How many satellites are orbiting the Earth in 2015?

Image courtesy of ESA Note: The debris field shown in the image is an artist's impression based on actual data. However, the debris objects are shown at an exaggerated size to make them visible at the scale shown

Image courtesy of ESA
Note: The debris field shown in the image is an artist’s impression based on actual data. However, the debris objects are shown at an exaggerated size to make them visible at the scale shown

If you’d like the updated details for 2016, please click here.

A satellite can be defined as an artificial body placed in orbit around a planet in order to collect information, or for communication. The United Nations Office for Outer Space Affairs (UNOOSA) monitors, and maintains a searchable database of, objects launched into space. According to UNOOSA, at the end of August 2015, there were 4 077 satellites orbiting the Earth, which equates to 56.63% of all satellites ever launched.

Of the satellites no longer in orbit, 1 329 have been recovered, 1 539 decayed and 175 deorbited; and interestingly given the definition above, 47 are on the Moon, 15 on Venus, 13 on Mars and 1 on the asteroid EROS. Last year also saw more launches than any other year in history with 239, by the end of August this year we’d only had 106 launches.

The Union of Concerned Scientists (UCS) details the currently active satellites through their database, and they note that at the end of August 2015, of the 4,077 satellites in orbit only 1,305 are active. This means there is currently 2 772 pieces of junk metal circling above your head!

So what are the thirteen hundred active satellites actually doing? According to the UCS over 50% of these satellites have a purpose described as communications. The secondary biggest purpose is Earth observation with 26% of active satellites, 333 in total, and we’ll look at these in more detail next week. The next largest category is technology demonstration with 141 satellites, followed by navigation with 91 satellites and finally the remaining 5% of satellites have a purpose described as space science.

Commercial users account for 52% of the satellites, followed by Governments with 30%, 27% have military users and 8% are civilian users. The percentages total more than one hundred percent as some satellites have for multiple purposes. The civil users are mostly Universities or other academic institutes that have launched their own satellites.

The USA is biggest operator of active satellites with over 500, followed by China and then Russia. The UK is listed as the operator on only 40 satellites, although we also have a share in the 26 European Space Agency (ESA) ones.

An interesting point is the most popular launch sites for satellites. The Plesetsk Cosmodrome in Russia has launched the most satellites in history, over 2,000. This is followed by Baikonur Cosmodrome in Kazakhstan with 1,500, with this site being famous for launching both Sputnik 1 and Yuri Gagarin’s first manned space flight in Vostock 1. After this are the American sites of Cape Canaveral, Florida and the Vandenberg Air Force Base in Lompoc, California, followed by the ESA launch site of French Guiana.

The UK currently doesn’t feature anywhere on the list, but the first steps to changing this are underway. The UK Government is planning to have a spaceport established in this country by 2018; with three sites in Scotland short-listed together with Newquay in Cornwall, which is an exciting prospect for Pixalytics as we are both based in south-west. The initial focus is likely to be sub-orbital flights, but who knows what could be launched in time.

When you next look up into the sky, remember that there are over four thousand hunks of metal shooting around the Earth at speeds of many thousands of the kilometres an hour high above the clouds!

Our Beaches Are Shrinking!

Do you remember the fun of building sandcastles at the beach? It’s something almost every child loves to do, but perhaps not for too much longer. According to an article published in The New York Times last week, seventy-five to ninety percent of the world’s natural sand beaches are shrinking. According to Professor Gillis of Rutgers University, this is due to a combination of increased storm activity, rising sea levels and human development of the shoreline.

Landsat 8 Image of Chesapeake Bay from the 28th February 2014. Image courtesy of the U.S. Geological Survey.

Landsat 8 Image of Chesapeake Bay from the 28th February 2014.
Image courtesy of the U.S. Geological Survey.

The impact of storms was demonstrated last winter when millions of tonnes of sand were stripped from our shores. The beach at Formby in Liverpool lost thirteen metres of coastline, whilst in Cornwall Perranporth lost about a million tonnes of sand, Fistral Beach in Newquay lost thousands of tonnes of sand and the beach at Bude almost disappeared completely.

A snapshot of sediment movement can be seen in the Landsat 8 image above of the mouth of Chesapeake Bay in Maryland, USA. The Chesapeake Bay Bridge–Tunnel can be clearly seen stretching to the north, with a number of boats passing through it. The image is displayed as a pseudo-true colour composite, combining the red, green and blue wavelengths with some enhancements to bring out specific features. The suspended sediment around the coast can be seen in the complex colour patterns of turbulence and movement, and during storms this sediment will include the larger, and heavier, sand particles.

However, anyone who visited the seaside this summer might not have noticed the major loss of sand from last year’s storms. This is because beach replenishment is a major activity in many areas, either because the beach forms part of the protective barriers for the land or because the beach is tourist attraction. Sand is not an infinite resource, and most replenishment comes from other beaches, dredging or mining. For example, this year areas around Bridport and Lyme Regis in Dorset were reshaped with sand recovered from harbour dredging.

Beach replenishment is not the only usage of sand. Sand is the most consumed natural resource on earth, and the biggest user is the construction industry in the production of concrete. However, it is also used in any process that requires silicon dioxide which includes everything from wine to toothpaste, glass and computer microprocessor chips. In fact, according to The New York Times, the US sand and gravel business is fastest growing sector in their economy.

Sand is becoming scarce in the world. We need to start taking care of our sand, and think carefully about how we use it. Should we replenish every beach that loses its sand? If we don’t do start to take shrinking sand seriously, future generations of children may never experience the joy of building sandcastles on a beach.