JuRa: The Juventas Radar on Hera Mission to Probe Internal Structure of Didymos and Dimorphos Asteroids

JuRa, the Juventas Radar, is the sounding radar of the Hera/ESA mission on cruise to the asteroid Didymos and its moon, Dimorphos. In 2027, it will, for the first time, do direct observation of the internal structure of an asteroid for the benefit of both science and planetary defense. The instrument is a 60 MHz monostatic radar with a 20 MHz bandwidth, operating in full linear polarization, onboard Juventas, a CubeSat that will operate from end of January to end of March 2027, in a sun-synchronous orbit with a radius ranging from 3.3 to 2 km. With an expected penetration depth of 100 meters or more, it will uncover the expected rubble pile structures of Didymos and Dimorphos, detect the presence of internal structures, and characterize the size and the level of heterogeneity of the constituent materials. This knowledge will provide a better understanding of the formation and stability conditions of a binary asteroids, and constrain physical models of accretion and evolution. This article describes the concept of radar sounding and tomographic imaging, then presents the Didymos and Dimorphos system and the objectives of JuRa. It then describes the JuRa's specifications and design.