• ColinWright 6 hours ago

    This tripped me up:

      "I was not a big fan of designing a
       mechanical clock unless there was
       another option."
    
    So either this should be "... unless there was no other option", or I'm completely misunderstanding.
    • dylan604 2 hours ago

      Looking at the way the system is rigged to the wall of the station is quite humorous to me in how it is taking full advantage of being weightless. From the arm the camera is attached to the tracker, and then the tracker being mounted to the one arm just seems like it would collapse on itself if it were on terra firma.

      I've seen some crazy/shitty rigging done, but this one gets a pass because it's in spaaaaaaaace

      • zokier an hour ago

        I do kinda struggle to understand the geometry here though. Especially in the picture with the black-out fabric, how is the camera rotating to track stars?

      • lysace 6 hours ago

        Neat.

        Debbie Downer: Looks like it fairly easily could have been made with like 50% less mass.

        Perhaps that wouldn't have mattered though.

        • polishdude20 3 hours ago

          They've got the camera mounted to it using a long moment arm in one of the photos. The tracker needs to be really rigid to hold it I'd think.

          • lysace 3 hours ago

            "Long" = like 70 cm.

          • dylan604 2 hours ago

            fairly easily how? bold statement with no explanation of your ideas on where the wasted mass is.

            the front/back plates? looks like your standard 3/8" aluminum plates. could they have used 1/4"? other materials like plastic/carbon would probably not have passed NASA requirements. plastic/carbon could chip into small pieces which is a very bad thing on the ISS. so you're left with a metal, and aluminum is pretty safe choice. it's clear there are several holes in these plates that are not tapped and are there solely as a means to reduce the weight.

            moving the pieces closer for a tighter fit resulting in a overall smaller unit size? this thing is meant for ease of use. extra space affords that, and making it more compact complicates its use.

            • echoangle an hour ago

              You could have made a lot of holes on those plate to reduce weight while still having it very rigid. Those plates are extremely oversized right now.

            • echoangle 6 hours ago

              True, I wonder how that would not be a factor, surely they always have stuff they could send up to the ISS as a backup. So if they would have made this 500g lighter, they could have sent 500g more food, for example.

              I also can't imagine that the resupply flights are volume limited instead of mass.

              • imglorp 4 hours ago

                NASA's 2-year cert for electronics requirement is puzzling. I understand rules about mission critical electronics: you want to (a) depend on it and (b) avoid fire, magic smoke, and blowing breakers on the Station. But for a non-critical application, you don't care about (a) and the risk of (b) from a 5V/2A microcontroller with a worm drive motor seems reasonably remote.

                • someguydave an hour ago

                  Nobody involved wants to take the risk, no matter how trivial

                  • echoangle 4 hours ago

                    Did you mean to post this under my comment? I don’t see the connection.

                    • imglorp 2 hours ago

                      Yes - it might have been 500g lighter if it wasn't fully mechanical.

                      • echoangle 2 hours ago

                        True, but even for a fully mechanical one, the one shown seems very heavy. It looks like weight wasn’t a real concern, which is strange. The plates are very thick and a lot of material could have been removed to reduce weight.

              • mkmk 4 days ago

                > Don is a bit of a machinist himself, so we decided to have some fun with the device name.

                I don’t get it, anyone able to explain?

                • snypher 6 hours ago

                  My only thought is 'RCSPAST' is the joke, but I still don't get it.

                  Edit: I think maybe Don's reputation as an in-space inventor (first patent for something invented in space) means the clock spring device got a long and contrived name for it's quite basic function.

                  • petee 6 hours ago

                    I think its just them being overly technical on the naming the mechanism, ie "Rotational Coil Spring Powered", rather than just being a plain ol Windup Star Tracker