Akari (satellite)

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Scale model of the Akari (ASTRO-F, 2006-005A) exhibited at Noshiro City Children's Center.jpg
Artist's conception of Akari
Mission type Infrared telescope
Operator JAXA
COSPAR ID 2006-005A OOjs UI icon edit-ltr-progressive.svg
SATCAT no. 28939
Website global.jaxa.jp/projects/sat/astro_f/
Mission duration5 years, 9 months
Spacecraft properties
Manufacturer ISAS
Launch mass952 kg (2,099 lb)
Dimensions5.5 m × 1.9 m × 3.2 m (18.0 ft × 6.2 ft × 10.5 ft)
Power2006-02-21 21:28
Start of mission
Launch date21:28,21 February 2006(UTC) (2006-02-21T21:28UTC) [1]
Rocket M-V, mission M-V-8
Launch siteM-V Pad, Uchinoura Space Center
End of mission
Deactivated24 November 2011 (2011-11-24)
Orbital parameters
Reference system Geocentric
Regime Sun-synchronous
Semi-major axis 6,884 km (4,278 mi) [2]
Eccentricity 0.0129527 [2]
Perigee altitude 423.9 km (263.4 mi) [2]
Apogee altitude 602.3 km (374.3 mi) [2]
Inclination 98.2 degrees [2]
Period 94.7 minutes [2]
RAAN 305.9392 degrees [2]
Argument of perigee 124.2012 degrees [2]
Mean anomaly 354.1441 degrees [2]
Mean motion 15.1995622 rev/day [2]
Epoch 9 July 2015, 13:43:21 UTC [2]
Revolution no.50455 [2]
Type Ritchey–Chrétien
Diameter0.67 m (2.2 ft)
Focal length4.2 m (14 ft)
Wavelengths1.7 to 180 µm (Infrared)
FIS: Far-Infrared Surveyor
IRC: Infra-Red Camera

Akari (ASTRO-F) is an infrared astronomy satellite developed by Japan Aerospace Exploration Agency, in cooperation with institutes of Europe and Korea. It was launched on 21 February 2006, at 21:28 UTC (06:28, 22 February JST) by M-V rocket into Earth sun-synchronous orbit. After its launch it was named Akari (明かり), which means light in Japanese. Earlier on, the project was known as IRIS (InfraRed Imaging Surveyor).


Its primary mission was to survey the entire sky in near-, mid- and far-infrared, through its 68.5 cm (27.0 in) aperture telescope. [3]

Technical design

Its designed lifespan, of far- and mid-infrared sensors, was 550 days, limited by its liquid helium coolant. [4]

Its telescope mirror was made of silicon carbide to save weight. The budget for the satellite was ¥13,4 billion (~US$110 million). [5]


By mid-August 2006, Akari finished around 50 percent of the all sky survey. [6]

By early November 2006, first (phase-1) all-sky survey finished. Second (phase-2) all-sky survey started on 10 November 2006. [7]

Due to the malfunction of sun-sensor after the launch, ejection of telescope aperture lid was delayed, resulting in the coolant lifespan estimate being shortened to about 500 days from launch. However, after JAXA estimated the remaining helium during early March 2007, observation time was extended at least until 9 September. [8]

On 11 July 2007, JAXA informed that 90 percent of the sky was scanned twice. Also around 3,500 selected targets have been observed so far. [9]

On 26 August 2007, liquid-Helium coolant depleted, which means the completion of far- and mid-infrared observation. More than 96 percent of the sky was scanned and more than 5,000 pointed observations were done. [10]

British and Japanese project team members were awarded a Daiwa Adrian Prize in 2004, by the Daiwa Anglo-Japanese Foundation in recognition of their collaboration. [11]

During December 2007, JAXA performed orbit correction manoeuvres to bring Akari back into its ideal orbit. This was necessary because the boiled off helium led to an increase in altitude. If this would have continued energy supply would have been cut off. [12]


A limited observation 'warm' programme continued with just NIR.

End of mission

In May 2011, Akari suffered a major electrical failure and the batteries could not take full charge from the solar panels. As a result, its science instruments were rendered inoperable when the satellite was in the Earth's shadow. [3] The operation of satellite was terminated officially on 24 November 2011. [13]


The Akari All-Sky Survey Point Source Catalogues was released on 30 March 2010. [15] [16] [17]

Astronomy and Astrophysics, Vol. 514 (May 2010) was a feature issue of Akari's result. [18]

See also

Related Research Articles

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The Japan Aerospace Exploration Agency (JAXA) is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into orbit, and is involved in many more advanced missions such as asteroid exploration and possible human exploration of the Moon. Its motto is One JAXA and its corporate slogan is Explore to Realize.

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