Very-long-baseline Interferometry - Space Radio VLBI

Space Radio VLBI

The latest development in radio astronomy observations is the Space Very Long Baseline Interferometry (SVLBI) program. This is used to perform radio astronomy with an extended baseline VLBI, of which one element is a space-based antenna.

The JPL SVLBI project, funded by NASA, supports the VSOP (VLBI Space Observatory Program) mission developed by the Institute of Space and Astronautical Science (ISAS) in Japan. The VSOP spacecraft HALCA is an 8 meter radio telescope, and was launched in February 1997. It is now in an elliptical orbit around the Earth to enable VLBI observations on baselines between space and ground telescopes. The primary targets are active galactic nuclei, but later masers, OH masers, radio stars, and pulsars will also be observed.

The baselines between space and ground telescopes provide 3 to 10 times the resolution available for ground VLBI at the same observing frequencies. Four ground tracking stations are involved with the SVLBI project. The whole system was supposed to operate automatically, needing only the observing schedule, Doppler predictions, and spacecraft state vectors to perform all the acquisition and tracking functions, with no operator inputs. This however has not yet been achieved and an operator presently is required to support this system.

Another space VLBI mission, RadioAstron, was launched in July 2011.