DARIS - A Low-Frequency Distributed Aperture Array for Radio Astronomy in Space
- Paper number
IAC-10.A3.4.4
- Author
Dr. Albert-Jan Boonstra, ASTRON, The Netherlands
- Coauthor
Mr. Noah Saks, Astrium GmbH, Germany
- Coauthor
Dr. Mark Bentum, University of Twente, The Netherlands
- Coauthor
Mr. Kees van t Klooster, European Space Agency (ESA), The Netherlands
- Coauthor
Prof. Heino Falcke, Radboud University Nijmegen, The Netherlands
- Year
2010
- Abstract
The frequency band below 30 MHz is one of the last unexplored bands in radio astronomy. This band is well suited for studying the early cosmos at high hydrogen redshifts, the so-called dark ages, extragalactic surveys, (extra) solar planetary bursts, transient radio sources and high energy particle physics. In addition, space research such as space weather tomography, are also areas of scientific interest. Due to ionospheric scintillation (below 30MHz) and its opaqueness (below 15MHz, depending on the ionospheric conditions), earth-bound radio astronomy observations in these bands are either severely limited in sensitivity and spatial resolution or entirely impossible. A radio telescope in space obviously would not be hampered by the Earth's ionosphere. In 2009 an ESA project, Distributed Aperture Array for Radio Astronomy in Space (DARIS), set out to investigate the space-based radio telescope concept. The focus of this feasibility study is on a moderate size three-dimensional satellite constellation operating as a coherent large aperture synthesis array. This aperture synthesis array would consist of 5 to 50 antennas (satellites) having a maximum separation of 100 km. Several antenna concepts were considered and simulated. An active antenna dipole array concept would be well suited, with moderate length (5 m tip-tip) dipoles at element level, would lead to a sky noise limited system. Multiple digital signal processing scenarios were considered as well. Ultimately, although a distributed signal processing approach would be favorable in terms of reliability and scalability, for complexity reasons the project has chosen to have several identical receiving nodes, and one centralized processing node. Analysis has shown that with current technologies, one MHz bandwidth can be processed with full duty cycle. The main limiting factor is the inter-satellite link bandwidth. Several deployment locations, such as Moon orbit, Earth-Moon L2, and dynamic Solar orbits were investigated. Each of those locations has its pro's and con's such as interference levels from the Earth, relative speed-vectors of the satellite nodes, and achievable down-link bandwidth to Earth. Two preferred deployment location were selected: Moon orbit and dynamic Solar orbit. The DARIS concept can be realized with only minor technological development with eight satellite antenna nodes and a mothership, launched by a Soyuz from Kourou. Conclusion: a new, feasible, unique distributed system of small satellites for low frequency radio astronomy is presented. In the paper a more detailed description of DARIS and the DARIS mission is given.
- Abstract document
- Manuscript document
IAC-10.A3.4.4.pdf (🔒 authorized access only).
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