Voyager 1 Imaging Science Subsystem final draft #1

 The Imaging Science Subsystem (ISS) of Voyager 1 was used to capture valuable scientific images of the Jupiter and Saturn system allowing valuable research insights before adventuring into deep space (JetPropulsionLab, n.d.). Voyager 1 played a crucial role in exploring the Jupiter system and paved the way for further deep space exploration around the Jovian systems. In terms of features, the system consists of two cameras, a 1500mm high-resolution narrow-angle f/8.5 camera and a 200mm lower resolution wide angle f/3 camera. (SETI, n.d.) As mentioned in the related webpage the high-resolution cameras allow scientific data collection such as atmospheric composition and coloured imagery of the planets. The operations of the cameras are controlled by a spacecraft computer which communicates with earth’s computer systems (NASA, n.d.).

Being launched in 1977, the spacecraft has the most technological advanced in its imaging system at the time. However, the modern spacecraft imaging system of James Web Telescope have improved based on Voyager 1 imaging system and brings more advantages for scientists to further study other planets with the images captured.

According to NASA, Voyager 1 cameras are both mounted in front of the vidicons with 8 filters in a commendable Filter Wheel. Both low resolution wide angle and high-resolution narrow-angle are television-type camera. The images of planetary atmosphere captured by the cameras helps data analysts to determine the wind velocities of each region observed (NASA, n.d). The imaging science subsystem helps to search for new rings by “map the radial and azimuthal distribution of material in the ring plane”. It attains comprehensive multi-spectral imaging across all satellites, determine rotation speeds and spin axis orientations, examine Triton's surface features at resolutions below 2 km, and explore for any unidentified moons (NASA, n.d). 

The Voyager Imaging Science Subsystem employed a magnetic deflection vidicon with a 25mm diameter, utilising a selenium sulphur target capable of retaining high-resolution images over 100 seconds. The active imaging area measures 11.14 x 11.14 mm, and each frame consist of 800 lines with 800 pixels per line. Electronic readout of one frame takes 48 seconds. Light flooding is used to remove residual image, followed by 14 erase frames to stabilise the vidicon target for the next exposure sequences. (VGR ISS Calibration Report, 1978)

Comparing to James Web Telescope launched in 2021, the imaging system of Voyager 1 seems very classic and simpler. James Web Telescope has near infrared camera (NIRCam) detector with optical baffles removed (NASA, n.d.). There are 2’ different types of detectors which is mercury-cadmium-telluride “H2RG” detector and arsenic doped silicon detector. The “H2RG” detector are for 0.6-5 micrometer “near infrared” while the other one has 5-28 micrometer for “mid-infrared” and has about 4 million pixels and 1 million pixels (NASA, n.d.).

According to NASA, the mercury-cadmium-telluride can possibly tune to sense longer or shorter wavelengths by varying the ratio of mercury to cadmium. This feature can help to tailor each camera detector and obtain the peak performance over the wavelength of which will be used (NASA, n.d.). The other feature is about MIRI, an instrument specialising in mid-infrared detection, which operates under the coldest temperatures among all the telescope’s instrument (Space.com, n.d.). MIRI required additional crycoolers to reach temperature of -266 degrees, which is only 7 degrees above absolute zero, where atomic motion ceases (Space.com, n.d.).

In conclusion, the Imaging Science Subsystem of Voyager 1 play a pivotal role in capturing valuable scientific images of the Jupiter and Saturn system, providing valuable insight before venturing into deep space. As a the most technically advanced spacecraft in 1977, Voyager 1 serve the foundation of subsequent space exploration spacecraft. However, the modern James Webb Space Telescope launched in 21, surpass the Voyager 1’s imaging capabilities with new technology like near-infrared detectors with adjustable wavelengths tailored camera detector and specialised instrument operating at extremely cold temperatures. While Voyager 1’s imaging system appear classic and simplier, it is the foundation of to enhanced our ability to study and understand the space better with technology advancement over the years.