Preventing a communication blackout in spacecraft during reentry
Preventing a communication blackout in spacecraft during reentry lead image
When a spacecraft travels through the atmosphere at speeds much faster than the speed of sound – say, during reentry – the friction between its surface and the surrounding air forms a plasma sheath, leading to a communication blackout lasting up to 10 minutes. Bruce Webb and Richard Ziolkowski created a structure that may help mitigate this lapse in communication.
“This blackout problem has occurred all the way since the Mercury program in the 1960s,” said Ziolkowski. “You’d be watching the Mercury capsule, and basically nobody knew what was happening for 2-5 minutes.”
All reentry vehicles, including modern shuttles, and even some hypersonic military aircraft, suffer from this problem. To address this, Webb and Ziolkowski came up with a design that can reduce the attenuation of radio waves by using a two-layer material.
Their design consists of two layers – one with a positive permittivity and negative permeability, and one with the opposite properties. By finely tuning the permittivity and permeability in the two layers, as well as the thicknesses of the layers, the researchers found in their numerical simulations that the design can help increase transmissions more than fivefold.
The work is currently in its preliminary stages, and a practical implementation will require multiple iterations of experimentation and design. Ziolkowski emphasized that there isn’t a one-size-fits-all solution, and factors such as the density and the thickness of the plasma all have an impact on antenna system transmissions.
“From a practical standpoint, you’d really have to design the whole system based on whatever scenario you’d expect the aircraft to be having to deal with,” Ziolkowski said.
Source: “Metamaterial-inspired multilayered structures optimized to enable wireless communications through a plasmasonic region,” by Bruce A. Webb and Richard W. Ziolkowski, Applied Physics Letters (2021). The article can be accessed at https://doi.org/10.1063/5.0041196 .
This paper is part of the Metastructures: From Physics to Application special topic; learn more here .
