The Balloon-borne Very Long Baseline Interferometry Experiment (BVEX)

Abstract

The Balloon-borne VLBI EXperiment (BVEX) is aimed at proving that a radio telescope mounted on a high-altitude helium balloon can be partnered with ground-based radio dishes to create an Earth-spanning radio telescope. BVEX uses VLBI (Very Long Baseline Interferometry), a powerful technique used in radio astronomy where many telescopes in different locations on Earth observe the same astrophysical object simultaneously. The data is later correlated to produce high-resolution images. High frequency VLBI has already enabled transformative science. For example, it was implemented by the Event Horizon Telescope in imaging the shadows of the supermassive black hole at the center of our galaxy. However, a major limitation of ground-based VLBI is the atmospheric absorption of high frequency radio waves. BVEX addresses this challenge by serving as an additional VBLI station nested in the stratosphere, operating above 99% of Earth’s atmosphere. This enables observations at frequencies that are largely inaccessible from the ground and improves the quality of high-resolution radio images. BVEX was launched on Friday, August 29th; however, the flight was terminated prematurely due to a severe leak in the balloon. Despite this outcome, the flight provided valuable engineering and operational insights for BVEX 2.0: an improved version of BVEX that is currently in development and will be launched in 2027!