Dear colleagues,

We would like to draw your attention to the following scientific session for the 46th COSPAR Scientific Assembly, which will be held in Florence, Italy, from 1-9 August 2026. The Call for Abstracts for COSPAR 2026 is now available. The scientific program and abstract submission system (deadline: 13 February 2026) are accessible via the COSPAR 2026 website below. We warmly invite interested colleagues to consider submitting an abstract and participating in our session. The deadline for early-bird registration is 17 May 2026. Further details and updates can be found at:

https://cospar2026.org

COSPAR-26-E1.16: HIGH RESOLUTION AND SPACE-BORNE RADIO ASTRONOMY: RECENT ACHIEVEMENTS, OPEN QUESTIONS AND FUTURE OPPORTUNITIES

Supermassive black holes power active galactic nuclei (AGN) and their relativistic jets, making them prime targets for extreme angular resolution studies. The Event Horizon Telescope (EHT) has achieved horizon-scale imaging of M87* and Sagittarius A*, revealing unprecedented details of their immediate environments. For several nearby AGN, high-resolution radio observations now resolve the innermost regions--down to hundreds of Schwarzschild radii--where jets are launched, collimated, and accelerated.

Building on the success of past Space VLBI missions, such as VSOP and RadioAstron, the time is ripe to review their key results and explore the next generation of missions, particularly those focusing on high-frequency observations. This session will examine the latest observational and theoretical advances in ground-based and space-based radio astronomy, open research questions, synergies between radio and high-energy observations, and the scientific opportunities enabled by upcoming instruments. In particular, future space radio interferometry promises to deliver the highest angular resolution ever achieved. At the other end of the spectrum, ultra-low wavelength (ULW) radio observations--below about 10 MHz (wavelengths >30 m)--remain inaccessible from the ground due to the Earth's ionosphere. Yet, this regime holds immense scientific potential, from detecting the highly-redshifted hyperfine line of neutral hydrogen from the Universe’s Dark Ages to characterizing magnetically-induced emissions from extrasolar planets. This session will also cover recent results from low-frequency ground facilities, early space-based tests, and plans for future lunar and free-flying ULW telescopes.

By bringing together experts in Space VLBI and ULW radio astronomy, this session aims to highlight the transformative role of space-based radio observations in addressing fundamental astrophysical questions.

Important Deadlines:
- November 10, 2025: Abstract submission opens  
- November 10, 2025: Registration and hotel accommodation open  
- February 13, 2026: Abstract submission closes  
- May 17, 2026: Early-bird registration deadline

Confirmed Solicited Speakers:
Jose L. Gomez (IAA-CSIC, Spain)
Efthalia Traianou (Heidelberg University, Germany)
Sara Issaoun (Center for Astrophysics | Harvard & Smithsonian, USA)
Leonid Gurvits (Joint Institute for VLBI ERIC, Netherlands)
Zhiqiang Shen (Shanghai Astronomical Observatory, China)
Joseph Lazio (Jet Propulsion Laboratory at California Institute of Technology, USA)
Sascha Trippe (Seoul National University, Republic of Korea)

SOC:
Maciek Wielgus (IAA-CSIC)
Tuomas Savolainen (Aalto University)
Gabriele Bruni (INAF)
Jae-Young Kim (UNIST)
Yuri Kovalev (MPIfR)
Dan Marrone (University of Arizona)
Cristina García Miró (Observatorio de Yebes)

We look forward to your contributions and participation.

Best regards,  
Jae-Young Kim on behalf of the Session Organizers

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