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| Taking Photo From Voyager 1 |
This is the “pale blue dot” image, a long distance photograph of a tiny, fragile Earth all alone in the darkness of space, taken by the Voyager 1 spacecraft. Taken on February 14th, 1990, it is one of the most iconic images in history. This image was taken as part of the Family portrait series of the images of the solar system. Shortly after these images were taken the cameras onboard the spacecraft were shut down for the last time. Today the Voyager is at a distance of 23.381 billion km (or 14.528 billion mi), making it the most distant man-made object from Earth. But how did Voyager manage to take these images of the planets in our solar system? Why were the cameras turned off? And what would we be able to see if they are turned back on today? In this video we will talk about the cameras onboard the Voyager 1 spacecraft which took the portrait of the solar system, and what would happen if we turn them back on. Launched in 1977, Voyager 1 is a spacecraft that has been on an incredible journey.
It is now 6.4 billion kilometers (3.7 billion miles) from the center of the solar system, and it has been able to look back at the home it left behind. It has flown past Jupiter, Saturn, Uranus and Neptune, and it has been able to take some incredible images. Voyager 1 is currently racing away toward the infinity of interstellar space, and our entire solar system looks like a string of small colored dots clustered just to the right of the constellation Orion. It is amazing to think about all that Voyager 1 has seen and accomplished on its journey! A trail of 39 grayscale shots – with zoomed-in color insets of each planet, assembled from another 21 color-filtered photos – makes up the famous solar system portrait. Even though Voyager 1 was still approaching the solar system's border, where the protective bubble of our Sun's solar wind gives way to interstellar space, the family portrait gives you a feeling of the size of our neighborhood and that there is a great lot beyond it still to be found.
The spacecraft was about 6.4 billion kilometers (4 billion miles) from Earth when it took the photos, and at that distance, even Jupiter appears as just a dot. Saturn's rings are barely visible, and Uranus and Neptune are just blurry smears. Earth is an even tinier speck, less than a pixel in the image. Yet despite its humble size, our world is still the most beautiful object in the Voyager 1 family portrait. The pale blue crescent of our home planet stands out against the blackness of space, a reminder of the fragility and preciousness of life. Venus occupies only a fraction of a pixel, while Mercury is so near to the Sun that it is undetectable in the Voyager 1 images. Mercury is the family member who always manages to sneak behind someone taller just before the picture is taken. And Mars, like the person who blinks just as the camera shoots, has lost its slender crescent in the glare of dispersed sunshine. Pluto, which was still considered a planet at the time because we hadn't realized that dwarf planets were a separate category of object to which the icy little world rightfully belongs, also doesn't appear in the photo because it's too small and too dim to be visible.
Voyager 1 was designed and built here on Earth in the 70s. Despite being in space for 45 years as of 2022, the computers and systems onboard the spacecraft are still functioning. The engineering of the spacecraft was beautiful and way ahead of its time, a perfect example of that are the cameras onboard the voyager 1. It is no easy feat to take the images we are discussing about today, in harsh environments of space. The Voyager 1 spacecraft has two cameras on board, a wide-angle camera and a narrow-angle camera. The wide-angle camera is used to take grayscale background photos, while the narrow-angle camera is used to take color photos of planets. Each of the color photos of the planets actually consists of three photographs, which Voyager’s narrow-angle camera snapped in rapid succession: one photo each with three different color filters in violet, green, and blue.
As a result, the Voyager 1 spacecraft has a unique set of images that provide an intimate look at our solar system’s planets. The Voyager Imaging Science Subsystem (ISS) is a modified version of the previous Mariner flights' slow scan vidicon camera systems. A high resolution Narrow Angle (NA) camera and a lower resolution, more sensitive Wide Angle (WA) camera comprise the system. The cameras are controlled by an imaging parameter table stored in one of the spacecraft's computers, the Flight Data Subsystem. As Voyager 1 gets further from the sun, objects appear more faint, so longer exposure times are used. Voyager 1 is also getting further from Earth, so telecommunications capability at each encounter decreases. The Voyager team had to program a sequence of commands in advance for the cameras, because instructions from home took about 5.5 hours to reach Voyager 1’s radio antenna. For example, they had to decide when and where to point the camera, which filter to use, and how long the exposure should be.
The exposures near Uranus and Neptune needed to be 15 seconds long with the narrow-angle camera, while the exposures for the Sun only needed to be 1/5000th of a second long. All of these factors had to be considered in order to get clear, quality photos from Voyager 1. Cameras with 800x800-14 m pixel resolution are installed at the end of Voyager's flexible scan platform. Each frame needed 5,120,000 bits, which could be stored on a magnetic tape with a capacity of 536 million bits at 115,200 bps or relayed back to on Earth at 8400 or 14,400 bps Deep Space Network receivers. The tape backup was required to save images during occlusion (when a planet or satellite obstructed the radio communication line) and was replayed at a lower data rate. Even with all of the meticulous filtering and exposure time, the photographs of the inner solar system are full with reflected beams and sunshine spots; Earth happens to be centered in one of them in the color inset shot.
That image, in particular, is a moving farewell to mankind from our most distant creation; 34 minutes after the photographs were shot, NASA engineers instructed Voyager 1 to turn off its cameras in order to conserve power for the lengthy journey into the unknown. There isn't much to see in interstellar space, after all. Regrettably the cameras onboard the Voyager spacecraft were disabled decades ago, just after taking the last distanced image of the solar system. This is because the space probe had traveled so far out into space that it no longer received enough light to function as intended. Both Voyagers' RTG nuclear batteries'' are nearing the end of their lives. These spacecraft might be decommissioned at any moment, and most likely within the next five years.
More and more scientific experiments are being shut off in order to preserve energy and extend their lives. Since then, the computer software that operates the cameras has been overwritten to make room for additional scientific data. Because it is becoming increasingly difficult to transmit data back to Earth, the ability to store more data aboard the spacecraft for subsequent transmission is advantageous. Each spacecraft's radioisotope thermoelectric generator produces 4 watts less each year. Due to dwindling electrical power, the Voyager crew was forced to decide which instruments to keep running and which to switch off. As part of power management, heaters and other spacecraft systems have been shut off one by one. The Voyager team has decided to continue running the sensors that are most likely to return critical data on the heliosphere and interstellar space – the fields and particle experiments. Engineers intend to begin shutting down fields and particle physics equipment one by one for Voyager 2 in 2020.
Because Voyager 2 is now operating one more instrument than Voyager 1, it will have to begin shutting off science equipment sooner. Engineers anticipate that each spacecraft will continue to operate at least one scientific instrument until roughly 2025. Even if science data is unlikely to be gathered after 2025, engineering data may be returned for several years longer. Depending on how much power the spacecraft still has to broadcast a signal back to Earth, the two Voyager spacecraft might remain in the Deep Space Network's range until around 2036. On top of this addressing our last question of what will happen if we turn on the cameras today? Would we be able to see anything? The cameras onboard the Voyager 1 can be activated, although it is not a priority for Voyager's Interstellar Mission. After taking its final photograph (the Solar System Family) in 1990, Voyager 1's cameras were shut off to conserve power and memory for the equipment that would detect the new charged particle environment of interstellar space.
Mission controllers uninstalled the software that controls the camera from both spacecraft. The computers on the ground that comprehend the programme and evaluate the photographs no longer exist. The cameras and their heaters have also been subjected to the extreme cold of our solar system for many years. Even if mission management rebuilt the computers on the ground, reloaded the software onto the spacecraft, and turned the cameras back on, it is unclear if they would operate. Furthermore, the Voyagers are currently in an extremely dark environment. While the cameras could still view certain brighter stars and planets, amateur telescopes on Earth can see these stars and planets far better. So the bottom line is, we might be able to turn the cameras back on, but they wouldn’t be any useful. They might be damaged due to exposure to cold deep space, and the cameras won’t do much good anyways as deep interstellar space is mostly black.