While more and more countries are sending artificial satellites to space on a regular basis, concerns over the collision of spacecraft and debris have been on the rise too.
Too many satellites moving at great speed are also an obstacle for telescopes to take high-resolution photos of outer space.
Some of these man-made objects are operational satellites, but most are defunct spacecraft, spent rocket stages and debris fragments created in collisions.
Moreover, there are small space rocks in space resulting from collisions among asteroids, comets, moons, and planets.
Artist's impression of satellites and space debris CollectedThe junk can travel at speeds up to 17,500 miles per hour or 28,163kmph.
An object up to 1cm in size could disable an instrument or a critical flight system on a satellite. Anything above 1cm could penetrate the shields of the US-led International Space Station’s crew modules, and anything larger than 10cm could shatter a satellite or spacecraft into pieces, the European Space Agency (ESA) said.
Severe impact
The Hubble Space Telescope was partially damaged several times as its outer shell and the solar panels were struck by space debris.
Sent by the US to space on April 24, 1990, the Hubble orbits Earth at a speed of roughly 17,000mph or 27,400kmph at an altitude of approximately 550km above Earth.
In April 2016, a window of the Cupola or observation area at the ISS suffered from an impact.
European Space Agency astronaut Tim Peake took a photo from inside the Cupola, showing a 7mm-diameter circular chip gouged out by the impact from a tiny piece of space debris, possibly a paint flake or small metal fragment no bigger than a few thousandths of a millimetre across.
The ISS is provided with extensive shielding around all vital crew and technical areas, so that minor strikes, like this one, pose no threat, the ESA said in an article, adding that larger debris would pose a serious threat.
How clumsy is our space?
According to Nasa, more than 25,000 objects larger than 10cm are known to exist as space debris and the estimated population of particles between 1cm and 10cm in diameter is approximately 500,000.
As of January 2022, the amount of material orbiting the Earth exceeded 9,000 tons, Nasa said, when the total number of operating satellites in space was 4,852.
The US, China and Russia among other countries have sent several hundred small and medium artificial satellites since January.
The US Space Surveillance Network (SSN) currently tracks about 20,000 objects larger than 4 inches or 10cm in low Earth orbit, the region of space at altitudes below 620 miles or 1,000km, according to space.com. The number was around 5,000 in 2003.
Experts at SSN use radar measurements to maintain a catalog and keep track of these objects to assess their trajectories into the future. They send the satellite operators warnings when two objects, for example, a piece of space debris and a satellite, may seem dangerously close to each other.
"A typical satellite operator may now be spending 30 to 50% of their time dealing with collision alerts," Tom Berger, a solar physicist and director of the Space Weather Technology Center at the University of Colorado, told space.com.
"Low Earth orbit satellite operators receive about one warning per day now. About one per week is serious enough to analyze in greater detail, and about every few weeks they have to maneuver to reduce the probability of the collision. It wasn't like that in the past."
Nicholas Johnson, Nasa chief scientist for orbital debris, said: “The greatest risk to space missions comes from non-trackable debris.”
