
Earth is threatened by space debris: What is Kessler syndrome and why we fear it
When space debris headed for the International Space Station (ISS) last November, seven astronauts had to react quickly. The Russian spacecraft attached to the station fired its engines for five minutes, pulling the ISS out of the path of the hazardous debris. Had the station not changed its orbit, the debris would have passed within four kilometers of them, which could have had catastrophic consequences, NASA warns.
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Such maneuvers are not uncommon. Since the ISS was first permanently inhabited in 2000, the station has changed its trajectory dozens of times to avoid collisions with space debris. That problem grows every year as the number of objects orbiting the Earth increases exponentially.
"In the last four years, the number of objects in space has grown dramatically," said Dr. Vishnu Reddy, professor of planetary sciences at the University of Arizona.
"We are getting closer to the situation we have been trying to avoid for years.
One of the biggest threats is a hypothetical scenario known as Kessler syndrome. According to this concept, collisions between space objects can cause a chain reaction in which debris destroys other objects, creating ever-larger clouds of debris. Such developments could make the orbit so congested that it becomes unusable for satellites and space exploration.
Although astronauts are most directly at risk, congestion also threatens the technologies we use every day, such as GPS, high-speed Internet and television services. Experts estimate that since 1957, there have been more than 650 accidents that have created thousands of pieces of space debris.
One of the most famous collisions occurred in 2009, when the defunct Russian Cosmos 2251 satellite collided with the active American communications satellite Iridium 33. That collision created a cloud of nearly 2.000 pieces of debris larger than 10 centimeters, and there were countless smaller particles, writes C- en-en.
Most debris in orbit is too small to track with existing technology, but even tennis ball-sized particles can cause serious damage. In orbit, objects move at such a speed that even the smallest can pierce metal, NASA warns.
"What worries me the most is that the data on the locations of the debris is not precise enough to safely avoid collisions," admits Dan Oltrog, a scientist at COMSPOC Corp.