Many moons ago, before the days of mobile/cell phones, I was sitting under a clear night sky in the Andalusian hills of southern Spain. Someone beside me suddenly exclaimed, ‘I just saw a shooting star!’ From the other side of me came the sardonic reply, ‘Space trash.’ A conversation then began regarding the probability of the observed moving object being man-made debris burning up in the atmosphere. Years later when writing A Little Matched World, a modern-day adaptation of Hans Chritian Andersen’s The Little Match girl, (available for free download at the above link), that discussion came to mind when writing dialogue for the character who saw ‘a shooting star’. By that time though, 2008, the proliferation of communication satellites was known about. Fast forward to a recent similar conversation, which made me aware that I didn’t know how many, although now in 2015 there were definitely more. This post is the result of my looking into it.
Actual numbers I’ve come across are varied and conflicting. This could be due to classification. It could also be because some users have been known to be less than forthcoming about potentially sensitive information. The data below is collated from various sources, several of them government or government-controlled.
Satellites, some of which can be described as orbiting platforms, are used in a variety of ways: meteorological, GPS, agricultural (Chinese authorities are big on crop monitoring), military and national defence, (which includes surveillance), scientific, and communication – television, Internet, telephone. Over 60 percent are said to be used for communications.
Communication satellites can be as large as a school bus and weigh up to 6 tons. Most weigh a few tons or less. Some, called microsats or nanosats, can be as small as 10cm and weigh 0.1kg. The largest man-made satellite currently in orbit is the International Space Station.
Communications satellites are geosynchronous, meaning they maintain fixed points and/or 24-hour orbits around the planet, usually around 22,000 miles/35,000km up. GPS satellites orbit at 12,000 miles/19,000km. Others, military for instance, orbit lower. The International Space Station orbits at around 260 miles/418km. Not all satellites are geosynchronous, some move more rapidly in a low-earth orbit (LEO).
Russia launched the first satellite, Sputnik 1, in 1957. The oldest still in orbit, which is no longer functioning, was launched in 1958. More than 50 countries own a satellite or a significant share in one, according to the Union of Concerned Scientists. Private companies also own them, some of whom use Sea Launch, a consortium of four companies from the United States, Russia, Ukraine and Norway, to launch them from international waters.
So how many are there?
Well, the Union of Concerned Scientists Satellite Database (updated quarterly) lists ‘more than 1000’ operational satellites currently in orbit. But an Analytic Graphics Inc. Google Earth plug-in shows the real-time position of 13,000 satellites around the Earth. This YouTube video demonstrates the visualization, while the following graphic posted on Twitter by Vala Afshar, chief marketing officer of network infrastructure company Extreme Networks, gives a static view.
But satellites aren’t trash. What about the ‘space trash’?
It’s currently estimated that 370,000 pieces of man-made space trash traveling at up to 22,000mph/35,000kph are currently in orbit around the Earth. These comprise a variety of materials including abandoned inoperative satellites, shrapnel from anti-satellite weapons tests, old boosters and other rocket parts, and wreckage from satellite collisions and explosions. Satellites that fly below a certain height are supposed to be put in an orbit that will make them fall to Earth and burn up within 25 years. Higher altitude satellites are boosted up to still higher orbits to move them out of the way.
The following image put together by Michael Najjar in collaboration with the Institute of Aerospace Systems at the Braunschweig University of Technology, is one that represents existing orbiting objects of the kind described above.
Another display of ‘stuff in space’ is the website Stuff In Space where you can see all but the smallest bits of the estimated 500,000 or so smaller orbital debris (1-10cm in diameter) and about 21,000 larger bits (larger than 10cm) that, according to NASA’s Orbital Debris Program Office, are orbiting the Earth right now.
Programmer James Yoder, designer of the website, which tracks the paths of the objects in realtime, says that, “The website displays anything currently trackable — low-earth orbit, geosynchronous, and anything else there is.”
Once loaded (and be advised, loading it into your browser is a geeky job!) the site presents a slowly spinning globe, accurately displaying day and night, surrounded by various colour-coded dots representing satellites (red), debris (grey), and discarded rocket bodies (blue).
Also displayed are the orbits of satellites and large debris, highlighted as blue lines and their names or designations, displayed in text. Related objects are collected in groups and there’s even a search function.
If you’re feeling particularly geeky, Yoder (love the name!), in admirable open source style, has posted the source code on Github.
So next time think you saw a shooting star, you might be right, but…