You may already know that half a dozen humans live 330 – 435 kilometers (205-270 miles) above Earth’s surface. The name of their temporary home is the International Space Station. Abbreviated as the ISS, it’s the most expensive object (worth more than $100 billion) that has ever been built by humans.
The conception, construction and joining of all the parts of the spacecraft has been so elaborate (and also expensive!) that it took contributions from many different countries, including the United States, Russia, Canada, Japan and various other European countries. Needless to say, it is the epitome of the most advanced space engineering and technology that humans have acquired thus far.
For more detailed information on the International Space Station, you can check out: Everything You Need To Know About The International Space Station (ISS)
Solar Arrays: Power Source of the ISS
The ISS operates in space, and there’s obviously no power mains out there that the ISS can “plug into” in order to keep it up and running. There’s only one power source in space, and the ISS depends on it entirely – the power of the sun. In simple terms, the International Space Station relies on solar energy, which has helped keep it orbiting around the Earth for the last 18 years, 1 month and 30 days (at the time of writing this article).
The most important component of the equipment aboard the ISS that helps to harness that solar energy is the solar panels. The ISS has 4 large solar array wings (which hold a total of 8 solar arrays); two are located on either side of the ISS, mounted on a central truss structure. The solar arrays are actually the most distinguishing component of any picture of the ISS, such as the one below:
The 4 sets of solar arrays generate 84-120 kilowatts of electricity – which is more power than the station actually needs at any given time for its operation and mission requirements (e.g., onboard experiments, research). To put this in perspective, the ISS produces enough electricity to power 40 homes!
Since the ISS needs electricity in order to operate and exist at hundreds of kilometers above Earth’s surface, the solar arrays are an indispensable asset to the ISS. Neither the ground support staff at Houston nor the astronauts onboard the ISS could afford to have those arrays damaged.
Unfortunately, the lower Earth orbit (where the ISS orbits) region is filled with debris, right?
Risks Posed by Space Debris
Space debris – or space junk, if you will – is really bad news, as it can cause catastrophic structural damage to any object or satellite it strikes. The 2013 movie Gravity is all about that – space debris hitting an artificial satellite and wreaking havoc!
Space debris poses a huge risk to the ISS and any other operational artificial satellites in the lower Earth orbit. With the exponential increase in the number of satellite launches every year around the globe, the problem of space junk has only gotten worsen.
So, what happens if and when the ISS solar arrays are hit by space debris?
ISS Solar Arrays and Space Debris
The solar arrays on the ISS are quite large – 112 feet long and 39 feet wide (34 x 11.9 meters). Given their size, it’s not that difficult for space debris to actually hit the large solar arrays on the ISS. As a matter of fact, it happens quite frequently!
Yes, the international space station gets hit by very small particles (of space junk) more or less constantly. However, the damage that these particles cause to the array depends on the former’s size. Fortunately, most of the stuff that strikes the ISS is very small – typically less than a millimeter.
Therefore, it doesn’t cause much serious damage to the arrays, which is great news!
However, hypothetically speaking, if something as big as a brick were to slam into the arrays, the damage could be anywhere from very serious to catastrophic.
There’s not much that can be done to avoid getting hit by space debris due to the sheer volume of it in the lower Earth orbit. Space scientists and researchers know this, so they carefully monitor the solar panels’ performance (before and after being struck by flying debris) and plan accordingly.
Strikes are inevitable, and they can’t be totally avoided. Thus, the ground support staff predicts the rate of degradation of the solar arrays in advance and makes them a large enough size so that they will remain operational and power the ISS for a very long time to come.