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I am keen to know more about common CubeSat mechanisms & components (antenna / solar array deployments / thruster / momentum wheel / robotic arm problems) that have worked well in the past and those that a fairly risky or unreliable etc. based on past experiences? Eg: thermal knife mechanism (ISIS) for CubeSat antenna deployments seems to have been flight proven so it looks reliable Also keen to know about other factors that may have contributed to failures or mishaps? Eg. not all space environmental factors considered etc.

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  • $\begingroup$ I am not sure how an antenna deployment mechanism is "robotic". Seems more purely mechanical. What exactly are you asking about? $\endgroup$ – Organic Marble Apr 9 at 17:15
  • $\begingroup$ I meant common mechanical or robotic mechanisms ... i.e activated by either a human being remotely OR by a set timer OR by any sensor onboard the spacecraft OR space environment etc. $\endgroup$ – rsf Apr 9 at 17:18
  • $\begingroup$ Seems pretty broad, but I'll with-hold judgement for now. $\endgroup$ – Organic Marble Apr 9 at 17:21
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    $\begingroup$ Welcome to Space Stack Exchange! We need to refine the question to make it answerable. That definition of mechanical/robotic is a start but could make it much broader than you intended. Do you want people to give examples of antenna / solar array deployments / thruster / momentum wheel problems (you might get lots of examples of these outcomes but its hard to delve into the most common causes) or are you really interested in things that look more recognizably like robotics (unfortunately also quite hard to define). How about class of mission, e.g. are you most interested in cubesats? $\endgroup$ – Puffin Apr 9 at 17:26
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This graph shows the common failure modes experienced during the first 100 cubesat missions.

Note the large fraction of failed missions that never made contact with the ground after launch; no failure analysis on those.

enter image description here

I assume ADC is Attitude Determination and Control, but it doesn't say so in the paper.

Source

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This question mixes up a few concepts.

First, something being "flight proven" in a cubesat is far different from being "flight proven" in a traditional large spacecraft. It is not being successful in space once that makes a device reliable, but rather the quality control of the production facility and the extensive testing done on ground, both prior to integration on the final satellite.

So if tell me that a star tracker flew on a commercial geostationary satellite from a traditional manufacturer, I'm pretty sure it is very reliable! Even then I'll ask for documentation about the past tests conducted on engineering and qualification units, and should there be any change on the design or the production method, I'll ask for delta-qualification tests, to ensure the change will not introduce failures. Also, I'll check statistical reliability studies so I can estimate the likelihood of failure over time. These testing and documentation process is costly, expensive and (AFAIK) done only for operational missions. (i.e. commercial, military or scientific, but not tech demonstration).

Meanwhile, it is already praiseworthy if a cubesat team has conducted thermal analysis properly. Maybe they did some basic testing such as putting into a vibration or thermal chamber, maybe they didn't. If they did, I really doubt that every component underwent a qualification campaign at equipment level, yet the cubesat got launched. This doesn't mean that every piece will fail, but rather tells that you can't assume that all the care taken on a large mission was also taken for a cubesat, which effectively lowers the value of a piece of hardware having being "flight proven" in a cubesat. I would also not be so sure you would hear about a cubesat failing, so maybe a given component was flown on a mission that never made first contact as is often the case, yet detailed information on the failure would be hard to find.

Usually, if you need figures for the reliability of a component you'd have to ask your supplier. Because the cubesat market is not that mature yet, no manufacturer can boast large reliability figures, and is working on improving their practice and methods. This means that you'd need at least an NDA to receive such information (which would be subject to change without prior notice). Even then, I'd expect you to receive inconclusive information, and only after a purchase order is signed.

Keep in mind however that the mentality around small satellites is that one is better building multiple satellites such that the loss of a few of them can be afforded. I.e. launch three cheap, small and unreliable satellites for less than the cost of one big expensive and reliable one.

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  • $\begingroup$ This does not answer the question "What have been the most common causes of mishaps or failures...." If you do not know the answer, it is best not to post an answer. $\endgroup$ – Organic Marble Aug 5 at 18:23
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    $\begingroup$ @OrganicMarble My exact point is that the question (although reasonable) cannot be well-answered. This answer explains why and what I recommend OP should do to achieve what he would expect to achieve if one could answer his question. That should be more helpful than no answers. Say I ask in MathStackExchange if Riemmann's Hypothesis is true, should my question remain unanswered indefinitely or should someone answer that this is an open problem in mathematics, and why it is hard to approach it? $\endgroup$ – Mefitico Aug 5 at 18:31
  • $\begingroup$ I am unconvinced that it is impossible to put together a history of cubesat failures. $\endgroup$ – Organic Marble Aug 5 at 18:32
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    $\begingroup$ And I am unconvinced that it is impossible to prove Riemann's hypothesis. Yet, as pointed out in my answer, a very common situation with cubesats is lack of first contact, which renders the actual failure almost impossible to identify. And changing products characteristics makes the past history a poor indication of expected performance which is what OP wants to know. $\endgroup$ – Mefitico Aug 5 at 18:37

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