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#21
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Dragon to cost about $140 million per launch
No, I didn't. *My original comment was that Dragon was quoted by SpaceX as being about one-tenth the cost of a Shuttle mission. *$1.4 billion divided by 140 equals 0.1. For a crew changeover mission, it's still going to be much less expensive to use Dragon than to use Shuttle; even with a resupply performed by shuttle at the same time. *They've never transferred more than few tonnes at each shuttle docking, except modules (hardly relevant)..- since the standing army cost to launch any shuttle was a ongoing expense...... 5 billion per year with one shuttle launched every 2 years, the cost of a single flight every other year 10 BILLION unless shuttle C had been built..... the infrastructure and launch teams the same, it would of retained the unique shuttle abilities at a realtively low cost..... featuring multiple resupply trips, the ability to launch new modules and big replacement parts, add a capsule somehow to the C version, with better safety, like launch boost escape... when a shuttle did fly, minimially man it with crew of 2, with ejection seats. or a jetisonable crew pod..... |
#22
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Dragon to cost about $140 million per launch
In article , bthorn64
@suddenlink.net says... On Thu, 27 Oct 2011 10:31:24 +1100, Alan Erskine wrote: There's another point to this. If anyone wants to build a replacement for ISS, they will be able to use Falcon Heavy - more than twice the payload of Shuttle. What would perform the control, communications, rendezvous and docking? Could a Dragon fly around with 35,000 lbs. of module on its nose? Possibly. If it doesn't have the fuel capacity needed, you could stack two Dragon service modules top of each other. Falcon Heavy gives you plenty of options to "throw mass" at this problem. Another possibility is the satellite bus that Orbital Sciences is using for their COTS station resupply spacecraft. Jeff -- " Ares 1 is a prime example of the fact that NASA just can't get it up anymore... and when they can, it doesn't stay up long. " - tinker |
#23
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Dragon to cost about $140 million per launch
In article , bthorn64
@suddenlink.net says... On Wed, 26 Oct 2011 08:14:03 -0400, Jeff Findley wrote: MPLM cargo is a bit more than 9,000 kg. Dragon up-mass is 6,000 kg and down-mass is 3,000 kg. In crew mode, Dragon supports up to 7 passengers. I don't believe Dragon is going to get anywhere near 6,000kg mass to ISS. Its shape and volume just don't lend themselves to it. I'll be happy to be proven wrong, though. That's the capacity SpaceX is advertising. Agreed that in practice, this could be different. Again, ISS assembly is complete. There is no requirement to duplicate shuttle's ability to deliver entire station modules to ISS. The requirement is cargo deliveries (and later crew rotation flights) . I'm not the one who compared Dragon's cost to Shuttle's cost. Alan opened that door, so the defense of Shuttle is allowed. In any case, I think we're living dangerously in having no 'large upmass' capability for Station. Are you really so certain there won't be another SARJ failure or something else requiring a big spare part that NASA has no way to launch anymore? And there is still talk of Node 4 to fly as an "exploration node" to ISS. I'd think that Delta IV Heavy or Falcon Heavy could loft large masses to ISS when used in conjunction with a Dragon service module or the service module that Orbital Sciences is using on their ISS resupply craft. The Russians have done the same thing with a Progress service module to deliver their docking modules to ISS (launched on a Soyuz launch vehicle). That and they've used TKS derived service modules to deliver large station modules (launched on Proton). Certainly the US can do the same. Dragon Payload Volume: 10 m3 (350 ft3) pressurized and 14 m3 (490 ft3) unpressurized compared to MPLM's pressurized volume of 31 m3. MPLM has about a 3 to 1 advantage in volume. I think it will be closer to 4 to 1 when you factor in volume that has to be set aside for the hatch, etc., in a basically conical structure. I said before, Dragon will run out of room (volume) long before it runs out of mass. I stand by that, but will be happy to admit I was wrong if SpaceX pulls it off. The other part of the 6 to 1 is the mass carried in addition to the MPLM by the Shuttle. Such as CMGs or ammonia tanks on the MPESS, and all the water delivered from Shuttle's fuel cells, which was substantial, not counted as Shuttle cargo, and counted as pure cargo by all other cargo haulers. So you weren't looking at a specific STS mission carrying an MPLM when you came up with your 6:1 ratio? Obviously the shuttle's unpressurized volume is huge, but again, we're talking ISS resupply missions, not assembly missions, so volume isn't quite as critical. Whoever said resupply only involves internal stowage? Kibo and Columbus were both built with external science equipment in mind, and now there is very little opportunity to fly external experiments. What little external capacity HTV has will likely end up being used for critical replacement parts like CMGs or ammonia tanks. Very little opportunity? I think not. HTV is flying and has provisions for unpressurized cargo. Dragon does as well (14 m3 volume for unpressurized cargo). I'm not sure about OSC's vehicle... Total program cost for the shuttle was $196 billion in 2011 dollars. There were 135 missions (including the two which destroyed Challenger and Columbia) so the cost per flight was $1.45 billion dollars. While that's true, Shuttle in an operational sense didn't cost that much. We already had Shuttle, we didn't have Falcon 9/Dragon. It wasn't going to cost $1.45 billion per flight out of NASA's budget at the time NASA was deciding whether or not to extend Shuttle. It was $700 million or so out of the U.S. Treasury per flight each year in 2006-2010. (It was a little higher than that, but I think we must assume that other "space support" budget would continue to exist if Shuttle were replaced by Dragon.) $700 million for one Shuttle flight versus, call it one Manned Dragon flight at $140 million each and four or five Cargo Dragons at, what $100 million each? The numbers get interesting. While the numbers are "interesting", shuttle isn't flying anymore. Commercial competition for ISS resupply is the capitalist way to go about moving forward. Costs should drop as competition should spur the commercial providers to innovate in a way that the prior single source cost-plus contracts did not. You're not a socialist, are you? ;-) If Dragon really does take six flights to replicate a typical shuttle crew rotation and resupply mission (I doubt it would), each Dragon flight would need to cost more than $240 million dollars. I think $150-200 million is probably going to be the ballpark for Manned Dragon, and I think that's a bargain. They currently claim $140 million, if I heard right, but Falcon 1 and 9 have both busted their budgets in the past (they are still very cheap, I'm not claiming otherwise, just not as cheap as they originally hinted they would be). If SpaceX ends up on the high side at $200 million, is losing Shuttle's huge upmass, downmass, and impressive in situ construction/repair capability, and the option to fly other missions like another Hubble repair (looking all the more desirable now that Webb has completely screwed the pooch) really worth $40 million? It will be interesting. SpaceX is working hard on making Falcon 9's first stage reusable. Even if they fail at this, reusable boosters for Falcon Heavy (a much easier problem to solve) would make 1/2 of the stages reusable, which means well over half of the engines could be reused per launch. Reusability could be a huge game changer for SpaceX both in terms of improved reliability and reduced cost. If the number is four Dragon flights to equal a typical MPLM flight, then SpaceX only needs to cost less than $360 million dollars. I think they'd have to screw up a lot, or be NASA regulationed to death to hit that high. Unfortunately, both are completely within the realm of possibility. True, but to me, this is still better than SLS. The one silver lining to NASA screwing the pooch on Ares I and Orion is that they *have* to rely on commercial providers for ISS resupply. If Ares I and Orion were flying, NASA might have given a single finger salute to the commercial providers and continued along the socialist path of US government only vehicles flying to ISS. I'm betting SpaceX can come in with costs lower than that if it's successful in reusing Dragon multiple times, which is the plan. I'm betting they might be able to lower costs, but they won't actually cut their prices. Mr. Musk is still a capitalist at heart. He'll lower his prices only so far to win contracts, no farther. Kind of a moot point since shuttle is retired. Comparing Dragon to Progress and Soyuz (or ATV or HTV) is a better choice. Just reponding originally to Alan, who compared one apple (Dragon) to a bushel of apples (Shuttle.) Ok. Jeff -- " Ares 1 is a prime example of the fact that NASA just can't get it up anymore... and when they can, it doesn't stay up long. " - tinker |
#24
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Dragon to cost about $140 million per launch
On 10/27/2011 08:03 AM, Jeff Findley wrote:
I'd think that Delta IV Heavy or Falcon Heavy could loft large masses to ISS when used in conjunction with a Dragon service module Dragon doesn't have a service module, as that term is usually understood. The "trunk", as SpaceX calls it, contains only the solar arrays, radiators, and external cargo accommodation. *All* Dragon propulsion capability is integrated into the capsule itself. or the service module that Orbital Sciences is using on their ISS resupply craft. The Russians have done the same thing with a Progress service module to deliver their docking modules to ISS (launched on a Soyuz launch vehicle). That and they've used TKS derived service modules to deliver large station modules (launched on Proton). Certainly the US can do the same. You can't just slap an inert module on the end of a service module and expect the stack to be controllable. If you look carefully at Orbital's Cygnus, the pressurized module has RCS clusters arrayed around the front end. They're fed by propellant lines running *through the module* to the service module in the aft end. Ditto the Progress-derived modules and the TKS. They've got RCS clusters at both ends for controllability. Bottom line is that the ISS module must be fairly tightly integrated with the service module. Very little opportunity? I think not. HTV is flying and has provisions for unpressurized cargo. Dragon does as well (14 m3 volume for unpressurized cargo). I'm not sure about OSC's vehicle... Current version of Cygnus has no unpressurized cargo accommodation, but a variant could be developed that would do so. If the number is four Dragon flights to equal a typical MPLM flight, then SpaceX only needs to cost less than $360 million dollars. I think they'd have to screw up a lot, or be NASA regulationed to death to hit that high. Unfortunately, both are completely within the realm of possibility. True, but to me, this is still better than SLS. The one silver lining to NASA screwing the pooch on Ares I and Orion is that they *have* to rely on commercial providers for ISS resupply. Well, no, they *could* just continue to use Soyuz and Progress provided Congress continues to waive INKSNA. Might even be cheaper if ISS ends in 2020. |
#25
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Dragon to cost about $140 million per launch
On 10/27/2011 07:49 AM, Jeff Findley wrote:
In , bthorn64 @suddenlink.net says... On Thu, 27 Oct 2011 10:31:24 +1100, Alan Erskine wrote: There's another point to this. If anyone wants to build a replacement for ISS, they will be able to use Falcon Heavy - more than twice the payload of Shuttle. What would perform the control, communications, rendezvous and docking? Could a Dragon fly around with 35,000 lbs. of module on its nose? Possibly. If it doesn't have the fuel capacity needed, you could stack two Dragon service modules top of each other. Falcon Heavy gives you plenty of options to "throw mass" at this problem. I already addressed part of this in my other reply, but if you're going to use two Dragons for this task, you need two Dragon *capsules* (Dragon doesn't have a service module) and the capsules would need to be on opposite ends of the module to provide sufficient control authority. Another possibility is the satellite bus that Orbital Sciences is using for their COTS station resupply spacecraft. Ditto here, unless you plan to mount RCS clusters to the other end of the module, as Orbital is doing with Cygnus. |
#26
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Dragon to cost about $140 million per launch
"Jorge R. Frank" scribbled something like ...
You can't just slap an inert module on the end of a service module and expect the stack to be controllable. If you look carefully at Orbital's Cygnus, the pressurized module has RCS clusters arrayed around the front end. They're fed by propellant lines running *through the module* to the service module in the aft end. Ditto the Progress-derived modules and the TKS. They've got RCS clusters at both ends for controllability. Bottom line is that the ISS module must be fairly tightly integrated with the service module. Seems to me the control-of-jets issue is more important than shared plumbing. I'd be thinking about 2 "thin" service modules, with either a wireless connection to a common control port, or a connection that could use a data bus that would be part of the payload module anyway. /dps |
#27
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ISS re-entry scenarios (was Dragon to cost about ...)
"Jorge R. Frank" scribbled something like ...
[...] if ISS ends in 2020. Wandering a bit further afield, have you heard if the simulations show any difference in how much debris will reach the earth for a whole-ISS entry interface vs individual modules entering seperately? I understand that "picking one's spot" argues for diving in as a single unit, although a cheap re-entry "tug" device could assist with control in the IMES scenario. /dps |
#28
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ISS re-entry scenarios (was Dragon to cost about ...)
On Oct 27, 4:38*pm, Snidely wrote:
"Jorge R. Frank" scribbled something like ... [...] if ISS ends in 2020. Wandering a bit further afield, have you heard if the simulations show any difference in how much debris will reach the earth for a whole-ISS entry interface vs individual modules entering seperately? I understand that "picking one's spot" argues for diving in as a single unit, although a cheap re-entry "tug" device could assist with control in the IMES scenario. /dps well a out of control tumbling ISS would likely see structural failure with ISS shedding modules all along its ground track |
#29
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Dragon to cost about $140 million per launch
On 10/27/2011 03:01 PM, Snidely wrote:
"Jorge R. scribbled something like ... You can't just slap an inert module on the end of a service module and expect the stack to be controllable. If you look carefully at Orbital's Cygnus, the pressurized module has RCS clusters arrayed around the front end. They're fed by propellant lines running *through the module* to the service module in the aft end. Ditto the Progress-derived modules and the TKS. They've got RCS clusters at both ends for controllability. Bottom line is that the ISS module must be fairly tightly integrated with the service module. Seems to me the control-of-jets issue is more important than shared plumbing. I'd be thinking about 2 "thin" service modules, with either a wireless connection to a common control port, or a connection that could use a data bus that would be part of the payload module anyway. True, but that's not what Jeff was proposing. He was proposing either Dragon or Cygnus. Dragon doesn't have a service module and Cygnus's service module isn't "thin" in the sense you're talking about. |
#30
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ISS re-entry scenarios (was Dragon to cost about ...)
On 10/27/2011 03:38 PM, Snidely wrote:
"Jorge R. scribbled something like ... [...] if ISS ends in 2020. Wandering a bit further afield, have you heard if the simulations show any difference in how much debris will reach the earth for a whole-ISS entry interface vs individual modules entering seperately? Won't make a whole lot of difference; the structure is aluminum and there is not much "shadowing" effect, especially if the station is maneuvered to a ZVV attitude after the deorbit burn (which would both ensure maximum drag and maximum exposure of modules). |
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