Shanghai Astronomical Observatory Astrophysics Colloquium

Title：Pushing the limits of high-resolution radio astrophysics

Speaker：Prof. Leonid Gurvits(PIFI Shanghai Astronomical Observatory Visitor)

Special Time：3:00 pm Apr. 14th (Tuesday)

Tencent Meeting：296-588-963

Location: Lecture Hall, 3rd floor

Abstract：The move of radio astronomy to space is inevitable. It is driven by two factors: spectrum coverage and angular resolution. For Earth-based radio astronomy, the former is limited by the opacity of the ionosphere at ultra-long wavelengths (frequencies below ~20 MHz) and the opacity of the atmosphere at mm/sub-mm wavelengths. Angular resolution is limited by the size of our planet: VLBI systems already operate at baselines practically equal to the Earth’s diameter. In addition to these two factors, the RFI situation on Earth is not improving.

In this presentation, I will address the second factor – the drive towards higher angular resolution with spaceborne VLBI capable of operating with baselines significantly longer than the Earth’s diameter. Over the past forty years, three space VLBI systems have operated in orbit: the TDRSS OVLBI demonstration (1986–1988), VSOP/HALCA (1997–2003), and RadioAstron (2011–2019). At present, the Chinese Lunar Orbital VLBI Experiment (LOVEX) is operating at record-breaking Earth-Moon baselines. I will briefly revisit the major accomplishments and lessons provided by these three systems. The accumulated experience allows us to identify several major bottlenecks in mission architecture that should be addressed in the development of future spaceborne VLBI.

I will also present a list of scientific objectives for future space VLBI missions, which need to be prioritised to ensure they are competitive in the highly challenging arena of space science endeavours. The emphasis will be on transformational science which requires the development of spaceborne mm/sub-mm VLBI. Such facilities will address science objectives which are and will remain beyond reach of any other astronomical facilities.

CV：Professor Leonid Gurvits, Senior Scientist Emeritus, specializes in VLBI studies of extragalactic radio sources and their cosmological applications. He has been involved in various capacities in several Space VLBI projects, including the Japanese-led VSOP and Russia-led RadioAstron missions. Leonid Gurvits has been the Principal Investigator of the VLBI Tracking Experiment with the ESA’s Huygens Probe on Titan and Planetary Radio Interferometry and Doppler Experiment (PRIDE) of the ESA’s Jupiter Icy Moons explorer (JUICE). He is currently involved in science working teams of several next generation spaceborne VLBI missions and the ESA’s gravitational wave Laser Interferometer Space Antenna (LISA) mission. Leonid Gurvits worked at the Joint Institute for VLBI in Europe as a Head of Space Science and Innovative Applications department through 2022. He is currently Professor Emeritus of the Faculty of Aerospace Engineering of the Delft University of Technology. Academician of the International Academy of Astronautics. In 2024–2025, Leonid Gurvits was a Visiting Professor at the Shanghai Astronomical Observatory under the Chinese Academy of Sciences President's International Fellowship Initiative. Currently, he is visiting ShAO as a PIFI Dsitiguished Scientist.

Koushare link to the recorded presentation