You Won’t Believe How the First Spy Satellites Worked

When you think of surveillance
satellites you think of systems beaming back high-res images of almost anywhere
on earth to secret government intelligence agencies but now that same
technology is also available for all of us with things like Google Earth however
when the very first surveillance satellites were launched things were
really quite a lot more primitive and you could forget about electronically
beaming images back to earth so how did they get the images back and how did
this affect missions like Apollo. In the Cold War era one of the biggest
problems for the US and the West in general was just not knowing what was
going on in the Soviet Union and to a similar extent Communist China not for
nothing did Churchill say that and Iron Curtain has descended across Europe. In
World War two the Allies relied upon airborne
reconnaissance to see what the Germans were up to and many of the secret
weapons like the v2 rocket and a v1 flying bomb were uncovered by aerial
photos but Western Europe is small in comparison to the Soviet Union you could
drop it in the middle of a Soviet Union and not know it was there at all.
Although the U.S. started aerial reconnaissance along the Soviet borders
in 1946, it was the start of a Korean War in 1950 which brought home the need
for more information on the Soviet Air Force and its capabilities and if it
could mount a surprise bomber attack with nuclear weapons on the US.
High-altitude overflights were gradually built up first with a Boeing B-47 a
predecessor to the B-52 and later with the lockheed U-2 spy plane there had
also been other aerial surveillance methods like project gen tricks which
used helium balloons to carry cameras at heights of up to a 100,000 feet
and blown by the westerly winds across the Soviet Union China but only around
6% of these were recovered with usable images, the rest were either shot down or
blown off-course. Clearly a better safer method was needed and quickly. In 1960
Gary Powers U-2 spy plane was shot down over the Soviet Union causing a major
diplomatic incident and forcing the U.S. to suspend over flights but the problem
had also been anticipated. The CIA who also ran the U-2 spy planes headed up a
project called Corona and have been working on put in a camera into a
satellite in a low Earth orbit 160 kilometers above the earth there it
would be safe from any Soviet defences and of a speed at which it traveled
some 27,000 km/h they could image huge tracts of land in a very short space of
time. The problem with putting a camera in space was up until then no one had
actually launched something into orbit and then safely recovered it back to
earth. Now you may well ask why didn’t they just use video cameras and beam the images back but that kind of technology just wasn’t ready and it wouldn’t be
until the late 1970s almost 20 years later before high-resolution digital
imagery would be good enough for intelligence gathering.
So the idea they came up with was to drop the exposed film from orbit in a
heat shield his bucket back to earth over the Pacific Ocean and then catch
its parachute over planes at about 15,000 feet. Now it might sound like a
crazy idea but catching it with a plane was actually the easy part and they’ve
done it before with the Genetrix surveillance balloons, the difficult part
was getting the film bucket to be in the same area as the waiting planes. To keep
the program secret and stop people from asking too many questions about the
number of test flights from a Vandenberg Air Force Base it was initially called
Discoverer, the cover story being that the satellites were carrying small
animals into orbit for research and then being dropped back to earth to see how
they were affected by the launch and being in space but the only things we
were really carrying were cameras. The idea of taking pictures from space and
then getting them back was one thing but in the late 1950s just getting the newly
developed Thor-Agena rocket safely off the launch pad was another. It took
12 attempts before on August the 10th 1960 Discoverer 13 became the first
man-made object to be safely recovered from space nine days before the Soviets
did the same with the Korabl Sputnik 2. After the testing period which lasted up
until Discoverer 39, the program’s name reverting back to Corona and it was
classified as top secret and remained that way until 1992.
Unlike the satellites of today which stay in orbit for years,
the corona ones were only intended to be there for maybe a few weeks most once
the film have been exposed and returned the rest of a satellite was no longer
needed and they couldn’t refill it so it became the world’s most expensive
disposable camera system. Each corona satellite used to panoramic cameras each
with 610 millimeter focal length lenses and they used 70 millimeter film that
had a resolution of a 170 lines per millimeter, twice that
of the best film used for world war ii reconnaissance. Two cameras enabled
stereographic imaging to be done allowing the image technicians to better
gauge the depth and size of objects seen on the ground. Instead of taking just
simple snapshots with the cameras looking straight down from orbit, the
lenses exposed the filmstrip as it moved through a 70 degree arc. This moving lens
was to avoid the movement blur caused by the speed of a satellite and to get an
almost continuous image strip of the ground below making the maximum use of a
film available. To stop the torque reaction of the lens as it returned to the
starting position from up setting the satellites orientation, though lower
heavier part of the lens on later models continuously rotated to act as a
counterbalance. The lenses themselves were made from the finest materials and
at a time were the most perfectly ground lenses ever made. The satellites operated
in a nearly polar orbit meaning they traveled almost north to south where the
orbit offset just enough so that it would move a few degrees further around
the globe with each orbit. In order to accurately judge the size of objects a
set of concrete calibration targets were created on the ground around Casa Grande
in Arizona that could be easily seen from space. Each one was a shape of a
maltese cross and about 18 meters in diameter. 256 of them were placed exactly one mile apart or 1.65 kilometers in a 16 by 16 mile grid.
Although they were abandoned in 1972 when the program came to an end some 143 of them
were still in position as of 2018. At the beginning of the corona program the best
resolution that could be seen was around 7 meters but with continual updates and
improvements in both the film and the cameras by the program’s end it was down
to one and a half meters. The amount of film also increased as new thinner
polyester based films were developed that were also much more tolerant of a
harsh conditions in space, something which had plagued the earlier acetate
films with breakages. By the end of the program each satellite had two separate
film buckets each containing up to 4900 metres of film
allowing one to be dropped off whilst the other was still in use. Once the film
had been exposed and the mission objectives had been covered it will be
ejected from a satellite protected by a detachable heat shield at around 60,000
feet a drogue parachute was deployed before then the main chutes carried it
down to around 15,000 feet here it will be captured by planes trailing an
airborne claw which when winched the bucket onboard the plane.
This method of airborne recovery became so successful that it continued to be
used on subsequent reconnaissance systems well into the late 1980s and the
Chinese were still using a similar system for their spy satellites up until
the 2000s. If a plane missed the film bucket or for some reason it was off
course and landed in the sea, it was fitted with a salt plug which would
dissolve after two days and sink the bucket rather let it float around in the
sea and possibly be captured by a foreign power.
But Corona was more than just a spy satellite, it became a testbed for some
of the key technologies that will be used in programs like Gemini, Mercury and
Apollo, from the re-entry of the Earth’s atmosphere at a specific point to
splashdown and recovery from the sea at a predefined area in the ocean. By 1972
Corona had done a 167 successful recoveries and
photograph over 920 million square kilometers of land. The photos the
program took affected every major US overseas military policy of a 1960s and
beyond and stopped much of the overreaction but had caused much of a
mistrust between the U.S. and the Soviets in the 1950s. Satellite
reconnaissance became the cornerstone of nuclear disarmament treaties for both
sides with chopped-up bombers left in the open for the other side to see from
space. After it was Declassified in 1992 its archives revealed much more about
the natural world and our ancient history than had been seen from the air
before and even now they are still used to see the effect that we have had on
the world over the decades since these photos were taken. So what do you think
of the early despising the sky and their ingenious methods they used to get the
images back to earth don’t forget to check out some of our other videos and
it just remains for me to say thanks for watching and please subscribe thumbs up and share.


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