View source for HALCA

{{Short description|Japanese space radio telescope}}
{{For|the Japanese singer|Halca}}
{{Infobox spaceflight
| name                  = HALCA
| names_list            = MUSES-B<br />VSOP<br />Haruka (はるか)

<!--image of the spacecraft/mission-->
| image                 = Haruka HALCA VSOP MUSES-B.jpg<!--omit the "file" prefix-->
| image_caption         = HALCA after the final assembly during a solar battery check at [[Uchinoura Space Center|Uchinoura]]<!--image caption-->
| image_alt             = <!--image alt text-->
| image_size            = <!--include px/em; defaults to 220px-->

<!--Basic details-->
| mission_type          = [[Space observatory|Astronomy]]
| operator              = [[Institute of Space and Astronautical Science|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

<!--Spacecraft properties-->
| manufacturer          = [[NEC|NEC Toshiba Space Systems]]
| launch_mass           = {{convert|830|kg|lb|abbr=on}}
| dimensions            = {{convert|1.5|x|1|m|ft|abbr=on}}
| power                 = <!--end-of-life power, in watts-->

<!--Launch details-->
| launch_date           = {{start date|1997|2|12|4|50|7=Z}}
| launch_rocket         = [[M-V|M-5]]-1
| launch_site           = [[Kagoshima Space Center|Kagoshima]] M-V Pad

<!--end of mission-->
| disposal_type         = Decommissioned
| deactivated           = {{end date|2005|11|30}}

<!--orbit parameters-->
<!--as science-related articles, SI units should be the principal units of measurement, however we usually use {{convert}} to display imperial units in parentheses after the initial values-->
| orbit_reference       = [[Geocentric orbit|Geocentric]]
| orbit_regime          = [[Highly elliptical orbit|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&nbsp;degrees
| orbit_period          = 376.1&nbsp;minutes
| orbit_RAAN            = 127.6566&nbsp;degrees
| orbit_arg_periapsis   = 143.9533&nbsp;degrees
| orbit_mean_anomaly    = 358.3371&nbsp;degrees
| orbit_mean_motion     = 3.82867831&nbsp;rev/day
| orbit_epoch           = 28 April 2016, 09:56:58&nbsp;UTC<ref name="n2yo">{{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 |access-date=28 April 2016}}</ref>
| orbit_rev_number      = 26766
| apsis                 = gee

<!--Telescope parameters-->
| telescope_type        = [[Reflector (antenna)|Mesh antenna]]
| telescope_diameter    = {{convert|8|m|ft|abbr=on}}
| telescope_wavelength  = 1.3, 6, 18 cm ([[Radio frequency|radio]])
}}
'''HALCA''' ('''Highly Advanced Laboratory for Communications and Astronomy'''), also known for its project name '''VSOP''' ('''VLBI Space Observatory Programme'''), the code name '''MUSES-B''' (for the second of the '''[[Mu (rocket family)|Mu]] Space Engineering Spacecraft''' series), or just '''Haruka''' (はるか)<ref>{{Cite web|url=https://translate.google.com/translate?hl=en&sl=ja&tl=en&u=http://www.isas.jaxa.jp/j/japan_s_history/chapter09/02/index.shtml|title="Haruka" large antenna and space VLBI (「はるか」大型アンテナとスペースVLBI)|website=ISAS JAXA + translate.google.com|access-date=2020-01-24}}</ref> was a Japanese 8 meter diameter [[radio telescope]] satellite which was used for [[Very Long Baseline Interferometry|Very Long Baseline Interferometry (VLBI)]]. It was the first such space-borne dedicated VLBI mission.

==History==
It was placed in a highly elliptical orbit with an [[apogee]] altitude of 21,400&nbsp;km and a [[perigee]] altitude of 560&nbsp;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&nbsp;GHz, 5.0&nbsp;GHz, and 22&nbsp;GHz, it was found that the sensitivity of the 22&nbsp;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&nbsp;GHz and 5.0&nbsp;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.<ref>{{Cite web|url=http://www.vsop.isas.jaxa.jp/obs/news/www.161.html|title=VSOP newsletter number 161|access-date=2012-02-17|archive-date=2020-09-13|archive-url=https://web.archive.org/web/20200913193840/http://www.vsop.isas.jaxa.jp/obs/news/www.161.html|url-status=dead}}</ref>

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 [[RadioAstron|Spektr-R]] mission as the only then operational space VLBI facility. Spektr-R stopped operating in 2019.

== Antenna ==
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.<ref>{{Cite web|url=https://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http://www.isas.jaxa.jp/j/japan_s_history/chapter09/02/04.shtml|title=Deployment of 8 m effective aperture antenna (有効口径8mアンテナの開発)|website=ISAS JAXA + translate.google.com|access-date=2020-01-24}}</ref> 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.<ref>{{Cite web|url=https://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http://www.isas.jaxa.jp/j/japan_s_history/chapter09/02/04.shtml|title=Natori's Tears: Successful deployment of large antennas under tension (名取の涙──緊張の中、大型アンテナの展開成功)|website=ISAS JAXA + translate.google.com|access-date=2020-01-24}}</ref>

==Highlights==
*Observations of hydroxyl [[Astrophysical maser|masers]] and [[pulsar]]s at 1.6&nbsp;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

==Gallery==
<gallery>
Haruka HALCA VSOP MUSES-B deployment test.jpg|Haruka during a deployment test
Haruka HALCA VSOP MUSES-B launch.jpg|Launch of Haruka on board of a M-V rocket
1.6 GHz image of M87, VLA and VLBA + HALCA.jpg|The large image shows [[Messier 87|M87]] as observed with the [[Very Large Array|VLA]], the insert shows observations with the [[Very Long Baseline Array|VLBA]] and HALCA
VSOP J1927+7358.gif| Multi-epoch observations of the [[quasar]] [[VSOP J1927+7358]], observed with VSOP between 1997 and 2001
Animation of HALCA around Earth.gif|Animation of HALCA around the Earth<br>{{legend2| Magenta| HALCA }}{{·}}{{legend2|Royalblue|Earth}}
</gallery>

==References==
{{Reflist}}

==External links==
{{Portal|Spaceflight}}
* [https://web.archive.org/web/20050626011913/http://www.isas.ac.jp/e/enterp/missions/halca/index.shtml HALCA]
* [http://www.vsop.isas.ac.jp/ VSOP] {{Webarchive|url=https://web.archive.org/web/20210321220443/http://www.vsop.isas.ac.jp/ |date=2021-03-21 }}

{{Radio-astronomy}}
{{Space observatories}}
{{Japanese space program}}
{{Orbital launches in 1997}}
{{Authority control}}

[[Category:Radio telescopes]]
[[Category:Space telescopes]]
[[Category:Satellites of Japan]]
[[Category:Spacecraft launched in 1997]]