| 词条 | HALCA |
| 释义 |
| name = HALCA | names_list = MUSES-B VSOP | image = | image_caption = | image_alt = | image_size = | mission_type = Astronomy | operator = ISAS | COSPAR_ID = 1997-005A | SATCAT = 24720 | website = {{url|http://www.isas.jaxa.jp/en/missions/spacecraft/past/halca.html|HALCA Home}} | mission_duration = 8 years, 9 months, 18 days | manufacturer = NEC Toshiba Space Systems | launch_mass = {{convert|830|kg|lb|abbr=on}} | dimensions = {{convert|1.5|x|1|m|ft|abbr=on}} | power = | launch_date = {{start date|1997|2|12|4|50|7=Z}} | launch_rocket = M-5-1 | launch_site = Kagoshima M-V Pad | disposal_type = decommissioned | deactivated = {{end date|2005|11|30}} | orbit_reference = Geocentric | orbit_regime = Highly elliptical | orbit_semimajor = {{convert|17259|km|mi|abbr=on}} | orbit_eccentricity = 0.5999671 | orbit_periapsis = {{convert|533.5|km|mi|abbr=on}} | orbit_apoapsis = {{convert|21244.1|km|mi|abbr=on}} | 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[1] | orbit_rev_number = 26766 | apsis = gee | telescope_type = Mesh antenna | telescope_diameter = {{convert|8|m|ft|abbr=on}} | telescope_wavelength = 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. HistoryIt 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. Highlights
References1. ^{{cite web |url=http://www.n2yo.com/satellite/?s=24720 |title=HALCA (MUSES-B) Satellite details 1997-005A NORAD 24720 |publisher=N2YO |date=28 April 2016 |accessdate=28 April 2016}} 2. ^http://www.vsop.isas.jaxa.jp/obs/news/www.161.html External links{{Portal|Spaceflight}}
4 : Radio telescopes|Space observatories|Satellites of Japan|Spacecraft launched in 1997 |
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