Scientists look at communicating with hypersonic vehicles using plasma resonance

Returning spacecraft hit the atmosphere at over five times the speed of sound, generating a sheath of superheated ionized plasma that blocks radio communications during the critical minutes of reentry. It’s a problem that’s vexed space agencies for decades, but researchers at China’s Harbin Institute of Technology are developing a new method of piercing the plasma and maintaining communications.

According to physicists Xiaotian Gao and Binhao Jiang of the Habin Institute, by redesigning the spacecraft antenna, it may be possible to maintain communications by setting up resonance in the plasma sheath. Essentially, this involves turning the layer between the spacecraft and the sheath into a capacitor in the antenna circuit. This causes the sheath to act as an inductor. Together, they create a resonant circuit.

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CrazyNeutrino said:

Returning spacecraft hit the atmosphere at over five times the speed of sound, generating a sheath of superheated ionized plasma that blocks radio communications during the critical minutes of reentry. It’s a problem that’s vexed space agencies for decades, but researchers at China’s Harbin Institute of Technology are developing a new method of piercing the plasma and maintaining communications.

According to physicists Xiaotian Gao and Binhao Jiang of the Habin Institute, by redesigning the spacecraft antenna, it may be possible to maintain communications by setting up resonance in the plasma sheath. Essentially, this involves turning the layer between the spacecraft and the sheath into a capacitor in the antenna circuit. This causes the sheath to act as an inductor. Together, they create a resonant circuit.

Beautiful, that makes perfects sense. It is a problem that has “vexed space agencies for” 55 years.

Plasma resonances are well known, low frequency plasma resonances are observed when spacecraft penetrate the magnetic fields of the other planets (Jupiter, Saturn, Uranus, Neptune) and are well known as Schumann resonances of Earth’s ionosphere. In both those cases the frequency is extremely low, of the order of a fer Hertz.

But for a small hot plasma such as that produced by a re-entering spacecraft, the frequency would be bumped up into the HF radio range of the rough order of 10 MHz. That’s doable – easily.