August 11, 2022

I, Science

The science magazine of Imperial College

By Harley Kelly
11 February 2022

We have all heard the iconic Pinocchio song “When you wish upon a Star”, but I wonder if the soon-to-be-released remake of Pinocchio will tweak the Blue Fairy’s song to better represent what we will really be seeing. But I guess “When you wish upon the space debris from a Russian Anti-Satellite missile test” just doesn’t have the same ring to it. Regardless, this is the reality we face.

As of January 2021, it was reported that 21,901 trackable artificial objects are in orbit around Earth – with roughly 17,500 of these being space debris, and hundreds of millions of smaller pieces known to exist. This is a growing issue not just for the people on board the International Space Station (ISS), which recently had to change orbit to prevent a potential collision with space debris, but also for the scientific community launching satellites. It begs the question: Who should space be available to? I’m sure that the household names of Elon Musk’s Space-X and Richard Branson’s Virgin Galactic came to mind while reading this. These companies aim to provide something called space tourism – space travel for recreational purposes.

As well as broken or decommissioned space junk, other ‘junk’, such as the 2,000 or so satellites of the planned 12,000 strong Space-X Starlink mega Constellation, litter Earth’s orbits. Of 49 satellites launched on 3rd February this year, for example, 40 were destroyed by a geomagnetic storm the next day. Others from the same launch took a Puerto Rican holiday, disintegrating as they re-entered the atmosphere over the country. Starlink hopes to provide remote communities with access to education or health services, or even communication during natural disasters. Its incontestable aim is to help, obviously not to monopolise space or the wireless communication industry. Unsurprisingly, these satellites are riddled with controversy – from the director general of the European Space Agency (ESA) suggesting that it would allow far less space (pardon the pun) for competitors, to the astronomy community claiming in 2020 that the satellites were far too bright due to incorrectly orientated solar panels. But isn’t this all justified by the satellites’ philanthropic purpose to provide Twitter to rural communities?

Now, as a space scientist who works with satellite data, this article might seem hypocritical. But I truly believe in the space sector and the amazing things that space can offer us. I feel that we really need to change how we do things. Not just because I want near-Earth space to be sustainable and available to future generations; but simply because I love looking at the stars.

Stargazing is already very difficult. You need to escape the light pollution from bright towns and cities to see the glorious carpet of stars in the sky. Light pollution can be defined as light which is either unneeded or unwanted. It’s because of this ground-based light pollution that astronomers are frequently found building telescopes in unpopulated, hard to reach corners of the globe.

Above image: Visible light pollution from a city reflecting off clouds | Courtesy of Adam Williams

Worryingly, space debris, satellites and aircraft are now making this escape from light pollution even harder. Debris scatters light, causing a diffuse artificial glow in the night sky, even in remote locations with no ground-based pollution. Furthermore, individual objects can reflect light in such a way that they appear as obscure streaks in observations or photographs. Once an astronomer has built a giant, expensive, remote observatory in a difficult to reach location, it is easy to understand their frustration at private companies and their mega constellations clumsily aiming their shiny solar panels earthward.

Above image displays human influence on the sky, with a streak from an aeroplane visible next to the moon | Courtesy of Adam Williams


But all hope is not lost for the forsaken stargazer. Space debris clean-up start-ups are popping up to help clear space. How they clear so-called ‘plots’ can vary: they can capture the debris and launch it earthward or use lasers to slow-up the debris so it falls down, burning up in our atmosphere. These solutions all come with risks. Despite this, ESA plans on launching ClearSpace-1, a space debris clean up mission built by the Swiss start-up ClearSpace. This mission plans on grabbing a washing machine sized piece of space junk and lowering its orbit, destroying both the satellite and the debris in Earth’s atmosphere.

You too can help protect the night sky. Organisations such as the International Dark Sky Association have compiled an endless list of ways to help you reduce ground-based pollution. One example is to ensure outdoor lights are switched off – and if they are needed, you can switch to dimmer bulbs and aim them towards the ground. Combatting light pollution is not a trivial task – I believe it is an important one. Many scientists like myself were once inspired by the stars in the night sky. If they disappear, perhaps some of those scientists might too.


Harley Kelly is a first-year physics PhD student in the Space and Atmospheric (SPAT) group. His research is based on the behaviour of surface waves in Earth’s magnetosphere. When he isn’t studying, Harley is either looking after his ridiculous number of tropical house plants or doing photography – of which he particularly enjoys taking photos of the stars!