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For the Japanese singer, see Halca (singer).
Mission type Astronomy
Operator ISAS
COSPAR ID 1997-005A
SATCAT no. 24720
Website www.isas.ac.jp/e/enterp/missions/halca/index.shtml
Mission duration 8 years, 9 months, 18 days
Spacecraft properties
Manufacturer NEC Toshiba Space Systems
Launch mass 830 kg (1,830 lb)
Dimensions 1.5 m × 1 m (4.9 ft × 3.3 ft)
Start of mission
Launch date 04:50, February 12, 1997 (1997-02-12T04:50)
Rocket M-5-1
Launch site Kagoshima M-V Pad
End of mission
Disposal decommissioned
Deactivated November 30, 2005 (2005-11-30)
Orbital parameters
Reference system Geocentric
Regime Highly elliptical
Semi-major axis 17,259 km (10,724 mi)
Eccentricity 0.5999671
Perigee 533.5 km (331.5 mi)
Apogee 21,244.1 km (13,200.5 mi)
Inclination 31.1880 degrees
Period 376.1 minutes
RAAN 127.6566 degrees
Argument of perigee 143.9533 degrees
Mean anomaly 358.3371 degrees
Mean motion 3.82867831 rev/day
Epoch 28 April 2016, 09:56:58 UTC[1]
Revolution no. 26766
Main telescope
Type Mesh antenna
Diameter 8 m (26 ft)
Wavelengths 1.3, 6, 18 cm (radio)

HALCA (Highly Advanced Laboratory for Communications and Astronomy), also known for its project name VSOP (VLBI Space Observatory Programme), or the code name MUSES-B (for the second of the Mu Space Engineering Spacecraft series), is a Japanese 8 meter diameter radio telescope satellite which was used for Very Long Baseline Interferometry (VLBI). It was the first such space-borne dedicated VLBI mission.

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. [2]

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 leaves the Russian Spektr-R mission as the only currently operational space VLBI facility.


  • 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


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