Article Written by: Heather Alexander
Satellites, our lives wouldn’t be complete without them. Since the beginning of the Space Race, Satellites have become a major part of how we observe our Solar System and the Universe, and also keep a close eye on our own planet. It boggles the mind to think how people coped before the use of satellites, how did they ever get anything done? Were we all just wandering around bumping into things?
There are so many satellites in orbit around our planet and outside our planet. At the start of January 2019 there were 4987 satellites orbiting over our heads providing us with all sorts of valuable data. In our history, 8378 satellites have been launched into Space. Between 2017 and 2018 a total of 835 satellites were launched. This is a staggering amount. So, you can tell by these numbers that it was really hard for us to pick just five to talk about.
Europe’s first mission to Mercury! BepiColombo is an ESA mission in conjunction with JAXA, and it will explore Mercury. It was launched on 20th October 2018 and has been identified by Europe’s space scientists as one of the most challenging long-term planetary projects. This is due to Mercury’s proximity to the Sun. This mission will help us to understand more about the planet closest to the Sun and provide information that we would have otherwise been unable to obtain through observations made from the Earth alone. The mission comprises on two spacecraft, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). BepiColombo will arrive at its destination in 2025 and will stay there for approximately one year. It will have to endure temperatures of up to 350oC and will investigate the origin and evolution of the planet, probe Mercury’s magnetosphere, perform a test of Einstein’s theory of general relativity and much more!
2. GPS Satellites
Where would we be without GPS? Stranded in a field in the middle of nowhere or driving down a lane that ends in a lake, that’s where! The Global Positioning System (GPS) was originally set up in 1970s and was called Navstar GPS. It was based in the USA and was mainly used by the Air Force. There are between 24 and 32 satellites in medium Earth orbit at an altitude of 20,200km and at a radius of approximately 26,600km. As of February 2016, 31 satellites are in use in the GPS constellation. The word constellation in this sense refers to a group of artificial satellites working together. The GPS system is still located in the USA and so Europe decided to create their own global navigational network, so that the countries in Europe would not have to solely rely on the GPS System or the GLONASS system used by Russia. The Galileo Global Navigation Satellite System (GNSS) went live in 2016 and as of August 2018 is now into the In-Orbit testing phase. Once operational it will consist of 24 satellites in medium Earth Orbit and will orbit at an altitude of 23,222km, higher than that of the GPS system.
3. MetOp Satellites
MetOp is a series of three polar orbiting satellites developed by ESA. A polar orbit means a satellite passes above both Earth’s poles of the body being orbited on each revolution. It therefore has an inclination of roughly 90 degrees to the equator. A satellite in a polar orbit will pass over the equator at a different longitude on each of its orbits. These satellites will also orbit at a lower altitude, typically at about 800km. These satellites are used to provide weather data that monitors the climate and improves weather forecasts and you all know how we love to talk about the weather so this is why we feel these satellites in particular are pretty awesome! They also work in conjunction with the National Oceanic and Atmospheris Administration (NOAA) in America. MetOp-A was launched in October 2006 and was Europe’s first polar orbiting satellite used for meteorology. MetOp-B was launched in September 2012 from the Baikonur Cosmodrome and MetOp-C was launched in November 2018. The second generation of MetOp Satellites is set to launch in 2022 with MetOp-SG.
4. The Hubble Space Telescope
We couldn’t talk about satellites without talking about one that has influenced anyone who is passionate about astronomy. The Hubble Space Telescope (HST) was launched in 1990 and orbits at an altitude of 596km. It orbits the Earth every 97 minutes and passes into the shadow of the Earth for 28-36 minutes in each orbit. This orbit is high enough that HST is above the Earth’s atmosphere and can conduct its operations without the negative effect of the atmosphere. This is how we are able to get the images that we do from this phenomenal telescope. After a slight mishap with a mirror that was quickly fixed, HST had racked up some impressive stats. It has made more than 1.3 million observations since its mission started in 1990. Astronomers who use HST data have published more than 15,000 scientific papers, making it the most productive scientific instrument ever built. Due to the combination of optics and sensitive detectors and with no atmosphere to interfere with the light reaching it, Hubble can spot a night light on the surface of the Moon from Earth. HST generates about 10 terabytes of new data per year. The total archive is currently over 150 TB in size. We could go on! That’s impressive.
5. Venus Express
ESA’s first mission to Venus. This mission began back in March 2001 when a call was made to the scientific community to come up with ideas on how best to use the spacecraft platform developed for Mars Express. The mission launched in November 2005 on the Soyuz-Fregat Rocket. The mission for the Venus Express was to study the atmosphere, the plasma environment and the surface of Venus in great detail. It took 5 months to get to Venus and once there it set up an eccentric polar orbit that lasted 9 days. After several manoeuvres over the series of days it then lowered into its operational orbit: a 24-hour elliptical, quasi-polar orbit. Venus Express, although similar to its predecessor Mars Express, had some significant changes made to it in order to survive getting to and orbiting around Venus. The thermal control system required larger, more efficient radiators and 23 layers of highly reflective gold insulation, instead of black. The abundance of incoming sunlight at Venus led to the redesign of its two solar arrays: they were about half the size of the panels on Mars Express and were fitted with triple junction gallium arsenide cells suitable for a high temperature environment. A surprising discovery made by the Venus Express was a surprisingly cold region high in the planet’s atmosphere that may be frigid enough for carbon dioxide to freeze out as ice or snow. Other strange discoveries included the discovery of a high altitude ozone layer and a mysterious layer of sulphur dioxide far above the main cloud layer.
So there you have it, only five of the most awesome satellites that we have sent into Space to orbit around the Earth, and travel further afield. If you enjoyed this article, let us know in the comments below and we will have a look at another five amazing satellites.