VLBI science in and increasingly crowded radio spectrum

Journal article, 2026

In this paper we discuss the impact of the current and future RFI situation on the radio observations performed with the Very Long Baseline Interferometry. This technique allows to reach very high sensitivity at milliarcsecond angular resolution, or less, and provides a fundamental contribution in several areas of astrophysics, ranging from space science and the solar neighbourhood to the cosmological epoch when the first black holes were formed. VLBI application to astrometry and geodesy enables accurate monitoring of coordinates of points on Earth and Earth in space, then it is essential to determine the position of natural and artificial space objects at specific epochs. Thanks to the technological progress over the past 20 years, VLBI now delivers total intensity and polarisation imaging, and provides a major contribution also to spectral line studies and time domain science. It is thus crucial for investigations in novel fields of research, such as for instance fast and slow transients.