Quote from: Bananas_on_Mars on 10/10/2018 01:37 pmOk, what's so special about hubble that we can't simply build a replacement? Not with all new and super fancy stuff like the want with WFIRST, but with the technology level Hubble has now? Hubble has been launched 30 years ago, upgraded the last time almost 10 years ago.Why isn't it possible to build something based on a commercial spacecraft bus, for let's say 500 mio. $ that's new and shiny and has the same capabilities of 30-10 year old hardware?Sure, we'll just manage the program along the lines of the Webb Space Telescope...
Ok, what's so special about hubble that we can't simply build a replacement? Not with all new and super fancy stuff like the want with WFIRST, but with the technology level Hubble has now? Hubble has been launched 30 years ago, upgraded the last time almost 10 years ago.Why isn't it possible to build something based on a commercial spacecraft bus, for let's say 500 mio. $ that's new and shiny and has the same capabilities of 30-10 year old hardware?
Why isn't it possible to build something based on a commercial spacecraft bus,
Quote from: Bananas_on_Mars on 10/10/2018 01:37 pmWhy isn't it possible to build something based on a commercial spacecraft bus, Commercial spacecraft buses are not designed for missions like HST.
And still there is the telescope part.
Quote from: Jim on 10/09/2018 05:54 pmNo need for a Dragon or crew. Just a spacecraft bus with rendezvous and docking capability and a separate non propulsive attitude control system. The propulsion system used for rendezvous and docking then can be used for reboost.You left out a tiny little detail: the need to disable Hubble's own attitude control system to allow the ACS of the docked spacecraft bus to take over. Which means completely changing the way the Hubble computers operate the telescope.
No need for a Dragon or crew. Just a spacecraft bus with rendezvous and docking capability and a separate non propulsive attitude control system. The propulsion system used for rendezvous and docking then can be used for reboost.
My main question would be if there is a path with high enough bandwidth from the pointing measurement and computation units in the Hubble to the added module.
You merely have to expand Crew Dragon's mission envelope somewhat to include servicing Hubble's cousins, the NRO's KH-11 satellites, and your funding problems are solved.
OK, but what would be? And even if they are not designed for such missions, what do they lack for such missions?
Quote from: Coastal Ron on 10/10/2018 02:00 pmOK, but what would be? And even if they are not designed for such missions, what do they lack for such missions?Propellantless attitude control system. Precise pointing. Large payload capability. Also, most commercial buses are just designed to point at the earth.
Quote from: Jim on 10/11/2018 01:22 pmQuote from: Coastal Ron on 10/10/2018 02:00 pmOK, but what would be? And even if they are not designed for such missions, what do they lack for such missions?Propellantless attitude control system. Precise pointing. Large payload capability. Also, most commercial buses are just designed to point at the earth.There's a second NRO bird, unless WFIRST is cannibalizing it.
Quote from: woods170 on 10/10/2018 06:50 amQuote from: Jim on 10/09/2018 05:54 pmNo need for a Dragon or crew. Just a spacecraft bus with rendezvous and docking capability and a separate non propulsive attitude control system. The propulsion system used for rendezvous and docking then can be used for reboost.You left out a tiny little detail: the need to disable Hubble's own attitude control system to allow the ACS of the docked spacecraft bus to take over. Which means completely changing the way the Hubble computers operate the telescope.Update the firmware.
What about a crew Dragon with 3x crew (2x experienced Shuttle-Hubble Astros) and CMG's in the trunk?! Two of the Astronauts could perform a pair of EVAs to install new gyros and batteries and the other Astro would be there to assist them in suiting up and 'flying' the Dragon.Can the Dragon be configured to do multiple EVAs? If the Falcon 9 is fully expended and launched to the 28.5 degree inclination orbit that Hubble is in: would the Dragon have enough delta-v to reach the telescope? Can a set of gyros and batteries fit in the Dragon's cargo trunk? I'd love to see someone do a feasibility study on a mission like this!! And could the Dragon dock with the docking unit that was left on the Hubble by the STS-125 crew? Could EVA's be done on the telescope without an RMS system? Or could the crew suffice with the pole system that was being looked at for the now abandoned Asteroid Rendezvous mission?Or would this be a mission better suited to an Orion, launched on a Delta IV-Heavy, now that the ICPS stage is going to be 'man rated'?Are there any Astronauts who repaired Hubble still on the active duty roster? How feasible would it be to reinstate 'Hubble Astronauts' who would still pass the physical or have only recently retired? Also: I know that it might be better to plow the mission's money into new space telescopes, or dock a 'stability' CMG control/command module to the base of Hubble......I'm only pondering this concept as a 'face saving' idea if - God fervently forbid - if the James Webb ends up in the drink after launch, or fails to deploy.
Quote from: Halidon on 10/11/2018 03:50 pmQuote from: Jim on 10/11/2018 01:22 pmQuote from: Coastal Ron on 10/10/2018 02:00 pmOK, but what would be? And even if they are not designed for such missions, what do they lack for such missions?Propellantless attitude control system. Precise pointing. Large payload capability. Also, most commercial buses are just designed to point at the earth.There's a second NRO bird, unless WFIRST is cannibalizing it.They are not spacecraft. NRO only provided optical assemblies.
I think it needs to be clarified that there are rate sensing gyros, and momentum/reaction wheels. What is replaceable on Hubble is the former, but I don't know if the reaction wheels are. It also uses replaceable magnetic torquers on the arrays for pointing. Corrections and clarifications welcome of course!
The Chandra x-ray telescope has now entered safe mode and a gyro failure is the preliminary root cause theory. It's like a bad week at the nursing home, the venerable Great Observatories are succumbing to inevitable end-of-life afflictions.Maybe this should be in a less SpaceXy thread, but I couldn't find one just for the Hubble situation or any thread specifically about Chandra. If I missed the proper location, mods please move.
Quote from: Mark Lattimer on 10/11/2018 12:46 pmYou merely have to expand Crew Dragon's mission envelope somewhat to include servicing Hubble's cousins, the NRO's KH-11 satellites, and your funding problems are solved. That is nonsense
And at this point, I do not have much faith in Webb getting to where it's going and safely deploying with it's nearly insane 'Rube Goldberg' mechanisms and procedures.