Crew Dragon or Orion to Hubble for CMG Replacement?

[Cherokee43v6]

Interesting to see this thread come back from the dead.

Way upthread there was discussion of a Dragon/Cygnus concept where the airlock would be on the Cygnus.

Since this is a SpaceX thread and since this originally was put up SpaceX was awarded a supply contract for Gateway, how about a DragonXL/CrewDragon mission concept?

Don't forget that the Space Shuttle's payload bay acted as a work platform to hold the Hubble.  It provided places to hold the replacement equipment ready for installation.  It provided the robotic arm that was required to move the astronauts into the the correct positions and hold them steady while performing the work.  Finally, it provided a measure of safety (and mental orientation), in that if an astronaut did happen to come loose from their tethers or bindings, nearly half their available sky was the ship.

Crew Dragon would not be able to provide any of that on its own.

[groknull]

What if a module was built that had a docking adapter and support for 2 Z-2 suits and would fit in dragon's trunk? It could separate and dragon could dock with it LEM style. All systems would be tested before the dragon hatch was opened. The Z-2 suits have a built in airlock called a suit port, so they would be attached to the module the whole time with the astronauts entering from the support module. Then two astronauts would enter the Z-2 suits with the help of a third who stays with the capsule. The dragon hatch could be closed when the suits are pressurized for some extra protection from failures of the suit airlocks (though the astros in the suits obviously would be relying on success of that suit airlock). Any large components needed would either be attached to the outside of the Z-2 support module, or pre positioned by a previous flight.

This would all be purpose built hardware and none of it could return, so definitely not an inexpensive or quick undertaking. I don't know if Z-2 would be up to the task. Astronaut positioning and locomotion would have to be resolved since a canada arm is not a given; though perhaps a smaller version could also be part of the Z-2 support module.

An airlock module/docking adapter also solves a few other issues:

Depressurizing Dragon - are the avionics/other systems rated for vacuum? With a separate airlock there is no need to depressurize Dragon.
Docking compatibility - the passive docking collar on HST is LIDS, which is *not* IDSS/NDS/SpxDS compatible.
Volume for suit storage and airlock systems

The module needs a few other systems as well. It needs at least enough GNC/prop capability to hold attitude for Dragon to dock with it. It will block the Dragon's nose cone thrusters, so the module would need to provide its own, commandable by the Dragon. It will block the Dragon's GNC sensors, so the module would also need to provide its own, with a command/data passthrough for the sensor data to reach Dragon.

If the module is launched separately on another F9, it could be made big enough to accommodate external robotics/HST components. Clearance with the Dragon nose cone would constrain the geometry of the module on that side.

If designed properly, the module could be left behind on HST to facilitate further servicing missions.

Many of the features and capabilities you suggest for an airlock module / docking adapter are already in the design of the Dragon XL for Lunar Gateway resupply.

Probable modifications needed:
- Addition of an active passive docking port on the cargo end of the Dragon XL with clearance for Dragon 2 nose cone.
- Addition of a sideways facing EVA hatch.
- Addition of external storage for mission specific modules and tools.

Features already present:
- Forward facing thrusters to functionally replace the occluded forward thrusters on the Dragon 2 docked aft.
- Solar arrays.
- Power, data and command connections already in docking port design.
- Maneuvering thrusters.
- Long duration capability.
- Standard docking port forward - could dock with ISS and left there between Hubble servicing (and other) missions.  Aft docking port would still allow visiting vehicles to dock.

Edit: active/passive

[Danderman]

If designed properly, the module could be left behind on HST to facilitate further servicing missions.

I am not sure that HST has enough control authority to operate usefully with a multi ton module hanging on the back.

[intrepidpursuit]

What if a module was built that had a docking adapter and support for 2 Z-2 suits and would fit in dragon's trunk? It could separate and dragon could dock with it LEM style. All systems would be tested before the dragon hatch was opened. The Z-2 suits have a built in airlock called a suit port, so they would be attached to the module the whole time with the astronauts entering from the support module. Then two astronauts would enter the Z-2 suits with the help of a third who stays with the capsule. The dragon hatch could be closed when the suits are pressurized for some extra protection from failures of the suit airlocks (though the astros in the suits obviously would be relying on success of that suit airlock). Any large components needed would either be attached to the outside of the Z-2 support module, or pre positioned by a previous flight.

This would all be purpose built hardware and none of it could return, so definitely not an inexpensive or quick undertaking. I don't know if Z-2 would be up to the task. Astronaut positioning and locomotion would have to be resolved since a canada arm is not a given; though perhaps a smaller version could also be part of the Z-2 support module.

An airlock module/docking adapter also solves a few other issues:

Depressurizing Dragon - are the avionics/other systems rated for vacuum? With a separate airlock there is no need to depressurize Dragon.
Docking compatibility - the passive docking collar on HST is LIDS, which is *not* IDSS/NDS/SpxDS compatible.
Volume for suit storage and airlock systems

The module needs a few other systems as well. It needs at least enough GNC/prop capability to hold attitude for Dragon to dock with it. It will block the Dragon's nose cone thrusters, so the module would need to provide its own, commandable by the Dragon. It will block the Dragon's GNC sensors, so the module would also need to provide its own, with a command/data passthrough for the sensor data to reach Dragon.

If the module is launched separately on another F9, it could be made big enough to accommodate external robotics/HST components. Clearance with the Dragon nose cone would constrain the geometry of the module on that side.

If designed properly, the module could be left behind on HST to facilitate further servicing missions.

Many of the features and capabilities you suggest for an airlock module / docking adapter are already in the design of the Dragon XL for Lunar Gateway resupply.

Probable modifications needed:
- Addition of an active passive docking port on the cargo end of the Dragon XL with clearance for Dragon 2 nose cone.
- Addition of a sideways facing EVA hatch.
- Addition of external storage for mission specific modules and tools.

Features already present:
- Forward facing thrusters to functionally replace the occluded forward thrusters on the Dragon 2 docked aft.
- Solar arrays.
- Power, data and command connections already in docking port design.
- Maneuvering thrusters.
- Long duration capability.
- Standard docking port forward - could dock with ISS and left there between Hubble servicing (and other) missions.  Aft docking port would still allow visiting vehicles to dock.

Edit: active/passive

The whole reason for using the X-2 suits is their self contained suit port airlock capability, which would eliminate the need for extensive support systems and an EVA suit sized airlock.

Dragon has capability to operate in proximity to station without using its nose thrusters. I know it uses those thrusters for orbit raising and lowering maneuvers, but it does have at least some control capability with those thrusters disabled. I don't know what dragons control capabilities would be with a mass on the nose. I think that falls into the "rockets are not legos" category of possibility.

I think that adding an additional hatch it a capsule, especially on a different axis, would basically require a complete redesign of the pressure vessel. Flying the support module on a separate flight does require it to have power generation, station keeping, navigation, and a whole spacecraft bus worth of capabilities that could hopefully be avoided by carrying it on dragon. If it does have all those capabilities, then maybe having it station keep near HST is a possible option. Designing an autonomous, long lived, human rated service craft seems like massive undertaking to me though. I would think that with the diminishing scientific value of HST I'd think that minimizing cost or developing things that have uses elsewhere like the Z-2 suit would be useful goals.

All that said, the Northrop maintenance vehicle might be a good place to start with a service craft bus if we were to go that route.

[Jorge]

What if a module was built that had a docking adapter and support for 2 Z-2 suits and would fit in dragon's trunk? It could separate and dragon could dock with it LEM style. All systems would be tested before the dragon hatch was opened. The Z-2 suits have a built in airlock called a suit port, so they would be attached to the module the whole time with the astronauts entering from the support module. Then two astronauts would enter the Z-2 suits with the help of a third who stays with the capsule. The dragon hatch could be closed when the suits are pressurized for some extra protection from failures of the suit airlocks (though the astros in the suits obviously would be relying on success of that suit airlock). Any large components needed would either be attached to the outside of the Z-2 support module, or pre positioned by a previous flight.

This would all be purpose built hardware and none of it could return, so definitely not an inexpensive or quick undertaking. I don't know if Z-2 would be up to the task. Astronaut positioning and locomotion would have to be resolved since a canada arm is not a given; though perhaps a smaller version could also be part of the Z-2 support module.

An airlock module/docking adapter also solves a few other issues:

Depressurizing Dragon - are the avionics/other systems rated for vacuum? With a separate airlock there is no need to depressurize Dragon.
Docking compatibility - the passive docking collar on HST is LIDS, which is *not* IDSS/NDS/SpxDS compatible.
Volume for suit storage and airlock systems

The module needs a few other systems as well. It needs at least enough GNC/prop capability to hold attitude for Dragon to dock with it. It will block the Dragon's nose cone thrusters, so the module would need to provide its own, commandable by the Dragon. It will block the Dragon's GNC sensors, so the module would also need to provide its own, with a command/data passthrough for the sensor data to reach Dragon.

If the module is launched separately on another F9, it could be made big enough to accommodate external robotics/HST components. Clearance with the Dragon nose cone would constrain the geometry of the module on that side.

If designed properly, the module could be left behind on HST to facilitate further servicing missions.

Many of the features and capabilities you suggest for an airlock module / docking adapter are already in the design of the Dragon XL for Lunar Gateway resupply.

Yes, I left unsaid the (tautological?) statement that however SpaceX implements the airlock module, it would make sense to use an existing design (Dragon or Dragon XL) as a starting point. Perhaps I shouldn't have left that unsaid.

[Jorge]

If designed properly, the module could be left behind on HST to facilitate further servicing missions.

I am not sure that HST has enough control authority to operate usefully with a multi ton module hanging on the back.

I am not sure either, but decided to mention the possibility, at least. (And the "If designed properly" clause leaves a lot of wiggle room for the module to be designed to assist HST control, at the cost of modifying HST to command the module.)

[Danderman]

This is an interesting discusión, but it would be nice if concepts could focus on limiting cost. Otherwise the “why not build a new telescope” meme would emerge.

[watermod]

This is an interesting discusión, but it would be nice if concepts could focus on limiting cost. Otherwise the “why not build a new telescope” meme would emerge.

Wait a year until Musk has a StarShip that opens it's maw to release mass numbers of StarLink sats.   
After it releases a load it can tank up from a tanker StarShip then go to Hubble with an open maw.
Have a small arm and several tethers on it.  Use the arm to tether Hubble and Hubble's solar arrays.
Have a giant bolt cutter on the end of the arm to snip off all the solar arrays and anything else sticking too far out.
Then use the arm to move it all inside the StarShip Maw.  Close the maw and return to Earth with Hubble. 
Fix it or put it in a museum ... whatever.   It's safely down and can be repaired on Earth.   Relaunch with StarShip and a
refueling should not be too bad.

[Danderman]

There is a risk that waiting for a Starship that can service HST might take longer than HST's remaining lifetime.

This topic is about servicing HST using Dragon.

[su27k]

I think the Mission Extension Vehicle (MEV) concept mentioned by Jim and russianhalo117 is a much better bet than trying to mod Crew Dragon for an one time only crewed service mission.

[Danderman]

I think the Mission Extension Vehicle (MEV) concept mentioned by Jim and russianhalo117 is a much better bet than trying to mod Crew Dragon for an one time only crewed service mission.

This is a robotic solution?

[su27k]

Yes, robotic mission. Back when they proposed it, Crew Dragon hasn't demonstrated automated docking with ISS, nor has NG MEV-1 demonstrated docking with a GEO satellite. Now these have all become reality, I think a robotic service mission should be a no-brainer.

[Danderman]

I was really hoping that this topic would stick to the issues around a Dragon mission to Hubble. If someone wants to talk about robotic missions, or building a new telescope, they are free to start a new topic for that.

One reason for a crewed mission is to replace gyros. Easy job for humans.

[Danderman]

In the early part of the last decade, SpaceX produced a presentation either about or including servicing of HST with Dragon. Anyone have a copy of that presentation?

It's probably somewhere on this site.

It might even be in this topic... 

[su27k]

I'm guessing this is the presentation you're looking for: https://forum.nasaspaceflight.com/index.php?topic=28805.msg893965#msg893965

I didn't know this presentation existed before, very interesting. That whole thread is worth re-reading, laid out a lot of problems with a crewed service mission using Dragon.

[Danderman]

I'm guessing this is the presentation you're looking for: https://forum.nasaspaceflight.com/index.php?topic=28805.msg893965#msg893965

I didn't know this presentation existed before, very interesting. That whole thread is worth re-reading, laid out a lot of problems with a crewed service mission using Dragon.

Bingo.

It seems a very limited and cumbersome approach, using a robotic arm that would be discarded during the mission. There almost doesn't seem to be a role for a crew in this architecture, since the arm could be operated from the ground.

It looks like the 2010 version of Dragon could not support EVA, don't know if that is true for the 2020 Crew Dragon.

[DistantTemple]

This is an interesting discusión, but it would be nice if concepts could focus on limiting cost. Otherwise the “why not build a new telescope” meme would emerge.

Wait a year until Musk has a StarShip that opens it's maw to release mass numbers of StarLink sats.   
After it releases a load it can tank up from a tanker StarShip then go to Hubble with an open maw.
Have a small arm and several tethers on it.  Use the arm to tether Hubble and Hubble's solar arrays.
Have a giant bolt cutter on the end of the arm to snip off all the solar arrays and anything else sticking too far out.
Then use the arm to move it all inside the StarShip Maw.  Close the maw and return to Earth with Hubble. 
Fix it or put it in a museum ... whatever.   It's safely down and can be repaired on Earth.   Relaunch with StarShip and a
refueling should not be too bad.

Not very safe for the belly flop manoeuvre! And then the boost upright.. then deceleration to land!. It will be well shaken, although at least not stirred!
So it would need to be very securely grasped by SS. I don't know the attachment points on Hubble, and if they could be reused securely.
If its destined for a museum, moderate damage may not be a critical issue. But it must land without crashing.... If thats unlikely, then put off the attempt until SS is improved... and then maybe we're back on the human servicing!

[John Santos]

Not very safe for the belly flop manoeuvre! And then the boost upright.. then deceleration to land!. It will be well shaken, although at least not stirred!
So it would need to be very securely grasped by SS. I don't know the attachment points on Hubble, and if they could be reused securely.
If its destined for a museum, moderate damage may not be a critical issue. But it must land without crashing.... If thats unlikely, then put off the attempt until SS is improved... and then maybe we're back on the human servicing!

Hubble was designed to be retrieved on the Shuttle.  It has standard shuttle trunion attachment points and can easily withstand the vertical, horizontal and rotational forces of a shuttle reentry and landing.  Do we know anything about how SS reentry compares to that?

The solar arrays are designed to be removable and replaceable.  They may also be retractable, but on one servicing mission, IIRC they tried to retract them but couldn't so they just released the arrays and they most likely soon reentered on their own (low mass, high drag.)

[Coastal Ron]

Not very safe for the belly flop manoeuvre! And then the boost upright.. then deceleration to land!. It will be well shaken, although at least not stirred!
So it would need to be very securely grasped by SS. I don't know the attachment points on Hubble, and if they could be reused securely.
If its destined for a museum, moderate damage may not be a critical issue. But it must land without crashing.... If thats unlikely, then put off the attempt until SS is improved... and then maybe we're back on the human servicing!

Hubble was designed to be retrieved on the Shuttle.  It has standard shuttle trunion attachment points and can easily withstand the vertical, horizontal and rotational forces of a shuttle reentry and landing.  Do we know anything about how SS reentry compares to that?

Hubble launched in a vertical position on the Shuttle so the real question is how would it do with horizontal forces. But if it was designed to be retrieved by the Shuttle, then it should do OK with a Starship retrieval.

[Coastal Ron]

I'm guessing this is the presentation you're looking for: https://forum.nasaspaceflight.com/index.php?topic=28805.msg893965#msg893965

I didn't know this presentation existed before, very interesting. That whole thread is worth re-reading, laid out a lot of problems with a crewed service mission using Dragon.

Bingo.

It seems a very limited and cumbersome approach, using a robotic arm that would be discarded during the mission. There almost doesn't seem to be a role for a crew in this architecture, since the arm could be operated from the ground.

It looks like the 2010 version of Dragon could not support EVA, don't know if that is true for the 2020 Crew Dragon.

In-space servicing by LEO spacecraft could be doable if a LEO "workshop" was used. Such a "workshop" would include an airlock, and it would also host the robotic arm. It could also be a free flying science platform when it wasn't needed otherwise.

Such a vehicle could be based on the current Cygnus spacecraft, with a modification to the Pressurized Cargo Module (PCM) where the end with a docking hatch was for human occupation, and on the far end would be the airlock with a side hatch for egress/ingress.

Because Dragon (or whoever) would be docked on the cargo entrance end, and the Cygnus Service Module (SM) is on the other end, there would need to be two arms (similar to the SpaceX concept), with one holding the target vehicle, and the other for servicing.

If we plan on doing in-space servicing with humans we need something like this anyways.