Our spectacular satellites...
Lessons on space from the comfort of your own home throughout week
GLASGOW Science Centre is running its GSCAtHome “From Earth To Space” programme for the half- term holidays, every day at 10am from October 12- 23. Nina Cameron introduces us to one of the favourite space items: satellites.
WHILE you might not realise it, you are already very familiar with the biggest of the Earth’s satellites. Mondays are named for it, the word “month” shares its origin with its name, and if you’re a Pink Floyd fan you probably already know what I’m writing about. It is, of course, the moon.
The moon is a natural satellite; it formed about 4.5 billion years ago, possibly as the leftovers from an enormous collision between a nascent Earth and a Mars- sized object called Theia.
According to Nasa, a satellite is an object that orbits a planet or a star. While there’s only one permanent natural satellite orbiting Earth, there are many more artificial satellites hurtling round our planet. These are satellites that have been made and launched into space by humans. As of April 1 2020, there are 2666 artificial satellites in space, in orbits that range from 240 kilometres above the surface of Earth to 36,000 kilometres distant.
While the moon has been orbiting the Earth for almost as long as the Earth has been orbiting the Sun, the age of artificial satellites hasn’t been going on quite so long. The Sovietbuilt Sputnik- 1 ( Russian for “satellite- 1”) beeped its way round the Earth every 96 minutes for three weeks after it launched in October 1957. Its radio signals announced to every corner of the globe and beyond that humans had officially entered the space age.
Of course, we’re not the only planet to have satellites, whether artificial or natural. Other planets in the solar system have moons ( 205 at the most recent count), and currently all the planets except Uranus and Neptune have had artificial satellites, built by scientists and engineers, to explore and investigate their mysteries from on high.
Of all the satellites we’ve sent out into the solar system, my favourite will always be Cassini, which deorbited and burnt up in Saturn’s atmosphere in 2017. As if it wasn’t enough to spend over 13 years in orbit around Saturn, it also dropped off the Huygens lander on Saturn’s largest moon Titan, and sent back stunning photos as it swooped past the gas giant’s swirling storms, delicate rings and dancing auroras.
While satellites are sometimes the only way we can find out about distant planets, they are also vital in monitoring humanity’s impact on our home planet. Since Sputnik- 1’ s radio signals helped scientists study the upper regions of our atmosphere, satellites have been giving us crucial information on the ways that our climate is changing, and how farming, logging and industry affect delicate, precariously balanced ecosystems around the world.
Remote sensing satellites can be used to save human lives too. After Hurricane Dorian hit the Bahamas in August 2019, the Zooniverse citizen science website used before and after satellite imagery to identify safe routes for emergency services to allocate aid and resources. On a personal level, you use global positioning satellites ( GPS) to stop you getting lost on long drives, but you can also use it to help mountain rescue pinpoint your exact location if you run into trouble up on Scotland’s hills.
The second largest of the Earth’s satellites is an artificial one, called the International Space Station, or ISS. Since the 2nd of November 2000, when Expedition 1 started, the ISS has been permanently crewed by almost 250 astronauts from 19 different countries, who work in shifts lasting roughly six months at a time. This means that if you were born after Expedition 1 boarded the station, for your entire life there has never been a time when humans haven’t been living on a roughly football- pitch sized satellite, which orbits the Earth every 92 minutes, at blistering speeds of 400 kilometres a minute.
Satellites, whether natural or artificial, crewed or uncrewed, in Earth’s orbit or exploring alien planets, are fascinating things. Our moon gives us clues as to how the Earth formed, weather satellites can track and allow us to prepare for extreme weather, and the ones we send into the far reaches of the solar system help us to answer questions that we have been asking for centuries.