The Cold War’s Flying Mechanical Eyes Or, A History Of NASA Satellites
This piece kicks off our Science-y September here at The Est. All month long, we’re on the prowl for stories that examine the wild and wooly behaviors and structures of the natural and physical world. (And yes, maybe even some tales about aliens, fingers crossed.)
Like many of the rabbit holes into which I often find myself tumbling in a flurry of internet tabs and dubious source vetting, this one began with a question: “How did they get the pictures back from early reconnaissance satellites?” A lot of the most interesting facts about history and nature are concealed behind deceptively simple questions like this.
My initial thought was, “Like . . . radio waves, right?” Is that even possible? Was it even something they were able to do back then with the technology they had? I know audio is transmitted this way, but is it encoded mechanically or digitally? Is the actual audio wave being somehow piggybacked onto the radio wave, then extracted upon receipt or is the audio turned into numbers which are then conveyed via radio and decoded at the destination? As it turns out, traditional terrestrial AM and FM radio are analog. They piggyback actual sound waves onto carrier signals more or less mechanically.
Fun Fact: It is believed that Isaac Newton’s original inclusion of indigo, which was added later along with orange, was partially influenced by the recent introduction of indigo dye to England by the East India Company as well as Newton’s desire to have the same number of colors as musical notes in a scale . . . because reasons.
As a point of clarification, radio waves are a band (that is, frequency range) within the larger electromagnetic spectrum. The electromagnetic spectrum is just a way for us to categorize the way light acts as determined by a single property: its frequency. We don’t often think of it this way, but every class in the electromagnetic spectrum (Gamma rays, X-rays, radio waves, UHF, etc.) is describing different frequencies of light. If you had a light source capable of vibrating at frequencies so many magnitudes displaced from one another and a mechanism to oblige it, you could turn ultraviolet light “down” in frequency into violet, blue, green, and down through the rest of the visible spectrum on into infrared, and through to radio waves.
So while the data we want to transmit is light — namely, the light reflecting off some patch of ground — in the mid-20th century, we were only able to record that light in a physical form. Unbelievably, though, as early as 1932, we were sending images electronically via radio waves. “Radio Facsimile” used a photosensor to scan an image line by line measuring luminance. This info, which remained analog, was then broadcast to a receiver unit, where the image was recreated line by line. The resolution wasn’t great, an issue compounded by the already low resolution of the cameras used in early satellites. Even more prohibitive, though, were the weight and volume of the equipment, the power needed to operate them, and the transmitter that would be required to utilize this technology on board a satellite.
In fact, they ended up trying this as part of the Samos program, which required much larger, more expensive rockets than other reconnaissance satellites due in part to the added payload of the scanning and transmitting equipment. It is believed the program was cancelled due to the low image quality. Either way, sometime while they were busy inventing a thinner film stock so they could snap more photos without going overweight, the idea of including large, heavy, automated scanning equipment; a transmitter; and extra power to radio fax shitty copies of photos to earth over an insecure broadcast sort of got taken off the table.
Fun Fact: The first wireless voice telecommunication device, patented by Alexander Graham Bell and his assistant Charles Sumner Tainter on February 19, 1880, was the photophone, which carried voice communications optically on a beam of light transmitted to a distant receiver.
It is interesting to note that the earliest use of radio waves for communication was wireless telegraphy, wherein radio signals were switched on and off to represent the characters and gaps of Morse code, demonstrated as early as 1854. Although Morse code is technically a quinary language (consisting of dots, dashes, intra-character gaps, short gaps, and medium gaps), it is transmitted using nothing more than the two states of on and off; that makes wireless telegraphy the first form of digital broadcasting.
So without any practical means of wirelessly retrieving photos from a satellite, how does one get at all that tasty, tasty data? It’s not like tethering satellites with wires hundreds of miles in length is practical . . . is it? Aside from the obvious impracticalities, the main hindrance to just lassoing our satellite with a bright orange extension cord is that the limitations of geostationary orbit make it pretty suboptimal for surveillance. Geostationary orbit is when a satellite orbits while remaining directly over the same place on the planet’s surface, and that is only possible over the equator. That uniform grid of satellites floating above every acre of the planet that you see in all the movies forming a perfect net of coverage? Yeah, that doesn’t, and more to the point couldn’t, exist.
Let’s dispel a myth about what orbit is: Orbiting isn’t floating. “But there’s no gravity in space, right?” Well, as it turns out, the mass of the earth doesn’t just stop pulling shit toward it once that shit leaves the atmosphere. In fact, at the height satellites orbit, they are experiencing a full 90% of the gravity we feel down here on the surface of the planet. And it’s pulling them right toward the ground. Super hard.
“So why don’t they all come crashing toward earth?” Because they are moving sideways so face-meltingly fast (over 10,000 miles per hour, in the case of geostationary satellites) that as you fall toward the earth, you fall past it just as fast. Orbit is a sort of terminal velocity freefall wherein you are continuously missing the ground. And it happens to be that just over 22,000 miles up, the speed required to achieve this equilibrium is the same RPM as the earth, thus enabling giant multi-ton hunks of metal to stay above the same spot on the ground all the time. At any given moment, thousands of pounds of government contract work may be hovering above your head while simultaneously careening sideways through space at almost 7,000 miles per hour.
Fun Fact: It not quite accurate to sat that the moon orbits the Earth, the moon and the Earth both orbit around a common barycenter located approximately 1,000 miles below the surface of the planet. The Earth and the moon exert precisely the same amount of gravitational force on one another irrespective of their masses; the only reason the Earth is not as easily swung around is because its much larger mass equates to greater conservation of momentum.
Because of this, an object in orbit (a “satellite,” regardless of what it is) must revolve around the center of mass or “barycenter” of the orbital system — be it a satellite and a primary or two objects in a binary system. This means that the only place a satellite can achieve geostationary orbit is on the plane that both is perpendicular to the primary’s rotational axis and intersects the barycenter of the system. In the case of manmade satellites and the earth, this means above the equator.
A spy satellite that can only see one patch of ground isn’t terribly useful when further encumbered by the fact that that patch must be on the equator, or within range of the camera from 22,000 miles above it. This is why Corona, this first reconnaissance satellite program, launched satellites into near polar orbits. Paths not synchronized to the planet’s rotation are able to get a view of many areas across the globe–including specific targets if you do the math.
So now we’re at least taking useful photos, but we still don’t know how to get them back so we can look at them. What if . . . and just go with me, here . . . what if we just drop the film back to earth? Believe it or not, this is precisely how film was retrieved from the first reconnaissance satellites.
While in orbit, the satellite would tip over 120º to point the film canister roughly downward and the thrust cone carrying the “film bucket” would be released into a decaying orbit. Beginning its descent at around 110 miles up, it would spend the first 2 miles just letting air resistance whip it around and slow its lateral velocity, then the thrust cone was separated and it fell unencumbered almost 100 miles further. At just over 11 miles above ground, a deceleration parachute opened to begin slowing it down from terminal velocity and a mile later, the main chute deployed.
Then, as it drifted down — and here’s where I start to get incredulous — a plane would fly by dragging a huge claw behind it. The claw, ideally, would snag the parachute, and the whole lot would be winched aboard. And if that doesn’t sound like it’s lifted out of a James Bond film, they even had a failsafe worthy of a classic espionage thriller. In the event the canister wasn’t caught and landed at sea, a salt plug gave it a three-day sea life for the Navy to grab it before it sunk to the bottom of the ocean to prevent giving up its sneaky, delicious secrets to the wrong government.
Satellites were equipped with over 3 miles of film, which was doubled in the fifth generation. While the first three generations were launched with only a single film bucket to return, the KH-4A, first launched in February of 1963, began the tenure of multi-bucket satellites that would drop film and stay in orbit to take more pictures which were dropped later.
A Corona film bucket actually being snagged by the dangling sky claw (excerpted from the documentary released when the program was declassified).
If we’re grading by achieving orbit, capturing intelligible photographs, and retrieving both the photos and the satellite, 30 of the first 52 missions failed. I mean, fuck; at the first launch attempt, the separation rockets ignited on the launch pad while the vehicle was being fueled.
Today, shortwave radio signals are encoded with digital images and broadcast back to the ground. It’s all prequels CGI, no original trilogy practical effects. So go ahead and relive the glory days of heroic engineers and astro-nautical achievement by reading this formerly top secret history of satellite reconnaissance, checking out this interactive model of a KH-4B that seems to be tied into some awful flash game, and skimming some of the 860,000 images that were released when the Corona program was declassified in 1995 by Slick Willie, the saxiest prezbo since Maceo Parker presided over the Parliament-Funkadelic brass section.
Hail to the chief, baby.