Almost 40 years ago, the spacecraft Voyager 1 and Voyager 2 went on a journey, eventually becoming the most remote man-made space objects from Earth in the history of space exploration. As part of their missions, both probes spent about two decades only to reach two gas giants of our solar system - Jupiter and Saturn. And while Voyager 1 decided not to linger in the system and immediately rushed to its outer borders, Voyager 2 also visited Uranus and Neptune along the way, becoming the first space probe in history to explore these worlds.
At the end of this summer, the probes will mark the 40th anniversary of their launch on August 20 and September 5, respectively. Despite the fact that spacecraft have been flying for so long and are far from home, they still keep in touch with the NASA aerospace agency, transmitting valuable information to it. Therefore, it is safe to say that in addition to being the most distant spacecraft, Voyager 1 and Voyager 2 also perform the longest missions in the history of space exploration.
In addition to the duration and range of space missions, Voyagers can be credited with many other achievements. For example, in 2012 Voyager 1 became the first and only spacecraft to reach interstellar space. In turn, Voyager 2 became the first and only probe to explore all four gas / ice giants of our solar system - Jupiter, Saturn, Uranus and Neptune.
Launch of the Voyager 2 space mission. August 20, 1977
The merit of the devices can also be added to the first discovery of active volcanoes outside the Earth (on Io, the satellite of Jupiter), obtaining the first evidence of the probable presence of a subsurface ocean on Europa, confirmation of the dense atmosphere around Titan (the only planetary object, not counting the Earth, which has a dense and rich in nitrogen atmosphere), the discovery of the rocky surface of Uranus' moon Miranda, as well as the ice geysers of Triton, the largest moon of Neptune.
All of these discoveries have brought enormous benefits to the astronomical community and paved the way for the launch of new space missions: the sending of probes Galileo and Juneau, Cassini-Huygens, and New Horizons.
“I believe that few missions will be able to achieve the level of scale that Voyager missions have, which have been surfing the vastness of space for almost 40 years. They opened for us the unknown wonders of the universe and truly inspired humanity to explore our solar system and space beyond it,”said Thomas Zurbüchen, head of NASA Science Mission Directorate in a recent press release.
But perhaps the most memorable about Voyager missions is what they carry on board. The so-called Golden Plates are fixed on the skin of each spacecraft, on which a collection of various earthly sounds, pictures and messages with the coordinates of the Earth and information about human history and culture is recorded. These records are a kind of "time capsules" and carriers of messages for any developed civilization that may meet on their way, about our existence.
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Both Voyagers, launched in 1977, carry 12-inch gold-plated records of images and sounds of the Earth.
As mentioned above, the vehicles are still in contact with the aerospace agency NASA and transmit valuable scientific information to it. The Voyager 1 probe is located approximately 20.9 billion kilometers (or 140 astronomical units) from Earth at the time of this writing. In relation to the plane of the planets, the probe continues to move north into interstellar space and sends us information about cosmic radiation, which in interstellar space is four times denser than around the Earth.
From this, scientists have found that the heliosphere - the space in which the planets of the solar system are located and there is a solar wind - acts as a kind of shield from external radiation. The Earth's magnetic field protects us from a significant volume of the solar wind (otherwise the wind would simply blow our atmosphere into space), and the space, called the heliopause, in turn, protects the planets of the system from atomic nuclei moving in space at a speed close to the speed Sveta.
At the same time, Voyager 2 is located at a distance of about 17.7 billion kilometers (114.3 astronomical units) from Earth. In relation to the plane of the planets, it moves southward and is expected to enter interstellar space in a few years. Like Voyager 1, it also studies the interaction of the heliosphere with the surrounding interstellar medium using a set of scientific instruments with which it measures particle charge levels, magnetic fields, radio waves, and solar wind plasma.
Once Voyager 2 enters interstellar space, both probes will be able to simultaneously collect information about the interstellar medium in different regions. According to scientists, this could tell us more about the magnetic environment that protects our system, and possibly provide new data on the history of the formation of the solar system. In addition, it will give us some idea of what dangers will have to face in the framework of possible future missions to interstellar space.
The illustration shows how the Hubble Space Telescope tracks the paths of the Voyager 1 and Voyager 2 spacecraft as they travel through the solar system to interstellar space
“It's amazing that both probes are still active after so many years,” said Edward Stone, a California Institute of Technology professor of physics and former vice president and director of the Jet Propulsion Laboratory and Voyager program coordinator.
“None of us, when we launched these probes 40 years ago, could even imagine that 40 years later they would still work and continue this pioneering journey. It is quite possible that their most amazing discovery will take place in about five years. They might find something that we might not even know existed."
Keeping probes in working order has always been a challenge for scientists, since the amount of energy they produce is reduced by about 4 watts annually. Controlling twin probes, constantly losing energy, forced modern engineers to resort to old diagrams and drawings to better understand the capabilities of the software and command functions of ancient devices.
In addition, it also provided an opportunity for former NASA engineers who worked on the Voyager program to offer their experience and expertise to the younger generation. The current program team has calculated that the energy of the probes remains until 2030. However, even after this date, they will continue to move along the paved trajectory at a speed of 48,280 kilometers per hour, overcoming one astronomical unit every 126 days.
The Voyager 1 space probe has begun its flight through the so-called "space purgatory" - the space between our solar system and interstellar space
At this rate, they will continue their journey until they eventually reach the nearest star in about 40,000 years. According to forecasts, in 225 million years, the Voyagers will make a complete orbital circumnavigation of the Milky Way, unless, of course, they collide with anything during this time. Therefore, it is quite possible that someday the Golden Records will find their addressee. Again, someday they will even be able to find their way home, back to Earth, thereby alerting our distant, very distant relatives of life in the 20th century.
Nikolay Khizhnyak