Suspended 400 kilometers above our heads, the International Space Station (ISS) crosses space at a speed of 8 km per second. That’s the equivalent of traveling from Atlanta to London in just 14 minutes. However, unlike meteorites that burn up in the atmosphere, the ISS continues to orbit the Earth, year after year. How does such a massive structure (it weighs the equivalent of 77 elephants) remain intact in these extreme conditions? Here’s what you need to know.
Why do meteorites burn up in the atmosphere?
Meteorites, these fragments of rock and metal, travel at dizzying speeds, between 12 000 and 40 000 km/h. When they enter the Earth’s atmosphere, they encounter a layer of particles – mainly nitrogen and oxygen – that make up the air we breathe. This collision with air molecules produces immense pressure and heat, causing a process called meteoric ablation.
Imagine a meteorite like a bulldozer charging at full speed. vitessecompressing the air particles in front of it. This compression generates intense heat, cracking the rock and ultimately causing it to explode in a shower of light that we colloquially call “shooting stars”.
This disintegration occurs mainly in the mesospherea layer of the atmosphere located between 48 and 80 kilometers altitude. At this height, the air is dense enough to trigger this phenomenon.
Why isn’t the ISS burning?
Unlike meteorites, the ISS does not cross the mesosphere. It evolves much higher, in a region called the thermosphèrelocated between 80 and 700 kilometers altitude. At this height, the atmosphere is so thin that a volume of air equivalent to that of the Lake Superior to gather the mass of a single apple.
With such particle density, there is not enough friction to produce the heat and pressure needed for disintegration. Thus, the station can orbit without risk of combustion.
Extreme temperatures, a challenge for engineers
Although the ISS is not burning, it is subject to spectacular thermal variations. When exposed to sunlight, the temperature rises to 121 °Cbut when it passes into the Earth’s shadow, it drops suddenly to -156 °C. These differences in over 277°C represent a major challenge.
Engineers designed the ISS with materials capable of withstanding these extreme conditions. Inside, the astronauts enjoy a comfortable temperature thanks to thermal regulation systems, similar to those we use to heat or cool our homes.
The crucial role of the ISS in scientific research
Since its commissioning in 1998, the ISS has been much more than just a technological feat. She became a floating laboratory where scientists conduct research on a variety of topics, ranging from medicine to earth sciences. Here are some of the major advances made on board:
- Improved water filtration techniques that benefit remote regions on Earth.
- Studies on plant growth in microgravitypaving the way for space agriculture.
- Better understanding of Earth’s energy and water cycles.
- Research on effects of prolonged space travel on the human bodywith a view to future missions to Mars.
The future of the ISS: a planned return to the atmosphere
The NASA plans to deorbit the ISS by 2030thus marking the end of his mission. Unlike space capsules equipped with heat shieldsthe station was not designed to survive atmospheric reentry. Once returned to the mesosphere, it will largely disintegrate, although some debris may reach the ocean.
Observe the ISS from Earth
For the curious, it is possible to see the ISS passing through the sky with the naked eye. Thanks to its size and its reflective solar panels, it appears like a point of light quickly crossing the horizon. Visit the official website of NASA to find out the times of its passage in your region.
The International Space Station is not only a testament to global scientific cooperation, but also a fascinating demonstration of the challenges of space exploration. As her future begins to take shape, she remains a shining example of what humanity can achieve when it reaches for the stars.
