Future of Planetary Atmospheric, Surface, and Interior Science Using Radio and Laser Links

Scientific studies using spacecraft radio links, which are shared with communications and navigation functions, have been carried out on almost every solar system exploration mission in the past five decades. They have led to numerous scientific discoveries as well as technological advances. These radio science experiments have investigated the interior structure of every planet in the solar system and several of their satellites, the Moon, and several comets and asteroids and sounded the atmospheres of every planet in the solar system except Mercury, and the atmospheres of Pluto and several large satellites, the Io Plasma Torus, Saturn's and Uranus' rings, and the solar corona. Future experiments at Mercury, the Jovian system, asteroid Psyche, and other targets are currently in various planning and development phases. Over the next 30 years, significant advances in radio and laser link science technologies, including one order of magnitude improvement achievable in range rate and range accuracy and advanced calibration techniques, could enable many additional scientific breakthroughs. Future exploration concepts focus on applications of small spacecraft and entry probes and can include constellations for studies of atmospheric dynamics, interior structures, and surface properties. Selected science‐enabling technologies specific to small spacecraft instrumentation on future missions are under study. Examples include field tests of radio scattering to determine surface properties, constellations for high‐resolution spatial and temporal atmospheric sounding, small science‐quality software‐defined transponders, miniature ultrastable oscillators, and advanced radio‐metric calibrations at the Deep Space Network. Plain Language Summary Radio links are used to communicate with spacecraft by sending them commands from ground controllers and receiving back science data. The same links are used to examine important properties of planetary atmospheres, surfaces, and interior structure by carefully studying small changes in the radio signal's frequency and other parameters caused by geophysical phenomena when the spacecraft are close to the planets. Improving the radio system on the spacecraft and ground stations can lead to additional scientific discoveries. There is a trend to use small spacecraft to explore the solar system in future, and research teams are preparing instrumentation systems that are compatible with such possible missions. Key Points Spacecraft tele