Author Topic: Should SpaceX Vehicles Have Androgynous Docking Ports?  (Read 10430 times)

Offline woods170

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Re: Re: SpaceX Dragon XL
« Reply #60 on: 04/01/2020 11:40 am »
Imagine how dumb you’d look if you had one of these scenarios happen where the crew could’ve been rescued but they can’t.

“I thought you said the port was androgynous?”
“Well, see the thing is...”

Wrong.

When Crew Dragon launches into orbit, there is no second Crew Dragon on stand-by for a fast rescue launch. Neither is a Starliner standing by. Nor an Orion.
And vice versa.

The scenario where a rescue vehicle was standing by for fast rescue launch only existed in the post-Columbia shuttle era.

Both Orion and the CCP vehicles are required to be robust enough to get themselves out of trouble.
If Dragon or Starliner has a problem detected with their landing system when near ISS but cannot dock, another visiting vehicle could dock with them.

A problem with the landing system will - in fact - be detected even before the vehicle undocks from ISS. The CCP vehicles are thoroughly checked out BEFORE undocking. That is why there is an URR (Undocking Readiness Review). Same was done with shuttle.

Problems with the landing system don't crop up two seconds after undock. Most likely time for an undetected problem with the landing system manifesting itself is when the landing system is activated. And in case of the CCP vehicles that is far past the point that any rescue docking could be performed.

Also, under the scenario you picture there would actually have to be another IDSS compliant vehicle present at the station. Which, in many cases, there won't be. Crew rotation to and from ISS in the CCP era is a mix of CCP vehicles and Soyuz. Needless to say, Soyuz doesn't carry an IDSS compliant docking system. And Starliner being present at the ISS when a Crew Dragon arrives or leaves is not a given (and vice versa).

Offline DistantTemple

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Re: Re: SpaceX Dragon XL
« Reply #61 on: 04/01/2020 11:56 am »
SpaceX looks as if "emergency launch capability" IS something they could offer in the near future. They have a stock of used boosters, and a production line of second stages.

It is something I imagine the military would be interested in. It certainly appears to be an additional protection for HSF, and even communications satellite operators may benefit from it!

I bet even now SX could launch within a week, if they could "steal" components lined up for less critical customers. In many cases this would not even delay such bumped customers much if the boosters and second stages are thoughtfully shuffled/reassigned.

Further if it was a paid for service for NASA and/or USGOV/military/Spaceforce then an additional hanger containing a couple of F9's and a couple of 2nd stages, some standard docking adaptors, and one D2 including an androgynous port, would cover the preparation.  The facility would not need to be dedicated, just additional space, with deliberate "extra stock" to guarantee the "contingency programme".

With a bit of forethought I bet SX could put up an emergency crew rescue within 3 days! Therefore planing to have an androgynous docking capability should not be ruled out. (It would require a spare and ready crew vehicle.)

There is also berthing. I thought I read that in the DXL documents. ( This is off topic but related: And there is also the possibility of spacewalking to the other vehicle, however without airlocks, that means bringing the vehicles to vacuum, and everyone having to be suited up - apart from anyone who can retreat to another connected module and close the hatch there.)

I have just read jarmund's, and other posts and replies just written above. But I will still post this. "If its too damaged to return, will it be too damaged to dock?" That needs more thought than a one-liner assumption! 

Edit: I am avidly reading all woods170's input (and the others discussing it). I am not arguing against what he knows and says is happening now, or the info he has from SX sources. But ISTM the general argument against SX having an emergency launch, and even astronaut rescue capability is not over, and becomes more compelling as their developments continue.
« Last Edit: 04/01/2020 02:26 pm by DistantTemple »
We can always grow new new dendrites. Reach out and make connections and your world will burst with new insights. Then repose in consciousness.

Offline Robotbeat

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Re: Re: SpaceX Dragon XL
« Reply #62 on: 04/01/2020 01:33 pm »
Imagine how dumb you’d look if you had one of these scenarios happen where the crew could’ve been rescued but they can’t.

“I thought you said the port was androgynous?”
“Well, see the thing is...”

Wrong.

When Crew Dragon launches into orbit, there is no second Crew Dragon on stand-by for a fast rescue launch. Neither is a Starliner standing by. Nor an Orion.
And vice versa.

The scenario where a rescue vehicle was standing by for fast rescue launch only existed in the post-Columbia shuttle era.

Both Orion and the CCP vehicles are required to be robust enough to get themselves out of trouble.
If Dragon or Starliner has a problem detected with their landing system when near ISS but cannot dock, another visiting vehicle could dock with them.
Ehm, it doesn't make any sense.  Either your are able to or you are not.
RCS failure, but attitude control remains. Also, failure of the instruments for docking.
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Offline woods170

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Re: Re: SpaceX Dragon XL
« Reply #63 on: 04/01/2020 03:08 pm »
Imagine how dumb you’d look if you had one of these scenarios happen where the crew could’ve been rescued but they can’t.

“I thought you said the port was androgynous?”
“Well, see the thing is...”

Wrong.

When Crew Dragon launches into orbit, there is no second Crew Dragon on stand-by for a fast rescue launch. Neither is a Starliner standing by. Nor an Orion.
And vice versa.

The scenario where a rescue vehicle was standing by for fast rescue launch only existed in the post-Columbia shuttle era.

Both Orion and the CCP vehicles are required to be robust enough to get themselves out of trouble.
If Dragon or Starliner has a problem detected with their landing system when near ISS but cannot dock, another visiting vehicle could dock with them.
Ehm, it doesn't make any sense.  Either your are able to or you are not.
RCS failure, but attitude control remains. Also, failure of the instruments for docking.

You are now talking multiple failures. Not only a failure of the landing system, but failure of RCS or docking instruments as well. Your failure scenario to justify androgynous docking system on CCP vehicles is becoming more-and-more unlikely.

RCS failure would be detected before undocking, due to earlier mentioned checkout of the vehicle prior to undocking. Same for docking instruments.

Besides, the CCP vehicles have back-ups for failure of the automated docking instruments. Like boresight camera's, handheld laser range finders, etc.

RCS is multiple redundant on both CCP vehicles. No way to lose ALL of the RCS yet still have attitude control.

You're grasping for straws here.

Offline jarmumd

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Re: Re: SpaceX Dragon XL
« Reply #64 on: 04/01/2020 04:34 pm »
Who has the hard-dock hooks in a passive-passive docking, even if it's berthed?  I can't see how it would work even in an off-nominal emergency.

So there several things here.  If you used an arm to berth a docking system, one of the systems would still need to drive their "active hooks" - just maybe not their active soft capture system.  So it's probably never completely true to have passive-passive docking, one side has to do something!  Technically either side could drive hooks*.

* SpaceX Docking System must be the active because it doesn't have passive hooks, only active hooks; NDS-B1/B2, IDA have both sets.

Offline jarmumd

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Re: Re: SpaceX Dragon XL
« Reply #65 on: 04/01/2020 04:40 pm »
Is the D2 docking port not an NDSB1 implementation?
Nope. Some parts are similar or exact, others are different.

Minor nit, The SpaceX Docking System is an implementation of the Nasa Docking System (NDS), which is a derivative of the IDSS.  NDS-B1/B2 is a specific mechanism, built by Boeing for NASA.  It's a bit confusing.

Offline russianhalo117

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Re: Re: SpaceX Dragon XL
« Reply #66 on: 04/01/2020 07:02 pm »
So then surely it would make sense for the Gateway modules to have androgynous docking adapters, so they can do both passive with active Orion & Dragon XL, and do active with passive HLS?
Increases mass and cost to have all ports be active. I would only expect the end cone ports to be active as they will be along the velocity vector when initially docking. When moved by arm to their final spot they can be berthed passive mode like a CBM. The IDSS specs did account for active-active and passive-passive configurations however nominal dockings will always have one active side in passive mode.

Who has the hard-dock hooks in a passive-passive docking, even if it's berthed?  I can't see how it would work even in an off-nominal emergency.
Both sides have both a passive set of hooks and an active set of hooks. For example this is the case the PMA's, IDA's and the Russian hybrid SSVP-M8000 and successor SSPA-GM docking ports (SSPA-GM is used on MLM-U and all future RS modules and visiting spacecraft. It supports both Drogue and Cone as well as APAS passive SCS petals which can be removed from there storage position and installed in their docking position either via IVA or while a spacecraft is docked). The SSPA-GM docking ports are also IDSS ready and only require an outfitting EVA to install the retroreflector system and other components. The Soft Capture System/Magnetic Capture System is not required to be deployed when an arm is used depending upon the size and mass of the object being moved and installed. For permanently installed modules both sets of HCS latches are driven closed. Per the standard for VV's it is at the discretion of the entity whether drive and engage both sets.
« Last Edit: 04/01/2020 07:08 pm by russianhalo117 »

Offline Negan

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Re: Re: SpaceX Dragon XL
« Reply #67 on: 04/01/2020 07:14 pm »
My guess would be whatever pressurized docking system Starship will use to dock to another Starship will also be an option for its other spacecraft. They won't be sending multiple crewed Starships to Mars without this ability.
« Last Edit: 04/02/2020 02:58 pm by Negan »

Offline gemmy0I

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Re: Re: SpaceX Dragon XL
« Reply #68 on: 04/01/2020 08:58 pm »
Both sides have both a passive set of hooks and an active set of hooks. For example this is the case the PMA's, IDA's and the Russian hybrid SSVP-M8000 and successor SSPA-GM docking ports (SSPA-GM is used on MLM-U and all future RS modules and visiting spacecraft. It supports both Drogue and Cone as well as APAS passive SCS petals which can be removed from there storage position and installed in their docking position either via IVA or while a spacecraft is docked). The SSPA-GM docking ports are also IDSS ready and only require an outfitting EVA to install the retroreflector system and other components. The Soft Capture System/Magnetic Capture System is not required to be deployed when an arm is used depending upon the size and mass of the object being moved and installed. For permanently installed modules both sets of HCS latches are driven closed. Per the standard for VV's it is at the discretion of the entity whether drive and engage both sets.
Fascinating info here, thanks for sharing!

At the risk of taking this thread (hopefully not too far) off-topic, just so I'm understanding what you're saying here: are you saying that all the Russian docking ports currently on the station are hybrids capable of being converted to APAS with a relatively simple EVA to install a few pieces of hardware already on-station? And that Nauka's new docking port will come pre-configured able to support either probe-and-drogue or IDSS dockings, so long as some simple reflectors and other components are installed on EVA?

Does this apply to visiting Soyuz and Progress vehicles' docking ports as well, i.e. are the ones currently in use "ready" to be converted to dock at an IDSS port with the addition of a few simple pieces of hardware during pre-launch outfitting?

Does this mean that the Shuttle could hypothetically have docked to Zvezda in a contingency situation, requiring only an IVA (or simply internal work while a Soyuz/Progress was docked) to install the APAS compatibility petals?

Offline russianhalo117

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Re: Re: SpaceX Dragon XL
« Reply #69 on: 04/01/2020 10:53 pm »
Both sides have both a passive set of hooks and an active set of hooks. For example this is the case the PMA's, IDA's and the Russian hybrid SSVP-M8000 and successor SSPA-GM docking ports (SSPA-GM is used on MLM-U and all future RS modules and visiting spacecraft. It supports both Drogue and Cone as well as APAS passive SCS petals which can be removed from there storage position and installed in their docking position either via IVA or while a spacecraft is docked). The SSPA-GM docking ports are also IDSS ready and only require an outfitting EVA to install the retroreflector system and other components. The Soft Capture System/Magnetic Capture System is not required to be deployed when an arm is used depending upon the size and mass of the object being moved and installed. For permanently installed modules both sets of HCS latches are driven closed. Per the standard for VV's it is at the discretion of the entity whether drive and engage both sets.
Fascinating info here, thanks for sharing!

At the risk of taking this thread (hopefully not too far) off-topic, just so I'm understanding what you're saying here: are you saying that all the Russian docking ports currently on the station are hybrids capable of being converted to APAS with a relatively simple EVA to install a few pieces of hardware already on-station? And that Nauka's new docking port will come pre-configured able to support either probe-and-drogue or IDSS dockings, so long as some simple reflectors and other components are installed on EVA?

Does this apply to visiting Soyuz and Progress vehicles' docking ports as well, i.e. are the ones currently in use "ready" to be converted to dock at an IDSS port with the addition of a few simple pieces of hardware during pre-launch outfitting?

Does this mean that the Shuttle could hypothetically have docked to Zvezda in a contingency situation, requiring only an IVA (or simply internal work while a Soyuz/Progress was docked) to install the APAS compatibility petals?
Sort of yes. Only the intermodule ports are compatible. The SSVP-G4000 ports where Soyuz, Progress and ATV dock are a flavour of the the original docking system on Almaz and Salyut and most ports on Mir. FGB's aft port was designed during early station operations to be converted to APAS to accept the never flown ICM in the event of SM failing to launch or indefinitely delayed due to Proton-K failures. The other SSVP-M8000 ports could not accept petals in flight but in all other respects are compatible in regards to its HCS.

See: http://russianspaceweb.com/docking.html for an explanation of docking ring types (not updated to reflect the new Russian implementation of IDSS).
« Last Edit: 04/01/2020 11:13 pm by russianhalo117 »

Offline baldusi

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Re: Re: SpaceX Dragon XL
« Reply #70 on: 04/02/2020 12:39 am »
I know NDS B1 has fixed petals. But does anything on the IDSS Rev E standard precludes the use of removable petals?

Offline jarmumd

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Re: Re: SpaceX Dragon XL
« Reply #71 on: 04/02/2020 01:33 am »
I know NDS B1 has fixed petals. But does anything on the IDSS Rev E standard precludes the use of removable petals?

Not to my knowledge, I think if you had a reason to have removable petals, you could.  It would be an operations thing though, since the astronauts would need to be trained in removing and attaching them.  And it would have to be on both sides, otherwise what's the point.

Offline baldusi

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Re: Should SpaceX Vehicles Have Androgynous Docking Ports?
« Reply #72 on: 04/02/2020 06:39 am »
The difference is 800mm vs 1100mm passage width. It's more than double the area. At least for the node ports, keeping the capability might be important. Unless they keep a CBM port.

Offline Robotbeat

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Re: Should SpaceX Vehicles Have Androgynous Docking Ports?
« Reply #73 on: 04/02/2020 02:38 pm »
The difference is 800mm vs 1100mm passage width. It's more than double the area. At least for the node ports, keeping the capability might be important. Unless they keep a CBM port.
Right. The docking port is the replacement for the CBM port in deep space and would be effectively permanent, so in some cases you might as well remove the petals.
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To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Negan

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Re: Should SpaceX Vehicles Have Androgynous Docking Ports?
« Reply #74 on: 04/02/2020 03:33 pm »
Should Dragon 2's  for the private flights be androgynous?

Offline russianhalo117

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Re: Should SpaceX Vehicles Have Androgynous Docking Ports?
« Reply #75 on: 04/02/2020 03:36 pm »
Should Dragon 2's  for the private flights be androgynous?
Yes. The Docking system is a permanently installed on each Dragon 2.

Offline jarmumd

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Re: Should SpaceX Vehicles Have Androgynous Docking Ports?
« Reply #76 on: 04/02/2020 04:02 pm »
The difference is 800mm vs 1100mm passage width. It's more than double the area. At least for the node ports, keeping the capability might be important. Unless they keep a CBM port.
Right. The docking port is the replacement for the CBM port in deep space and would be effectively permanent, so in some cases you might as well remove the petals.

There is a quote I love:  He who sets the requirements first, wins. 

It's probably the way of things to design anything you need to transfer, to be able to fit through the existing docking port.  Rather than to design the docking port for things that you don't know you need to transfer yet.

Offline Robotbeat

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Re: Should SpaceX Vehicles Have Androgynous Docking Ports?
« Reply #77 on: 04/02/2020 04:06 pm »
The difference is 800mm vs 1100mm passage width. It's more than double the area. At least for the node ports, keeping the capability might be important. Unless they keep a CBM port.
Right. The docking port is the replacement for the CBM port in deep space and would be effectively permanent, so in some cases you might as well remove the petals.

There is a quote I love:  He who sets the requirements first, wins. 

It's probably the way of things to design anything you need to transfer, to be able to fit through the existing docking port.  Rather than to design the docking port for things that you don't know you need to transfer yet.
I'm going to steal that quote.

It does tend to limit use of ISS spares and legacy hardware.
« Last Edit: 04/02/2020 04:07 pm by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Negan

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Re: Should SpaceX Vehicles Have Androgynous Docking Ports?
« Reply #78 on: 04/02/2020 04:20 pm »
Should Dragon 2's  for the private flights be androgynous?
Yes. The Docking system is a permanently installed on each Dragon 2.

I meant fully androgynous.

In other words: two SpaceX docking systems can NOT dock to each other, because they are not fully androgynous. The active hooks on one side would find NO passive hooks on the other side to latch onto.

Offline russianhalo117

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Re: Should SpaceX Vehicles Have Androgynous Docking Ports?
« Reply #79 on: 04/02/2020 06:56 pm »
Who has the hard-dock hooks in a passive-passive docking, even if it's berthed?  I can't see how it would work even in an off-nominal emergency.

So there several things here.  If you used an arm to berth a docking system, one of the systems would still need to drive their "active hooks" - just maybe not their active soft capture system.  So it's probably never completely true to have passive-passive docking, one side has to do something!  Technically either side could drive hooks*.

* SpaceX Docking System must be the active because it doesn't have passive hooks, only active hooks; NDS-B1/B2, IDA have both sets.
As with Rassvet installation on ISS docking system power, data and momentum required to engage the probe locking mechanism in the cone was done via the arm.

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