The thread for space cadets!
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hobbsyoyo
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For now at least. I didn't have the time at my last job to keep posting new articles and it cost me money to keep it going to I shut it down. I have thought about reopening it but I also think I need hobbies that are not either space related or video games.
Nah, embrace who you are. If space and video games are what bring you joy, keep at it.
warpus
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I have a question about BFR refuelling. From all the images I've seen, it seems that a BFR is going to refuel another BFR. So the BFR that's going to act as a fuel tanker, it won't have 100% fuel left, right? After getting in orbit I mean. And it'll be the exact same size as the thing it's refuelling. Doesn't that seem a bit inefficient? Don't you want your fuel depot to be much larger, so that you can dock many things to it and refuel? This way it seems you have to launch 2 BFR's at the same time (or weeks apart or whatever), per each refuelling. How is that gonna work? They'll launch 2 BFR's each time they need to refuel one? Doesn't that double the cost?
hobbsyoyo
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Launching a bigger tanker would require designing and building a separate design. This way the design between tanker and ship are much more closely aligned which helps avoid having to set up an entirely separate production line which would dramatically increase the price.
The propellant will boil off in a few tens of hours or days anyways, likely far faster than you could line up multiple docking manuevers. So yes while there are inefficiencies to this approach it would require far more resources to make a theoretically perfect fuel transfer system than what they have come up with.
The tanks on the tanker will have a much higher volume than the ship though since it won't have a crew or payload compartment. So maybe they could top off two ships or something. But yes more or less each Mars bound flight will require at least one tanker.
This will increase costs but if the BFR is as cheap to operate (or at least close to) an airline then it won't be super stupid expensive to do this. Airline type reuse and costs are a major design goal of the system. We'll see how close they get to that.
The propellant will boil off in a few tens of hours or days anyways, likely far faster than you could line up multiple docking manuevers. So yes while there are inefficiencies to this approach it would require far more resources to make a theoretically perfect fuel transfer system than what they have come up with.
The tanks on the tanker will have a much higher volume than the ship though since it won't have a crew or payload compartment. So maybe they could top off two ships or something. But yes more or less each Mars bound flight will require at least one tanker.
This will increase costs but if the BFR is as cheap to operate (or at least close to) an airline then it won't be super stupid expensive to do this. Airline type reuse and costs are a major design goal of the system. We'll see how close they get to that.
warpus
Sommerswerd asked me to change this
That makes sense, thanks
Is it just me or do I remember seeing an image of a BFR with it's 1st stage still attached, floating around in space? I don't think that makes sense to me, so I probably didn't see it, but..
Is it just me or do I remember seeing an image of a BFR with it's 1st stage still attached, floating around in space? I don't think that makes sense to me, so I probably didn't see it, but..
Perhaps the fuel can be delivered separately in some sort of very durable container, and loaded into the engine already in space. Like, on the ISS
That will make design more expensive though...
The problem is rockets are by design controlled bombs. Putting anything nuclear on top of them, even if it's inert, will be problematic for people. An extra terrestrial source would be a great help getting those kind of engines off the drawing board.
Well, rockets are going into space with fission materials on board for decades already. Risk of contamination is a problem, but not the biggest obstacle for this technology, IMO.
warpus
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I didn't think so! I guess there's no need, since the BFR can fly to and land anywhere in the solar system (right?)
I'm not sure what image I'm thinking of, maybe it was a mockup by a non spaceX employee
The problem is political more than technological fully agree there
Maybe it can fly anywhere in the solar system, but I doubt it is going to be capable of landing anywhere in the outer solar system.
warpus
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I guess not on the gas giants. Maybe I'm misquoting Musk, or he wasn't being precise
hobbsyoyo
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They said that about the old BFR design which was much bigger. Not sure for this one. Though if the mass fractions are the same I assume it would have the same DV.
But in any case that would habealmost certainly been an exaggeration or required like a fleet of tankers flying along with it and being expended and left behind after various burns
warpus
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Fleet of tankers eh.. They should hire me on as a consultant
hobbsyoyo
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I agree launch is a problem but you really can out the fissile materials in casks which are basically indestructible. They'd be stupid heavy but then again like I said before, you'd have to launch a proper nuclear stage inin pieces anyways so it I don't think it's an insurmountable problem. Especially with rockets like Falcon Heavy and New Glenn.
hobbsyoyo
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warpus
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Green cards seem easy to get if you're an athlete. Imma start working out some more
hobbsyoyo
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So I'd like to spend a post talking about the gross inefficiency and stupidity in the US Space program. I think the achievements of SpaceX paints an overly rosy picture of what's going on over here so I'd like to balance that out.
So for starters, the launch gantry for the SLS is now leaning. NASA says it's not a problem that needs fixing but who knows whether or not that will remain the case in 2-5 years or whenever the SLS actually flies. The real tragedy here is that NASA spent $1 billion dollars to build this gantry for a program that was cancelled and then re-purposed it for SLS. It will be used exactly once for the first SLS flight and then will have to be torn down and rebuilt for the upgraded version of the SLS - assuming that doesn't get cancelled too. I know that this gantry was built for manned spaceflight which inflates costs but I can see no real reason why it should cost a billion dollars. I also think the notion that they have to totally rebuild it (at likely an even higher price tag) for an upgraded SLS is just stupid.
There are also reports that basically admit that as a research lab, the ISS has been a failure. The agency that NASA stood up to oversee ISS research (CASIS) has essentially failed to meet the modest goals that they were tasked with since its founding. It's to the point that for some years they were only using less than 30% of the astronaut time allotted to run experiments. That's mind boggling to me - especially given the fact that astronaut time should be the bottleneck for research given the ISS has spent the last ~decade with less than a full compliment of astronauts. I like the ISS and want it to continue but the fact that we're paying tens of billions of dollars to maintain it and getting marginal science returns from it is a disaster in my opinion.
Finally, as a sign of how screwed up procurements are in the US space industry, Aerojet Rocketdyne is attempting to renegotiated a development contract with the USAF to cut in half their share of development funding for a rocket engine. The USAF decided that the Atlas V's use of Russian engines was a problem and awarded Aeroject a lucrative contract to develop a replacement. Aerojet only had to put in 1/3 of the total funds themselves and at the time of the contract were in a position to secure future work building the engine for the replacement rocket for the Atlas V (called Vulcan).
Aerojet essentially squandered this lead and dragged their feet on development. They started R&D quite slowly and at every turn have tried to game the system to get more funds to push development further. They went from the front runner for Vulcan work to the distant second as Blue Origin (who are putting in much more of their own money) developed their own engine for both Vulcan and the New Glenn rocket. Now Aerojet has turned to the USAF and asked them to be allowed to cut their contribution for the program from 1/3 to 1/6 of the project cost. And the Air Force seems to be going along with this plan! Really this whole ordeal is pretty indicative of how badly the government manages procurement in this industry overall. This rocket engine has no customers and while it's always worthwhile in my opinion for the government to fund development work, the questions of cost and utility should always be an important consideration and here it is not.
So for starters, the launch gantry for the SLS is now leaning. NASA says it's not a problem that needs fixing but who knows whether or not that will remain the case in 2-5 years or whenever the SLS actually flies. The real tragedy here is that NASA spent $1 billion dollars to build this gantry for a program that was cancelled and then re-purposed it for SLS. It will be used exactly once for the first SLS flight and then will have to be torn down and rebuilt for the upgraded version of the SLS - assuming that doesn't get cancelled too. I know that this gantry was built for manned spaceflight which inflates costs but I can see no real reason why it should cost a billion dollars. I also think the notion that they have to totally rebuild it (at likely an even higher price tag) for an upgraded SLS is just stupid.
There are also reports that basically admit that as a research lab, the ISS has been a failure. The agency that NASA stood up to oversee ISS research (CASIS) has essentially failed to meet the modest goals that they were tasked with since its founding. It's to the point that for some years they were only using less than 30% of the astronaut time allotted to run experiments. That's mind boggling to me - especially given the fact that astronaut time should be the bottleneck for research given the ISS has spent the last ~decade with less than a full compliment of astronauts. I like the ISS and want it to continue but the fact that we're paying tens of billions of dollars to maintain it and getting marginal science returns from it is a disaster in my opinion.
Finally, as a sign of how screwed up procurements are in the US space industry, Aerojet Rocketdyne is attempting to renegotiated a development contract with the USAF to cut in half their share of development funding for a rocket engine. The USAF decided that the Atlas V's use of Russian engines was a problem and awarded Aeroject a lucrative contract to develop a replacement. Aerojet only had to put in 1/3 of the total funds themselves and at the time of the contract were in a position to secure future work building the engine for the replacement rocket for the Atlas V (called Vulcan).
Aerojet essentially squandered this lead and dragged their feet on development. They started R&D quite slowly and at every turn have tried to game the system to get more funds to push development further. They went from the front runner for Vulcan work to the distant second as Blue Origin (who are putting in much more of their own money) developed their own engine for both Vulcan and the New Glenn rocket. Now Aerojet has turned to the USAF and asked them to be allowed to cut their contribution for the program from 1/3 to 1/6 of the project cost. And the Air Force seems to be going along with this plan! Really this whole ordeal is pretty indicative of how badly the government manages procurement in this industry overall. This rocket engine has no customers and while it's always worthwhile in my opinion for the government to fund development work, the questions of cost and utility should always be an important consideration and here it is not.
warpus
Sommerswerd asked me to change this
How will SLS be able to complete with the BFR?
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