Polaris Program (Dragon and Starship crewed missions led by Isaacman)

[SDSmith]

Another thing I think we need to look at is Dragon on orbit endurance. Consumables, fuel, ECLSS... Especially when accounting for cabin depressurization.

Dragon is shorter than Shuttle, but how much can it be expanded? Shuttle had a larger crew to spread workload around. Because it had an airlock, the non-eva crew was able to do more work than the non-eva crew in dragon will (I would think - they are basically in EVA too at that point)

I think a boost mission would be a priority. Gyro replacement would be a bonus. So the mission would proceed something like: Launch, Dock, Boost, EVA(s), repress, undock, deorbit. First do no harm mentality - probably only replacing the failed gyros, leaving current operational gyros intact.

This site contains good reference information about STA-125 and the Hubble EVA plans. Haven't read through it all yet, but of anyone else is looking to learn more, maybe this will interest you. I'm trying to grasp just how involved an EVA would be...

https://www.nasa.gov/centers/johnson/news/flightdatafiles/foia_archive.html
 https://www.nasa.gov/centers/johnson/pdf/345766main_EVA_125_F_A.pdf

The Crew Dragon already carries enough air supply to repressurize the cabin in case of a full depressurization, so that's a non-issue.

IIRC, nominally the Dragon only carries a few days worth of supplies. For example, the Inspiration 4 flight only lasted 3 days.  The first Polaris Dawn mission is supposed to last 5 days.

Presumably more internal storage space could be used for more supplies for longer duration flights, but IMO a 5 day flight should be more than sufficient for a Hubble reboost and one EVA for gyro replacement.

Repress: I do know that they can repressurize at least once. The question is:

1. how many EVAs would be necessary for servicing?
2. How many contingency EVAs do they need to plan for?
3. How many times can they repressurize?

(If 1+2 > 3 then they need to plan for that. Multiple possible solutions exist: Adding consumables for additional repress events, reducing consumables lost during depress, or planning multiple missions, etc.)

It's not an "issue" or a "Non-Issue". Definitely not a 'show stopper'. It's just another interesting factor they need to consider.

Edit:

Consider this: If Dragon can support 1 repress event, and it takes (1) 2-person 6h EVA.
What if the EVA is being schedule?
What if there is an EVA emergency ending early?

You can't just leave Hubble open on the operating table.

So you:
A. Modify dragon to support (2) repress events.
B. Plan a second contingency servicing mission.
C. Accept risk of reentering unpressurized and performed second EVA without repressurizing at the end.

I think one EVA is probably sufficient too, btw. But I don't think planning for only 1 eva is wise. I'm sure Polaris is all over this...

One other item to think about. Weather delays. That could add a day or two.

[ace5]

Very simple Crew Dragon re-boost (no EVA servicing) concept, with a Docking Module for interface with Hubble aft end.

[AstroWare]

Very simple Crew Dragon re-boost (no EVA servicing) concept, with a Docking Module for interface with Hubble aft end.

I don't get how that concept helps...?

Added transposition/docking
Added (2) addition docking systems
Forward thrusters blocked by new module
No room in trunk for a propulsion pallet.

What is the new docking module even for? Just  Adapting the Hubble interface to Dragon interface?

What am I missing...

[sevenperforce]

Ha. Thanks. I don't watch or listen to the NSF broadcasts so missed that. Seems like the simplest, least R&R/Cost way to do a mission like this. I still think if this goes ahead it will end up being two missions. One for boost and another (maybe) replacement of Giros.

Screen capture (cropped) from last night's NSF live showing @brickmack's rendering of Dragon forward thrusters boosting hubble

My prediction appears to have been correct (based on the Isaacman tweet).

With an extensible soft capture adapter, it's possible that they wouldn't need the towel bars at all. They could extend the adapter, execute soft capture, and then retract the adapter, pulling the base of Hubble flush against the trunk. The trunk handles all gee-loading on Dragon during launch compressively, so the trunk will easily be able to transfer the comparatively much lower forces directly into Hubble's structure.

[Orbiter]

Very simple Crew Dragon re-boost (no EVA servicing) concept, with a Docking Module for interface with Hubble aft end.

I don't get how that concept helps...?

Added transposition/docking
Added (2) addition docking systems
Forward thrusters blocked by new module
No room in trunk for a propulsion pallet.

What is the new docking module even for? Just  Adapting the Hubble interface to Dragon interface?

What am I missing...

It looks similar to a concept for an addon in Orbiter spaceflight simulator. The docking module looks like it would also serve as an airlock, as Dragon's airlock would be blocked.

[whitelancer64]

Another thing I think we need to look at is Dragon on orbit endurance. Consumables, fuel, ECLSS... Especially when accounting for cabin depressurization.

Dragon is shorter than Shuttle, but how much can it be expanded? Shuttle had a larger crew to spread workload around. Because it had an airlock, the non-eva crew was able to do more work than the non-eva crew in dragon will (I would think - they are basically in EVA too at that point)

I think a boost mission would be a priority. Gyro replacement would be a bonus. So the mission would proceed something like: Launch, Dock, Boost, EVA(s), repress, undock, deorbit. First do no harm mentality - probably only replacing the failed gyros, leaving current operational gyros intact.

This site contains good reference information about STA-125 and the Hubble EVA plans. Haven't read through it all yet, but of anyone else is looking to learn more, maybe this will interest you. I'm trying to grasp just how involved an EVA would be...

https://www.nasa.gov/centers/johnson/news/flightdatafiles/foia_archive.html
 https://www.nasa.gov/centers/johnson/pdf/345766main_EVA_125_F_A.pdf

The Crew Dragon already carries enough air supply to repressurize the cabin in case of a full depressurization, so that's a non-issue.

IIRC, nominally the Dragon only carries a few days worth of supplies. For example, the Inspiration 4 flight only lasted 3 days.  The first Polaris Dawn mission is supposed to last 5 days.

Presumably more internal storage space could be used for more supplies for longer duration flights, but IMO a 5 day flight should be more than sufficient for a Hubble reboost and one EVA for gyro replacement.

Repress: I do know that they can repressurize at least once. The question is:

1. how many EVAs would be necessary for servicing?
2. How many contingency EVAs do they need to plan for?
3. How many times can they repressurize?

(If 1+2 > 3 then they need to plan for that. Multiple possible solutions exist: Adding consumables for additional repress events, reducing consumables lost during depress, or planning multiple missions, etc.)

It's not an "issue" or a "Non-Issue". Definitely not a 'show stopper'. It's just another interesting factor they need to consider.

Edit:

Consider this: If Dragon can support 1 repress event, and it takes (1) 2-person 6h EVA.
What if the EVA is being schedule?
What if there is an EVA emergency ending early?

You can't just leave Hubble open on the operating table.

So you:
A. Modify dragon to support (2) repress events.
B. Plan a second contingency servicing mission.
C. Accept risk of reentering unpressurized and performed second EVA without repressurizing at the end.

I think one EVA is probably sufficient too, btw. But I don't think planning for only 1 eva is wise. I'm sure Polaris is all over this...

1. They should only need one EVA for replacing of the 3 failed gyros, which would be the quickest, simplest, and cheapest thing to do. Replacing an instrument would require a lot more from NASA in terms of budget, EVA training, etc.

2. I would plan for just the one EVA. No contingency should be needed.

3. At least once, with margin. I don't know if they can fully repress multiple times. I'd guess it is not a standard capability.

In the event of an emergency, you get the person with the emergency back in the Dragon ASAP. The other person should be able to close up Hubble and then return to Dragon. Then the mission is ended and the crew returns to Earth.

B is most likely, with C as a possibility, but a highly undesirable one as that eliminates margin of safety on reentry.

[AstroWare]

Another thing I think we need to look at is Dragon on orbit endurance. Consumables, fuel, ECLSS... Especially when accounting for cabin depressurization.

Dragon is shorter than Shuttle, but how much can it be expanded? Shuttle had a larger crew to spread workload around. Because it had an airlock, the non-eva crew was able to do more work than the non-eva crew in dragon will (I would think - they are basically in EVA too at that point)

I think a boost mission would be a priority. Gyro replacement would be a bonus. So the mission would proceed something like: Launch, Dock, Boost, EVA(s), repress, undock, deorbit. First do no harm mentality - probably only replacing the failed gyros, leaving current operational gyros intact.

This site contains good reference information about STA-125 and the Hubble EVA plans. Haven't read through it all yet, but of anyone else is looking to learn more, maybe this will interest you. I'm trying to grasp just how involved an EVA would be...

https://www.nasa.gov/centers/johnson/news/flightdatafiles/foia_archive.html
 https://www.nasa.gov/centers/johnson/pdf/345766main_EVA_125_F_A.pdf

The Crew Dragon already carries enough air supply to repressurize the cabin in case of a full depressurization, so that's a non-issue.

IIRC, nominally the Dragon only carries a few days worth of supplies. For example, the Inspiration 4 flight only lasted 3 days.  The first Polaris Dawn mission is supposed to last 5 days.

Presumably more internal storage space could be used for more supplies for longer duration flights, but IMO a 5 day flight should be more than sufficient for a Hubble reboost and one EVA for gyro replacement.

Repress: I do know that they can repressurize at least once. The question is:

1. how many EVAs would be necessary for servicing?
2. How many contingency EVAs do they need to plan for?
3. How many times can they repressurize?

(If 1+2 > 3 then they need to plan for that. Multiple possible solutions exist: Adding consumables for additional repress events, reducing consumables lost during depress, or planning multiple missions, etc.)

It's not an "issue" or a "Non-Issue". Definitely not a 'show stopper'. It's just another interesting factor they need to consider.

Edit:

Consider this: If Dragon can support 1 repress event, and it takes (1) 2-person 6h EVA.
What if the EVA is being schedule?
What if there is an EVA emergency ending early?

You can't just leave Hubble open on the operating table.

So you:
A. Modify dragon to support (2) repress events.
B. Plan a second contingency servicing mission.
C. Accept risk of reentering unpressurized and performed second EVA without repressurizing at the end.

I think one EVA is probably sufficient too, btw. But I don't think planning for only 1 eva is wise. I'm sure Polaris is all over this...

1. They should only need one EVA for replacing of the 3 failed gyros, which would be the quickest, simplest, and cheapest thing to do. Replacing an instrument would require a lot more from NASA in terms of budget, EVA training, etc.

2. I would plan for just the one EVA. No contingency should be needed.

3. At least once, with margin. I don't know if they can fully repress multiple times. I'd guess it is not a standard capability.

In the event of an emergency, you get the person with the emergency back in the Dragon ASAP. The other person should be able to close up Hubble and then return to Dragon. Then the mission is ended and the crew returns to Earth.

B is most likely, with C as a possibility, but a highly undesirable one as that eliminates margin of safety on reentry.

Looking into the gyro replacement on STS-125, and it looks like you can't replace just the three failed gyros. They are built into assemblies (rate sensing units, RSU) which each contain (2) gyros. So to replace (3) failed gyros means at least (2) RSU replacements. Maybe 3. And at that point, they would probably replace all 3 anyways...

Edit

Look at this document:

https://www.stsci.edu/files/live/sites/www/files/home/hst/about/space-telescope-users-committee/presentations-and-documentation/_documents/2022_may/hst-gsfc-project-report.pdf

on pages 13-14.

RSU1 is completely failed (gyro 1/2)
RSU2 is fully functional
RSU3 is partially failed (gyro5)

Therefore:

Replacing RSU1 is low risk, high reward
Replacing RSU3 would be next priority
Replacing RSU2 is lowest priority


End edit


Luckily they are small, like a briefcase size, and should fit out the forward hatch. That means they can be transported in the dragon cabin - no need for truck stowage. They are also all located in the same bay (bay2) on hubble. Edit: FYI - 27lbs ea.

Unfortunately that means you need to design replacements for the whole RSU not just the gyros. Any on a shelf somewhere?? Lol

STS 135 EVA#2 which did the (3) RSU replacements seems to have budgeted 3h 20 min. But this includes remote manipulator support... So I'd expect somewhat longer times if no equivalent capabilities are developed to assist.

(Trying to learn all this - so experts please correct as needed)

As to contingency and emergency, the emergency could affect both astronauts equally. Eg. A serious problem with Dragon, or last minute debris conjunction, Or a medical emergency requiring repressurizing dragon. I still think some plan should exist to perform 2 EVAs...

[AstroWare]

Very simple Crew Dragon re-boost (no EVA servicing) concept, with a Docking Module for interface with Hubble aft end.

I don't get how that concept helps...?

Added transposition/docking
Added (2) addition docking systems
Forward thrusters blocked by new module
No room in trunk for a propulsion pallet.

What is the new docking module even for? Just  Adapting the Hubble interface to Dragon interface?

What am I missing...

It looks similar to a concept for an addon in Orbiter spaceflight simulator. The docking module looks like it would also serve as an airlock, as Dragon's airlock would be blocked.

The caption was that it was a method for easy boost-only mission.

An airlock serves to support EVA. But blocks the forward Draco's for boost. So it would support a servicing mission - not a boost mission.

The concept would be better if it was launched to orbit mated to the trunk. Then used to dock to Hubble in reverse. Boost with forward Draco's. Then detach trunk from airlock and perform transposition and docking. Now use airlock for servicing.

[whitelancer64]

I think we are getting ahead of ourselves here. There really isn't any need to attempt to replicate the Study that NASA and SpaceX are doing by going off of limited information and guesswork.

There's really just a few basic options for Polaris Dawn 2.

0. No interaction with Hubble at all. This should be considered the baseline option. NASA says they don't want to risk Hubble, so Jared Issacman goes off and does his own thing with a group of private astronauts in some other orbit.

1. A reboost only mission. This is the fastest and cheapest option, with very little cost to NASA other than sharing data on the soft capture mechanism with SpaceX and temporarily turning off Hubble.

2. A reboost and EVA for replacement of the gyro assemblies. Thes eare the simplest things to replace on Hubble and they may be able to use existing flight spares or get these assemblies made fairly quickly. It may require having at least one NASA astronaut on board the mission.

3. Reboost and replacement of the gyros and a science instrument. The most complex and expensive option, and likely would force the mission to take place years from now as a replacement instrument is built.  I think if something like this were to happen, it would be a NASA-led follow-on to a successful Polaris Dawn mission of option 1 or 2.

[Asteroza]

Gonna ask a dumb question here, but can Dragon disconnect from the trunk early, flip, then dock to the trunk before heading off to Hubble? That would allow a dedicated airlock module in the trunk that can support extended ops.

Sorta Apollo style, flipping the CSM to connect with the LEM. Connecting via IDSS allows access to power and consumables from the trunk, without the whole mess of qualifying new stuff within Dragon or new umbilical lines through the clamp. Hell, functionally an IDSS dockable trunk module would be kinda similar to Dragon XL...

[whitelancer64]

Gonna ask a dumb question here, but can Dragon disconnect from the trunk early, flip, then dock to the trunk before heading off to Hubble? That would allow a dedicated airlock module in the trunk that can support extended ops.

Sorta Apollo style, flipping the CSM to connect with the LEM. Connecting via IDSS allows access to power and consumables from the trunk, without the whole mess of qualifying new stuff within Dragon or new umbilical lines through the clamp. Hell, functionally an IDSS dockable trunk module would be kinda similar to Dragon XL...

No, for several reasons:

1. The Trunk is not a hollow tube. There's a crossbrace section at the top that external cargo gets mounted to. There's also thermal and micrometeorite protection for the heat shield. Without the Trunk the heat shield would be completely exposed.

2. The Trunk has solar panels and radiators that are required to power and cool the Dragon respectively. separating the Dragon from the Trunk means it has no power or ability to manage heat.

3. to reroute power and coolant lines to go through the nose would require a very significant redesign of the Dragon.

If you want to put an airlock module in the Trunk, it would have to stay in the Trunk. "Backing up" to dock it to the Hubble would be the easiest way to deliver it to Hubble.

[Redclaws]

I think we are getting ahead of ourselves here. There really isn't any need to attempt to replicate the Study that NASA and SpaceX are doing by going off of limited information and guesswork.

Yeah, but it's *fun*, and isn't that why we're here?  Sure, we could get too worked up about it, but trying to sort out how things might go is fun.

[mikelepage]

My favorite way to do this : two Dragons

1) Dragon airlock (with a bigger side hatch which allows to do EVA with a back pack) and a docking interface with Hubble in the trunk ; it is derived from Cargo Dragon (no Super Dracos)
2) Crew Dragon : carry the crew and the ORUs in the trunk.

Dragon A/L docks with the Hubble at Dragon A/L trunk level. Crew Dragon docks with the front docking of the Dragon A/L.

EVA is through side hatch of Dragon A/L, first installing hand rails and so forth to create a path between both trunks. Then the ORUs are manually transferred along the created paths by the EVA crew

Airlock is built in a Dragon to make it recoverable, reusable and recover the suits. All what is lost is the Hubble interface in the trunk and the spent ORUs in the other trunk (also some spent ORUs could be put in the Airlock Dragon for return and expertise)

Reboost is performed with the thrusters around the front hatch of the Dragon A/L once the crew Dragon has separated so it is the cleanest possible wrt Hubble

The reboost is performed with the non human rated Dragon so the propellant quantity devoted to reboost can be higher (no need for propellant for ejection at launch for instance).

Non EVA crew can remain in a pressurized environment in the Crew Dragon during the EVAs.

I think the two-Dragon idea has merit, but I don't understand why it's necessary is it to develop a custom Dragon config with a large airlock door? Seems to me the plan is to have the EVA astronauts connected to Dragon via umbilicals the whole time.

In which case, why not just have:
1) Cargo Dragon (trunk contains payload that docks to Hubble)
2) Crew Dragon (with side airlock from which EVA servicing is performed)

Use the Cargo Dragon to host the non-EVA astronauts. Outfit the pressurised compartment of Cargo Dragon with a temporary ECLSS package that is removed, along with any extra supplies - when the crew depart. Then boost Hubble with Cargo Dragon, and keep the mission otherwise exactly as you described. With both Dragon craft being stock-standard and fully reuse-able, it could be relatively cheap.

[Zed_Noir]

Gonna ask a dumb question here, but can Dragon disconnect from the trunk early, flip, then dock to the trunk before heading off to Hubble? That would allow a dedicated airlock module in the trunk that can support extended ops.

Sorta Apollo style, flipping the CSM to connect with the LEM. Connecting via IDSS allows access to power and consumables from the trunk, without the whole mess of qualifying new stuff within Dragon or new umbilical lines through the clamp. Hell, functionally an IDSS dockable trunk module would be kinda similar to Dragon XL...

Just mimic the operation for the Apollo CSM connecting to the LEM. Have the airlock/docking module installed on top of the upper stage enclosed by the Dragon trunk. Once in orbit the Dragon separates from the upper stage and turn around to docked with the airlock/docking module then the whole stack moves away from the upper stage.

Have a wild idea could the airlock/docking module have pass through tubes for the Dragon nose mounted Draco axial thrusters? Of course that requires good seals from the Draco exhaust ports to the pass through tubes when the Dragon docks with the airlock/docking module.

[AmigaClone]

My favorite way to do this : two Dragons

1) Dragon airlock (with a bigger side hatch which allows to do EVA with a back pack) and a docking interface with Hubble in the trunk ; it is derived from Cargo Dragon (no Super Dracos)
2) Crew Dragon : carry the crew and the ORUs in the trunk.

Dragon A/L docks with the Hubble at Dragon A/L trunk level. Crew Dragon docks with the front docking of the Dragon A/L.

EVA is through side hatch of Dragon A/L, first installing hand rails and so forth to create a path between both trunks. Then the ORUs are manually transferred along the created paths by the EVA crew

Airlock is built in a Dragon to make it recoverable, reusable and recover the suits. All what is lost is the Hubble interface in the trunk and the spent ORUs in the other trunk (also some spent ORUs could be put in the Airlock Dragon for return and expertise)

Reboost is performed with the thrusters around the front hatch of the Dragon A/L once the crew Dragon has separated so it is the cleanest possible wrt Hubble

The reboost is performed with the non human rated Dragon so the propellant quantity devoted to reboost can be higher (no need for propellant for ejection at launch for instance).

Non EVA crew can remain in a pressurized environment in the Crew Dragon during the EVAs.

I think the two-Dragon idea has merit, but I don't understand why it's necessary is it to develop a custom Dragon config with a large airlock door? Seems to me the plan is to have the EVA astronauts connected to Dragon via umbilicals the whole time.

In which case, why not just have:
1) Cargo Dragon (trunk contains payload that docks to Hubble)
2) Crew Dragon (with side airlock from which EVA servicing is performed)

Use the Cargo Dragon to host the non-EVA astronauts. Outfit the pressurised compartment of Cargo Dragon with a temporary ECLSS package that is removed, along with any extra supplies - when the crew depart. Then boost Hubble with Cargo Dragon, and keep the mission otherwise exactly as you described. With both Dragon craft being stock-standard and fully reuse-able, it could be relatively cheap.

Instead of using the Cargo Dragon to host the non-EVA astronauts, dock the two Dragons nose to nose. The EVA crewmembers will then board the Cargo Dragon and use it as an airdock for the EVA. The Cargo Dragon will also include any replacement for the mission.

After the EVA(s) the crew all reboards the Crew Dragon and undocks from the complex, after which the cargo dragon reboosts Hubble.

[kevinof]

One Dragon can't dock to another. They would need docking port changes to support active/passive modes.

My favorite way to do this : two Dragons

1) Dragon airlock (with a bigger side hatch which allows to do EVA with a back pack) and a docking interface with Hubble in the trunk ; it is derived from Cargo Dragon (no Super Dracos)
2) Crew Dragon : carry the crew and the ORUs in the trunk.

Dragon A/L docks with the Hubble at Dragon A/L trunk level. Crew Dragon docks with the front docking of the Dragon A/L.

EVA is through side hatch of Dragon A/L, first installing hand rails and so forth to create a path between both trunks. Then the ORUs are manually transferred along the created paths by the EVA crew

Airlock is built in a Dragon to make it recoverable, reusable and recover the suits. All what is lost is the Hubble interface in the trunk and the spent ORUs in the other trunk (also some spent ORUs could be put in the Airlock Dragon for return and expertise)

Reboost is performed with the thrusters around the front hatch of the Dragon A/L once the crew Dragon has separated so it is the cleanest possible wrt Hubble

The reboost is performed with the non human rated Dragon so the propellant quantity devoted to reboost can be higher (no need for propellant for ejection at launch for instance).

Non EVA crew can remain in a pressurized environment in the Crew Dragon during the EVAs.

I think the two-Dragon idea has merit, but I don't understand why it's necessary is it to develop a custom Dragon config with a large airlock door? Seems to me the plan is to have the EVA astronauts connected to Dragon via umbilicals the whole time.

In which case, why not just have:
1) Cargo Dragon (trunk contains payload that docks to Hubble)
2) Crew Dragon (with side airlock from which EVA servicing is performed)

Use the Cargo Dragon to host the non-EVA astronauts. Outfit the pressurised compartment of Cargo Dragon with a temporary ECLSS package that is removed, along with any extra supplies - when the crew depart. Then boost Hubble with Cargo Dragon, and keep the mission otherwise exactly as you described. With both Dragon craft being stock-standard and fully reuse-able, it could be relatively cheap.

Instead of using the Cargo Dragon to host the non-EVA astronauts, dock the two Dragons nose to nose. The EVA crewmembers will then board the Cargo Dragon and use it as an airdock for the EVA. The Cargo Dragon will also include any replacement for the mission.

After the EVA(s) the crew all reboards the Crew Dragon and undocks from the complex, after which the cargo dragon reboosts Hubble.

[CT Space Guy]

NG MEV would be a better choice for this task.    Cygnus/Service module is an option too.

But those boys won't be doing it for little to no cost to the government.

[Mongo62]

Scott Manley's video on the proposal:

[Barley]

Instead of using the Cargo Dragon to host the non-EVA astronauts, dock the two Dragons nose to nose. The EVA crewmembers will then board the Cargo Dragon and use it as an airdock for the EVA.

Is the side hatch of (Cargo) Dragon designed to be used for EVA in flight?

IIRC there have been instances of the closeout crew having difficulty closing the hatch from the gantry.  I don't know if would have been a serious problem during a mission or if they were just being fussy because they were on the ground and could afford to be fussy.

[ace5]

Very simple Crew Dragon re-boost (no EVA servicing) concept, with a Docking Module for interface with Hubble aft end.

I don't get how that concept helps...?

Added transposition/docking
Added (2) addition docking systems
Forward thrusters blocked by new module
No room in trunk for a propulsion pallet.

What is the new docking module even for? Just  Adapting the Hubble interface to Dragon interface?

What am I missing...

You missed the fact that this is just an imagination exercise