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I'm always fascinated by these spacecraft that far outlive their designed mission lifetime, and then sometimes need a software hacks to continue operating, ofte

I'm always fascinated by these spacecraft that far outlive their designed mission lifetime, and then sometimes need a software hacks to continue operating, often with reduced capabilities. Just recently we had the news about Voyager 1 needing a remote updated to avoid some corrupted memory region, and I believe Hubble runs with only one gyroscope now, because the other ones either died or were slowly dying (while still far exceeding the original mission duration). I can imagine the satisfaction the software engineers feel if they can eek out a few more years of mission life out of a piece of expensive hardware that too far out to service directly.

deleted 2y ago
[deleted]
eb0la 2y ago
Probably the key is to assume worst case scenario will always apply. After all space is an hostile enviroment you cannot control, and you need to have the device working for at least the whole mission lifetime.
- its_ethan 2y ago
  Another factor is that when NASA says the expected mission life is like 30 days or whatever, it doesn't mean they are designing to just meet that 30 day target. I can only speak to mechanical design, but the margins that NASA uses are huge, at least compared to consumer tech (I've worked in both). The 30 days is more like what they are "liable" for achieving per their directive. Liability isn't quite the right word, but the missions are pretty small in their official spec/definitions.
kelnos 2y ago
> Hubble runs with only one gyroscope now, because the other ones either died or were slowly dying IIRC there are six total gyros on Hubble. Some of them have failed. Earlier this year, one of the three remaining failed as well, so they're down to two. They've dropped to a one-gyro mode now so they won't wear out both at the same time. Once the one they're using fails, they'll switch to the last one. The two remaining gyros are of a set of "better" gyros that were installed on a servicing mission 15 years ago or so. They could repair it (as well as give the satellite a much-needed orbit re-boost), but for now they've passed on doing so, presumably for budgetary reasons. Regardless, completely agree that it's incredible that these spacecraft often outlive their mission plan, sometimes drastically so. Hubble was projected to have 15 useful years (1990-2005), but it's still kicking (though not without the cost of past repair and upgrade missions), and should hopefully last well into the next decade. Longer, presumably, if it becomes compelling enough to spend the money to further service it.
- adolph 2y ago
  > They could repair it (as well as give the satellite a much-needed orbit re-boost), but for now they've passed on doing so, presumably for budgetary reasons. It isn't clear anyone could "repair it." Part of NASA's reticence has to do with Hubble's sensitivity and that any docking would be completely new since the Space Shuttle was the only vehicle to service Hubble. Additionally at least some see good science continuing '"There's a greater than 70% probability of operating at least one gyro through 2035," Crouse said.' [0] A more conspiratorial part of me says there are imaging secrets the makers prefer to keep. On the other hand, there is the viewpoint that '"Up until now, there's only been, you know, one group that would ever touch Hubble. And I think that they have an opinion of whether — of who should or shouldn't be allowed to touch it," Isaacman said. "I think a lot would say, 'I'd rather it burn up' than, you know, go down a slippery slope of, you know, the space community growing. So I think that's a factor now, unfortunately."' [1] Personally, I see sunk cost fallacy as being a strong force in humanity. Additionally, the back and forth that may delay is resistance that will make Isaacman's solution better and certainly won't deter him. 0. https://www.space.com/jared-isaacman-hubble-space-telescope-reboost https://www.space.com/jared-isaacman-hubble-space-telescope-... 1. https://www.npr.org/2024/05/16/1250250249/spacex-repair-hubble-space-telescope-nasa-foia https://www.npr.org/2024/05/16/1250250249/spacex-repair-hubb...
  - rbanffy 2y ago
    It is possible to repair it and we know that because it was repaired many times before. It’d need at least some brand new hardware though. Until reusables make it cheap to launch a replacement (and so cheap the replacement doesn’t need to be built as carefully and expensively) it’s preferable to repair it. Or not, as ground-based observatories have evolved considerably since the Hubble was launched.
    - adolph 2y ago
      Possible covers a broad range of effort levels and outcome risks. At a minimum a solution for controlled deorbit is required within 10 years or so. You'd think that something that could use the SCM [0] to catch it could also reboost it or stage a human repair mission, but some involved are not as sanguine as a lay person. "The last time we went to Hubble, it was on the space shuttle, and it was quite a long time ago," Clampin said. "And, of course, Hubble is an old spacecraft now; a lot of the people who were very involved in the early serving missions have retired and there's a lot of work we would have to do to get back up to speed on how to do that." [1] On the other hand, even keeping a program running while a solution is developed might be too much given the rules NASA must follow. "Announced on Wednesday is the cancellation of the VIPER mission to the moon, this is shocking because the Rover is finished construction and just needs a test session. Moreover, NASA is contractually required to pay Astrobotic to fly a NASA payload to the moon, so they have to pay for this anyway. Instead of a rover NASA will send ballast to the moon." [2] 0. https://esahubble.org/about/general/soft_capture/ https://esahubble.org/about/general/soft_capture/ 1. https://www.space.com/jared-isaacman-hubble-space-telescope-reboost https://www.space.com/jared-isaacman-hubble-space-telescope-... 2. https://www.youtube.com/watch?v=4OS9kq0-ssg https://www.youtube.com/watch?v=4OS9kq0-ssg
mbonnet 2y ago
Expected mission lifetime is often a function of "if thing X, Y, Z goes wrong". As you get past X, Y, and Z, mission lifetime will grow significantly. For example, for the James Webb telescope, its expected lifetime was limited by expected precision of orbit insertion by the Ariane 5 that launched it. Ariane 5 performed perfectly, so the resulting precision means the lifetime of the telescope is extended.
- dotancohen 2y ago
  Isn't JWST limited by the chilling hydrogen onboard?
  - OldGuyInTheClub 2y ago
    No, it has a cryocooler for MIRI that keeps the relevant components at <7K without cryogen. https://www.youtube.com/watch?v=FUH61gx149c https://www.youtube.com/watch?v=FUH61gx149c

deleted 2y ago

[deleted]

eb0la 2y ago

Probably the key is to assume worst case scenario will always apply. After all space is an hostile enviroment you cannot control, and you need to have the device working for at least the whole mission lifetime.

its_ethan 2y ago
Another factor is that when NASA says the expected mission life is like 30 days or whatever, it doesn't mean they are designing to just meet that 30 day target. I can only speak to mechanical design, but the margins that NASA uses are huge, at least compared to consumer tech (I've worked in both). The 30 days is more like what they are "liable" for achieving per their directive. Liability isn't quite the right word, but the missions are pretty small in their official spec/definitions.

kelnos 2y ago

> Hubble runs with only one gyroscope now, because the other ones either died or were slowly dying IIRC there are six total gyros on Hubble. Some of them have failed. Earlier this year, one of the three remaining failed as well, so they're down to two. They've dropped to a one-gyro mode now so they won't wear out both at the same time. Once the one they're using fails, they'll switch to the last one. The two remaining gyros are of a set of "better" gyros that were installed on a servicing mission 15 years ago or so. They could repair it (as well as give the satellite a much-needed orbit re-boost), but for now they've passed on doing so, presumably for budgetary reasons. Regardless, completely agree that it's incredible that these spacecraft often outlive their mission plan, sometimes drastically so. Hubble was projected to have 15 useful years (1990-2005), but it's still kicking (though not without the cost of past repair and upgrade missions), and should hopefully last well into the next decade. Longer, presumably, if it becomes compelling enough to spend the money to further service it.

adolph 2y ago
> They could repair it (as well as give the satellite a much-needed orbit re-boost), but for now they've passed on doing so, presumably for budgetary reasons. It isn't clear anyone could "repair it." Part of NASA's reticence has to do with Hubble's sensitivity and that any docking would be completely new since the Space Shuttle was the only vehicle to service Hubble. Additionally at least some see good science continuing '"There's a greater than 70% probability of operating at least one gyro through 2035," Crouse said.' [0] A more conspiratorial part of me says there are imaging secrets the makers prefer to keep. On the other hand, there is the viewpoint that '"Up until now, there's only been, you know, one group that would ever touch Hubble. And I think that they have an opinion of whether — of who should or shouldn't be allowed to touch it," Isaacman said. "I think a lot would say, 'I'd rather it burn up' than, you know, go down a slippery slope of, you know, the space community growing. So I think that's a factor now, unfortunately."' [1] Personally, I see sunk cost fallacy as being a strong force in humanity. Additionally, the back and forth that may delay is resistance that will make Isaacman's solution better and certainly won't deter him. 0. https://www.space.com/jared-isaacman-hubble-space-telescope-reboost https://www.space.com/jared-isaacman-hubble-space-telescope-... 1. https://www.npr.org/2024/05/16/1250250249/spacex-repair-hubble-space-telescope-nasa-foia https://www.npr.org/2024/05/16/1250250249/spacex-repair-hubb...
- rbanffy 2y ago
  It is possible to repair it and we know that because it was repaired many times before. It’d need at least some brand new hardware though. Until reusables make it cheap to launch a replacement (and so cheap the replacement doesn’t need to be built as carefully and expensively) it’s preferable to repair it. Or not, as ground-based observatories have evolved considerably since the Hubble was launched.
  - adolph 2y ago
    Possible covers a broad range of effort levels and outcome risks. At a minimum a solution for controlled deorbit is required within 10 years or so. You'd think that something that could use the SCM [0] to catch it could also reboost it or stage a human repair mission, but some involved are not as sanguine as a lay person. "The last time we went to Hubble, it was on the space shuttle, and it was quite a long time ago," Clampin said. "And, of course, Hubble is an old spacecraft now; a lot of the people who were very involved in the early serving missions have retired and there's a lot of work we would have to do to get back up to speed on how to do that." [1] On the other hand, even keeping a program running while a solution is developed might be too much given the rules NASA must follow. "Announced on Wednesday is the cancellation of the VIPER mission to the moon, this is shocking because the Rover is finished construction and just needs a test session. Moreover, NASA is contractually required to pay Astrobotic to fly a NASA payload to the moon, so they have to pay for this anyway. Instead of a rover NASA will send ballast to the moon." [2] 0. https://esahubble.org/about/general/soft_capture/ https://esahubble.org/about/general/soft_capture/ 1. https://www.space.com/jared-isaacman-hubble-space-telescope-reboost https://www.space.com/jared-isaacman-hubble-space-telescope-... 2. https://www.youtube.com/watch?v=4OS9kq0-ssg https://www.youtube.com/watch?v=4OS9kq0-ssg

mbonnet 2y ago

Expected mission lifetime is often a function of "if thing X, Y, Z goes wrong". As you get past X, Y, and Z, mission lifetime will grow significantly. For example, for the James Webb telescope, its expected lifetime was limited by expected precision of orbit insertion by the Ariane 5 that launched it. Ariane 5 performed perfectly, so the resulting precision means the lifetime of the telescope is extended.

dotancohen 2y ago
Isn't JWST limited by the chilling hydrogen onboard?
- OldGuyInTheClub 2y ago
  No, it has a cryocooler for MIRI that keeps the relevant components at <7K without cryogen. https://www.youtube.com/watch?v=FUH61gx149c https://www.youtube.com/watch?v=FUH61gx149c