Sky Matters: Space is becoming crowded with satellites

The number of satellites currently in orbit above the Earth numbers over 1,800. These satellites perform important functions that many of us use every day.

For example, all our SatNav devices rely on satellites in geostationary orbit at a height of 36,000 km. Most of the TV we watch from abroad is beamed to us by satellite — hence the reason so many of us have satellite dishes — and we are all familiar with weather satellite images.

Less obviously, an increasing amount of our internet traffic is handled via networks of satellites. Several companies are providing broadband in rural and isolated regions using medium-sized satellites in low-earth-orbit (up to about 1,000km).

And as we move into a new era when private companies are planning to launch literally thousands of satellites to improve these services and add additional ones, it is true to say that space is becoming crowded.

Why does this matter? Isn’t space huge? Well, yes, and no.

The issue is that there are a limited number of preferred orbits and as these become more populated with satellites they also become more populated with debris — bits and pieces that have fallen off the rockets bringing satellites into orbit, for example.

There are already approximately 23,000 objects in orbit measuring 10cm or more in diameter that are actively tracked by the US military. If these collide with a satellite they have the capacity to destroy it in an instant.

Objects between 1-10cm are much harder to track and it is estimated there may be around 500,000 of these. For objects smaller than 1cm, there is no reliable way to track them and they may number in the millions. While less catastrophic in the event of a collision, such smaller pieces of debris can nevertheless render a small satellite defunct.

And the situation is even worse than this picture would suggest. The more debris, of any size, that we dump into orbit, the more collisions will result, generating more debris in an upward spiral that could threaten the sustainability of our use of space.

Worryingly, we could find ourselves in a position within a decade in which new satellite launches are severely restricted because of the amount of debris in space.

This would be particularly damaging to the aspirations of emerging space nations such as Ireland. While we haven’t launched any satellites of our own as yet, as technology rapidly advances it will become ever more desireable or even necessary.

Just as we are in control of our electricity distribution network, we may wish to have control over critical communications networks using our own satellites rather than always relying on others to do so for us, with all the national security concerns that brings.

Satellites play a key role in realising the Sustainable Development Goals that were unanimously adopted at the UN in 2015. They help monitor and predict the path of disruptive weather events.

They can spot fires or flooding and reveal information on the state of food supplies. They provide emergency communications in the remotest of areas.

And they provide incontrovertible data on the march of climate change and its influences on the Earth’s ecosystems.

As satellite technology improves, so too does their ability to help us live sustainably. So any threat to the sustainability of the growing fleet of satellites acts to reduce our capability to live sustainably on the surface of our planet. We need to act now before the situation deteriorates – there is time, but actions are required.

As a farming nation, sustainability of the land and sea is in our blood – but in a world where technology and climate are changing faster than ever, we would do well to add “space” to the list.