Crew Dragon or Orion to Hubble for CMG Replacement?

[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.

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.

Let me know where you can find money in the Federal budget for all that.

[cosmicvoid]

After reading all 101 posts in this thread, I'm unable to find an explanation of what "CMG" means. Is this an acronym that everybody but me knows?

[markododa]

After reading all 101 posts in this thread, I'm unable to find an explanation of what "CMG" means. Is this an acronym that everybody but me knows?

It means Control moment gyroscope https://en.wikipedia.org/wiki/Control_moment_gyroscope

[cosmicvoid]

It means Control moment gyroscope https://en.wikipedia.org/wiki/Control_moment_gyroscope

Thank you!

[Danderman]

CMGs are for ISS, not HST.

[Tommyboy]

CMGs are for ISS, not HST.

Then what does Hubble use to control its orientation instead of CMGs?

[cdebuhr]

CMGs are for ISS, not HST.

Then what does Hubble use to control its orientation instead of CMGs?

Hubble uses reaction wheels.  ts also got a number of magnetorquers used to keep the reaction wheels within their nominal range of stored angular momentum.

[Coastal Ron]

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.

Let me know where you can find money in the Federal budget for all that.

There is no constitutional limit to how much money NASA can be provided, so there is no need to "find" money, there is only the need to identify a need great enough for Congress to fund it.

But if you wanted to keep NASA's budget in the range it is today, then there would be plenty of room in the budget if the SLS and Orion were cancelled. And seeing how what I'm proposing is very similar to the Gateway, I'd say the requirements could be merged Artemis, so not really a big budget bump to build it.

Of course cancelling the SLS and Orion are the biggest issues to address, but I've been suggesting for a long time that the U.S. President should declare that we are extending our economic sphere of influence out into space, and the first step is to create a reusable transportation out to the region of the Moon. This can be supported by existing commercial launchers (all of them, not just SpaceX), which replaces the SLS, and the reusable space-only transportation elements can be the replacement for the Orion.

Essentially this builds a "Transcontinental Railroad" equivalent to the region of the Moon, which would be operated by the private sector (and international partners too I hope). And this puts the elements needed for in-space servicing in place too, or provides most of it so that the unique elements don't cost too much or take too much time to build.

My $0.02

[Hog]

Picture 1: ISS Control Moment Gyroscope

Picture 2: HST Reaction Wheels

[pb2000]

I think moving Hubble to the ISS is the best bet as it opens a ton of opportunities. Would a stripped down Dragon 1 refitted with aux tanks have enough delta-V to do it?

[Orbiter]

I think moving Hubble to the ISS is the best bet as it opens a ton of opportunities. Would a stripped down Dragon 1 refitted with aux tanks have enough delta-V to do it?

If I'm doing my math right, not even close. The ΔV required for a 23 degree inclination change at 600km would be roughly 3 km/s.

[Danderman]

What would be the capability of a Crew Dragon to increase the altitude of HST, assuming a standard propellant load?

[Robotbeat]

Looks like Dandermann is the one that looks most prescient here.