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If the JWST survives launch but has a subsequent mechanical problem that prevents it deploying properly (and it’s the kind of problem that would have been fixab

by jl6 5y ago

If the JWST survives launch but has a subsequent mechanical problem that prevents it deploying properly (and it’s the kind of problem that would have been fixable on Hubble, using a shuttle mission) would it be feasible to mount a robotic rescue mission to chase it down and remote-hands it back to life? For less than the cost of just launching another JWST?

nabla9 5y ago
The JWST will not orbit Earth. It will be located near the second Lagrange point (L2) over 1,500,000 km away (The Moon is just 405,000 km from the Earth). Space Shuttle could not have reached it.
- wyldfire 5y ago
  How long can it stay stable at that point? Does it have thrusters to keep a station there? If so, how long is the fuel for them provisioned for? Does use of the thrusters impact the sensors that the telescope uses?
  - pageandrew 5y ago
    The orbit needs to be actively maintained. The telescope was designed for a 5.5 year mission, but NASA says it could last up to 10.5 years with proper fuel management. It has two different types of thrusters under the "Propulsion Subsystem". > One kind is called "Secondary Combustion Augmented Thrusters" (SCAT), and they are used for orbit correction (like applied changes in velocity for each maneuver the spacecraft makes and also for orbit station-keeping). The SCATs are bi-propellant thrusters, using hydrazine (N2H4) and dinitrogen tetroxide (N2O4) as fuel and oxidizer, respectively. > The other kind of thruster on Webb is called a MRE-1, or mono-propellant rocket engine, since it only uses hydrazine. There are eight MRE-1s on Webb, and they are used for attitude control and momentum unloading of the reaction wheels Ref: https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-spacecraft-bus/jwst-propulsion https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-s...
  - spywaregorilla 5y ago
    > Does use of the thrusters impact the sensors that the telescope uses? The point of sitting in a lagrange point is that you can stay there without moving due to two gravitational forces. That's not perfectly accurate, but I don't think it needs constant thrust, just occasional taps.
  - deleted 5y ago
    [deleted]
  - hguant 5y ago
    The L2 point is unstable with a period of 23 days? I believe, so the JWT needs a course correct burn to stay positioned correctly (called station keeping). It does have thrusters - a ring of 16 hydrazine "burning" units that can produce thrust on 3 axis. The fact that the L2 point is unstable and that thrusters are required puts a lifetime on the telescope - I think NASA plans for a minimum of 5 1/2 years and are hoping to get up to 10. That's entirely reliant on the fuel supply. The use of thrusters does impact the sensors the telescope uses. NASA et al schedule usable telescope time around burns, and general attitude shifts/correction. The telescope uses a bunch of gyroscopes/flywheels to point itself in the proper direction, during maneuvers like that the sensors aren't operable.
    - wyldfire 5y ago
      > The fact that the L2 point is unstable and that thrusters are required puts a lifetime on the telescope - I think NASA plans for a minimum of 5 1/2 years and are hoping to get up to 10. That's entirely reliant on the fuel supply. So when the fuel is exhausted the orbit decays and the unshielded telescope disintegrates on re-entry into Earth's atmosphere?
      - lmm 5y ago
        > So when the fuel is exhausted the orbit decays and the unshielded telescope disintegrates on re-entry into Earth's atmosphere? Or drifts off into its own orbit around the Sun, but essentially yes.
- pklausler 5y ago
  It's not an orbit, per se, but... it will go around the Earth once per year.
  - phkahler 5y ago
    >> it will go around the Earth once per year. I think more accurately it will go around the sun once per year. The earth will provide the extra gravitational pull (toward the sun) needed to orbit the sun at a larger radius than the earth in the same amount of time as the earth.
    - pklausler 5y ago
      Sure, but it also goes around the Earth once per year, too, sidereally.
      - phkahler 5y ago
        Sure, but I doubt anyone would say that about some of the other lagrange points.
    - sp332 5y ago
      It equally orbits the sun and the earth. Normally, objects with smaller orbits take less time to make a circuit. But this is placed where the earth's gravity pulls it back, just enough to make it take one (earth) year to finish its smaller orbit. So gravity from the earth and the sun are involved.
  - nabla9 5y ago
    Only in the same sense as mars goes around the Earth. Meaningless concept. It never crosses inside Earth orbit. Maybe "co-orbits the Sun with the Earth using Earth's gravity"
geenew 5y ago
It has a docking clamp, though that's for future-proofing. Apparently the initial type of mission envisioned was a crewed Orion vehicle, though I'm sure a wide variety of missions could attach. My guess was that the clamp was mainly for possible future replenishment of consumables, though presumably some sort of robotic-arm-equipped repair mission could attach as well. A crewed mission seems possible, too, assuming one of the planned Lunar craft could be modified to go to the Lagrange point. https://www.space.com/3833-nasa-adds-docking-capability-space-observatory.html https://www.space.com/3833-nasa-adds-docking-capability-spac... https://en.wikipedia.org/wiki/Spacecraft_Bus_(JWST)#Docking_ring https://en.wikipedia.org/wiki/Spacecraft_Bus_(JWST)#Docking_...
- imglorp 5y ago
  Nothing in the current fleet of new capsules have arms or airlocks. There is hope for the robotic refueling type mission though, or at least the kind where a new utility bot attaches to an old satellite and takes over propulsion to extend its life. https://nexis.gsfc.nasa.gov/rrm_refueling_task.html https://nexis.gsfc.nasa.gov/rrm_refueling_task.html
  - messe 5y ago
    > Nothing in the current fleet of new capsules have arms or airlocks. True, but a docking adapter with an airlock that works with starliner and dragon is technically feasible. That said, it would still likely require recertification, as its inclusion would effect abort modes.
BitwiseFool 5y ago
The JWST orbits out beyond the Moon, so I don't know if the Orion capsule and European Service Module even has the Delta-V to make it to that Lagrange point and back. Plus, I'm also unsure about the life support and duration requirements for such a mission. I imagine the only realistic repair mission would be with a Starship crew, seeing as Orion and all the other Commercial Crew vehicles would probably require some additional components to make it out that far and to sustain their crews. Starship seems big enough and far enough along in development to be viable. Edit: The JWST has a docking ring to let Orion service it. But I don't know if the SLS in it's available configurations can get it up there. It seems like a contingency but I don't see any solid information about an Orion service mission.
- wolverine876 5y ago
  The GP asked about robotic, not human missions.
  - BitwiseFool 5y ago
    My mind skipped over that. I don't have a good answer for a robotic mission but I imagine NASA won't fund it.
ultramegachurch 5y ago
Highly unlikely. That would require designing a new spacecraft from the ground up while also developing new robotics and operations technologies. I'd peg that mission at $300 - $500 million. NASA would almost certainty be better off documenting lessons learned and pursuing a new observatory.
- nrdgrrrl 5y ago
  They've spent almost 10 billion dollars on this telescope so far. What's another 0.5 billion for a repair mission?
  - ultramegachurch 5y ago
    That 0.5 billion (which to be clear, is a number I made up) won't guarantee that JWST will be fixed. The "fixer" spacecraft could end up failing itself. Or it could discover new problems that it's not equipped to handle. Also, congress would be extremely critical of NASA if JWST fails. They would not be excited to shell out another $0.5 billion for a chance to fix it.
    - vimacs2 5y ago
      Not to mention that we don't even currently have a real capability to repair the currently malfunctioning Hubble telescope anymore. That was designed for maintenence from the now non-existent space shuttle in mind. Trying to accomplish the same with the Dragon would be unknown territory and it seems that there is little desire from both NASA and congress to even bother. JWST in comparison is a far trickier and complicated beast to tinker with. This is the biggest reason why they are so paranoid about any fault before orbital launch. It would be all but impossible to service it - on both a technical and political level.
- mcbutterbunz 5y ago
  > I'd peg that mission at $300 - $500 million. If that was the cost for that mission, it would be worth it considering JWST cost about 20x that amount.
derekp7 5y ago
I would think that a cheaper (or multiple cheaper) versions could be made if they don't require the long lifespan and reliability that previous launch costs inflicted. Once Starship is going, and if it proves to be as low cost as the current projections, I could see multiple space telescopes being designed cheaply for a launch every year, each one designed in a narrow configuration that serves a specific purpose. But I really don't know what all goes into making a space telescope so expensive currently.
- phkahler 5y ago
  >> But I really don't know what all goes into making a space telescope so expensive currently. I think you already said it. The long life (high reliability) requirement, and I'll add the complexity of having it unfold. Both of those become non-issues if you build the telescope right into a space-X starship. There may be other issues with that, but the mirror wouldn't need to fold ;-)
  - bumby 5y ago
    Are you speaking to the reliability of the launch vehicle or of the satellite? The launch itself is typically not a primary cost driver of a satellite mission. Complexity may be, due to constraints of the fairings but the manufacturing and quality checks drive quite a bit of the cost
    - ckozlowski 5y ago
      I think they mean reliability of the satellite. The JWST is going to be parked at a Lagrange point that's going to put it out of reach of most everything. At the time it was conceived, robotic servicing was even further off. A crewed mission was right out. Costs went far up in part because unlike Hubble, servicing was going to be virtually impossible.
      - anticensor 5y ago
        Starship has a sufficient delta-v to service it.
ufmace 5y ago
The trouble with robotic repair missions is that it could work pretty well if you knew 100% exactly what was wrong, and exactly what else might go wrong while applying the fix for whatever went wrong. The more potential unknowns, the harder it is. It's much harder to make a robot with enough general flexibility that it could probably handle diagnosing and repairing an unknown issue, or handle something going wrong while trying to carry out a planned repair sequence. Bolts jammed, too loose, too tight, tanks of stuff springing leaks, electrical short in some unknown place, component overheating for unknown reason, all sorts of things can go wrong that are tough to diagnose remotely or with a special-purpose robot.
- nhoughto 5y ago
  And you’d need to have it designed to be serviceable once deployed. I’d imagine there would be a few assumptions going into the design process, “once deployed humans won’t ever need to get to that..”
- MayeulC 5y ago
  How about deploying it near the ISS?
Torkel 5y ago
Latency is a bitch. So remote hands from earth is most likely a no-go, for this reason alone. And if you bring astronauts close, then I guess that some EVAs in existing suits starts looking appealing vs developing those remote hands.
- system2 5y ago
  They wouldn't operating it like they play computer games. Mars rover has a major latency too, they can simply instruct it with limits and work slightly slower.
deepsun 5y ago
Also, all robotic space repair satellites are very into military tech (even taking pictures of open space is very strictly controlled, because you may inadvertently take a picture of a military satellite). Not event talking about disabling err.. repairing, de-orbiting, spinning etc other satellites. That types of tech is opposed by military, that's actually one of the reason we don't clear dangerous space garbage (especially considering some of that garbage is actually working military satellites).
- NavinF 5y ago
  > taking pictures of open space is very strictly controlled, because you may inadvertently take a picture of a military satellite Citation needed
  - deepsun 5y ago
    I worked in a private space company, that I was told by SatOps folks. I remember they said only US citizens on US territory could process the photos.
OrvalWintermute 5y ago
It is conceivable that on-orbit repair missions like OSAM-1 could fix a mission with a mechanical failure, depending on the orbit that it reaches. https://nexis.gsfc.nasa.gov/osam-1.html https://nexis.gsfc.nasa.gov/osam-1.html
dylan604 5y ago
Seems to me it would be easier to design a craft to dock with it and bring back to an easier for humans to reach location. Then push it back out to where it needs to go. I'm sure there's some delta-v math to determine the fuel requirements, and I'm guessing it would also make a huge difference on how fast you wanted it back.

by jl6 5y ago

nabla9 5y ago

The JWST will not orbit Earth. It will be located near the second Lagrange point (L2) over 1,500,000 km away (The Moon is just 405,000 km from the Earth). Space Shuttle could not have reached it.

wyldfire 5y ago
How long can it stay stable at that point? Does it have thrusters to keep a station there? If so, how long is the fuel for them provisioned for? Does use of the thrusters impact the sensors that the telescope uses?
- pageandrew 5y ago
  The orbit needs to be actively maintained. The telescope was designed for a 5.5 year mission, but NASA says it could last up to 10.5 years with proper fuel management. It has two different types of thrusters under the "Propulsion Subsystem". > One kind is called "Secondary Combustion Augmented Thrusters" (SCAT), and they are used for orbit correction (like applied changes in velocity for each maneuver the spacecraft makes and also for orbit station-keeping). The SCATs are bi-propellant thrusters, using hydrazine (N2H4) and dinitrogen tetroxide (N2O4) as fuel and oxidizer, respectively. > The other kind of thruster on Webb is called a MRE-1, or mono-propellant rocket engine, since it only uses hydrazine. There are eight MRE-1s on Webb, and they are used for attitude control and momentum unloading of the reaction wheels Ref: https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-spacecraft-bus/jwst-propulsion https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-s...
- spywaregorilla 5y ago
  > Does use of the thrusters impact the sensors that the telescope uses? The point of sitting in a lagrange point is that you can stay there without moving due to two gravitational forces. That's not perfectly accurate, but I don't think it needs constant thrust, just occasional taps.
- deleted 5y ago
  [deleted]
- hguant 5y ago
  The L2 point is unstable with a period of 23 days? I believe, so the JWT needs a course correct burn to stay positioned correctly (called station keeping). It does have thrusters - a ring of 16 hydrazine "burning" units that can produce thrust on 3 axis. The fact that the L2 point is unstable and that thrusters are required puts a lifetime on the telescope - I think NASA plans for a minimum of 5 1/2 years and are hoping to get up to 10. That's entirely reliant on the fuel supply. The use of thrusters does impact the sensors the telescope uses. NASA et al schedule usable telescope time around burns, and general attitude shifts/correction. The telescope uses a bunch of gyroscopes/flywheels to point itself in the proper direction, during maneuvers like that the sensors aren't operable.
  - wyldfire 5y ago
    > The fact that the L2 point is unstable and that thrusters are required puts a lifetime on the telescope - I think NASA plans for a minimum of 5 1/2 years and are hoping to get up to 10. That's entirely reliant on the fuel supply. So when the fuel is exhausted the orbit decays and the unshielded telescope disintegrates on re-entry into Earth's atmosphere?
    - lmm 5y ago
      > So when the fuel is exhausted the orbit decays and the unshielded telescope disintegrates on re-entry into Earth's atmosphere? Or drifts off into its own orbit around the Sun, but essentially yes.
pklausler 5y ago
It's not an orbit, per se, but... it will go around the Earth once per year.
- phkahler 5y ago
  >> it will go around the Earth once per year. I think more accurately it will go around the sun once per year. The earth will provide the extra gravitational pull (toward the sun) needed to orbit the sun at a larger radius than the earth in the same amount of time as the earth.
  - pklausler 5y ago
    Sure, but it also goes around the Earth once per year, too, sidereally.
    - phkahler 5y ago
      Sure, but I doubt anyone would say that about some of the other lagrange points.
  - sp332 5y ago
    It equally orbits the sun and the earth. Normally, objects with smaller orbits take less time to make a circuit. But this is placed where the earth's gravity pulls it back, just enough to make it take one (earth) year to finish its smaller orbit. So gravity from the earth and the sun are involved.
- nabla9 5y ago
  Only in the same sense as mars goes around the Earth. Meaningless concept. It never crosses inside Earth orbit. Maybe "co-orbits the Sun with the Earth using Earth's gravity"

geenew 5y ago

It has a docking clamp, though that's for future-proofing. Apparently the initial type of mission envisioned was a crewed Orion vehicle, though I'm sure a wide variety of missions could attach. My guess was that the clamp was mainly for possible future replenishment of consumables, though presumably some sort of robotic-arm-equipped repair mission could attach as well. A crewed mission seems possible, too, assuming one of the planned Lunar craft could be modified to go to the Lagrange point. https://www.space.com/3833-nasa-adds-docking-capability-space-observatory.html https://www.space.com/3833-nasa-adds-docking-capability-spac... https://en.wikipedia.org/wiki/Spacecraft_Bus_(JWST)#Docking_ring https://en.wikipedia.org/wiki/Spacecraft_Bus_(JWST)#Docking_...

imglorp 5y ago
Nothing in the current fleet of new capsules have arms or airlocks. There is hope for the robotic refueling type mission though, or at least the kind where a new utility bot attaches to an old satellite and takes over propulsion to extend its life. https://nexis.gsfc.nasa.gov/rrm_refueling_task.html https://nexis.gsfc.nasa.gov/rrm_refueling_task.html
- messe 5y ago
  > Nothing in the current fleet of new capsules have arms or airlocks. True, but a docking adapter with an airlock that works with starliner and dragon is technically feasible. That said, it would still likely require recertification, as its inclusion would effect abort modes.

BitwiseFool 5y ago

The JWST orbits out beyond the Moon, so I don't know if the Orion capsule and European Service Module even has the Delta-V to make it to that Lagrange point and back. Plus, I'm also unsure about the life support and duration requirements for such a mission. I imagine the only realistic repair mission would be with a Starship crew, seeing as Orion and all the other Commercial Crew vehicles would probably require some additional components to make it out that far and to sustain their crews. Starship seems big enough and far enough along in development to be viable. Edit: The JWST has a docking ring to let Orion service it. But I don't know if the SLS in it's available configurations can get it up there. It seems like a contingency but I don't see any solid information about an Orion service mission.

wolverine876 5y ago
The GP asked about robotic, not human missions.
- BitwiseFool 5y ago
  My mind skipped over that. I don't have a good answer for a robotic mission but I imagine NASA won't fund it.

ultramegachurch 5y ago

Highly unlikely. That would require designing a new spacecraft from the ground up while also developing new robotics and operations technologies. I'd peg that mission at $300 - $500 million. NASA would almost certainty be better off documenting lessons learned and pursuing a new observatory.

nrdgrrrl 5y ago
They've spent almost 10 billion dollars on this telescope so far. What's another 0.5 billion for a repair mission?
- ultramegachurch 5y ago
  That 0.5 billion (which to be clear, is a number I made up) won't guarantee that JWST will be fixed. The "fixer" spacecraft could end up failing itself. Or it could discover new problems that it's not equipped to handle. Also, congress would be extremely critical of NASA if JWST fails. They would not be excited to shell out another $0.5 billion for a chance to fix it.
  - vimacs2 5y ago
    Not to mention that we don't even currently have a real capability to repair the currently malfunctioning Hubble telescope anymore. That was designed for maintenence from the now non-existent space shuttle in mind. Trying to accomplish the same with the Dragon would be unknown territory and it seems that there is little desire from both NASA and congress to even bother. JWST in comparison is a far trickier and complicated beast to tinker with. This is the biggest reason why they are so paranoid about any fault before orbital launch. It would be all but impossible to service it - on both a technical and political level.
mcbutterbunz 5y ago
> I'd peg that mission at $300 - $500 million. If that was the cost for that mission, it would be worth it considering JWST cost about 20x that amount.

derekp7 5y ago

I would think that a cheaper (or multiple cheaper) versions could be made if they don't require the long lifespan and reliability that previous launch costs inflicted. Once Starship is going, and if it proves to be as low cost as the current projections, I could see multiple space telescopes being designed cheaply for a launch every year, each one designed in a narrow configuration that serves a specific purpose. But I really don't know what all goes into making a space telescope so expensive currently.

phkahler 5y ago
>> But I really don't know what all goes into making a space telescope so expensive currently. I think you already said it. The long life (high reliability) requirement, and I'll add the complexity of having it unfold. Both of those become non-issues if you build the telescope right into a space-X starship. There may be other issues with that, but the mirror wouldn't need to fold ;-)
- bumby 5y ago
  Are you speaking to the reliability of the launch vehicle or of the satellite? The launch itself is typically not a primary cost driver of a satellite mission. Complexity may be, due to constraints of the fairings but the manufacturing and quality checks drive quite a bit of the cost
  - ckozlowski 5y ago
    I think they mean reliability of the satellite. The JWST is going to be parked at a Lagrange point that's going to put it out of reach of most everything. At the time it was conceived, robotic servicing was even further off. A crewed mission was right out. Costs went far up in part because unlike Hubble, servicing was going to be virtually impossible.
    - anticensor 5y ago
      Starship has a sufficient delta-v to service it.

ufmace 5y ago

The trouble with robotic repair missions is that it could work pretty well if you knew 100% exactly what was wrong, and exactly what else might go wrong while applying the fix for whatever went wrong. The more potential unknowns, the harder it is. It's much harder to make a robot with enough general flexibility that it could probably handle diagnosing and repairing an unknown issue, or handle something going wrong while trying to carry out a planned repair sequence. Bolts jammed, too loose, too tight, tanks of stuff springing leaks, electrical short in some unknown place, component overheating for unknown reason, all sorts of things can go wrong that are tough to diagnose remotely or with a special-purpose robot.

nhoughto 5y ago
And you’d need to have it designed to be serviceable once deployed. I’d imagine there would be a few assumptions going into the design process, “once deployed humans won’t ever need to get to that..”
MayeulC 5y ago
How about deploying it near the ISS?

Torkel 5y ago

Latency is a bitch. So remote hands from earth is most likely a no-go, for this reason alone. And if you bring astronauts close, then I guess that some EVAs in existing suits starts looking appealing vs developing those remote hands.

system2 5y ago
They wouldn't operating it like they play computer games. Mars rover has a major latency too, they can simply instruct it with limits and work slightly slower.

deepsun 5y ago

Also, all robotic space repair satellites are very into military tech (even taking pictures of open space is very strictly controlled, because you may inadvertently take a picture of a military satellite). Not event talking about disabling err.. repairing, de-orbiting, spinning etc other satellites. That types of tech is opposed by military, that's actually one of the reason we don't clear dangerous space garbage (especially considering some of that garbage is actually working military satellites).

NavinF 5y ago
> taking pictures of open space is very strictly controlled, because you may inadvertently take a picture of a military satellite Citation needed
- deepsun 5y ago
  I worked in a private space company, that I was told by SatOps folks. I remember they said only US citizens on US territory could process the photos.

OrvalWintermute 5y ago

It is conceivable that on-orbit repair missions like OSAM-1 could fix a mission with a mechanical failure, depending on the orbit that it reaches. https://nexis.gsfc.nasa.gov/osam-1.html https://nexis.gsfc.nasa.gov/osam-1.html

dylan604 5y ago

Seems to me it would be easier to design a craft to dock with it and bring back to an easier for humans to reach location. Then push it back out to where it needs to go. I'm sure there's some delta-v math to determine the fuel requirements, and I'm guessing it would also make a huge difference on how fast you wanted it back.