Alexander Kuranov, 73, has devoted his life to the study of hypersonic propulsion. His work involved the fundamental physics of plasma and material science, which used to be unclassified and published in the open literature.

However, the military applications of hypersonic technology have made Russia increasingly worried about leaks of information to the West and China. Russia is especially concerned about protecting knowledge that is being used to build its fleet of vehicles capable of evading missile defense systems.

Russia's centerpiece weapons system is the Avangard. It's a nuclear-capable glide vehicle delivered atop an intercontinental ballistic missile that can move through the air in a zigzag manner 20 times faster than sound, which is 10 times the speed of a bullet from a high-power rifle. At that speed, it takes 48 seconds to fly from Washington to New York. The next in line is the 3M22 Zircon, an anti-aircraft-carrier hypersonic cruise missile launched from a submarine that Russia has scheduled for deployment in the first half of 2022.

Kuranov has been the general director of the Hypersonic Systems Research Institute in St. Petersburg. His latest effort was focused on the development of a novel hypersonic aircraft called Ajax (pronounced Ayaks). Its design is based on the idea of the prominent Soviet-era rocket engineer Vladimir Freigstadt to recycle the energy of the fireball created by a spacecraft on its entry into Earth's atmosphere. Other areas of research include civilian applications of extreme-heat studies, such as the protection of heat-stressed technological elements.

Kuranov is a prominent figure in Russian hypersonic research. In addition to directing the HRSI, he holds the position of professor in the department of controlled systems and technologies at the St. Petersburg Polytechnical University. He is also a CEO of the holding company Leninets that partially sponsors research at the HRSI. It is believed that his commercial ties with the West and his scientific contacts with Western researchers, American ones in particular, are the reason for his arrest by the FSB security service earlier this week.

After a short court hearing Thursday, Kuranov was detained on suspicion of high treason until Oct. 9. According to Russian media reports, he is accused of passing sensitive information to representatives of unspecified foreign countries.

Kuranov's situation is far from ideal. Renowned Russian hypersonic scientist Victor Kudryavtsev was imprisoned in 2018 for the alleged transfer of sensitive information to the Belgian Von Karman Institute for Fluid Dynamics. This is a charge that the VKI denied in an open statement.

After spending more than a year in Lefortovo prison, he was diagnosed with terminal stage 4 lung cancer. His 77-year-old co-worker Sergey Meshcheryakov was placed under house arrest. Another co-worker, Roman Kovalev was sentenced to seven years in a maximum-security colony. Recently arrested hypersonic scientists include professors Anatoly Gubanov and Valery Golubkin of the Moscow Central Aerohydrodynamic Institute. Both have denied charges of passing secrets to NATO.

Top line: Russian leaders are clearly paranoid about losing the edge in hypersonic and other modern weaponry to the United States and China. As the competition is growing, so is the number of arrests, making Russian scientists increasingly fearful of their interactions with the West.

Eugene M. Chudnovsky is a distinguished professor at the City University of New York and the co-chair of the Committee of Concerned Scientists.