Why is India's spacecraft "shiny and new" after landing? Unveiling the difference in heat shield technology between China and India

Why is India's spacecraft "shiny and new" after landing? Unveiling the difference in heat shield technology between China and IndiaThe "life or death test" for spacecraft returning to EarthThe "blackout zone" of return capsule landingChina's Shenzhou return capsule: Ablative heat shieldIndia's Gaganyaan return capsule: Radiative heat shieldBoth Chinese and Indian heat shield technologies have their advantages and disadvantages. Ablative heat shielding technology is relatively inexpensive but consumes a large amount of material and produces considerable smoke, impacting the environment to a certain extent

Why is India's spacecraft "shiny and new" after landing? Unveiling the difference in heat shield technology between China and India

After the landing of China's Shenzhou 18 return capsule, its surface was completely charred, whereas India's Gaganyaan spacecraft return capsule remained pristine, as if it had just rolled off the factory floor. This has sparked discussions among netizens: has India's space technology surpassed China's? The truth is not so simple; there are fundamental differences in the heat shield technology employed by the two.

The "life or death test" for spacecraft returning to Earth

When a spacecraft returns to Earth, it faces a "life or death test": entering the atmosphere at high speed, experiencing intense friction with the air, generating heat reaching thousands of degrees Celsius. To prevent the return capsule from being incinerated and ensure the safety of the astronauts, countries around the world are dedicated to developing advanced heat shield technology.

The "blackout zone" of return capsule landing

After the return capsule enters the atmosphere at high speed, it enters a special zone known as the "blackout zone". During this time, no radio communication is possible between the return capsule and the ground. This is because the high-temperature plasma generated by the high-speed motion blocks the transmission of signals.

China's Shenzhou return capsule: Ablative heat shield

The Shenzhou spacecraft return capsule employs ablative heat shielding technology. Its exterior is covered with special materials, mainly composed of fiberglass and high-temperature resin composites. When the return capsule experiences high temperatures due to friction with the atmosphere, these materials burn and vaporize, simultaneously absorbing heat. This technology is like a "human shield," sacrificing itself to ensure the safety of the return capsule.

India's Gaganyaan return capsule: Radiative heat shield

India's Gaganyaan spacecraft return capsule, on the other hand, uses radiative heat shield technology, with its outer layer covered in silicon carbide materials. Silicon carbide has a higher sublimation temperature and can withstand higher temperatures. It acts like a "heat sink," absorbing and storing heat within the material, protecting the return capsule from high-temperature damage.

Differences in Chinese and Indian technology: Not about superiority or inferiority

Both Chinese and Indian heat shield technologies have their advantages and disadvantages. Ablative heat shielding technology is relatively inexpensive but consumes a large amount of material and produces considerable smoke, impacting the environment to a certain extent. Radiative heat shielding technology has higher costs but consumes less material, is more environmentally friendly, and better preserves the integrity of the return capsule's surface.

India's insufficient test altitude: Incomparability

It is important to note that India's Gaganyaan spacecraft unmanned test flight reached a mere 17 kilometers, far below the 100-kilometer Krmn line, which marks the boundary of space. Therefore, comparing it to the Shenzhou return capsule lacks comparability.

Conclusion

China and India are constantly exploring and developing in the field of space technology, each adopting different technological approaches, reflecting the technological accumulation and development directions of different countries. While India's Gaganyaan spacecraft heat shield technology appears more impressive, its insufficient test altitude does not permit a true comparison with China's Shenzhou spacecraft. What matters is that the continuous progress in space technology by both China and India will drive humanity's exploration and understanding of the universe, contributing to the common development of mankind.

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