By Philippe RECLUS
The analogy of the Earth as a spaceship is a very apt one. In fact, our planet is a closed system, meaning it exchanges very little matter with the outside world. This relative isolation is due to several factors:
– The immensity of space: the distances between stars are colossal. Even the closest celestial objects, like the Moon, are light-years away from other star systems.
– The Earth’s atmosphere: our atmosphere acts like a shield, protecting the Earth from cosmic rays and micrometeorites. It also slows the re-entry of extraterrestrial objects into our atmosphere, often burning them out completely.
– The Earth’s magnetic field: this field deflects a large proportion of the charged particles coming from the Sun, forming a radiation belt around the Earth that protects us from solar winds.
Exchanges with the outside world are nevertheless limited.
– Meteorites: from time to time, meteorites break through the atmosphere and crash to earth, bringing tiny quantities of extraterrestrial matter with them.
– Solar wind: despite the Earth’s magnetic field, some solar wind particles manage to penetrate the atmosphere, particularly at the poles, creating the aurora borealis.
– Cosmic rays: these high-energy particles from outer space reach the Earth, albeit in limited quantities thanks to the protection of the atmosphere.
Can we do better?
The question of “doing better” is an interesting one, but it depends on what we mean by “better”.
– Increasing exchanges: if the aim is to increase exchanges with the outside world, this would mean developing technologies to explore space in greater depth and bring back samples from other planets or asteroids. This is what space agencies around the world are already doing.
– Better protection: if the aim is to better protect the Earth from outside influences, we need to strengthen detection systems for potentially dangerous asteroids and develop ways of deflecting them.
In conclusion, the Earth is a relatively isolated system, but this isolation is not absolute. Exchanges with the outside world are limited, but have played an important role in our planet’s history. The question of whether we should seek to increase or decrease these exchanges is a complex one, and depends on our long-term objectives for spaceship Earth.