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I keep reading about how there are ~350 single points of failure once Webb is successfully launched. Can someone with expertise and chime in about why the teles
by YossarianFrPrez 5y ago
I keep reading about how there are ~350 single points of failure once Webb is successfully launched. Can someone with expertise and chime in about why the telescope wasn't designed with more built-in deployment redundancies? It would seem to be good engineering practice to ensure that there are back-up systems, etc.
- evgen 5y agoRedundancy costs mass and there are a lot of deployment steps that simply cannot be made redundant. The trick is folding everything to fit into the constraints of the payload fairing. Good engineering is to design within these limits and but if you make it too safe you end up with something that is not worth launching.
- hollander 5y agoPlus you don't get to send a Space Shuttle to L2 in case the mirrors are malfunctioning.
- bumby 5y agoRedundancy is only one way to increase reliability. For example, having redundant elements can allow you to use cheaper components and meet the same level of reliability as a single, more expensive component but at the cost of mass (or vice versa). Most often, there are reliability requirements that are defined at a very high level, and a reliability engineer helps determine the right tradeoffs to meet those requirements. In addition, some of the points of failure don't lend themselves well to redundancy, like release mechanisms. For certain risks, like human-rated spaceflight, they may just have requirements like "no single-point failures", which means redundancy is a must.