Space based radio interferometer using small satellites

Abstract

Radio Interferometry is a powerful technique utilized in radio astronomy for mapping radio emissions of celestial sources. However, an important aspect of any image is the angular resolution. Resolution achieved due to ground-based radio interferometry is limited by the diameter of the earth however, it can be improved if we place the radio telescopes on satellites orbiting in space. This extension of radio interferometry to space is known as Space-based Very Long Baseline Interferometry (SVLBI). It represents a cutting-edge approach to radio astronomy. This technique leverages a network of satellites, instead of ground-based telescopes, to capture high-resolution images of celestial objects. This project tackles the challenge of optimizing satellite constellations for SVLBI through the development of an independent simulator called the Antariksh Interferometry Simulator (AI-Sim). AI-Sim has been integrated with Common Astronomy Software Application (CASA), a widely used astronomical radio-data analysis software package. This combination offers valuable insights into space programs, enabling them to design radio astronomy missions with enhanced observational capabilities. It helps in evaluating the distribution of baseline lengths (uv coverage) achieved with different satellite configurations, examines how point spread function (P.S.F.), a crucial image quality metric, varies across different satellite constellations thereby impacting on achievable angular resolution and also simulates observations of diverse celestial objects and reconstructs high-fidelity images. This thesis extends current knowledge of u-v coverage in multi-satellite SVLBI. It explores how the number, type, and orbital parameters of satellites impact the ability to capture high-fidelity images. We conclude that by simulating observations with 2 satellites in Low Earth Orbits and 3 in Medium Earth Orbits, the project identifies optimal configurations for SVLBI. Simulations for various sky models, using this satellite configuration and CASA have also been presented in the thesis.