I'll address your points in order... I know you'll probably be the only one to read this, but that's fine.
First, DART was not a failure. Sure, it didn't do what it was supposed to, but already some lessons have been learned from it. Bear in mind, I'm not a part of that mission, so I don't know details. The craft managed to adjust its orbit autonomously to rendezvous with its target. It registered and recognized the target with its cameras, computed required changes in orbit, and successfully rendezvou'd with it... too successfully, in fact. As I understand it, noisy GPS signals resulted in excessive thruster firing, and in the end it collided with the target. Fuel spent, it retreated to a final graveyard orbit. Not the dismal failure you implied.
Regarding superior robotic technology, I'm guessing you don't understand the heritage of technology we're using. The servicing robotics have been fully developed and are sitting in a clean-room in Canada. The hardware was developed over the past couple decades in preparation for use on ISS. We've taken actual flight-ready hardware from that project with the promise of building replacements. The HST capture robotics draw upon many components, systems, and assemblies common to the dexterous robot for ISS, the Canadarm on ISS, and the SRMS on Shuttle. Nothing new in the robotics. All heritage hardware. Further to that, all operations needed to fully service Hubble are being proven on the ground with a validated dexterous robot 1G simulator. Advanced robotics development was not a requirement for this mission. In fact there was no time for that, so we've gone with what we know works.
You sound eager to jump on my turns of phrase. There's not room in a/. post to be fully descriptive. When I say "pretty much the same" I mean this:
The batteries and rate gyros MUST be changed out. Both robotic and shuttle missions will do this. How they do it is different. The shuttle mission will bring new batteries, take out the old ones, and put in the new ones. The robotic mission will bring new batteries and patch the connectors over to them, leaving the old batteries in place. The shuttle mission will bring up new gyros, take out the old ones, and put in the new ones. The robotic mission will bring up new gyros attached to the new WFC3 instrument, and patch them into the 486 computer, leaving the old gyros in place. The COSTAR instrument is to be changed out and replaced with COS. This is not a critical operation, but is highly desired. Both the Shuttle and robotic mission will do this. The tasks are effectively identical for human and robot, with several aspects better performed by robot (inserting COS, closing aft-shroud doors). 4 connectors and 1 ground strap must be transfered from the old instrument to the new. This is easy for humans, and hard for the robot. The FGS (fine guidance sensor) instrument is to be replaced with an upgraded version of the same. Again, not critical, but highly desired. Like COS, several aspects of the operation are better performed by robot. Again, 8 connectors and 1 ground-strap must be transfered. This is hard for the robot, easy for humans.
These are Hubble servicing priorities, regardless of how the mission is done. It's possible the shuttle mission would add the ability to fix the power regulator for STIS. This is unlikely however, as access to the many many bolts required to be loosened is tough for both humans and robots, and requires much time.
Reaction wheel changeout is a contingency task for the robotic mission. It might be added to the human. If a need arises, this task could be added to the robotic mission up to 30days pre-launch.
Anyway, there you have it... priorities are priorities, irrespective of the way you carry them out. Not much will change from robotic to human mission, as time constraints prevent the shuttle mission from adding everything they want.
The instruments are housed inside the HRV in a thermally controlled keep-alive state. Bay doors are left closed
It'll get dumped overboard along with the large spacecraft that brought it there. Together they'll likely make it to ground (water in this case). All that's left behind is the relatively small propulsion module to later de-orbit Hubble.
There are several important factors in deciding between them. Lets look at the pros and cons.
Cost:
1. Shuttle servicing will cost about $300M to fly the mission plus ~$1.5B-2B to keep the shuttle program and staff going for an extra 4-6 months. Total cost then is conservatively $2.3B.
2. Robotic Deorbit Only is estimated to cost about $850M, for development, launch, and operation of the vehicle.
3. Robotic servicing is expected to cost $1.4B for dev, launch, and operation through splashdown.
However(!) if we take option 1 or 2, we'll have to fly a 'robotic proving' mission around 2015 or so to enable missions to Moon and Mars. This could cost anywhere from $500-800M (likely closer to 800 if it's to be at all ambitious). So lets look at the total score-card:
Doing another shuttle servicing mission will teach us very little. Sure, we'd learn some EVA techniques, management techniques, things like that. But nothing significant. That's why we'd need to launch a robotic proving mission in 2015.
Robotic Deorbit would teach us a lot about autonomous rendezvous (since my last post it's apparent that we need to work a little harder on that; DART bumped into its target, I hear). Bear in mind that craft had no forward-link commanding from the ground... it was entirely autonomous. It cost only $100-something million to dev, launch and "operate". These are lessons we need to learn to go to the Moon, and Mars.
Robotic Servicing would teach us a lot about the autonomous rendezvous and proximity operations (see above) since it's the same problem here as the robotic deorbit. It will also teach us a HUGE amount about ground-to-space tele-robotic operations. So much so that if it works we could be confident enough not to need an expensive proving mission later on. We'll be doing complex robotic tasks on things that were designed for humans (on space-station, everything's designed to be robot-friendly). We'll be pushing the envelope of our knowledge.
Don't let that put you off though. We're pushing the envelope on the ground here, right now. We've pushed it so far now that most tasks on the Hubble robotic mission will be trivial. We aim to push it far enough that ALL tasks will be trivial (or at most 'complex') by the time we launch. We have a robust capacity to re-plan and re-approach a problem on orbit. We have the advantage of time (see next pro/con) on our side. And we have contingency in case some more critical item fails before we launch. I believe that up to 30 days before launch we have the ability to re-manifest the cargo. Don't quote me on that figure though.
Now lets look at perhaps the most important feature of each mission: The quality of the result:
Some say a shuttle servicing mission will do a better job at servicing Hubble. This used to be the case. In looking at the robotic mission we had to give up some things. The STIS failed last summer, as some of you may remember. The robotics guys evaluated that task, and decided it would be too difficult. Many bolts in hard-to-reach places, etc. So that was dropped. However, I've recently heard on the wind that a Shuttle mission will only have a few days of EVA available between tile inspection and prep for landing. The shuttle mission will be forced to leave things out too, and the result is that the priorities we identified for the robotic mission are pretty much the same priorities we'd have for the sh
You bring up a valid point, and this fact has not gone overlooked.
The dexterous arms (There are two on the mission) are fully developed and are already built. Because of the Hubble mission timeline development of new arm technology would have been infeasible.
The Space Station program had three identical arms built (SPDM) for launch... sometime. We've taken the spare arm from them as-is, and they will build another for us just like it (built-to-print). Then, with no Hubble mission schedule pressure, we'll build them a replacement spare.
The arm we took has been fully tested and passed the acceptance review by the Canadian Space Agency. No new tech here, and it's ready to be flown to ISS for manned use, so it's certainly ready for us.
The long grapple arm is using -identical- joint design to the SPDM's that we're taking. It has longer booms obviously, though the company that is building it are certainly experts in the field (4 SRMS shuttle arms, 1 SSRMS station arm, and so far two OBSS booms for shuttle tile inspections).
By FAR, the robot system is the furthest advanced part of the Hubble mission. Really it looks like it's coming down to two Hard Parts(tm). As you say, the autonomous capture is hard. that's being worked on, and the final issues are scheduled to be resolved by CDR in September. Also, the tools are hard. The robot is finished (we're taking them as-is; only minor mods). HST is finished, obviously. it's the interface that's hard, and that's the tools.
These have progressed significantly in the past year, with tool-tests and demos on-going virtually weekly at GSFC.
Then, as you say also, the integration of these systems is the 3rd of 2 hard parts. A good integration plan is in place with a few issues to be resolved by CDR as well. The PDR reviewers were all highly impressed with progress thus far, and thought there was no reason not to proceed to CDR.
The XSS-11 rendezvous stuff is virtually the same tech as the Hubble rendezvous stuff. It's the software that'll be somewhat different.
I'm not saying everything's figured out and that this mission will be easy. It's not. It's hard. But it's being done the Right Way(tm).
Hope that helps.
Robotic servicing
on
Hope for Hubble
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· Score: 5, Informative
As someone working on the Hubble robotic servicing mission (I know most/.ers will say this biases my opinion; really it just means I can speak from a position of knowledge), I can state 100% that this mission can be done, and can be done on schedule.
Let me break down the phases of the mission for those who are unaware:
1.) Launch - needs little explanation - a Delta IV or Atlas V heavy lift launches the HRV into Hubble's orbital plane
2.) Checkout & Commissioning - The robot arm and other HRV elements are tested and verified operational
3.) Orbit Phasing & Rendezvous - The craft will be commanded to approach Hubble. Autonomous systems will be used to coordinate the final stages of this approach, using technologies currently being proven out on the XSS-11 spacecraft which launched this week, and to be launched next week on the DART spacecraft.
4.) Capture & Berthing- The robot arm is set up for capture, and when the vision system determines that the end effector is within tolerances, an autonomous capture is performed. HRV is performing station-keeping until just before, and when HRV and HST are known to have a negative relative drift rate (receding), the capture process is allowed to begin. A capture ends with the arm grappled to one of HST's shuttle grapple fixtures. The vision system is in development, and the hardware has been space-proven for the past ~20 years on Shuttle... in fact the exact same end-effector design has been used on all previous HST servicing missions. After Capture, the arm decelerates HST and then engages it into the HRV latches (same latching arrangement as on a shuttle servicing mission).
5.) Battery Augmentation - HST's batteries will die soon, and are one of the prime schedule drivers for the mission. The dexterous robot (two armed robot) connects wire conduits from the HRV batteries to the outside of HST and routes solar array power to them. The hardest part of this task is transfering the 2 prime or 2 redundant connectors on each of the port and starboard diode boxes (located just under the solar array masts). This operation has been proven out on the ground, using a validated flightlike 1G testbed version of the actual dexterous robot, and a hi-fi Hubble mockup. In fact I think operators demo'd this very op just yesterday for maybe the 20th time. Trust me... it's highly doable.
6.) Changout WideField and add Gyros - The gyroscopes are the next most likely item to fail on HST, and are another schedule driver. With the new two-gyro mode currently under investigation, the lifetime of HST could likely be extended beyond the 2007 timeframe. The Rate-Gyro Assemblies are attached conveniently to the outside of WFC3, the replacement wide-field camera for WFPC2. WFPC2 is the camera responsible for most of the majestic galaxy and planetary photographs we seen in the news and magazines. WFC3 will improve yet again over that. Changing out WFPC2 involves de-mating the internal connectors, removing the ground-strap, unlatching the instrument, and sliding it out of the -V3 radial instrument bay rails. The old instrument is transported down to a stowage location in the HRV, and the new instrument is installed in the empty HST bay in the reverse sequence. This entire operation has been demo'd several times over the past year.
7.) Changeout COSTAR - After the two critical repairs (batteries and gyros), we move into the get-aheads and upgrades. The COSTAR instrument, sitting in axial bay 4, has performed corrective optics functions since its installation during the first servicing mission. Now that all HST instruments are built with integrated corrective optics, this instrument is obsolete, and can be replaced by something more productive; the Cosmic Origins Spectrograph (COS). To perform the changeout, the robot must unlatch and open the -V2 aft shroud doors, attach a handling fixture to COSTAR, attach a connector transfer panel to the handling fixture, transfer the 4 COSTAR harness connectors, transfer the ground
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I'll address your points in order... I know you'll probably be the only one to read this, but that's fine.
/. post to be fully descriptive. When I say "pretty much the same" I mean this:
First, DART was not a failure. Sure, it didn't do what it was supposed to, but already some lessons have been learned from it. Bear in mind, I'm not a part of that mission, so I don't know details. The craft managed to adjust its orbit autonomously to rendezvous with its target. It registered and recognized the target with its cameras, computed required changes in orbit, and successfully rendezvou'd with it... too successfully, in fact. As I understand it, noisy GPS signals resulted in excessive thruster firing, and in the end it collided with the target. Fuel spent, it retreated to a final graveyard orbit. Not the dismal failure you implied.
Regarding superior robotic technology, I'm guessing you don't understand the heritage of technology we're using. The servicing robotics have been fully developed and are sitting in a clean-room in Canada. The hardware was developed over the past couple decades in preparation for use on ISS. We've taken actual flight-ready hardware from that project with the promise of building replacements. The HST capture robotics draw upon many components, systems, and assemblies common to the dexterous robot for ISS, the Canadarm on ISS, and the SRMS on Shuttle. Nothing new in the robotics. All heritage hardware. Further to that, all operations needed to fully service Hubble are being proven on the ground with a validated dexterous robot 1G simulator. Advanced robotics development was not a requirement for this mission. In fact there was no time for that, so we've gone with what we know works.
You sound eager to jump on my turns of phrase. There's not room in a
The batteries and rate gyros MUST be changed out. Both robotic and shuttle missions will do this. How they do it is different. The shuttle mission will bring new batteries, take out the old ones, and put in the new ones. The robotic mission will bring new batteries and patch the connectors over to them, leaving the old batteries in place. The shuttle mission will bring up new gyros, take out the old ones, and put in the new ones. The robotic mission will bring up new gyros attached to the new WFC3 instrument, and patch them into the 486 computer, leaving the old gyros in place. The COSTAR instrument is to be changed out and replaced with COS. This is not a critical operation, but is highly desired. Both the Shuttle and robotic mission will do this. The tasks are effectively identical for human and robot, with several aspects better performed by robot (inserting COS, closing aft-shroud doors). 4 connectors and 1 ground strap must be transfered from the old instrument to the new. This is easy for humans, and hard for the robot. The FGS (fine guidance sensor) instrument is to be replaced with an upgraded version of the same. Again, not critical, but highly desired. Like COS, several aspects of the operation are better performed by robot. Again, 8 connectors and 1 ground-strap must be transfered. This is hard for the robot, easy for humans.
These are Hubble servicing priorities, regardless of how the mission is done. It's possible the shuttle mission would add the ability to fix the power regulator for STIS. This is unlikely however, as access to the many many bolts required to be loosened is tough for both humans and robots, and requires much time.
Reaction wheel changeout is a contingency task for the robotic mission. It might be added to the human. If a need arises, this task could be added to the robotic mission up to 30days pre-launch.
Anyway, there you have it... priorities are priorities, irrespective of the way you carry them out. Not much will change from robotic to human mission, as time constraints prevent the shuttle mission from adding everything they want.
The instruments are housed inside the HRV in a thermally controlled keep-alive state. Bay doors are left closed
It'll get dumped overboard along with the large spacecraft that brought it there. Together they'll likely make it to ground (water in this case). All that's left behind is the relatively small propulsion module to later de-orbit Hubble.
I've posted about this topic before (here: http://science.slashdot.org/comments.pl?sid=146007 &cid=12230905, and here: http://science.slashdot.org/comments.pl?sid=146007 &cid=12232506)
There are several important factors in deciding between them. Lets look at the pros and cons.
Cost:
1. Shuttle servicing will cost about $300M to fly the mission plus ~$1.5B-2B to keep the shuttle program and staff going for an extra 4-6 months. Total cost then is conservatively $2.3B.
2. Robotic Deorbit Only is estimated to cost about $850M, for development, launch, and operation of the vehicle.
3. Robotic servicing is expected to cost $1.4B for dev, launch, and operation through splashdown.
However(!) if we take option 1 or 2, we'll have to fly a 'robotic proving' mission around 2015 or so to enable missions to Moon and Mars. This could cost anywhere from $500-800M (likely closer to 800 if it's to be at all ambitious). So lets look at the total score-card:
Shuttle: $2.3B + $800M = $3.1 Billion
Deorbit: $850M + $800M = $1.65 Billion
Robotic: $1.4B - ~250M already spent = $1.15 Billion
So that was cost. Now lets look at education:
Doing another shuttle servicing mission will teach us very little. Sure, we'd learn some EVA techniques, management techniques, things like that. But nothing significant. That's why we'd need to launch a robotic proving mission in 2015.
Robotic Deorbit would teach us a lot about autonomous rendezvous (since my last post it's apparent that we need to work a little harder on that; DART bumped into its target, I hear). Bear in mind that craft had no forward-link commanding from the ground... it was entirely autonomous. It cost only $100-something million to dev, launch and "operate". These are lessons we need to learn to go to the Moon, and Mars.
Robotic Servicing would teach us a lot about the autonomous rendezvous and proximity operations (see above) since it's the same problem here as the robotic deorbit. It will also teach us a HUGE amount about ground-to-space tele-robotic operations. So much so that if it works we could be confident enough not to need an expensive proving mission later on. We'll be doing complex robotic tasks on things that were designed for humans (on space-station, everything's designed to be robot-friendly). We'll be pushing the envelope of our knowledge.
Don't let that put you off though. We're pushing the envelope on the ground here, right now. We've pushed it so far now that most tasks on the Hubble robotic mission will be trivial. We aim to push it far enough that ALL tasks will be trivial (or at most 'complex') by the time we launch. We have a robust capacity to re-plan and re-approach a problem on orbit. We have the advantage of time (see next pro/con) on our side. And we have contingency in case some more critical item fails before we launch. I believe that up to 30 days before launch we have the ability to re-manifest the cargo. Don't quote me on that figure though.
Now lets look at perhaps the most important feature of each mission: The quality of the result:
Some say a shuttle servicing mission will do a better job at servicing Hubble. This used to be the case. In looking at the robotic mission we had to give up some things. The STIS failed last summer, as some of you may remember. The robotics guys evaluated that task, and decided it would be too difficult. Many bolts in hard-to-reach places, etc. So that was dropped. However, I've recently heard on the wind that a Shuttle mission will only have a few days of EVA available between tile inspection and prep for landing. The shuttle mission will be forced to leave things out too, and the result is that the priorities we identified for the robotic mission are pretty much the same priorities we'd have for the sh
You bring up a valid point, and this fact has not gone overlooked.
The dexterous arms (There are two on the mission) are fully developed and are already built. Because of the Hubble mission timeline development of new arm technology would have been infeasible.
The Space Station program had three identical arms built (SPDM) for launch... sometime. We've taken the spare arm from them as-is, and they will build another for us just like it (built-to-print). Then, with no Hubble mission schedule pressure, we'll build them a replacement spare.
The arm we took has been fully tested and passed the acceptance review by the Canadian Space Agency. No new tech here, and it's ready to be flown to ISS for manned use, so it's certainly ready for us.
The long grapple arm is using -identical- joint design to the SPDM's that we're taking. It has longer booms obviously, though the company that is building it are certainly experts in the field (4 SRMS shuttle arms, 1 SSRMS station arm, and so far two OBSS booms for shuttle tile inspections).
By FAR, the robot system is the furthest advanced part of the Hubble mission. Really it looks like it's coming down to two Hard Parts(tm). As you say, the autonomous capture is hard. that's being worked on, and the final issues are scheduled to be resolved by CDR in September. Also, the tools are hard. The robot is finished (we're taking them as-is; only minor mods). HST is finished, obviously. it's the interface that's hard, and that's the tools.
These have progressed significantly in the past year, with tool-tests and demos on-going virtually weekly at GSFC.
Then, as you say also, the integration of these systems is the 3rd of 2 hard parts. A good integration plan is in place with a few issues to be resolved by CDR as well. The PDR reviewers were all highly impressed with progress thus far, and thought there was no reason not to proceed to CDR.
The XSS-11 rendezvous stuff is virtually the same tech as the Hubble rendezvous stuff. It's the software that'll be somewhat different.
I'm not saying everything's figured out and that this mission will be easy. It's not. It's hard. But it's being done the Right Way(tm).
Hope that helps.
As someone working on the Hubble robotic servicing mission (I know most /.ers will say this biases my opinion; really it just means I can speak from a position of knowledge), I can state 100% that this mission can be done, and can be done on schedule.
Let me break down the phases of the mission for those who are unaware:
1.) Launch - needs little explanation - a Delta IV or Atlas V heavy lift launches the HRV into Hubble's orbital plane
2.) Checkout & Commissioning - The robot arm and other HRV elements are tested and verified operational
3.) Orbit Phasing & Rendezvous - The craft will be commanded to approach Hubble. Autonomous systems will be used to coordinate the final stages of this approach, using technologies currently being proven out on the XSS-11 spacecraft which launched this week, and to be launched next week on the DART spacecraft.
4.) Capture & Berthing- The robot arm is set up for capture, and when the vision system determines that the end effector is within tolerances, an autonomous capture is performed. HRV is performing station-keeping until just before, and when HRV and HST are known to have a negative relative drift rate (receding), the capture process is allowed to begin. A capture ends with the arm grappled to one of HST's shuttle grapple fixtures. The vision system is in development, and the hardware has been space-proven for the past ~20 years on Shuttle... in fact the exact same end-effector design has been used on all previous HST servicing missions. After Capture, the arm decelerates HST and then engages it into the HRV latches (same latching arrangement as on a shuttle servicing mission).
5.) Battery Augmentation - HST's batteries will die soon, and are one of the prime schedule drivers for the mission. The dexterous robot (two armed robot) connects wire conduits from the HRV batteries to the outside of HST and routes solar array power to them. The hardest part of this task is transfering the 2 prime or 2 redundant connectors on each of the port and starboard diode boxes (located just under the solar array masts). This operation has been proven out on the ground, using a validated flightlike 1G testbed version of the actual dexterous robot, and a hi-fi Hubble mockup. In fact I think operators demo'd this very op just yesterday for maybe the 20th time. Trust me... it's highly doable.
6.) Changout WideField and add Gyros - The gyroscopes are the next most likely item to fail on HST, and are another schedule driver. With the new two-gyro mode currently under investigation, the lifetime of HST could likely be extended beyond the 2007 timeframe. The Rate-Gyro Assemblies are attached conveniently to the outside of WFC3, the replacement wide-field camera for WFPC2. WFPC2 is the camera responsible for most of the majestic galaxy and planetary photographs we seen in the news and magazines. WFC3 will improve yet again over that. Changing out WFPC2 involves de-mating the internal connectors, removing the ground-strap, unlatching the instrument, and sliding it out of the -V3 radial instrument bay rails. The old instrument is transported down to a stowage location in the HRV, and the new instrument is installed in the empty HST bay in the reverse sequence. This entire operation has been demo'd several times over the past year.
7.) Changeout COSTAR - After the two critical repairs (batteries and gyros), we move into the get-aheads and upgrades. The COSTAR instrument, sitting in axial bay 4, has performed corrective optics functions since its installation during the first servicing mission. Now that all HST instruments are built with integrated corrective optics, this instrument is obsolete, and can be replaced by something more productive; the Cosmic Origins Spectrograph (COS). To perform the changeout, the robot must unlatch and open the -V2 aft shroud doors, attach a handling fixture to COSTAR, attach a connector transfer panel to the handling fixture, transfer the 4 COSTAR harness connectors, transfer the ground