Gregory's ServerThe Globus used complex gear trains driven by solenoids to move the globe.
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 The spacecraft's initial position was entered into the Globus by turning the central knob, rotating the globe. The Globus did not receive any position input from an inertial measurement unit (IMU) but just projected the spacecraft's location from the initial value. The orbital period could be adjusted ±5 minutes. Followers riding on a spiral cone cam turned at adjustable speeds based on their position, slow at the top, faster at the bottom. Three adjustments (minutes, tenths, and hundredths) were added by differential gears. Latitude and longitude were displayed on indicators. They depended on complex trig functions, computed by specially-shaped cams. Coincidentally, the latitude indicator matches the Ukrainian flag. 🇺🇦 The globe showed geographical features as well as the boundaries of the USSR and politically-aligned regions. As well as tracking their position, cosmonauts could judge the safety of potential landing sites, both physically and politically. But why does the globe have dots indicating NASA communication sites such as Goldstone, Bermuda, and Merritt Island? This Globus must be from the Apollo-Soyuz project (1975), where an Apollo spacecraft docked with Soyuz in orbit. To determine the landing position, the globe rotated through a specified angle, simulating a partial orbit. A drive motor did this rotation, stopping when the swing arm hit the adjustable angle limit switch. A second limit switch handled rotation back to the orbital position. This photo shows the Globus in the Soyuz-TM control panel (1986). Soviet control panels were very different from American ones, grids of buttons instead of masses of switches and meters. Here's a closer look at three sets of differential gears. The Globus made heavy use of differentials to add or subtract rotational values. Although mostly mechanical, the Globus used relays to control the landing position motor. Pairs of diodes across the relays absorbed inductive kickback. A potentiometer to output the orbital position as a voltage. This view of the Globus shows the wiring bundles. There are a lot of wires for a device that is mostly mechanical. For more details on the Globus INK, see my blog post: https://www.righto.com/2023/01/inside-globus-ink-mechanical-navigation.html. @kenshirriff looks like the link doesn't work because it needs www. for the domain
 @HeNeArXn It should work now; the original link didn't survive cut-and-paste. @kenshirriff The Mercury spacecraft had a similar mechanical globe called the Earth Path Indicator: https://www.rrauction.com/auctions/lot-detail/340932005505026 @emgre @kenshirriff interestingly that one doesn't seem to be driven at a great circle, so I wonder how that works reliably (since then it can't be fixed to the globe and be able to show every position?) @kenshirriff this is so fascinating. Thank you for the stellar write up on it! @kenshirriff I suspect that its accuracy would have been poor, going by the mechanical nav kit I’ve used or seen used in Jaguar and Harrier. @kenshirriff I'm fascinated by #9, which is right at the intersection of Honduras, Guatemala, and Belize. The nearest big city near the mark is San Pedro Sula, Honduras. But the closet *soviet-aligned* country would be Nicaragua, even though the mar is really too far west for that. But in 2017 ROSCOSMOS opened a GLOSNASS station in Laguna de Nejapa, Nicaragua, so its not impossible there was earlier coordination.   @PavelASamsonov @kenshirriff I guess they knew which friends were reliable and which ones were not. @KanaMauna @kenshirriff Then it's weird to have Yugoslavia on there given that Tito was explicitly anti-Soviet by 1975. @kenshirriff @PavelASamsonov True. Maybe this item dates to early in the Apollo-Soyuz project, which started in 1972? @KanaMauna @PavelASamsonov Yes, I'm pretty sure this is from Apollo-Soyuz. @kenshirriff @KanaMauna Yeah but Yugoslavia split with the USSR in 1948, there's no time during the space race when it would have been considered an ideological ally @PavelASamsonov @kenshirriff @KanaMauna @kenshirriff as a kid of the '80, that's a strange series of country boundaries in the European zone, I mean, Poland with both Germanies?  @kenshirriff Seeing Monrovia on the Globus makes me both happy and wonder about the criteria for being on there. |
The globe uses a clever mechanism to rotate in two dimensions. Rotating along the dotted axis traces out the 51.8° orbit. Turning a concentric shaft causes the two halves of the globe to rotate around the polar axis, held by the fixed metal equator.