Archives For Limits of correctness

Cassini Descent Module (Image source: NASA)

When is an interlock not an interlock?

I was working on an interface problem the other day. The problem related to how to judge when a payload (attached to a carrier bus) had left the parent (much like the Huygens lander leaving the Cassini spacecraft above). Now I could use what’s called the ‘interlock interface’ which is a discrete ‘loop back’ that runs through the bus to payload connector then turns around and heads back into the bus again. The interlock interface is there to provides a means for the carriers avionics to determine if the payload is electrically mated to the bus. So should I use this as an indication that the payload has left the carrier bus as well? Well maybe, maybe not.

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