1) Anyone care to speculate/confirm whether a Dragon 2 can dock to a Dragon XL?
Quote from: pochimax on 03/30/2020 08:56 pmQuote from: woods170 on 03/30/2020 02:06 pmQuote from: pochimax on 03/30/2020 12:52 pmIf DragonXL does a slow transfer to NRHO (months), how did SpaceX comply with the unique capability of a fast transfer to Gateway (<30 days)? If NASA request this unique capability.The standard DragonXL launch and travel is not a fully expendable Falcon Heavy? And the fast transit is a fully expendable?I' m a little bit lost.Can you point to the specific requirement for a <30 days transfer to Gateway? I can't seem to find it.File: Attachment_01_GLS_SOW.pdf5.0 MISSION UNIQUE CAPABILITIES (SUBCLIN 103) [pages 29-30]Fast Transit to Gateway: Provide end-to-end cargo delivery services withcargo transit time of 30 days or less. NASA shall have the ability to order this capability within the time defined in the GLS Space System Architecture contract attachment.Perfect! Thank you. It is sometimes challenging to find specifics when an RFP has a kazillion attachments It is a mission unique capability. Here is the first paragraph, which basically explains it all:Quote from: Attachment_01_GLS_SOW5.0 MISSION UNIQUE CAPABILITIES (SUBCLIN 103)The contractor shall provide Mission Unique Capabilities for requirements over and abovelogistic service requirements obtained under subCLINs 101 and 102.These capabilities may be added throughout the life of the contract or they may be incorporated inresponse to specific task order requirements.So, these are non-standard capabilities which MAY be - someday - required by NASA. As such, they are not part of the baseline solution offered by SpaceX.What I think (but I'll have to check with my sources) is that SpaceX is perfectly capable of sending Dragon XL on an expedited trajectory to Gateway, but at the cost of reduced cargo up-mass.Another solution would probably be to to fly FH in fully expendable mode. Which will result in the launch being more expensive to NASA and thus the total number of launches under the fixed price cost cap decreasing.
Quote from: woods170 on 03/30/2020 02:06 pmQuote from: pochimax on 03/30/2020 12:52 pmIf DragonXL does a slow transfer to NRHO (months), how did SpaceX comply with the unique capability of a fast transfer to Gateway (<30 days)? If NASA request this unique capability.The standard DragonXL launch and travel is not a fully expendable Falcon Heavy? And the fast transit is a fully expendable?I' m a little bit lost.Can you point to the specific requirement for a <30 days transfer to Gateway? I can't seem to find it.File: Attachment_01_GLS_SOW.pdf5.0 MISSION UNIQUE CAPABILITIES (SUBCLIN 103) [pages 29-30]Fast Transit to Gateway: Provide end-to-end cargo delivery services withcargo transit time of 30 days or less. NASA shall have the ability to order this capability within the time defined in the GLS Space System Architecture contract attachment.
Quote from: pochimax on 03/30/2020 12:52 pmIf DragonXL does a slow transfer to NRHO (months), how did SpaceX comply with the unique capability of a fast transfer to Gateway (<30 days)? If NASA request this unique capability.The standard DragonXL launch and travel is not a fully expendable Falcon Heavy? And the fast transit is a fully expendable?I' m a little bit lost.Can you point to the specific requirement for a <30 days transfer to Gateway? I can't seem to find it.
If DragonXL does a slow transfer to NRHO (months), how did SpaceX comply with the unique capability of a fast transfer to Gateway (<30 days)? If NASA request this unique capability.The standard DragonXL launch and travel is not a fully expendable Falcon Heavy? And the fast transit is a fully expendable?I' m a little bit lost.
5.0 MISSION UNIQUE CAPABILITIES (SUBCLIN 103)The contractor shall provide Mission Unique Capabilities for requirements over and abovelogistic service requirements obtained under subCLINs 101 and 102.These capabilities may be added throughout the life of the contract or they may be incorporated inresponse to specific task order requirements.
<snip>I do wonder how many other customers there would be for this kind of thing. Surely the creation of a class of small, temporary and private space station(s) in LEO would help SpaceX fund SS/SH development?1) Anyone care to speculate/confirm whether a Dragon 2 can dock to a Dragon XL? 2) Could it be done autonomously? (e.g. so crew of two could just be payload specialists, or spaceflight participants).3) Just because Dragon XL is not designed to re-enter the atmosphere need not make it "expendable" if it could be reused by multiple visiting vehicles. 4) If Dragon XL is being designed to host a Canadarm, could it retrieve payloads from the trunk of a visiting Dragon 2?5) Would it be possible to use the visiting Dragon 2 as an airlock (i.e. shut the hatch between D2 and Dragon XL and open and close the main side hatch)?....
Quote from: Robotbeat on 03/28/2020 05:08 pmQuote from: jarmumd on 03/28/2020 01:46 pmQuote from: dgmckenzie on 03/28/2020 11:37 amIf it is supposed to transfer both pressurized and unpressurized cargo, how could it have docking at both ends?Also, SpaceX would need to build their own IDSS passive docking port. Contrary to popular belief, the current system does not have the equipment to act as a passive for other vehicles to dock (ie not androgynous)....Citation needed. The standard specifies it must be androgynous (at least for active side). If it's not androgynous, it's not IDSS.For Crew Dragon, androgyny is a safety consideration as well to allow rescue. Doubtful that they'd change the spec for Dragon XL as that'd require more certification.If you're right, then you should be able to provide a reference. If you're just supposing, then you should say so.I'm the citation, I work on docking systems.Also, if you look at any high resolution picture of the SpaceX docking system, there are no passive strikers or hooks, so there is nothing to soft or hard capture to.
Quote from: jarmumd on 03/28/2020 01:46 pmQuote from: dgmckenzie on 03/28/2020 11:37 amIf it is supposed to transfer both pressurized and unpressurized cargo, how could it have docking at both ends?Also, SpaceX would need to build their own IDSS passive docking port. Contrary to popular belief, the current system does not have the equipment to act as a passive for other vehicles to dock (ie not androgynous)....Citation needed. The standard specifies it must be androgynous (at least for active side). If it's not androgynous, it's not IDSS.For Crew Dragon, androgyny is a safety consideration as well to allow rescue. Doubtful that they'd change the spec for Dragon XL as that'd require more certification.If you're right, then you should be able to provide a reference. If you're just supposing, then you should say so.
Quote from: dgmckenzie on 03/28/2020 11:37 amIf it is supposed to transfer both pressurized and unpressurized cargo, how could it have docking at both ends?Also, SpaceX would need to build their own IDSS passive docking port. Contrary to popular belief, the current system does not have the equipment to act as a passive for other vehicles to dock (ie not androgynous)....
If it is supposed to transfer both pressurized and unpressurized cargo, how could it have docking at both ends?
Quote from: mikelepage on 03/31/2020 06:51 am<snip>I do wonder how many other customers there would be for this kind of thing. Surely the creation of a class of small, temporary and private space station(s) in LEO would help SpaceX fund SS/SH development?1) Anyone care to speculate/confirm whether a Dragon 2 can dock to a Dragon XL? 2) Could it be done autonomously? (e.g. so crew of two could just be payload specialists, or spaceflight participants).3) Just because Dragon XL is not designed to re-enter the atmosphere need not make it "expendable" if it could be reused by multiple visiting vehicles. 4) If Dragon XL is being designed to host a Canadarm, could it retrieve payloads from the trunk of a visiting Dragon 2?5) Would it be possible to use the visiting Dragon 2 as an airlock (i.e. shut the hatch between D2 and Dragon XL and open and close the main side hatch)?....@jarmumd posted up thread regarding your 1) queryQuote from: jarmumd on 03/28/2020 05:24 pmQuote from: Robotbeat on 03/28/2020 05:08 pmQuote from: jarmumd on 03/28/2020 01:46 pmQuote from: dgmckenzie on 03/28/2020 11:37 amIf it is supposed to transfer both pressurized and unpressurized cargo, how could it have docking at both ends?Also, SpaceX would need to build their own IDSS passive docking port. Contrary to popular belief, the current system does not have the equipment to act as a passive for other vehicles to dock (ie not androgynous)....Citation needed. The standard specifies it must be androgynous (at least for active side). If it's not androgynous, it's not IDSS.For Crew Dragon, androgyny is a safety consideration as well to allow rescue. Doubtful that they'd change the spec for Dragon XL as that'd require more certification.If you're right, then you should be able to provide a reference. If you're just supposing, then you should say so.I'm the citation, I work on docking systems.Also, if you look at any high resolution picture of the SpaceX docking system, there are no passive strikers or hooks, so there is nothing to soft or hard capture to.
Also, if you look at any high resolution picture of the SpaceX docking system, there are no passive strikers or hooks, so there is nothing to soft or hard capture to.
QuoteAlso, if you look at any high resolution picture of the SpaceX docking system, there are no passive strikers or hooks, so there is nothing to soft or hard capture to.Is it true? I thought an APAS can act as active or passive as needed. <removed image. PLEASE, do NOT embed images. Attach only>
How hard would it be to retrofit passive elements to an existing design? Is the lack of strikers or hooks a critical design flaw, or is it something that can be rectified if SpaceX actually cared?
Quote from: rakaydos on 03/31/2020 11:39 amHow hard would it be to retrofit passive elements to an existing design? Is the lack of strikers or hooks a critical design flaw, or is it something that can be rectified if SpaceX actually cared?I think you are missing the point. Everything is built to the minimum that meets requirements. Every extra thing, passive docking components, airlocks, it's not just the hardware, it's the money to build it, test it, the documentation to certify it. I know many people on this forum think it's easy, and sure it's not that hard to get the machinists to build it. But certifying it is probably more the double the cost and more critically, the time.Every time you add something, you need to think about "what if". What if something fails, then something else fails, or combinations of other failures. Every "what if" is analysis and documentation and meetings. Now multiply that by every component - the work load becomes exponential. Minimum Viable Product is the name of the game.
When RFP's are put out for systems that are needed and you've got one, two, or three options you are pretty much stuck with those options.
For big contracts engineers are utilized and a better sense of value can be determined. However, when there is limited competion you have to pick from the options available.
Even if an option is "overpriced" for what is being done...
Also just as a side note, regardless of the capability of the individuals that work for the government they are hindered by the system that moves slow and inefficiently.
It's interesting, because lack of passive capability reduces safety of the IDSS design. One of the main features of an androgynous design (over probe and drogue, for instance) is ability to rescue and overall operational flexibility and contingency.
Quote from: Robotbeat on 03/31/2020 05:30 pmIt's interesting, because lack of passive capability reduces safety of the IDSS design. One of the main features of an androgynous design (over probe and drogue, for instance) is ability to rescue and overall operational flexibility and contingency.In general, you aren't wrong, but where we are today it doesn't matter. For instance, to your points on rescue, operational flexibility, contingency.... how? Rescue what?What would the scenario have to be to have Orion or CST-100 dock to a Dragon (if it was equipped)? In any contingency you might be thinking of, the existing spacecraft must have enough redundancies and equipment to make it back to earth safely. Why design for something that is so far out of the fault space? There is no reasonable circumstance in which you could launch a rescue spacecraft in time to do anything. The exception to this is if one is already docked to the ISS.And if you are already at the ISS, what's the point? And if things were so bad that you needed to go from one spacecraft to the other, wouldn't it make more sense to just open the hatches, throw a line and go across? Or, why would you be docking two healthy spacecraft in this scenario? If one is so damaged it cannot return to earth, are you sure it could even be docked to?In case my tone comes across wrong, understand that I do agree with you in principal, but once you go down the rabbit hole, you'll see there just isn't a credible reason now to have this capability, and I haven't seen a reasonable need to have it in the future, specifically for commercial crew or cargo resupply.
Quote from: Robotbeat on 03/31/2020 05:30 pmIt's interesting, because lack of passive capability reduces safety of the IDSS design. One of the main features of an androgynous design (over probe and drogue, for instance) is ability to rescue and overall operational flexibility and contingency.In general, you aren't wrong, but where we are today it doesn't matter. For instance, to your points on rescue, operational flexibility, contingency.... how? Rescue what?What would the scenario have to be to have Orion or CST-100 dock to a Dragon (if it was equipped)? In any contingency you might be thinking of, the existing spacecraft must have enough redundancies and equipment to make it back to earth safely. Why design for something that is so far out of the fault space? There is no reasonable circumstance in which you could launch a rescue spacecraft in time to do anything. The exception to this is if one is already docked to the ISS.And if you are already at the ISS, what's the point? If a spacecraft is so damaged it cannot return to earth, are you sure it could even be docked to?In case my tone comes across wrong, understand that I do agree with you in principal, but once you go down the rabbit hole, you'll see there just isn't a credible reason now to have this capability, and I haven't seen a reasonable need to have it in the future, specifically for commercial crew or cargo resupply.
Another one was Dragon autonomously docking to Orion with orion serving as a passive side because its AR&D wasn’t finished, yet. This was one possibility considered for getting a 2020 trip around the Moon with people in orion.
It's like the Shuttle Columbia rescue scenario - fast-track another Shuttle to launch to rescue the crew - but imagine if there had been something like Dragon or Starliner that could have docked to the Shuttle. And while Starliner and Dragon are currently going to ISS, the ISS will be splashed someday. Or maybe one is flying some independent tourists, or to a private space station. Missions that find themselves in danger are almost always failures of imagination. Not allowing for the possibility of being able to be docked to in an emergency situation IMO is a failure of imagination as well.
Quote from: whitelancer64 on 03/31/2020 06:39 pmIt's like the Shuttle Columbia rescue scenario - fast-track another Shuttle to launch to rescue the crew - but imagine if there had been something like Dragon or Starliner that could have docked to the Shuttle. And while Starliner and Dragon are currently going to ISS, the ISS will be splashed someday. Or maybe one is flying some independent tourists, or to a private space station. Missions that find themselves in danger are almost always failures of imagination. Not allowing for the possibility of being able to be docked to in an emergency situation IMO is a failure of imagination as well.I don't think there is any credible scenario where a spacecraft is "fast-tracked" to launch a rescue. For the foreseeable future, all spacecraft are visiting a space station. Maybe there is a scenario where you can't dock to the station, but another capsule can dock to you? Maybe. But what if Shuttle were putting up a satellite or going to Hubble? There just isn't the fuel for a capsule to go and rescue them, starting at the ISS. So apply that to anything coming in the future. I just don't think there is such a thing as a capsule going to rescue another capsule. Maybe some form of proximity operations at a station, but then you probably also have other options.I'll caveat that to say that I do think that we would need an androgynous docking system if we had multiple commercial lunar landers. But even then, weight is so critical to lunar operations, I think you would explore every other option in fault space before taking a large amount of useless mass with you. If you only have a single lander, then it's the same as the ISS. And if you were to have an "Active" on an Orion, and a "Passive" on a lander, well then you have contingencies at gateway because you could do Orion->Lander or Orion->Gateway->Lander, so there still isn't a need for androgyny.
There just isn't the fuel for a capsule to go and rescue them, starting at the ISS.
I just don't think there is such a thing as a capsule going to rescue another capsule.
Quote from: jarmumd on 03/31/2020 05:53 pmQuote from: Robotbeat on 03/31/2020 05:30 pmIt's interesting, because lack of passive capability reduces safety of the IDSS design. One of the main features of an androgynous design (over probe and drogue, for instance) is ability to rescue and overall operational flexibility and contingency.In general, you aren't wrong, but where we are today it doesn't matter. For instance, to your points on rescue, operational flexibility, contingency.... how? Rescue what?What would the scenario have to be to have Orion or CST-100 dock to a Dragon (if it was equipped)? In any contingency you might be thinking of, the existing spacecraft must have enough redundancies and equipment to make it back to earth safely. Why design for something that is so far out of the fault space? There is no reasonable circumstance in which you could launch a rescue spacecraft in time to do anything. The exception to this is if one is already docked to the ISS.And if you are already at the ISS, what's the point? If a spacecraft is so damaged it cannot return to earth, are you sure it could even be docked to?In case my tone comes across wrong, understand that I do agree with you in principal, but once you go down the rabbit hole, you'll see there just isn't a credible reason now to have this capability, and I haven't seen a reasonable need to have it in the future, specifically for commercial crew or cargo resupply.It's a good point. The only way I see it working is how they did it with shuttle at the end, with every manned U.S space launch, a secondary option must be ready to launch within a given time frame (48/72 hours?). With Orion, Starliner and Crew Dragon, we have the options.