Agnirva Space Premier League - Expedition #32193: Peering into the Atmosphere: How a Japanese Superconductor Sounder is Mapping Our Planet from Space

When we think of satellites studying Earth’s atmosphere, we often imagine instruments capturing images or tracking storms. But what if we told you there's a far more sophisticated way to explore our skies—using superconductors? That’s exactly what the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station (ISS) is all about.

Developed by the Japan Aerospace Exploration Agency (JAXA), SMILES is designed to analyze the composition and behavior of Earth's middle atmosphere—the part located between about 10 km and 100 km above the surface. This zone is crucial because it houses the ozone layer, regulates climate, and responds dynamically to solar and human influences.

So, what’s so special about SMILES? The key lies in its use of superconductors. Superconductors are materials that, at very low temperatures, can conduct electricity without resistance. SMILES uses these in its sensitive microwave receivers to detect faint emissions from atmospheric gases. These emissions occur naturally when molecules like ozone, chlorine monoxide, and water vapor absorb and re-radiate energy in the submillimeter wave spectrum—a part of the electromagnetic spectrum that lies between microwaves and infrared.

Mounted on the Japanese Experiment Module (Kibo) aboard the ISS, SMILES scans the Earth’s limb, or edge, capturing highly detailed vertical profiles of trace gases. This limb-viewing technique allows it to observe how concentrations of gases change with altitude, which is crucial for understanding atmospheric chemistry and transport.

One of SMILES’ big wins is its ability to measure these gases with unprecedented precision. Its data has helped scientists better understand phenomena like ozone depletion and the effects of greenhouse gases. This is especially important because the ozone layer acts as a shield, protecting life on Earth from harmful ultraviolet radiation.

But there's more. SMILES also helps monitor the impact of human activity on atmospheric chemistry. For instance, it provides data on man-made compounds like chlorofluorocarbons (CFCs), which were once commonly used in refrigeration and aerosol sprays but are now regulated due to their ozone-depleting potential.

The experiment’s long duration—spanning many ISS expeditions—has made it possible to track atmospheric trends over time. And because the ISS travels around the globe every 90 minutes, SMILES can gather data from all latitudes, including hard-to-reach polar regions.

From a student’s perspective, SMILES is a textbook example of interdisciplinary science: it combines physics, chemistry, engineering, and environmental science. It also showcases how advanced technologies, like superconductors and limb-sounding techniques, can work together to provide a clearer picture of our planet’s health.

In the age of climate change, understanding how our atmosphere works is more important than ever. And thanks to SMILES, we now have a more detailed and dynamic view of the skies above.

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