HALCA

• Name — HALCA • Names List — MUSES-B VSOP Haruka (はるか) • Mission Type — Astronomy • Operator — ISAS • Cospar Id — 1997-005A • Satcat — 24720 • Mission Duration — 8 years, 9 months, 18 days • Manufacturer — NEC Toshiba Space Systems • Launch Mass — 830 kg • Dimensions — 1.5 x • Launch Date — 1997 2 12 4 50 7=Z • Launch Rocket — M-5-1 • Launch Site — Kagoshima M-V Pad • Disposal Type — Decommissioned • Deactivated — 2005 11 30 • Orbit Reference — Geocentric • Orbit Regime — Highly elliptical • Orbit Semimajor — 17259 km • Orbit Eccentricity — 0.5999671 • Orbit Periapsis — 533.5 km • Orbit Apoapsis — 21244.1 km • Orbit Inclination — 31.1880 degrees • Orbit Period — 376.1 minutes • Orbit Raan — 127.6566 degrees • Orbit Arg Periapsis — 143.9533 degrees • Orbit Mean Anomaly — 358.3371 degrees • Orbit Mean Motion — 3.82867831 rev/day • Orbit Epoch — 28 April 2016, 09:56:58 UTC • Orbit Rev Number — 26766 • Apsis — gee • Telescope Type — Mesh antenna • Telescope Diameter — 8 m • Telescope Wavelength — 1.3, 6, 18 cm (radio)

It was placed in a highly elliptical orbit with an apogee altitude of 21,400 km and a perigee altitude of 560 km, with an orbital period of approximately 6.3 hours. This orbit allowed imaging of celestial radio sources by the satellite in conjunction with an array of ground-based radio telescopes, such that both good (u,v) plane coverage and very high resolution were obtained. Although designed to observe in three frequency bands: 1.6 GHz, 5.0 GHz, and 22 GHz, it was found that the sensitivity of the 22 GHz band had severely degraded after orbital deployment, probably caused by vibrational deformation of the dish shape at launch, thus limiting observations to the 1.6 GHz and 5.0 GHz bands. HALCA was launched in February 1997 from Kagoshima Space Center, and made its final VSOP observations in October 2003, far exceeding its 3-year predicted lifespan, before the loss of attitude control. All operations were officially ended in November 2005. A follow-up mission ASTRO-G (VSOP-2) was planned, with a proposed launch date of 2012, but the project was eventually cancelled in 2011 due to increasing costs and the difficulties of achieving its science goals. It was expected to achieve resolutions up to ten times higher and up to ten times greater sensitivity than its predecessor HALCA. The cancellation of ASTRO-G left the Russian Spektr-R mission as the only then operational space VLBI facility. Spektr-R stopped operating in 2019.

The large 8 meter antenna was designed to unfold in space as the unfolded configuration did not fit inside the rocket fairing. The antenna was a metal mesh of 6000 cables. To form an ideal shape the length of the cables were adjusted on the backside of the antenna. One concern was that the cables could entangle. The deployment of the main reflector started on February 27, 1997. The deployment was done over three hours on the first day and was completed in 20 minutes during the next day.

• Observations of hydroxyl masers and pulsars at 1.6 GHz • Detection of interference fringes for quasar PKS1519-273 between HALCA and terrestrial radio telescopes • Routines imaging of quasars and radio galaxies etc. by means of experimental VLBI observations with HALCA and terrestrial radio telescope networks

• Illustration — Haruka during a deployment test • Illustration — Launch of Haruka on board of a M-V rocket • Illustration — The large image shows M87 as observed with the VLA, the insert shows observations with the VLBA and HALCA • Illustration — Multi-epoch observations of the quasar VSOP J1927+7358, observed with VSOP between 1997 and 2001 • Illustration — Animation of HALCA around the Earth