Perspective
Space Pollution
Faiqa Anbreen
Human curiosity has always sought fulfillment in looking up to the stars and exploring what lies beyond the boundaries blanketing our planet. This quest led us to develop capacity in terms of physics obeying machinery which could traverse through and beyond the delimitation of the ionosphere. The first notable precedent in this exploratory journey was set by Russians on October 4, 1957, by launching the first man-made satellite, Sputnik in space, which redefined what was possible, over boarding human aspirations with optimism which led America followed by sending Explorer I into the orbit on January 31, 1958 upping the benchmarks for one after another mission to follow which kept breaking earlier records till we were able to establish our permanent presence in the Lower and Higher Earth Orbits.
The orbital space around the Earth is classified as Low Earth Orbit (LEO) ranging from 300–2000 km, Medium Earth Orbit (MEO) ranging from 2000–35,786 km and the Geosynchronous Orbit (GSO) which matches the Earth’s sidereal rotation period and functional to 35,786 km. Beyond that is the High Earth Orbit. The satellites which are sent to space serve various purposes and based on their mission activity, an orbit is chosen accordingly. LEO is the favorite spot for communication and navigation satellites, besides that LEO is home to International Space Station (ISS).
There are non-operational objects orbiting Earth, which are commonly termed as space debris. In 1961, when Russians launched Vostok 1, with Yuri Gagarin making the first human space flight, it was a target for space debris. This indicates that just within 4 years of the first satellite launch, space was filled with unwanted objects. In June 1961, the US Transit 4-A satellite’s upper stage became the first known disintegration in space, which resulted in 294 trackable pieces of space garbage. The quantity of debris has increased over years, a certain number been trackable because NASA and the Department of Defense (DOD) have been diligently maintaining a catalog of objects which are bigger than 10 cm in diameter. The trackable and non-trackable objects pose a threat to the functional satellites in space, one of the biggest and crucial targets is ISS.
ISS sustains in the orbit with a 408 km altitude, where astronauts perform various experiments in space. The space debris as small as a nut or a bolt can be a big threat to ISS, because the orbital velocity of space debris is as high as 28163 km/h, which upon impact can damage a satellite, a spacecraft and can punch a hole in ISS, resulting in depressurization of life-supporting module. It is a similar situation where a fish eats a plastic bag in the ocean and dies. The space agencies collaborating on ISS especially NASA is always ready if such a situation arises, if there is a threat to ISS, the station is lowered or raised in the orbit, or the trajectory will be changed with a debris avoidance maneuver.
One of the instances that I can account for is the disintegration of the space shuttle Columbia. Even though the Columbia wasn’t hit by debris in space, but at the time of launch when a small piece of foam from the main red hydrogen tank hit the wing of the shuttle it damaged a heat shield tile. Upon the reentry, the high temperatures caused the fire and eventual break down of Columbia killing all seven astronauts. Similarly, the space debris can cause damage to space crafts like Soyuz, which is currently ferrying astronauts back and forth from Earth to ISS.
Once the debris is created in space, it can stay there for hundreds of years or it can fall back or get destroyed while reentering the earth’s atmosphere. When objects collide in space, the fragments can end up in a higher or a lower orbit, if they end up landing into a higher orbit, they increase the threat, while if they end up in a lower orbit, they will end up burning on the entry. According to NASA, there are 500,000 pieces of debris as small as the size of a marble, 100,000,000 pieces as tiny as 1 mm, 23000 fragments as large as a softball and the total mass of these ineffectual items has reached to 7000 metric tons.
The recent experiment by India to destroy a satellite in orbit was uncalled for. It created debris numerous enough to pose a threat to ISS. A pretentious display of power led to a further increase in unwanted objects in space.
Singapore based company Astroscale is aiming to clean space from junk. There are various risk mitigation technologies, which are implemented to reduce the amount of space debris. End-of-life disposal is implemented in a satellite so that it reenters the Earth’s atmosphere within 25 years of completing the mission if they are in LEO. For satellites in higher orbits, the only prudent way is to maneuver the satellites into a graveyard orbit, where they will pose minimal or no threat to functional satellites. A technique for deorbiting the satellites is passivation, incorporated into the design architecture to discharge batteries and shed the remaining propellant to prevent explosion in space.
Space is a resource that should get utilized optimally based on the services that are benefiting humans, respecting it for being a source of constant inspiration and proliferation of human curiosity and abstain from considering it as a platform to gloat one's weapon muscularity.
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Author:
Faiqa Anbreen
Faiqa is an Engineer at Safran Aerospace Group and a PhD student in Aerospace Engineering and Computational Mathematics”. Contributes to A350XWB design and whirling in quest to understand turbulence.
faiqa.anbreen05@gmail.com
