How NASA found the lost moon of India 8 years ago

Spacecraft, no matter how valuable they are, have a certain lifespan. These can be months or years. At the end of their lifetime, the vehicles are either left in orbit, or lowered into the Earth’s atmosphere, if there is such an opportunity, where they burn. During the time that has elapsed since the beginning of man’s exit into space, there have been many abandoned devices to the mercy of fate.

Systems of this kind are not only in orbit of the Earth, but also in other regions of space. One of them is the non-working Indian satellite Chandrayaan-1 . He stopped giving signals before the end of his life, but the result was the same - he was lost. Now he was found with the help of the Goldstone Complex.

The difficulty of detecting the device was that it is small. This is a cube with faces of 1.5 meters in length. In an ordinary telescope it is impossible to see it. The satellite was launched on October 22, 2008, and became the first Indian spacecraft that was sent beyond the limits of the Earth's orbit. A month later, he went to the calculated position and began to transmit a signal to Earth. Scientists expected that the device will create a detailed atlas of the lunar surface, as well as study the chemical composition of the moon in detail.
')
Signals satellite ceased to serve less than a year after launch. For 312 days in orbit, he made a little more than three thousand revolutions around the moon. In fact, the satellite was lost, no one knew exactly where he was and what happened to him. Thanks to the new method of working with the Goldstone Complex for Long-Range Space Communications, scientists from the Jet Propulsion Laboratory discovered it. In addition, experts were able to observe another device - the Lunar Reconnaissance Orbiter (LRO), which continues to work. However, its coordinates were known, so, according to the scientists themselves, localizing the satellite is easy: “It was relatively easy to find the LRO, since we worked with the mission equipment transmitting the satellite coordinates. Finding Indian Chandrayan-1 is more difficult, I had to conduct a small investigation, since the last contact with him was in August 2009. "

Goldstone radar is often used to observe the movement of small asteroids, which are millions of kilometers from Earth. But scientists were not sure whether they could detect a small cube near the moon. As it turned out, this is possible .


Lunar Reconnaissance Orbiter (LRO)

As for the radar, the different systems are very different from each other, despite the fact that everyone uses microwaves. At the police radar range is about one and a half kilometers. The radar, which is used to monitor the movement of aircraft with a range of more than 100 kilometers. And the 70-meter Goldstone radio telescope has a range of 380,000 km. Radio waves sent by a telescope are reflected from the surface of the moon. On Earth, they are again received using another radio telescope with a mirror diameter of 100 meters. This is Green Bank , a parabolic radio telescope of the National Radio Astronomy Observatory located in Green Bank, West Virginia, United States.

On the moon there are regions with gravitational anomalies that affect the movement of objects in the vicinity. According to scientists, Chandrayan-1 over the past few years could just break on the surface of the moon. But no, as it turned out, it still rotates in a 200 km orbit.

Astronomers have calculated that the Indian satellite should regularly pass through the poles of the moon. On July 2, 2016, the project team sent Goldstone to a point at an altitude of about 160 kilometers above the North Pole of the Moon. According to calculations, Chandrayan-1 should pass through this point once every 2 hours and 8 minutes. For four hours of observation, a radio telescope spotted a small object that went through this point twice.

Experts analyzed the radio signal reflected from the moon in order to estimate the speed of the object and the distance to it. By all measures, it was similar to the desired object, except for the location. As it turned out, it was really Chandrayaan-1, which strongly deviated from the planned trajectory, going forward half a cycle from the calculated position. After the scientists calculated its new orbit, they began to observe the object. For three months, experts were able to obtain additional information about him. After a detailed analysis, the initial assumption that the observed object, Chandrayaan-1, was confirmed. This was confirmed by additional observations made using the Arecibo Observatory.


Antenna radio telescope Goldstone

The “hunt” for LRO and Chandrayaan-1 was successful. Scientists have received confirmation that the use of powerful radio telescopes can detect the presence of even very small objects that are near the moon. Thus, ground-based astronomical systems can become an integral part of monitoring the implementation of lunar missions.