function that cannot be broken down into 20MT chunks, lower cost will win out.
« Last Edit: 09/03/2017 02:30 PM by Norm38 »

Online Norm38

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Coming back to thread opening, the next orbital station program is already underway and yes, it will be launched by EELV-sized launchers.
Larger core module than ever before though, at around 22 tons, reportedly.

1/6th the size of ISS, 1/2 that of MIR. And China isn't going to use SpaceX for launches anyway. EELV is what they have to work with. To the point that was made earlier, yes anyone designing a station today has to base it on expendable EELVs. But it'll be interesting to see what happens once the ITSy and New Glenn class RLVs are flying.

Online BobHk

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Why bother using anything but ITS/ITSy S1 Booster when you can have an expandable Bigelow made to order fit on top and launched into orbit?  You get larger modules into orbit that way.  Dont need human crew for the mission.

If I understand your proposal correctly, S1 going to LEO, it won't work even if S1 could get there because S1 is not designed for anything even close to LEO re-entry velocities.  Throw away an expensive S1 per launch.

You proceed from a false assumption.  THe S1, being reusable, is not thrown away.  You simply launch something its capable of putting into LEO on its own or something with a 2nd stage motor and fuel to get it to its location.

Redesigning the crew and fuel ships SpaceX plans to be cargo carriers will result in just another 'shuttle' design with too many compromises.

Offline philw1776

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Why bother using anything but ITS/ITSy S1 Booster when you can have an expandable Bigelow made to order fit on top and launched into orbit?  You get larger modules into orbit that way.  Dont need human crew for the mission.

If I understand your proposal correctly, S1 going to LEO, it won't work even if S1 could get there because S1 is not designed for anything even close to LEO re-entry velocities.  Throw away an expensive S1 per launch.

You proceed from a false assumption.  THe S1, being reusable, is not thrown away.  You simply launch something its capable of putting into LEO on its own or something with a 2nd stage motor and fuel to get it to its location.

Redesigning the crew and fuel ships SpaceX plans to be cargo carriers will result in just another 'shuttle' design with too many compromises.

The whatever with engines and fuel that launches Bigelow into LEO gets expended.
Simply use an ITSy to launch whatever as ITSy S2 returns for re-use.

S1 is designed for relatively slow re-entry velocities around 2.5 Km/sec, nowhere near 8.5 Km/sec.
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Offline the_other_Doug

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Why bother using anything but ITS/ITSy S1 Booster when you can have an expandable Bigelow made to order fit on top and launched into orbit?  You get larger modules into orbit that way.  Dont need human crew for the mission.

If I understand your proposal correctly, S1 going to LEO, it won't work even if S1 could get there because S1 is not designed for anything even close to LEO re-entry velocities.  Throw away an expensive S1 per launch.

You proceed from a false assumption.  THe S1, being reusable, is not thrown away.  You simply launch something its capable of putting into LEO on its own or something with a 2nd stage motor and fuel to get it to its location.

Redesigning the crew and fuel ships SpaceX plans to be cargo carriers will result in just another 'shuttle' design with too many compromises.

The whatever with engines and fuel that launches Bigelow into LEO gets expended.
Simply use an ITSy to launch whatever as ITSy S2 returns for re-use.

S1 is designed for relatively slow re-entry velocities around 2.5 Km/sec, nowhere near 8.5 Km/sec.

Or, to put it more plainly, the ITS (or ITSy) Stage 1 can't place a non-propulsive payload directly into orbit and also be recovered.  It won't be able to stand the far more extreme heating of re-entering the atmosphere from orbital velocities than from the much slower staging velocities it will see when carrying a propulsive upper stage to where whatever Stage 2 you put on it can then get itself into orbit.

This is not to say you could not use an ITS or ITSy S1 to put a non-propulsive payload int orbit.  But you would be treating that S1 as expendable -- not what you're trying to do with that hardware.  ;)
-Doug  (With my shield, not yet upon it)

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