Author Topic: Polaris Program (Dragon and Starship crewed missions led by Isaacman)  (Read 72747 times)

Offline su27k

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Past threads about using Commercial Crew vehicles to service Hubble, I think they also have some of the discussion about technical constraints:

Commercial Hubble Repair

Crew Dragon or Orion to Hubble for CMG Replacement?

BTW, it's interesting re-reading these threads that how some of the constraints that we thought made this a non-starter - such as EVA from Dragon - suddenly become a non-issue in just a few years, sometimes us in the peanut gallery has the right idea after all :P

Offline rsnellenberger

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Just for reference purposes, a picture of Hubble (taken from a missing video) that shows the base with the passive docking ring installed on the last servicing mission. There are no apparent docking targets as such, so there will be some work required to "train" the approach and docking software.

(Edit: replaced screen grab with much clearer NASA SM4 photo)
« Last Edit: 10/01/2022 01:37 pm by rsnellenberger »

Offline Jim

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NG MEV would be a better choice for this task.    Cygnus/Service module is an option too.
« Last Edit: 10/01/2022 01:57 pm by Jim »

Offline edzieba

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There are no apparent docking targets as such, so there will be some work required to "train" the approach and docking software.
Fiducial is visible in the centre of the LIDS ring.

NG MEV would be a better choice for this task.    Cygnus/Service module is an option too.
In terms of efficiency, sure. But between paying NG for a MEV (and mission specific R&D) vs. SpaceX and Isaacman offering to perform the mission (and R&D) effectively at-cost, an inefficient cheap mission may be more viable.

I'm sure that whilst NASA are working on their side of the reboots evaluation study, alternatives will be evaluated too. And there's nothing to stop NG also getting directly involved on a me-too SAA study.

Offline Jorge

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There are no apparent docking targets as such, so there will be some work required to "train" the approach and docking software.
Fiducial is visible in the centre of the LIDS ring.

More than just a fiducial. There are three reflective features arranged in a triangle around the base of the fiducial, with a fourth on a standoff post. Having the fourth out-of-plane with the other three enables an unambiguous estimate of "pose" (relative attitude). Then there are three more reflective features in a larger triangle outside the passive iLIDS ring, next to each of the "towel bars". Those features can be resolved separately at longer ranges than the inner four.
« Last Edit: 10/01/2022 06:33 pm by Jorge »
JRF

Offline whitelancer64

My prediction is that they will end up doing 2 missions, first a cargo Dragon reboost, which might just need a docking adaptor for the docking system installed on the Hubble in the last servicing mission.  Presumably in the trunk, so the Dragon thrusters can point the right way to boost the Hubble.  NASA may or may not be able to scrape together some money to pay SpaceX to develop the docking adaptor and fly the mission, but it would be pocket change compared to what they would have spent to deorbit it.  This would be pretty low risk, NASA has gotten very comfortable with cargo Dragon. 

Then a Polaris manned mission with Jared and at least one NASA astronaut to do servicing, at a minimum a gyro swap out.  By then, EVA from the Dragon will have been tested by Jared and crew on Polaris Dawn.  NASA will presumably pay something to fly their astronaut, but most of the NASA money for that phase will probably go into building whatever parts are getting swapped out and training on what they want to do, support for the mission, etc. 

I'm guessing there will be a lot of support in NASA to do this, though, far more of the public has heard of Hubble and likes it than has heard of Artemis. 

If true about flying a NASA astronaut, it would be interesting to see if they choose one of the STS-125 crew that's still active.

For the record, there is only one active NASA astronaut who has performed an EVA on the Hubble, that is Drew Feustel.

Drew Feustel did three EVAs to service Hubble on STS-125, including to replace the Advanced Camera for Surveys (which was not originally intended to be servicable), and replacing batteries, so he's very familiar with Hubble. He's got to be 100% the go-to EVA guy if there is a new Hubble servicing mission.

Megan McArthur was STS-125's robotic arm specialist and was the last person to "touch" Hubble. She's already familiar with the Dragon spacecraft, having flown on Crew-2

Having both onboard such a mission would be both appropriate and fitting.
« Last Edit: 10/01/2022 07:11 pm by whitelancer64 »
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Offline whitelancer64

Either de-rating the Dragon SuperDracos or replacing them outright with baseline Dracos would solve the RCS physical placement issues. There’d still be some cosine losses, but no need for a new-build thruster module in the Trunk. Cheap and cheerful!

The showstopper, as I see it, is the capsule’s apex cap and the way it would fit - or not - up against the base of Hubble (handrails etc). The old Cargo Dragons had no nose covering during re-entry so maybe that’ll be the way forward.

The Crew Dragon's nose cone is jettisonable. I think might be worth the loss of the nose cone to be able to dock with Hubble.
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Offline jarmumd

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Fascinating - thanks for the details! Glad to have these "nitpicks" as I certainly don't want to tell fish-tales. ;) (I learned most of what I know on the subject from a combination of Wikipedia and various NSF posts where people in the know have commented on specific details as you've done here.) I've bookmarked your post for future reference... :)

Since I have your $0.02, may I follow this up with a few more questions so I can be more knowledgeable about this going forward:

1. Would it be correct to say that, although IDSS isn't quite as low-impact as LIDS (due to not having the "active force feedback control"), it is still much lower-impact than the legacy APAS-95 used by the Shuttle? Basically, that IDSS is a compromise on the more "ideal" design of LIDS that gets most of its benefits (compared to legacy APAS) without quite as much implementation complexity (and without diverging as much in mechanical compatibility from legacy APAS; I'm guessing Russia was the "international partner" who requested these design changes since they wanted the use a unified implementation)?

2. Wikipedia's article on IDSS states that IDSS utilizes "6 servo-actuated legs" to "remove any relative motion [prior to retraction]". How does this differ from the more advanced "active force feedback control" used by LIDS? Is it a question of IDSS waiting until after initial capture to damp out relative motion versus LIDS actively compensating for it from the first moment of contact? Or is this where the distinction of magnets vs. latches/servos comes into play?

3. For berthing scenarios where a robotic arm is used to precisely maneuver a vehicle/module to the port, does the soft-capture mechanism matter at all, or is only the hard-capture mechanism needed since the robotic arm already has (enough) control of the vehicle's positioning on all relevant axes? The ability to support both docking and berthing is often cited as a key feature of both IDSS and LIDS; was this ever prohibitive with legacy APAS or is selling this up for IDSS/LIDS just "marketing speak"? :)

4. [if you (or anyone else) know the answer...] Is the reason why Russia went to the trouble of creating its "hybrid" APAS/SSVP ports for the attachment of large modules (which, IIRC, use an APAS hard-capture ring in conjunction with the SSVP system's probe-and-drogue soft-capture mechanism) because this allowed them to use the wider tunnel and superior structural connection of the APAS hard-capture ring in conjunction with a lower-impact (and/or less-complicated) soft-capture system?

For context, since you use IDSS in kinda the wrong way, here is my post from my post on page 9:
It's a little complicated, but only because people tend to make a lot of assumptions which aren't valid.  The biggest one is that everyone follows the IDSS, they don't necessarily.  To add more to the confusion, there is the NDS standard and NDS hardware, in this post I'm going to denote the hardware as NDS*.  NDS* is a Boeing built docking adapter for NASA.

Orion and CST-100 use the NDS*.  Block 1 is not androgynous, I don't know for certain if Block 2 is.  For it to be androgynous it must have active and passive Hard Capture hooks, and passive strikers for the other active's soft capture latches.  Unless it's truly androgynous (where one system can be active or passive), there must be an active and a passive. 

Dragon 2 uses it's own docking system, but is compatible with NDS.  So it's not correct to say that Dragon 2 uses an NDS*.  They built their own system.   You can also see all this in photos.  Like CST-100/NDS*, neither have passive docking hooks or strikers.

It's kinda like buying two different USB thumb drives.  They work differently inside, but both can interface with the same USB port.

1) Are NDS and SXDS lower impact than APAS?  I don't know.  I've heard that they are, but I haven't actually seen the force profiles.  Just don't want to tell you something I don't know explicitly.

2) All docking systems remove the relative motion between the spacecraft.  The key is how they do it.  Force sensing vs force slipping vs mechanisms.  It's a difference in complexity where LIDS was the most complex and most avionics vs more simple mechanisms (APAS has very little computing due to it's mechanism).

3) Integrating berthing (with an arm), and docking is a really big deal.  It really hasn't been done (it may have, but I'm not certain).  There is a lot of complexity since there is integration between both the arm and the docking system.  This is a little different than CBM.  The arm puts the CBM in the proper range for CBM to active, and then the arm goes limp.  Docking/Berthing would mean the arm has to actively "fight" the docking system (ish - its complex and different).

4) I don't know the answer.  But, there are advantages to a removable probe over non-removable petals.  Especially when it comes to assembling a space station.  So you may be right.

Online FutureSpaceTourist

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twitter.com/truthful_ast/status/1575637811981537282

Quote
Polaris Dragon docked to Hubble

https://twitter.com/rookisaacman/status/1576310153053278208

Quote
Looking good.. may want to flip Dragon 180 degrees though.   Just a guess 😉

Offline kevinof

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Seems like a smart way. Presume they would also need cameras/range finder in the truck to help with docking. No doubt they have already thought of this and have a solution  :)


twitter.com/truthful_ast/status/1575637811981537282

Quote
Polaris Dragon docked to Hubble

https://twitter.com/rookisaacman/status/1576310153053278208

Quote
Looking good.. may want to flip Dragon 180 degrees though.   Just a guess 😉

Offline rakaydos

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Seems like a smart way. Presume they would also need cameras/range finder in the truck to help with docking. No doubt they have already thought of this and have a solution  :)


twitter.com/truthful_ast/status/1575637811981537282

Quote
Polaris Dragon docked to Hubble

https://twitter.com/rookisaacman/status/1576310153053278208

Quote
Looking good.. may want to flip Dragon 180 degrees though.   Just a guess 😉
If there is a docking mechanisim in the trunk, and hubble is about the same diamiter as the trunk itself... is there any plume-related reason you cannot use the superdracos on Dragon , in a "pull" configuration?

Offline darkenfast

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Seems like a smart way. Presume they would also need cameras/range finder in the truck to help with docking. No doubt they have already thought of this and have a solution  :)


twitter.com/truthful_ast/status/1575637811981537282

Quote
Polaris Dragon docked to Hubble

https://twitter.com/rookisaacman/status/1576310153053278208

Quote
Looking good.. may want to flip Dragon 180 degrees though.   Just a guess 😉
If there is a docking mechanisim in the trunk, and hubble is about the same diamiter as the trunk itself... is there any plume-related reason you cannot use the superdracos on Dragon , in a "pull" configuration?

Both plume and the fact that the Super-Dracos are way too powerful.
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Offline kevinof

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Seems like a smart way. Presume they would also need cameras/range finder in the truck to help with docking. No doubt they have already thought of this and have a solution  :)


twitter.com/truthful_ast/status/1575637811981537282

Quote
Polaris Dragon docked to Hubble

https://twitter.com/rookisaacman/status/1576310153053278208

Quote
Looking good.. may want to flip Dragon 180 degrees though.   Just a guess
If there is a docking mechanisim in the trunk, and hubble is about the same diamiter as the trunk itself... is there any plume-related reason you cannot use the superdracos on Dragon , in a "pull" configuration?

Both plume and the fact that the Super-Dracos are way too powerful.
Yes I had assumed that they would never use the Superdracos for any boosting of any vehicle. Aft end in means they will be using the forward thrusters that  are usually used for deorbit which makes sense.

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

Offline kevinof

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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

Offline AstroWare

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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


Offline 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.
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"There are lies, damned lies, and launch schedules." - Larry J

Online FutureSpaceTourist

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https://twitter.com/jeff_foust/status/1576960102074023938

Quote
Isaacman: training schedule for Inspiration4 was six months. Looking at eight to nine months for Polaris Dawn.

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twitter.com/jeff_foust/status/1576961303998238721

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Isaacman: if we can boost Hubble above altitude of Starlink constellation and “put some enhancements” on it, could operate for 20 more years. [Depends on what those enhancements are.]

https://twitter.com/jeff_foust/status/1576962193752576002

Quote
Isaacman reiterates that any Hubble servicing could be done “at little or no cost” to taxpayers thanks to commercial space funding. “That’s all that should matter.” [It’ll be an interesting government procurement process, to be certain.]

Offline AstroWare

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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... :)
« Last Edit: 10/03/2022 04:36 pm by AstroWare »

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