Comment by relaxing
14 days ago
So the root cause was the lubricant in the gyros couldn’t stand up to operating temperatures.
I’d be interested to read a postmortem of the systems engineering approach there.
14 days ago
So the root cause was the lubricant in the gyros couldn’t stand up to operating temperatures.
I’d be interested to read a postmortem of the systems engineering approach there.
The lesson there - dig multiple levels deep in supply chain
Alas.. the speed & resources of a startup. But we're learning.
I work near space but not in space. I'm not sure I understand your process here. I see 2 possibilities: 1. You bought something the manufacturer spec lied about. While true we often validate specs, our terrestrial stuff is a lot cheaper so we can afford the spares. That said, if we buy something that doesn't meet the spec, you best believe we're taking the actions necessary. 2. This was built or designed inhouse, and the requirements didn't flow down correctly. That's also not great.
To be honest, postmortems (especially from startups) toe a fine line of scaring off investors, and this write-up seems a bit too glaze-y. I'm very happy for you that so much worked so effortlessly post launch, but that's more a success story than a postmortem. I'd like to see more of the root cause analysis for the issue, both technically and programmatically.
To be certain, if you're in the trenches of this anomaly investigation you'll get the full root cause and corrective action presentation, but that's not what this post is for.
You're correct on 1, we ended up hitting an edge case in their spec that they hadn't adequately tested to and the upper level management and engineering leadership were swift to accept the fault and implement fixes with us going forward.
From a SE perspective, as a "COTS" product, we had spec'd correctly to them, they accepted our requirements and then executed each unit's acceptance test plan (aka lower level than first unit quals or life tests where this should have been caught) on the ground without anything amiss. We ran through our nominal and off nominal cases at the higher level of assembly, but not for a duration that caught this on the ground. It wasn't until we were at extended operation on orbit the issues began.
Sadly like you state, space isn't like on the ground, you can't buy spares or replace things that fault, even for a true high volume COTS product that might slip through the acceptance testing.
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Presumably part of the ground tests consist of putting a prototype in a thermal chamber and running it a bit above max temp for a week and a bit below min temp for a week to check functionality+margins...
Wonder why this didn't pick it up? Perhaps the test wasnt long enough?
> Perhaps the test wasnt long enough?
Small (ok, maybe not so small) fortunes are spent on accelerated testing in the space domain. The test and validation gear is immense, using it is extremely expensive (especially when you get to full scale) and access is limited. They may well have been limited to that week for many reasons and conditions being what they are there is a fair chance that the space environment caused an issue that would have shown up if they had had a much longer test but that if there is no trend or if instrumentation is not sufficient simply doesn't show up at all.
For instance, if you're not measuring current into each and every actuator, or if the resolution at which you are sampling is too low then there may well be a developing issue that you are completely blind to.