Human journey into space began in 1957, when the Soviet Union (today’s Russia) launched Sputnik, the first ever artificial satellite. Since then, thousands of rockets have been launched, which have put into space numerous satellites, spacecraft, and space stations. Not all of them are functional today, nor has everything been brought back to Earth. Several of them, their parts, and random objects such as nuts and bolts are still up there as space junk. Worse, they are tumbling through space at a high speed putting functional satellites in Low Earth Orbit (LEO) at risk. There are fears that collisions between debris could set off a chain reaction, with the result that LEO would become unusable.
In 2007, China tested an anti-satellite missile by destroying one of its weather satellites. Two years later, an American and a Russian spacecraft accidentally collided. According to an estimate, these two events alone increased the amount of large debris in the LEO by about 70%. Space agencies have begun taking steps to mitigate the problem. A Japanese company launched one such initiative recently. Called Elsa-D, the mission intends to demonstrate a space debris removal system.
Mission Elsa-D
On March 22, 2021, a Soyuz rocket put 38 payloads into space. Among them was the ‘The End-of Life Services by Astroscale demonstration mission’ (Elsa- D), developed by a Japanese company called Astroscale. It is the world’s first Commercial mission to demonstrate a space debris removal system. Elsa-D consists of two spacecraft: a 175-kg “servicer and a 17-kg client”. Client is the fake debris that the servicer will have to release, grab, and repeat.
How does it work?
Astroscale’s demo mission aims to test its magnet strategy. A magnetic plate has been built into both the servicer and the client. The mission was designed to separate both the components a few weeks after the launch. Once released the servicer will hunt the client down, latching on to it using the magnetic docking plate, then releasing the client for another capture practice.
If that basic manoeuver goes well, the task will become increasingly complex Astroscale will remotely instruct the components to tumble, spinning like a dead satellite normally would. That will force the servicer to assess its target and line up with the prototypes docking magnet
Eventually, the servicer will pull the “debris” towards the Earth’s atmosphere where both the components will burn up. If such a technology were to be put to use, then future satellites should come built with this types of magnetic docking plate to enable removal once they become defunct and then?
Hundred million bits
Space debris refers to all the human-made objects such whole and abandoned satellites pieces of broken satellites deployed rocket bodies and other room objects such as tiny flecks of paint from spacecraft and event tools left behind by astronauts during space walk. Most of them orbit Earth and some even beyond it Some of the have made it to Venus and Man. Twenty tonnes of them have been found on the Moon, says NASA According to the European Space Agency, more than 2.400 dead satellites A computer generates artists impression of space junk. PHOTO: ESAVAFP and 100 million bits of debris are already circling Earth. And the debris keeps piling up as satellites have gotten smaller, cheaper, and easier to launch.
How are they monitored?
Scientists use radar to keep track of space debris. The US Space Surveillance Network keeps track of known orbital objects wing ground-based radar systems such as the TIRA Haystack and EISCAT radars and the Cobra Dane Telescopes and observatories such as the ESA Space Debris Telescope and the Goldstone provide additional data. As of 2020, the United States Space Surveillance Network was tracking more than 14,000 pieces of space debris larger than 10 on across. It is estimated that there are about 2.00,000 pieces between 1 and 10 and macros.
What are the risks?
In-orbit risks
- The damage can be as small as a dent on a shuttle window to the destruction of an entire satellite. In 1996, a French satellite was hit and damaged by debris from a French rocket that had exploded a decade earlier. Objects in LEO travel at speeds up to 10km/second, fast enough to cause significant damage to satellite, spacecraft or spacewalking astronauts. The rising number of space debris increases the potential danger to all space vehicles, especially to ones with humans aboard, the International Space Station (ISS), for instance.
- In 2020 alone, the ISS was manoeuvred away from space debris on three occasions, since a collision could endanger the astronauts on board. A number of space shuttle windows have been replaced because of damage caused by paint flecks.
- The density of the junk may become so great that it could hinder our ability to use weather satellites, and hence to monitor weather changes.
Debris that re-enters Earth
Space trash is often attracted by Earth’s gravitational pull. It is pulled lower and lower until it finally reaches Earth’s atmosphere. Most objects burn up when they enter Earth’s atmosphere due to the compression of atmospheric gases, but larger objects can reach the Earth intact. But most of them fall into the ocean, simply because Earth is mostly covered by water. According to NASA website, an average of one catalogued piece of debris has fallen back to Earth each day over the last 50 years. But there have not been any significant damage. No one has ever been killed by re-entering space debris. People on Earth should avoid contact with the fallen debris, such as rocket parts, because of the possible presence of hazardous chemicals in them.
What is the solution?
- The solution involves steps to clean up the mess, mitigate damage, and avoid future debris. There are systems in place to track the debris and avert disasters. Various space organisations have been working on reducing the amount of trash by adopting better designs of rockets and other objects. For example, making rockets reusable could vastly cut down waste.
- The UK’s TechDemosat-1 (TDS-1), launched in 2014, was designed in such a way that once its mission is over, a system, like a parachute, would drag the satellite to re-enter the atmosphere and bum up. Some satellites at the end of their lifecycle are made to fall out of orbit and bun up in the atmosphere, provided they still have fuel left in them for the descent Some satellites are sent even farther away from Earth.
- Technologies to remove space junk are also being developed. Cleaning the debris that already exists comes at a high cost, because it will take multiple trips to remove objects from space. Other proposals include the use of a laser to remove debris by changing their course and making them fall towards the atmosphere of Earth and later burn up.
- In December 2019, the European Space Agency awarded the first contract to clean up space debris. ClearSpace-1 is slated to launch in 2025. It aims to remove a 100-kg Vega Secondary Payload Adapter left by the rocket Vega flight W02 in an 800-km orbit in 2013. A “chaser” will grab the junk with four robotic arms and drag it down to Earth’s atmosphere where both will burn up.
Picture Credit : Google
