…I was just wondering, can anyone here identifty was instrument this is, on a photograph of a control panel from a Soyuz panel? It’s function is pretty obvious, I suppose, but I’d like to know what it’s actual name is, how it works, and what other functions it has, if any, besides pointing out where the capsule is over Earth.
Well, thanks for your time,
I’ve asked on the Bad Astronomy and Space.com message boards, to see if anyone there has an idea. It’ll be interesting to find out.
D-uh I can’t believe you’re even asking this - it’s so obvious.
It’s a porthole - the photograph having been taken in orbit with the earth in partial view.
Probably not a whole lot of help Ranchoth, but this page identifies it as " a globe for showing the subsatellite point".
That would be this page.
In the case of American spacecraft (reference to Mercury technical diagrams) its name is “Earth Path Indicator”.
Oh, right… the knowledge of location and orbital path inclination is used in case a manual-command reentry is necessary (you combine it with a visual earth-horizon or celestial alignment for vehicle attitude – taken through a calibrated scope – in order to time your retro burn) so you’ll know where you’ll land. The drive system for the “ball” and how it’s synched to the spacecraft’s gyros/inertial navigation system/computer depends on what spacecraft you’re on.
… and some more info:
http://www.sscnet.ucla.edu/geog/gessler/collections/ calls the device a “Mission Globe”.
http://hrst.mit.edu/hrs/apollo/soviet/essays/essay-tiapchenko1.htm has more that I ever imagined about the Soviet/Russian instrumentation systems. Page 4 indicates that the mechanical Mission Globe is not included in the current ISS “lifeboat” Soyuz-TMA (latest 2 launches), replaced by a video-display readout.