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[New] Space Launch System / Orion Discussion Thread

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10 minutes ago, jadebenn said:

Dragon is a pretty terrible cargo carrier for Lunar COTS, though. There's no way it would be able to bring any downmass back to Earth from NRHO, so the Dragon heatshield is useless mass and reuse would be impossible.

I wasn't thinking return to Earth for Dragon LCOTS. If it could do that, then we could also just launch crew on Dragon instead of Orion. I doubt that the gateway will need downmass that Orion can't offer for a while.

Without the heatshield, parachutes, and superdracos, you would have an easier time getting there too.

(Tangent about how much cargo D2 could get to NRHO)

From what I can find, going from TLI to NRHO is around 450m/s (FH would get D2 to TLI just fine I think). I am having a very hard time finding a proper dry mass for dragon 2 and a proper fuel load... I am finding everything from 6.5 tons and 1.3 tons to 9.5 tons and 2.2 tons... I am going to go with the numbers on the environmental assessment for landing. https://www.faa.gov/about/office_org/headquarters_offices/ast/environmental/nepa_docs/review/launch/media/draft-ea_spacex-dragon-gulf-landing.pdf

Dry mass 7.7 tons, fuel mass up to 2.2 tons. Draco ISP of 300s. Delta V is about 740m/s. However, we have not factored in cargo. If we assume 100m/s for docking, undocking, and de-orbit plus safety margin, we need a total of 550. Running the numbers gives us, unfortunately, only 3 tons of cargo, half of what dragon is rated for. However, the heat shield, superdracos, and parachutes aren't light, so once we remove those we get maybe 3.5 tons or 4 if we're lucky. For comparison normal enhanced Cygnus can also carry 3.5-4 tons.

(End tangent)

And that's off the shelf besides the removal of entry equipment and addition of comms/other lunar equipment.

I can't find any numbers on Cygnus but it's almost certain that it has less Delta-V than Dragon 2, as it wasn't designed with launch abort or propulsive landing in mind. It would take a lot more effort to modify Cygnus to be able to reach Gateway than it would Dragon 2.

Dragon 2 can also dock off the shelf, whereas Cygnus berths, and there won't be a robot arm on gateway for a while. This can be changed fairly easily compared to other things, but it's still a change.

If we're only thinking about minimal modifications to get going quickly with a low dev cost, Dragon 2 seems like a really good choice.

However... They already have to get a Cygnus Derivative to the gateway for the MHM/HALO module, so if they're already doing the development on getting something Cygnus-y to have the fuel, comms, docking, etc. to get to gateway, it would mean that they could do the same thing to a Cygnus if they play their cards right.

Which means that in this case, Cygnus is a really good choice because they already have to do big modifications to something closely related, including comms, which would still have to be modified on D2.

I wonder if they are considering just one provider or two... If two, then D2/Cygnus variants seem like good choices (one can get there almost off the shelf, one has the modifications already paid for). However, I doubt that Gateway will need two resupply carriers... I can't imagine needing more than one per crew, and that's one a year max.

 

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9 minutes ago, Ultimate Steve said:

However... They already have to get a Cygnus Derivative to the gateway for the MHM/HALO module, so if they're already doing the development on getting something Cygnus-y to have the fuel, comms, docking, etc. to get to gateway, it would mean that they could do the same thing to a Cygnus if they play their cards right.

Which means that in this case, Cygnus is a really good choice because they already have to do big modifications to something closely related, including comms, which would still have to be modified on D2.

I'd guarantee you that's Orbital's NGIS's game-plan.

They'll already have to replace the berthing mechanism with an NDS port for the MHM, so that's something they'd know how to do with a Lunar Cygnus. They'd also have equipment designed to withstand the NRHO environment, and experience using it. The main differences from the MHM would presumably be the lack of extra docking ports, and less-beefy life support systems.

Edited by jadebenn

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1 hour ago, jadebenn said:

Dragon is a pretty terrible cargo carrier for Lunar COTS, though. There's no way it would be able to bring any downmass back to Earth from NRHO, so the Dragon heatshield is useless mass and reuse would be impossible.

I honestly wouldn't be surprised if they instead form a partnership with NGIS and have a Lunar Cygnus launch on FH instead.

Cygnus has no downmass from anywhere at all.

Dragon would be fine for a lunar version of COTS, as was said, delete chutes, etc, it merely needs to be disposed of (ditto Cygnus), not sent home (which would require a SM, anyway).

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It could be made to work. But since it's going to be disposed of and can't do downmass from NRHO, I find it hard to see how Cygnus wouldn't be the superior option here.

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1 hour ago, jadebenn said:

It could be made to work. But since it's going to be disposed of and can't do downmass from NRHO, I find it hard to see how Cygnus wouldn't be the superior option here.

What Atlas V gets it to TLI? a 541 or 551?

Yeah, probably best, but expensive, the launch alone is about 150 M$ (vs 90 M$ for Dragon). Or they could fly Cygnus on FH, lol.

It might be interesting to see if the cargo version of Crew Dragon could return from NRHO, however, then SpaceX could test a direct entry with that vehicle. If it works, they would have some downmass. Not that there is any reason to have ay, there's not really much of interest to do at Gateway.

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9 hours ago, Ultimate Steve said:

 

Idk about reusability though. If you gave dragon 2 an actual service module, then it might actually be able to take crew to and from gateway on an expendable Falcon heavy, but you would have to probably modify the heat shield, comms, and life support. And also get fh man rated.

Even if you could get a D2 to NRHO with crew, it would have too little volume, which is why we need Orion.

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2 hours ago, Barzon Kerman said:

Even if you could get a D2 to NRHO with crew, it would have too little volume, which is why we need Orion.

Include CST-100, as well. The difference in usable volume between the 3 is in fact very small. The 2 Commercial Crew vehicles have very sparse interiors, with a lot of room, Orion has a much larger pressurized volume, but the usual volume is only about half the pressurized volume (interior is filled with equipment).

 

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31 minutes ago, Barzon Kerman said:

yes, but that equipment is needed. If it wasnt, it wouldn't be there.

It's a matter of where the equipment actually is (inside vs outside the pressure vessel) as well. The duration issue is largely a function of the service module, all the commercial crew vehicles are larger than Apollo in volume (substantially). If CST-100 or Dragon were given proper SMs, the only issue would be reentry. I realize you were replying to a post about using Commercial Crew as crew vehicles, I was only discussing using cargo Dragon 2 as a resupply ship. SpaceX has said that Dragon could do a direct entry from the Moon, though, so it might be interesting to see them try that (say downmass cargo, uncrewed).

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On 8/22/2019 at 12:13 PM, wumpus said:

Of all the innovations that have come out of SpaceX, why did NASA/Boeing have to pick up "Elon time"?

What innovations? Unless over-promising and under-delivering massively is an innovation.  

I don't think SpaceX has any patents. They stand on the shoulders of many other great innovators.

The landing rockets shtick was done decades ago. If it saves any real money is unknown.

 

 

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3 hours ago, Kerbal7 said:

What innovations? Unless over-promising and under-delivering massively is an innovation.  

I don't think SpaceX has any patents. They stand on the shoulders of many other great innovators.

The landing rockets shtick was done decades ago. If it saves any real money is unknown.

Absolutely, 100% agree, SpaceX is so insignificant, unoriginal and derivative that I’m really quite baffled as to why would someone even mention it here in the thread dedicated to such an innovative marvel of engineering which is SLS.

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Apart from the fact that there are sound business reasons not to file patents, most patented things are evolutionary rather than revolutionary.

For every patent that covered a game-changing invention, there'll be many more covering small improvements to it, and many more still covering variations on that invention that are just different enough to avoid the original patent. Different doesn't even imply better - the older a technical field is, the more baroque the patents get, simply because most of the truly innovative solutions to a problem have already been patented.

Number of patents is really a very crude measure of innovation, although its a very easily measured one, which is why people like it. And that's without getting into a debate over the term 'innovation' which is one of those all-things-to-all-people words. 

TL: DR, I wouldn't regard SpaceX's lack of patents as any sort of commentary on their innovation or lack of innovation.

Source: 20 odd years working with patents in various capacities.

 

Edit. The same comments apply to any company. I’m not singling SpaceX out for any special treatment here.

Edited by KSK

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I can think of three main reasons for patents:

1) you don't want people to use your idea

2) you do want people to use your idea, but you want them to pay for it

3) you want to make sure that you can use your idea without somebody else claiming you stole it from them

 

If you have reason to think nobody else can use your idea anyway, there's no real point to patenting.

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Some posts have been removed.

While we understand there is a lot of crossover between the two topics, and some cross topic talk is to be expected, let's stay focused on NASA/SLS.   If there is some mention of SpaceX, that's fine, it'll happen, as they work closely together, but let's not drag the discussion solely about SpaceX, they have their own thread. 

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