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When Zone 1 crossed the invisible boundary of the solar system, its instruments detected something strange. Outside the solar bubble, the space around the spacecraft seemed to thicken. In particular, the plasma density, i.e. the concentration of charged particles outside the heliosphere, increased. Five years later, its twin probe, Voedr 2, confirmed this discovery. Right now, these two machines are plunging into the space between the stars. Their journey will last so long that they will outlive not only their creators, but perhaps even the stars themselves in our sky. But there is one detail in this whole story that still doesn't fit in my head. How do we still get information from them?
How do spacecraft built half a century ago, now traveling tens of billions of kilometers from Earth, manage to send us data about these anomalies right now? The history of these machines began with a rare cosmic coincidence. In the mid-1960s, a student at NASA's Jet Propulsion Laboratory noticed an incredible fact while studying orbital mechanics. In the late 1970s, the giant planets Jupiter, Saturn, Uranus, and Neptune were supposed to line up in a perfect configuration. The beauty of this phenomenon was that the planets revolved around the Sun at different speeds. And such a parade of planets only happens once every 176 years. Before
that, humanity simply lacked the technology to get that far. After that, the planets would disperse in their orbits. It was a unique window of opportunity, now or never. The thing is, in space you can't just fly in a straight line like we do on Earth. Everything is constantly moving in a circular motion, continuously attracted by gravity. To reach a distant planet, a spacecraft cannot simply rush forward. It must constantly change its flight path, which requires a tremendous amount of energy. Humanity has many rockets capable of lifting enough fuel for a direct flight to Neptune. The journey would have taken a grueling 30 years, but this parade of planets allowed for the use of gravitational maneuvering.
The principle is similar to a slingshot, but instead of a real sling, the device is held by the invisible force of the planet's gravity. As a planet moves in its orbit, its gravity captures an approaching probe, pulling it along, transferring some of its orbital energy, and throwing it further into space with enormous acceleration that requires no fuel. This trick reduced the travel time from 30 years to just 12. NASA jumped at the chance. To play it safe, they built two identical probes with maximum survivability, duplicate computers, backup engines, and dual communication systems. In fact, Voyager 2 launched first in August 1977 on a longer, slower trajectory designed to visit all
four planets. Voyager 1 was launched 16 days later on a faster, more direct route. Its mission was to overtake its twin and conduct a detailed study of the largest moons of Jupiter and Saturn. Thanks to its higher speed, Voyager 1 jumped ahead even before it reached Jupiter. What they brought to Earth changed science forever. Scientists expected to see ordinary dead rocks. Instead, Jupiter met them with wild turbulence. Voyager 1 took a series of photographs that were edited into a timelapse on Earth. For the first time, scientists saw that Jupiter's atmosphere is not a static picture, but a living machine of jet streams, vortices, and storms. And on the moon Io,
astronomers discovered active volcanoes with bluish plumes. Next was Saturn, with its system of hundreds of rings. This is where the twins' paths diverged, and it was clearly according to plan. Voyager 1's trajectory was plotted to fly very close to Titan, the only known moon with a dense atmosphere. Titan's gravity acted so strongly that it drastically altered the probe's course, sending it up and beyond the plane of the planets into deep space, sacrificing any chance of visiting other worlds. Meanwhile, Voyager 2 continued its grand tour, becoming the only spacecraft in history to visit the ice giants. As it approached Uranus, the umbrella detected a bizarre anomaly.
Not only does Uranus spin on its side as it orbits, its magnetic field is tilted 59° from its axis of rotation, and its magnetic center is offset from the planet's core. For comparison, the Earth's magnetic field resembles a giant bar magnet. Its magnetic axis is tilted about 11° relative to its rotational axis, and the source of the field is deep within the planet. Things are much stranger with uranium. The magnetic axis is tilted by almost 59° and is significantly off-center. As a result, as the planet rotates, its magnetic shield does not spin smoothly, but instead wobbles in space. The probe then reached Neptune, recording the most powerful winds in the solar system at up to 2,400 km/h. If you imagine winds of this speed in the
Earth's atmosphere, the manifestations would be supersonic. They wouldn't just tear off roofs, they would blow buildings, cars, and infrastructure to pieces like a hurricane that we don't even have a category for. After Neptune, Voyager 2's cameras turned off. In 1990, after the famous photograph of the pale blue aunt, Voyager 1's cameras were also powered down. There were no more nearby worlds to photograph, and every watt of energy was becoming too precious. And since then, the main value of the probes has shifted to their other instruments: particle detectors, magnetometers, and plasma sensors. These are the instruments that sense invisible radiation and magnetic fields, transmitting data to the ground that no
telescope could ever capture. The cameras are off, and the spacecraft are flying through the cold void between the stars. However, the paradox is that even after almost half a century, invaluable scientific data from the edge of the solar system is still making its way to Earth. And this brings us back to the main question: how do we hear them in the first place? To understand the scale of this engineering marvel, you need to look at the equipment on board. The total amount of RAM of all six computers on each of the Voyagers is only 68 KB. This is less memory than the microchip in a modern electronic car key. The smartphone in your pocket is a million times more powerful than the entire flight control system, and the data
is collected and stored on an old eight-track digital tape recorder. Technology, a place that is now in a museum, but what is most impressive is the communication system. The spacecraft transmits data to the ground using a transmitter with a power of about 20 watts. This can be compared to a dim light bulb in your refrigerator. The Voyagers are more than 24 billion km away from us. A radio signal traveling at the absolute speed of the universe, the speed of light, would take over 22 hours to cross this abyss. During this incredibly long journey, the radio waves are scattered over a huge area and only a
tiny fraction of the original signal reaches Earth. By the time the signal reaches Earth, its power drops to fractions of an Atovat. I've never even heard of such a thing before. And imagine, that's less than 1 billionth of a watt. It's a whisper so faint that without giant antennas it would simply dissolve into the background noise of the universe. So how can you even extract such a signal from the choppy interference of deep space? The answer lies right here, on the ground. NASA uses the Deep Space Network, or DSN. Three complexes of massive 70-meter radio antennas located in
the deserts of California, Spain, and Australia. They are strategically placed so that as the Earth rotates, at least one dish is always pointed at the distant probes. These antennas collect invisible radio waves on their huge surface and focus them onto a single point. However, the giant dish catches everything in a row: radiation from distant galaxies, the background noise of the Earth's ether, and its own internal noise. How to isolate a single, ultra-weak signal from this cacophony? NASA engineers use a three-stage filtration process. First, they must eliminate winter radio interference. This includes signals from our cell towers, radars, and satellites. That is why
DSN stations are built in remote deserts far from civilization and they operate on strictly reserved radio frequencies. Second, they need to filter out radiation from other stars and galaxies. For this, the 70-meter antenna has high directivity. It focuses on a tiny, mathematically calculated patch of sky, ignoring everything outside it. In addition, engineers know the exact base frequency on which Voyager broadcasts. But because the spacecraft is moving incredibly fast, this frequency is constantly distorted. This is where the Doppler effect comes into play. Remember the ambulance siren. When a car is heading straight for you, it sounds high, but when it moves away, it drops sharply and sounds lower. This
happens because a moving object compresses or stretches the waves it emits. As the probe bounces off the ground, its radio waves are stretched in space and the signal's frequency shifts downward. NASA computers calculate this distortion in real time and tune ground receivers to this offset frequency, filtering out the rest of the space radio noise. But there remains a third, much more insidious problem. Even the heating equipment itself creates noise. The chaotic movement of electrons inside the metal creates background white noise in the receiver. If left unchecked, this internal thermal hum would instantly drown out
Voyager's purified signal. To solve this problem, the most sensitive components of the receivers are cooled to temperatures close to absolute zero. This suppresses the internal thermal noise of the electronics and allows engineers to hear a signal that is weaker than almost everything around it. Absolute zero, by the way, is -273°. according to Celsius. This is the absolute limit of cold in nature, beyond which thermal motion is reduced to an absolute minimum. Only through a combination of geographic isolation, precise antenna pointing, and extreme cryogenic cooling is humanity able to capture this infinitely faint signal from the edge of the solar system.
It was these signals, carefully deciphered, that helped explain the anomaly we mentioned at the very beginning. Why did space begin to compress when the probes left the solar system? Scientists assumed that the exit into interstellar space would be a smooth transition into a very rarefied medium. But the boundary of our solar system, the so-called heliopause, works differently. Our sun constantly emits a stream of charged particles known as the solar wind. It blows in all directions, creating a giant protective bubble around the planets called the heliosphere. However, the space between the stars is also not empty. It is filled with cold plasma, gas, and dust left over from ancient explosions on new ones. When the
solar wind reaches the outer edge of the heliosphere, it encounters and interacts with this interstellar medium. This is a chaotic border zone. The solar wind pushes from the inside, the interstellar plasma pushes from the outside. And right at this boundary, the density of particles changes dramatically. Today, in 2026, both probes have overcome this barrier and are cruising through the cold spaces between the stars. But their time is running out. Their main enemy now is not micrometeorites or radiation. This is a lack of energy. Where the Voyagers are, the sun still appears as a very bright star, but the light is too weak to make using solar energy practical. Instead, the Voyagers operate on radioisotope thermoelectric generators. Contrary to
popular belief, these are not miniature nuclear reactors. They have no controlled chain reactions, complex electronics, or moving parts that could break in half a century. The design of the generator is ingeniously simple. Inside is a sturdy capsule containing plutonium 238. This isotope decays naturally and continuously, releasing enormous amounts of heat that keeps the capsule extremely hot. Thermocouples and semiconductor plates are densely packed around it When one end of this plate touches a hot plutonium capsule and the other is pointed into the icy vacuum of space, this extreme temperature difference generates an electric current. But you can't fool physics. The half-life of plutonium-238 is 88 years. This
means that the isotope is steadily decaying, releasing less and less heat. and the thermocouples themselves sometimes degrade. As a result, generators lose power year after year. Of the original 11 scientific instruments on each spacecraft, only a few are still alive. There are two of them left on Voyager 0, and three on Voyager 2. To extend the life of the probes, NASA engineers remotely shut down the system one by one, constantly making very difficult decisions about which sensors to sacrifice next. This raises a logical question: how does the spacecraft even receive these commands? All of this works over the same deep space communication network, simply in transmission mode. While
the probe whispers to the ground with a power of 20 watts, 70-meter dishes on Earth send a powerful, narrowly focused radio beam into space with a power of tens of thousands of watts. Overcoming the same 24 billion km, this signal is also much weaker. But each Voyager, equipped with its own massive 3.7- meter dish, records commands from the ground with jeweler's precision. The connection speed is simply terrible. A pitiful 16 bits per second. Because of this, downloading a command package takes hours, and confirming its execution takes almost two days. This is how, with the help of a team from the ground, engineers had to turn off even the heaters that protected the devices from freezing. To the great surprise of scientists, vintage
electronics continue to function even in the bitter cold of deep space. However, energy reserves are steadily falling. In the next few years, around the early 2030s, there won't be enough energy even to support the operation of the transmitters. The engineers will be forced to send one last command and the connection will be lost forever. There will be complete silence on Earth, but for the Voyagers themselves, the loss of communication will be only the beginning of their endless journey. When the transmitters finally go out, the Voyagers will cease to be scientific instruments, but they will not turn into ordinary space debris. A package is bolted to the side of each spacecraft. This is an iconic gold record, a
gilded copper disc that carries the sounds of the earth, music, and photography. Yeah.
