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Can someone explain to my dumbass how they helped calibrate the photos or satellites?
These were film cameras, so the computer on board can't look through the camera and see if the objects are in focus, can they?
Earlier quoted context omitted.
It's not mentioned in the article, but I guess this means that compass navigation wasn't possible at the time?
They did have compasses, but those do not give you your position. So if you've been flying for four hours at night, with a thirty mph wind, you could be 120 miles away from where you planned on being. You need some way of getting an absolute position, which these provided.
Can someone explain to my dumbass how they helped calibrate the photos or satellites?
Think of it as an eye chart for satellites.
tl/dr: U.S. Military spy satellite camera calibration.
Right. Since each "mysterious" X was equipped with a "US Army Corps of Engineers" brass plate, it was kind of obvious they were calibration targets for something military. The article says "focusing", but they were probably used to get more precise orbital elements for satellites. This was pre-GPS, and calibration across geography on a planetary scale was tough.
Earlier quoted context omitted.
Here is a few more picture more: http://www.messynessychic.com/2013/11/15/the-forgotten-giant... I also find these kind of things cool. Forgotten structures that once served an important roll but now are mostly forgotten.
Interesting story and cool photos. Couldn't get to the end due to website design issues. Were these for horseback delivery or for airplanes? Terrible, terrible UX in the form of a jittery delayed popover that fills the entire phone screen. If you are going to do this (and I can't stand the fact that it actually works on many people), make it so easy to dismiss and fast to load that I close it instead of instictively…
Shortly thereafter, though, a few things happened that made the arrows pretty obsolete. Mapping of course, was a big one; you could now navigate a lot more reliably through unknown territory. More importantly, a network of radio beacons was set up. Charts had lists of radio beacons, with their frequencies. Pilots could tune in to hear them repeatedly chirp their identification in morse code, and use radio direction finders to set their heading accordingly.
There's one other feature that was developed in that time period which also made pilots' navigation job a lot easier. The federal highway system meant that there were good, very visible, roads, serving as routing beacons in their own way. Pilots would, and still do for a lot of general aviation planes, route close to highways, because they're also a very obvious landmark that carves a path through the country.
TL;DR - They were used by the US Army during the Cold War to calibrate spy satellite cameras.
tl/dr: U.S. Military spy satellite camera calibration.
Right. Since each "mysterious" X was equipped with a "US Army Corps of Engineers" brass plate, it was kind of obvious they were calibration targets for something military. The article says "focusing", but they were probably used to get more precise orbital elements for satellites. This was pre-GPS, and calibration across geography on a planetary scale was tough.
My guess is that they served a function for calibrating ground control points rather than orbital elements. Even today, NORAD publishes orbital elements (TLEs) for spacecraft deduced by radar (and also optical means). I think other radio ranging techniques were also used before GPS. Trying to point at Earth-fixed point with only an inertial attitude (without a position/velocity) seems really tough.
Today, lots of CubeSats don't have GPS, so they eagerly await getting TLEs from NORAD. It seems like this Twitter is always the first with new data:
Can someone explain to my dumbass how they helped calibrate the photos or satellites?
Okay, I just spent 20 minutes trying to figure that out and I'm still not very far. These were film cameras, so the computer on board can't look through the camera and see if the objects are in focus, can they?
Can someone explain to my dumbass how they helped calibrate the photos or satellites?
Okay, I just spent 20 minutes trying to figure that out and I'm still not very far. These were film cameras, so the computer on board can't look through the camera and see if the objects are in focus, can they?
Earlier quoted context omitted.
I found two: 32.807001, -111.722184 and 32.791790, -111.705250 I'd like to find more to see the 'grid' mentioned in the article.
https://www.google.com/maps/d/u/0/viewer?mid=1IudNrZA1xnpWjK...