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38 minutes ago, tater said:

Arm in trunk?

It would be a good deal of work and you can not just jettison the trunk sides its used for solar and radiators. 
You also has to  expose the dragon interior to vacuum as its no air lock. Yes it was the same for Gemini and the lunar lander. 
Also all spacecrafts need this, its an reason why the crew wear pressure suits. 

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3 minutes ago, magnemoe said:

It would be a good deal of work and you can not just jettison the trunk sides its used for solar and radiators. 
You also has to  expose the dragon interior to vacuum as its no air lock. Yes it was the same for Gemini and the lunar lander. 
Also all spacecrafts need this, its an reason why the crew wear pressure suits. 

They are opening Dragon anyway for Polaris EVA.

38 minutes ago, Ultimate Steve said:

Recover Hubble via Starship with Dragon EVA support?

No way. Better to repair it or boost it. Least until SS has a large number of landings.

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30 minutes ago, tater said:

No way. Better to repair it or boost it. Least until SS has a large number of landings.

I don't think it is particularly likely (especially after Jared's tweet just now) but presumably a recovery mission won't take place for a long while - In that time starship, in theory, will be able to prove itself.

Regarding the tweet, Dragon has carried docking adapters before, but there was always a robotic arm involved. I wonder how they plan to get around that.

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16 minutes ago, Ultimate Steve said:

Regarding the tweet, Dragon has carried docking adapters before, but there was always a robotic arm involved. I wonder how they plan to get around that.

The difference is that it doesn't need an IDA, just a slightly different docking port; Inspiration4 already showed they can change the docking port pretty easily, so it shouldn't be a problem

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9 minutes ago, Beccab said:

The difference is that it doesn't need an IDA, just a slightly different docking port; Inspiration4 already showed they can change the docking port pretty easily, so it shouldn't be a problem

The elephant in the room here is EVAs - if Dragon docks to Hubble via the port that's already there, there's no way for the crew to do an EVA unless the side hatch is modified to be capable of opening in space.

Just now, Rutabaga22 said:

Could you put an airlock in the dragon trunk for evas or is that impossible?

I believe crewed flights can't carry anything in the trunk because of launch abort COM concerns, but I can see a way around that by installing the airlock atop F9 Stage 2 (rather than attached to the inside of the trunk) and doing a transposition and docking maneuver a la Apollo after launch to retrieve it.

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3 minutes ago, RealKerbal3x said:

unless the side hatch is modified to be capable of opening in space

Yep, i was just thinking that - if it was possible for Apollo, Gemini and Vostok, it should be doable for Dragon as well even if maybe not too straightforward. We'll have to wait and see for another 10 minutes however

3 minutes ago, RealKerbal3x said:

I can see a way around that by installing the airlock atop F9 Stage 2 (rather than attached to the inside of the trunk) and doing a transposition and docking maneuver a la Apollo after launch to retrieve

Agreed, i suggested the same back when Polaris Dawn had just been announced. If you need an airlock it's either that or a dual launch with a Cargo Dragon (or Starship one day)

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Another possibility -- place an extensible adapter in the trunk of Crew Dragon and have it rendezvous tail-first, with crew on EVA available to troubleshoot any problems attaching properly to Hubble.

Remember that the main thrusters on Crew Dragon are under the nosecone so if you want to reboost Hubble efficiently you'd want to dock tail-first.

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12 minutes ago, RealKerbal3x said:

I believe crewed flights can't carry anything in the trunk because of launch abort COM concerns, but I can see a way around that by installing the airlock atop F9 Stage 2 (rather than attached to the inside of the trunk) and doing a transposition and docking maneuver a la Apollo after launch to retrieve it.

Something like this?
unknown.png

or this?
unknown.png

Edited by Rutabaga22
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4 minutes ago, Rutabaga22 said:
16 minutes ago, RealKerbal3x said:

I believe crewed flights can't carry anything in the trunk because of launch abort COM concerns, but I can see a way around that by installing the airlock atop F9 Stage 2 (rather than attached to the inside of the trunk) and doing a transposition and docking maneuver a la Apollo after launch to retrieve it.

Something like this?
unknown.png

Crewed flights can absolutely carry stuff in the trunk, but it just can't be very large. See, here's where the top of the F9US sits:

main-qimg-1e03c7a1a902e7dc9f622d1109423a

AND YES they are doing a feasibility study for reboosting Hubble with SpaceX!

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Just now, Rutabaga22 said:

Btw, would it be possible to have a pressurized trunk for specialized missions or Pyaloads?

Not really, no. You'd have to have a complete redesign. And there's no way to pass through the heat shield so getting back to the trunk would require an EVA.

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They confirmed that they contemplate a direct docking with the existing soft-capture mechanism, without the need for a grapple arm.

Hubble's current velocity at apogee is 7.593 km/s and its perigee is 333.7 miles. To flip the perigee and apogee and bring the new apogee up to the 375 miles mentioned on the call, Hubble's velocity would have to increase to 7.611 km/s. So it only needs a change in velocity of about 18 m/s.

Crew Dragon carries 1,388 kg of propellant and its main thrusters get 300 s of specific impulse in vacuum. Crew Dragon has a mass of approximately 12.5 tonnes on orbit and Hubble has a mass of approximately 11 tonnes. It would need 143 kg of propellants to develop 18 m/s of dV, which would be a burn of around 77.7 seconds.

My guess, then, is that Crew Dragon (assuming a good insertion by Falcon 9) has enough capability to fully circularize Hubble's orbit at ~375 miles and return to LEO and then deorbit.

 

 

They just said they are looking at pulling off up to 70 km of reboost which would bring it to almost 380 miles. I'm guessing that using the onboard propellant is the limiting factor, then. If they were docking nose-first and putting new thrusters in the trunk then they could put much more propellant back there. That mode would make it impossible to EVA unless they used the ground access hatch.

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4 hours ago, sevenperforce said:

AND YES they are doing a feasibility study for reboosting Hubble with SpaceX!

They really should just Kerbal that up, throw a booster with Clamp-o-Tron SR and enough juice to balance out the whole thing... and 

 

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18 hours ago, RealKerbal3x said:

The elephant in the room here is EVAs - if Dragon docks to Hubble via the port that's already there, there's no way for the crew to do an EVA unless the side hatch is modified to be capable of opening in space.

I believe crewed flights can't carry anything in the trunk because of launch abort COM concerns, but I can see a way around that by installing the airlock atop F9 Stage 2 (rather than attached to the inside of the trunk) and doing a transposition and docking maneuver a la Apollo after launch to retrieve it.

In this case I assume the orbital module would be inside the trunk but connected to the upper stage. In orbit they would need to do an Apollo style flip and dock, after moving forward enough for the trunk to clear the orbital module, after docking the orbital module is released from upper stage. 
This let you put an docking adapter who can dock to Hubble adapter and hopefully an airlock.

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30 minutes ago, magnemoe said:

In this case I assume the orbital module would be inside the trunk but connected to the upper stage. In orbit they would need to do an Apollo style flip and dock, after moving forward enough for the trunk to clear the orbital module, after docking the orbital module is released from upper stage. 

This let you put an docking adapter who can dock to Hubble adapter and hopefully an airlock.

Yes, but then you have no way to reboost Hubble, because the main thrusters are under the nosecone.

Cosine losses on the aft translational thrusters would be prohibitive.

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10 minutes ago, sevenperforce said:

Yes, but then you have no way to reboost Hubble, because the main thrusters are under the nosecone.

Cosine losses on the aft translational thrusters would be prohibitive.

Would it be possible to use the SuperDracos? I suppose they’d need to be modified from the current abort-use-only design. Would probably only need or want to fire two of them

Edited by StrandedonEarth
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4 minutes ago, StrandedonEarth said:

Would it be possible to use the SuperDracos? I suppose they’d need to be modified from the current abort-use-only design. Would probably only need or want to fire two of them

I don't believe so. Modifications to allow them to be restarted would invalidate human-rating. Also they are less efficient than the Dracos, both in terms of vacuum specific impulse and cosine losses.

I think the gee-loading could potentially be within limits, although it would be iffy. The SuperDracos are not only canted out but are also canted at an angle to allow roll control by differential throttling, so you'd have to fire a minimum of four. Even at 20% (minimum throttle), that's 58.4 kN, reduced by cosine losses to 56.4 kN. Crew Dragon masses about 12.5 tonnes and Hubble is 11 tonnes and so that's about 0.25 gees which is probably just on the edge of what Hubble and the docking system can handle.

I'm sure that adapting the docking software to allow "back-in parking" is a shorter pole than major hardware redesigns. 

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One other cool possibility: SpaceX could use a Dragon XL spacecraft with an APAS docking adapter on the tail end and a hatch on the side. The XL could perform all the reboosts using its main forward thrusters and it could also allow Polaris II to dock with it and use it as an airlock to test Hubble servicing.

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On 9/29/2022 at 10:35 PM, sevenperforce said:

Crewed flights can absolutely carry stuff in the trunk, but it just can't be very large. See, here's where the top of the F9US sits:

main-qimg-1e03c7a1a902e7dc9f622d1109423a

AND YES they are doing a feasibility study for reboosting Hubble with SpaceX!

Why is half of the height of the trunk off limit and coned, yes they have stuff like radiators who I suspect its the cutoff on the lower overhead view. 
And interior volume of dragon is much larger than I thought. I assumed the lower on meter was the service module part. 

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