The HALCA (MUSES-B) Satellite

Last modified: June 1999

The working name of the VSOP satellite was MUSES-B -- as it was the second Mu Space Engineering Satellite. Mu is the name of ISAS's launching rocket. The MUSES-A satellite was renamed Hiten after its launch in 1990. (Hiten is the name of a figure from Japanese mythology.) MUSES-B is the second in the Space Engineering Satellite series. MUSES-B was chosen for the VSOP project satellite due to the many technological and engineering challenges faced in placing an antenna in space for VLBI.

A line drawing of the satellite shows a number of the components of the satellite.

MUSES-B was the first launch with ISAS' new M-V rocket. The satellite was successfully launched in 12 February 1997, and the satellite renamed HALCA, an acronym for `Highly Advanced Laboratory for Communications and Astronomy'. The two-way Ku-band communications between the satellite and the ground tracking stations, used for uplinking the reference phase signal and downlinking the radio astronomical data in real-time, represents one of the main new technologies included in the mission.

The alternative trans-literation from the Japanese is `Haruka', meaning `far-away' which aptly describes the satellite at apogee when it is 21,000km above the Earth. A rendering of the kanji for `haruka' is given below: it is the combination of the blue `L' and the black.

ISAS's X-ray satellite ASCA (formerly Astro-D) has a similar `pair' of names: it is the acronym for the Advanced Satellite for Cosmology and Astrophysics, and in Japanese is `Asuka', or `flying bird'.

An artist's impression of the satellite in orbit shows HALCA after the main antenna was deployed.

After three (planned) perigee raising maneuvers, HALCA is now in an orbit with an apogee altitude of 21,400 km and a perigee altitude of 560 km. The elliptical orbit will allow imaging of celestial radio sources by the satellite and ground based telescopes, with good (u,v) plane coverage and high resolution. The orbit has an inclination of 31 degrees (the latitude of the Kagoshima Space Center), and a period of about 6.3 hours.

The lifetime of the MUSES-B mission is nominally three years. It is expected that radiation damage to the solar panels will provide one of the strongest limitations on the satellite's performance after this time.

Further details of the satellite are given in the paper DESIGN OF THE SPACE-VLBI SATELLITE MUSES-B by Hirosawa et al. available in postscript (93kbyte) formats.