Sky Matters: If you look closely, you could see a constellation of satellites

Mon, 03 May, 2021 - 06:00

Niall Smith

Satellites give us a view of our planet that we simply cannot get using any other technology. For that reason alone, they are an invaluable tool for monitoring the state of the environment. They provide continuous information on hurricanes, floods, fires, volcanic eruptions, deforestation, pollution, melting ice caps, holes in the ozone layer, and many other forms of disaster whether naturally occurring or the result of us humans.

On a cheerier note, they help us to stay connected to one another, support the best use of our land and sea resources through imaging and satnav, and will be critical to the realisation of safe autonomous vehicles and smarter cities.

Data from satellites gives us the knowledge to build a more sustainable world. Satellites make it impossible for countries to conceal many of their most environmentally destructive habits. They fly with impunity across human-made country boundaries. With advancing technologies such as synthetic aperture radar, even clouds no longer provide a hiding place from a satellite’s gaze. By pinpointing the sources of activities that challenge the sustainability of our world, they can help us build one better structure for the needs of all species. And they democratise on a global scale by simultaneously enabling us to share information in a way that cannot easily be suppressed.

Of course, we humans are inventive, creative, biased, fearful, suspicious …. human, in fact. Sometimes we stretch the interpretation of what satellites are showing us beyond the limits of credulity. “Climate change is not caused by humans” is one interpretation that directly contradicts the data from different types of satellites in different orbits with different instruments built by different countries at different times.

Apportioning blame to countries or practices responsible for climate change is more difficult, especially politically, but the aggregate sum of data from satellites leaves no doubt about the direction of travel of the Earth’s land, sea and air temperature. And it’s not good at the moment.

As more and more satellites are launched into space, some of the sustainability issues that we face on the ground move into orbit. Traffic jams are replaced or replicated by “satellite jams” where a large number of satellites in similar orbits increase the likelihood of collisions. But unlike collisions on Earth, where gravity confines the debris to a very small footprint, the lack of gravitational influence in orbit enables the debris to spread out into a debris field, lots of bits of broken satellites floating in random orbits just waiting to cause more collisions.

The more satellites, the bigger the problem, and we’re rapidly reaching that scenario now. There are over 10,000 pieces of dangerous debris in some of the most cherished orbits – yes, just like on Earth, it’s all about location, location, location as some orbits are more “useful” than others.

The boom in satellite numbers is being driven by technological advancement. Smaller satellites can now do what much larger ones did only 10 years ago. They’re cheaper and faster to build, and more can be launched together at one time on the same rocket. Unfortunately, there are also few regulations attached to the use of satellites, and where such exist they vary from country to country. The new “constellations” of satellites are increasingly visible from the ground, possibly irritating for skywatchers and definitely unwanted by the professional astronomical community. And to add to this, there is growing concern about radio-frequency interference.

Critically, the fastest way to connect the 3 billion people who currently have no internet access is via satellite communications. That is a potential game-changer for the sustainability of our planet, for with communications comes better education and an opportunity for us all to better understand how we, collectively, achieve sustainability.

As is the case with other technologies, the opportunities offered by satellites will be realised, or not, by us humans. In turn, the sustainability of our planet rests with the actions we take. And no other species has the intelligence to say that.