How To Hack A Spacecraft To Die Gracefully

Last week, the Rosetta spacecraft crashed into comet 67P/Churyumov-Gerasimenko after orbiting it since 2014. It was supposed to do that: the mission was at an end, and the mission designers wanted to end it by getting a close look at the surface of the comet. But this raises an interesting problem: how do you get a device that is designed to never stop to actually stop?

A spacecraft like Rosetta is built from the ground up to keep going, to reboot and go into a backup mode, phone home and wait for instructions if it encounters a problem. This is called a safe mode, and it has saved the spacecraft several times before. If it was left unfixed, when the spacecraft hit the comet, it would trigger a special safe mode called FDIR (Failure Detection, Isolation and Recovery) that would keep sending a diagnostic signal back to earth until the mission controllers responded.

But this mission was at an end, and if the probe was left constantly rebooting and transmitting a cry for help, it could interfere with other spacecraft using the same frequency. Even a weak signal could interfere with another spacecraft, so the designers wanted to shut it down completely.  So, they used an interesting approach: they patched the software on the spacecraft to stop it phoning home. The day before it was crashed into the comet, they sent it a patch that removed the safe mode and replaced it with a passive mode that hadn’t been used since before launch, where the spacecraft would simply sit and wait for instructions if it hit a problem. A few hours before the crash, this patch was activated, and the probe was now without a backup plan. So, when it hit the comet, it entered this passive mode, and it will stay in this mode for as long as the batteries last, forever waiting for a command to restart that will never come…

Thanks to [Daniel] for the tip!

64 thoughts on “How To Hack A Spacecraft To Die Gracefully

  1. That line about it rebooting and transmitting a cry for help almost brought a tear to my eye.

    The poor spacecraft, alone slowly dying on a strange uninhabitable comet. If only it had an Apple Watch and could send its heart beat to someone that cared……

    1. It’s a spacecraft, operating as and being a computer in space. It is not a living being. It cannot think. It has no emotions or consciousness. It’s literally a hardened computer in space. Why does this fact coupled with personification style writing induce an emotional response? If it was written as a technical document, would it have the same impact? Is this why there is such a preponderance or at least affinity for scientists to tend to be more logical, less emotional and statistically (depending on the particular scientific field as there is considerable variance) male gendered?

      1. “Quote: “Is this why there is such a preponderance or at least affinity for scientists to tend to be more logical, less emotional and statistically male gendered?”

        You have the question backwards and it is not surprising given that you seem to believe that intelligence and an ability to rationalize logically are on the same axiom and opposed to heightened ability to emphasize.

        Indeed intelligence and empathy are completely different axioms and any specific quantification on one of these axioms has no implication of any quantification on the other.

        So your question could more correctly be stated as follows –

        Is the fact that scientists are statistically male gendered the cause of a lack of appreciation for more statistically female qualities such as a high capacity for empathy and does that contribute to the statistical male gender?

        1. I agree that intelligence and empathy are generally separate elements. They are, however, still somewhat related or at the very least correlated and do not exist purely in isolation. When one does an analysis of the available BLS data, you see a strong correlation between some items over time such as actual occupation and gender. There are some reasons why we see this, related to culture, discrimination, societal expectations, biological differences in terms of practical differences in which gender bears children, etc. Some of it comes down to the simple fact that women prefer some jobs just as men prefer some jobs. There is nothing inherently “wrong” about that any more than what gender you are attracted to or what kind of political views you hold. But the fact remains that certain scientific and certain mechanical fields are not just slightly male. They are overwhelmingly male. The same goes for other fields with respect to them being overwhelmingly female. Again, this is not a judgement but more of an observation of actual data. Why that is specifically is undoubtedly multifaceted.

          Look under Service occupations. It’s 94.1% female in Dental assistants. 13.6% female in police and sheriff’s patrol officers. 94.9% female in childcare workers. Speech-language pathologists is 98.6% female. Cement masons, concrete finishers, and terrazzo workers has 0.2% female workers. Installation, maintenance, and repair occupations in particular are EXTREMELY male oriented. Pipelayers, plumbers, pipefitters, and steamfitters are just 0.7% female. Bus and truck mechanics and diesel engine specialists are 0.1% female. That means that for every 999 male workers, you will expect to see one female worker.

          There are 7,652,000 Construction and extraction occupations. 2.7% of them are held by females. This isn’t even close to some “ideal” 50:50 ratio that everybody seems to strive to have in every single occupation and I am not sure you can even argue that this is some macro level desire to repress and prevent females from entering those fields. It is entirely possible that women, all else equal, simply prefer to avoid working on those specific fields compared to alternative fields. The same goes for men too. Many men simply choose to not work in childcare or work as dental assistants. I am sure there are contributing factors that are at play but they can only offset so much if the person does not enjoy the actual work they are doing on a daily basis.

          Not sure I agree with your interpretation of how this is reworded either. What you are saying sort of breaks down a bit as well so I am not entirely sure I follow your argument exactly but you wrote:

          “Is the fact that scientists are statistically male gendered the cause of a lack of appreciation for more statistically female qualities such as a high capacity for empathy and does that contribute to the statistical male gender?”

          I don’t think you can handwave the realities of many decades (after women’s rights) of people choosing their own occupations and state that if females were statistically more likely to be in these occupations that the tables would suddenly “turn” in a different direction and suddenly everybody would appreciate more “traditionally associated” female qualities. That feels like both a stretch but also working in the wrong direction as well. There is certainly an argument that some jobs are so overwhelmingly male or female that it can be challenging for the opposite gender to “break into” them. But it is also likely that, numerically, very few people actually want to. That part is still subject to debate and discussion but it is nevertheless interesting that some of these fields have remained so skewed for so long in spite of other societal changes.

          Science as a broad category is not male or female dominated, from a numbers game and the gender gap is narrowing over time (for science in general). However, it does seem that there is a bit of a skew towards the types of science that lend themselves to be more logical and less emotional to attract more males than females, all else equal. Engineers more than scientists show this skew more acutely. I don’t think we can infer a lack of appreciation or empathy as contributing to the male gender though. My argument would be more along the lines that more men than women are born with lower emotional empathy and more logical reasoning thought processes. That’s not a good or a bad thing, just an observation of people across time. I also think that, to a degree, emotional intelligence and general intelligence are malleable and fluid and can change to a degree. My whole point was more that the original author of this article personified this spacecraft and in doing so, incites sympathy, emotional reaction and attachment. At the end of the day, it’s still a lifeless spacecraft but what people take from that can differ, depending on their unique perspectives. On the whole, does the gender of the reader influence how they feel about the author’s narrative? Is that correlated or because the emotional / and logical or rational side tends to skew along gender lines? I cannot say anybody could answer that definitively but there does seem to be more than a slight degree of correlation there.

          1. You are ignoring huge amounts of history to try and prove your point. For example there was a recent HaD article about how most of the first mainframe programmers were female, yet I don’t see you mentioning that statistic in your argument. It seems to me you have already decided how things are and are merely cherry picking to bring people to your side.

          2. I never said women were not or could not be good at anything, just like I never said men could not be good at anything. My point, in part, was stating that the actual statistical relative incidences of certain professions tends to skew towards one gender or another. Others are closer to 50:50. There just tends to be certain themes to some broad job categories that might help differentiate them. Why are so few men involved in childcare or dental hygiene? Why are so few women involved as brick masons? Why do engineers tend to skew male?

            Is it due in part to innate, gender correlated logical vs empathic differences? I don’t know but it seems like it’s at least a notable correlation.

          3. +2

            Personally, I would’ve liked more females in my engineering classes. Nevertheless, the push to get women into stem needs to be balanced to get more women into roofing. Even if it make them cry. Ok, the last part was sarcasm, but I still heard screams from several states away.

      2. Well, It’s not like ESAs PR department isn’t personificating Rosetta (and Philae) quite a little bit…
        So it’s really just like you can feel empathy for anything that can be personified and be made to somehow look cute, as this was and to some extent still is an important human instinct. Nature just didn’t expect us ever seeing comics of advanced washing machines with smiling faces on them.

      3. When I Heard the Learned Astronomer
        Walt Whitman, 1819 – 1892

        When I heard the learn’d astronomer,
        When the proofs, the figures, were ranged in columns before me,
        When I was shown the charts and diagrams, to add, divide,
        and measure them,
        When I sitting heard the astronomer where he lectured with
        much applause in the lecture-room,
        How soon unaccountable I became tired and sick,
        Till rising and gliding out I wander’d off by myself,
        In the mystical moist night-air, and from time to time,
        Look’d up in perfect silence at the stars.

    2. How about putting it this way – you’ve just spent 20 or so years with a satellite – from plans on paper, to technical drawings, to actual device, to launch, flight, hibernation mode, and finally science gathering. No all the actual off-world work is done, and all that is left is going through and analyzing the data. Anyone is going to have some emotional attachment to a project of this magnitude.
      There’s also the media part, where it draws readers in if they have something personified to root for.

          1. No. Elon Musk will say “You paid me $200K to get here. If you want to go home it’s $2,000,000. As long as NASA keeps funding me. And I don’t go bankrupt first. I’d run for president if I were born in America.”

    1. I believe that the slow landing (~2mph) was very intentional. It allowed the spacecraft to transmit close-up images of the comet back to Earth before impact. If other sensors were running, it may also have been able to characterize the low-level “atmosphere” of the comet.

          1. Saddest moment in unmanned space exploration maybe? Although if you think about it, more people have died than spacecraft, or computers in general at this point in history (If I remember correctly, it won’t be long before that’s not longer true). So from a statistical standpoint, the Rosetta was more “rare” than a human, and therefore the death more tragic (if only from a statistical point of view).

  2. Rosetta is harmless in comparison to the Chinese space station that’s going to be coming down out of control in the not too distant future.

    Here’s the orbit. Looks like it could come down almost anywhere in the U.S., as well as Southern Europe, Africa, South America, and much of Asia. China should have handle this better.

      1. Given the 10k USD/lb payload fee, probably not. Couple that with the improvements in efficiency, highly unlikely. Lastly factor in understanding of microgravity effects on humans & general effects of space travel, changed mission goals, and new players in space travel (JAXA, ESA, SpaceX), retrofitting probably costs more than starting from scratch.
        Classic “in for a penny” fiscal fallacy.
        It’s like restoring a classic car, you don’t do it for economics, you do it for love & posterity. Neither of which are gov’t mandates.

        1. Well that’s kinda what I was talking about, the new players haven’t quite got enough heavy heavy lift to stick one up there for a couple or 3 years, but they might have enough to stabilise it and fuel it.

          Also not sure the classic car analogy quite fits because it costs a lot less to return a classic to functional than it does original. Seats out of a Ford Taurus to actually sit on etc, rather than respringing, reupholstering, hand stitching in NOS material with the exact right stitch spacing etc etc.

          1. Apparently, one of the modules (Leonardo) was repurposed to the ISS before Spacelab was decomissioned. Cannibalizing for parts probably played a role in salvage decisions.
            Skylab wasn’t designed (apparently) to cope with intense sun spot activity so it had a planned obsolescence.
            Mir’s fate was sealed by the fire and financial obligations to the ISS plans, which as discussed below, probably prevented smaller space agencies from salvaging it.
            If your space program is just starting out (comparatively) why not let the established players foot the bill for the expensive parts if they’ll let you split cab fare to the new and improved Hab? Sure, you don’t get to say you have your own station, but you get to run your experiments without all the investment. The diplomats get to say they worked with the international community, and you get to tell your budget committee you’ve completed all your research goals and then some. As usual politicking controls government funded science.

          2. In Skylab, there was no facility to refill the water or oxygen tanks, it was designed from the start as disposable. 90% of the reason they built it, was because the final couple of Apollo missions to the Moon had been cancelled. But the hardware had been built. So they had a heavy lift Saturn V and a load of hardware hanging about. Skylab itself was built from the third stage of Saturn V. They removed the fuel tanks and engines, and fitted it into a habitat.

            There was tons of really interesting things learned from Skylab. Not the least was when the third crew went on strike. First strike in space. Taught the psychologists a lot.

            There’s a book, “A House In Space”, I read as a kid, it’s great. Really gets you in there in the daily life of the astronauts.

    1. My opinion is that, if they can at reasonable cost, they should target junk in space to a dumping area on the moon, for latter material recycling. Even if that only happens in 50-200 years time. The hard part was getting it into space, letting it fall back to earth, just seams like wasted energy to me.

      1. if the thing is uncontrolled, it’s hard to “target” anything. Second, the moon is really far away, reserving propellant to boost it to the moon be a bit ridiculous.

    2. How should they have handled it then? Do you really think losing control of the station was planned?

      Nations with much more experience have lost control of misc. spacecrafts having them crash uncontrollably, in some cases with much more impact (no pun intended) spreading nuclear waste, hydrazine and other dangerous pollutants . In this case larger parts will burn during reentry and the parts that survive that will most likely fall into uninhabited areas.

  3. the whole “interfering with other spacecraft that are on the same frequency” things makes me seriously question NASA’s choices seriously like there’s no other frequency or modulation or what ever out there…… canning a perfectly good spacecraft just because it outperformed what it was supposed to do its just moronic and very very sad…..

    1. Any noise is noise for other spacecraft who are listening to weak signals from earth, and if there’s going to be another launch at the same comet, you can’t have the possibility that Rosetta is there rebooting randomly decade after decade whenever sunlight hits its panels and then beaming off radio transmissions in random directions.

      At the very least, it would probably trigger another UFO hoax because the antenna won’t be pointing at earth anymore, and there’s a possibility of an echo from some other orbiting body being detected by radio telescopes. After all, they’re listening for very very weak signals.

      1. Besides, the other problem is that Rosetta would lose power anyhow and drift off the comet without active course corrections, and end up who knows where. It wouldn’t have enough fuel to get back to the comet if it wakes up again, so it would end up stranded in deep space with no useful instruments to actually do anything out there.

    2. any talk from the space agencies about how a spacecraft “outperformed” are bullshit. the figures they give the public for life expectancy are bare minimum so that the taxpayers don’t get pissy when something doesn’t last quite as long as it was supposed to. if the subcontractors building the buses and instruments don’t make it well past the “expected” mission life, they can expect to have some very quiet, very unpleasant conversations with the agencies. and whatever the space agencies actually want from the spacecraft, the engineers are designing it to last twice that.

      1. Clearly that was a comment written by someone that has never designed high-reliability hardware for space. I have heard, in person, customer’s positive reactions to the value of exceeding contracted design lifetime requirements. This is largely because the government has been spending tax dollars on entitlements and freebies for votes instead of investing in our technical infrastructure in space, or anywhere else. When a spacecraft fails, you just don’t pop over to LockMart and buy another one.

        High reliability design is an engineering art based on a long history of successes and failures. Implying otherwise is pure ignorance and an insult to the designers that have sweat blood over incredibly complex designs. Designs are to specification and if a spec is derived, it is mathematically derived to provide an overall system reliability figure. And, that reliability is driven by contract and mission, not personal whims.

        Just remember to thank spacecraft engineers and designers the next time you use your GPS or you are watching a hurricane track. None of that is possible without their knowledge, talent and dedication.

        1. > I have heard, in person, customer’s positive reactions to the value of exceeding contracted design lifetime requirements.

          of course there’s value. that’s why the space agencies expect you to exceed what they tell the public.

          > This is largely because the government…

          take another toke, buddy.

          > High reliability design is an engineering art based on a long history of successes and failures. Implying otherwise…

          did you even read what i wrote? i’m describing the behaviors of space agencies, and mention the engineers exactly once. and to clarify, i’m not suggest the engineers double the lifespan for kicks, but rather because their employers tell them to, because the subtly implied aspects of the contract aren’t, obviously, written down.

          > Designs are to specification and if a spec is derived, it is mathematically derived to provide an overall system reliability figure.

          haaah. have you got a bridge for me, too? i sat in on a number of those meetings, and certainly saw the PDR/CDR slides from the ones i wasn’t in. none of the people in attendance could give less of a shit about mathematically derived reliability figures.

          > And, that reliability is driven by contract and mission, not personal whims.

          the final requirements are driven by what their bosses tell them to do, and their bosses tell them that if the spacecraft lasts exactly as long as the contract says, that they can expect to be shitlisted.

      1. IIRC they were able to wake it up and make one small course change. Either it had just enough fuel left for that, having leaked most of it away while it slept, or a valve stuck open and it lost its remaining fuel after that change.

        Did they shut it down for good or will it be useful for something on its current trajectory?

  4. Just thinking about unintended consequences…. you know if you’ve got two piles of snow you shovelled off your driveway, and one has a twig on it, the sun comes out, one with the twig is half the size after a day in the sun. … because the other one is reflecting a lot of heat, on the other one, the twig is warming up…

    .. anyway.. this could have shot the comet in the head for similar reasons… have it lose a crap load of mass this visit near the sun and change orbit and never come back.

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