We produce a lot of stuff on Earth, mostly junk. In 1956 McLean created the standard cargo container, which is still the standard today. These shipping containers move the stuff we make around the world, from where it is made to where it is sold.

Let us use the containers to symbolise the number of stuff we have moving around the surface of the Earth. This is a very strong lower limit on the number of things, because most things are static and not moving.

The best estimates say that the total number of shipping containers currently being used is between 43 and 72 million. To give an idea of scale, if place 43 million containers end to end they will go 13.3 times around the Earth, at the surface.

Now we are taking over the Earth’s orbit. Since 1957, when the USSR launched Sputnik into orbit, we have consistently sent between 100 and 200 objects into space each year. But since 2016 this number increased tremendously. In 2021, more than 1800 objects have been launched into space. Except for a few probes to other planets, asteroids, comets and the Sun, mostly of what we launched to space is in in a thin orbital layer around the Earth.

Space is filling up. There are companies extending the shipping container concept to Earth’s orbit. That is simultaneously cool and very scary. If we repeat the calculation above, of wrapping a “train” of the Earth-based shipping containers around the planet, but at 450 km above the surface, which is where the ISS is, we would still complete 12.4 laps.

A big problem is that the things we have been putting in space stop working and fall apart into smaller and smaller pieces. This so-called space debris is much more abundant than the useful objects we have in orbit. Space debris is dangerous as it may collide with and damage satellites that are crucial for telecommunications and Earth monitoring. Debris can also damage in-orbit stations such as the ISS.

The collision speeds in Low Earth Orbit are tremendous: 10 km/s, which is 36000 km/h and more than 10 times faster than a bullet. Since kinetic energy is proportional to the square of the velocity, 10x faster means 100x more kinetic energy. So a cm-sized piece of debris can really cause a lot of damage. How can we protect the important assets we have in space?

The space expansion is not going to slow down. So, there are companies (in Portugal: Neuraspace, Spacengineer) thinking about the debris problem and trying to deal with it. We can dodge the debris and shield against it, but we also need to think about producing less of it, as well as clearing up the one already in orbit. Can you think of clever ways to help dodging, shielding or clearing up space debris?

But besides the physical pollution and damage orbital debris can cause, and the barrier it can pose to leaving the Earth safely, the increasing amount of stuff in orbit is starting to block our view. Astronomers and astrophysicists are increasingly concerned about the light pollution caused by the large amounts of satellites we are putting in orbit, which makes it harder to see and study the deep universe. We cannot forget that pure research, driven by curiosity and awe for nature, is what enables technological development. There are many examples. Astronomy is also one of the main sources of inspiration for the younger generations. Do you have an idea to help us continue to study the universe, while exploring orbital space with satellites?