Prior to the 1990s, all of NASA's space photographs were captured on film. While it literally opened a new universe for the eyes of the world, the technology had its short comings.
Manually focused lenses often resulted in blurry photographs. Often, it was difficult, if not impossible to accurately identify locations that were being photographed. Plus, there was a long delay between when the photographs were taken to when prints could be made and circulated to people back on Earth. Development through the 1980s and into the 90s would usher in some radical changes to photography in space to help address these problems.
The first major breakthrough came with the NASA Nikon F4 Electronic Still Camera (ESC); the first digital SLR camera used by NASA aboard the Space Shuttle Orbiters, making its debut in 1991. The camera body incorporated digital imagery and auto focus.
The next breakthrough was the development of the Handheld Earth-Oriented Real-Time Cooperative User-Friendly Location-Targeting and Environmental System (HERCULES). This system paved the way for the electronic recording of data related to the images captured, in addition to providing a real-time downlink back to Earth to transmit the images plus the ability to capture ad-hoc images relayed to space from Earth.
The NASA Nikon F4 ESC was not a shoe-in to be the camera choice when the HERCULES project was in its first planning stages. The Pentagon and sponsors representing the US Army, US Navy and US Air Force auditioned both the F4 ESC as well as Kodak's digital SLR, the Kodak Hawkeye II
The Hawkeye II had a rectangular CCD sensor measuring 1035 x 1320, and was built on a Nikon F3 manual focus body. A proposal was done for NASA and Kodak presented the HE II around late 1989.
The Department of Defense invited both NASA and Kodak to Washington to demonstrate their camera systems in what turned out to be a shoot-out of sorts. In the end, both the Hawkeye II and the F4 ESC were given 'test drives' in space.
The NASA Nikon F4 ESC flew first, although not part of the HERCULES system on mission STS-48 in September of 1991. The Kodak Hawkeye II followed in November of that year on STS-44.
After both cameras did their test flights, the images were reviewed; assessing image quality (particularly noise), and feedback collected about the use & handling of the gear, and three departments of the DOD (Navy, Air Force and Army) supported the NASA Nikon F4 ESC to fly as the imaging system for HERCULES. The Pentagon made it official. Not all was lost for Kodak however, as the Hawkeye II led to the development of the DCS (again based on the F3 body), which would be the first portable DSLR intended for commercial use.
The HERCULES consisted of a number of key components. At the system's core was the NASA Nikon F4 ESC mounted to a Naval Research Laboratory (NRL) HERCULES Inertial Measurement Unit (HIMU) which contained a three-axis ring-laser gyro. The unit was tethered to the Electronics Box (ESCEB) which housed removable data storage disks of the images captured. Completing the system was a specially modified GRID Systems portable computer mounted atop a NASA developed Playback-Downlink Unit (PDU) and a NRL HERCULES Attitude Processor (HAP).
The HERCULES payload involved all three divisions of the DOD: The Army supplied the image intensifier that was used, the Air Force supplied ground processing of the payload and Navy personnel were the astronauts that actually flew the system (most notably: Steve Oswald and Kenneth Cockrell).
Before taking a photograph, the astronaut would enter the Shuttle's location and orbit into the computer, then aim the camera at two stars to align the IMU. The astronaut would then aim the camera at the subject, and when the shutter release was pressed, the IMU calculated the direction the camera was pointed and the computer would take that and calculate the subject's latitude and longitude on Earth. Accuracy was determined to be within 1-2 nautical miles.
The HERCULES payload would fly on two Shuttle missions: STS-53 in late 1992 and Spring of 1993 on STS-56 both aboard the Shuttle Discovery.
During the two HERCULES missions, Department of Defense contractor Autometric performed the image processing in place of PIXAR which had that duty with the initial flight of the F4 ESC. Autometric's involvement however would last for just the two HERCULES payload missions.
The HERCULES payload only flew two missions in space. Although successful, the Department of Defense had an increased need for multispectral and higher resolution imaging products beyond what the F4 ESC was capable of. As such, that drove a change in the camera system. A multispectral camera from the Xybion Corporation was pursued to take over imaging duties on future missions of the HERCULES.
What was learned would help shape future on-demand electronic photography in space, such as the EarthKam system