After 45 years of inactivity, LES-1 surprisingly sent a signal back to Earth, making it one of the oldest “zombie” satellites.
In March 2012, British amateur radio enthusiast Phil Williams discovered a strong and consistent signal from space near Earth while using his own radio equipment to monitor radio signals from space at a frequency of 237 MHz, repeating every 4 seconds.
Based on this discovery, Phil Williams used his knowledge to conclude that it was not a natural phenomenon. Upon analysis, he found that this radio signal from near-Earth space was actually caused by an artificial satellite designated “LES-1.”
Incredibly, “LES-1” had been abandoned for nearly half a century, and now it suddenly sent a signal back, which was indeed unbelievable. This sparked widespread discussion, with some even suggesting that the satellite had been activated by extraterrestrials to send some kind of message to humanity.
The Lincoln Experimental Satellite 1, also known as LES-1, is a communication satellite and the first among nine satellites in the Lincoln Experimental Satellite program. It was launched by the United States Air Force (USAF) on February 11, 1965, pioneering many advanced technologies of the time, including the active use of military SHF (Super High Frequency) bands. (Photo: Zhihu).
What is the truth?
Data records show that “LES-1” is a test communication satellite linked to the Lincoln Laboratory in the United States. It was used to test the effects of the ionosphere on radio communications in space. It was launched on February 11, 1965.
However, this satellite failed to achieve its intended geosynchronous orbit and instead entered an elliptical orbit at an altitude of about 2,800 km. Moreover, its orbital state was also inaccurate and uncontrollable.
Although “LES-1” was launched into space, it could not operate normally as planned, and thus became a derelict artificial satellite in Earth’s orbit. Since 1967, no radio signals had been received from this satellite.
The Lincoln Experimental Satellite (LES) series was the first active communication satellite project of the Lincoln Laboratory at MIT. (Photo: Zhihu).
Why after 45 years could the abandoned “LES-1” send signals back to Earth?
After news of Phil Williams’ discovery spread, it attracted a multitude of amateur radio operators, all confirming the origin of the signal. The Lincoln Laboratory in the United States was also surprised upon hearing this news, and after further confirmation, the laboratory discovered that the signal indeed came from the long-abandoned artificial satellite “LES-1.”
Through analysis of “LES-1’s” orbit when Phil Williams received the signal, scientists believe that “LES-1” was not taken by extraterrestrials, but rather the strange signals were emitted due to multiple orbital changes, with its orbital altitude having decreased by hundreds of kilometers from its original position. At this time, “LES-1” is located within the Van Allen radiation belt.
The LES-1 satellite emits strange signals due to multiple orbital changes. (Illustration: Zhihu).
The Van Allen radiation belt is a region of high-energy particle radiation surrounding Earth, formed by high-energy charged particles trapped by Earth’s magnetic field. Scientist James Van Allen discovered its existence in 1958. The strongest part of this high-energy particle radiation belt is distributed in the sky at a distance of hundreds to thousands of kilometers from Earth.
Scientists suggest that when high-energy charged particles in the Van Allen radiation belt bombard “LES-1,” this may have reactivated its signal transmission circuitry. Additionally, scientists speculate that the reason “LES-1” is still able to emit signals could be due to some solar panels covering its multi-faceted surface that may still be operational, albeit with an inconsistent power supply. The signal from “LES-1” repeats every four seconds, likely due to continuous power fluctuations.
In fact, similar situations have occurred with other satellites in the series; for example, its sibling “LES-5” was also found emitting signals many years after it was decommissioned, but its signals were not as peculiar as those from “LES-1.”
The signal from “LES-1” repeats every four seconds, likely due to continuous power fluctuations. (Illustration: Zhihu).
That “LES-1” can still transmit radio signals after more than 40 years is truly remarkable, showing that some parts of the satellite can still function after many years. However, scientists are not pleased with this, as “LES-1” is now just a piece of useless space debris.
According to information from the United Nations Office for Outer Space Affairs, since the launch of the world’s first artificial satellite “Sputnik 1” by the Soviet Union on October 4, 1957, the total number of artificial satellites launched into space has exceeded 16,000. Currently, only about 7,000 of them are still operational in space, while the rest have been decommissioned and most have become space debris orbiting Earth.
The increasing amount of space debris caused by human space activities. (Illustration: Zhihu).
With the growing amount of space debris, there are currently no better methods for its removal due to high costs. Today, the increasing amount of space debris caused by human activities poses a threat to the development of the human space industry. While many major space powers have established tracking and warning systems for space debris, the vast amounts of debris still pose a potential threat to spacecraft and astronauts orbiting Earth.
