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Asteroid Multi-band Imaging Camera (AMICA)

NSSDCA ID: 2003-019A-01

Mission Name: Hayabusa
Principal Investigator:Dr. Tsuko Nakamura

Description

The Asteroid Multi-band Imaging Camera (AMICA) on Hayabusa is designed to collect scientific images and also to be used for optical navigation. The AMICA system consists of a refracting telescope, a filter wheel, a CCD, and associated electronics. The total assembly is mounted on the corner of the bottom-facing deck of the spacecraft near the sampler horn and measures 12.0 x 13.5 x 18.0 cm. AMICA has a field-of-view of 5.7 x 5.7 degrees giving a frame size of about 1 km at 10 km range.

The camera assembly has a mass of 1.74 kg. The optical system is a refracting telescope with five lenses behind a quartz optical parallel window. The focal length is 120 mm and the effective lens diameter is 15 mm (F/8.0). Mounted at the end of the telescope is a filter wheel with eight positions. Each filter is sector-shaped and can be rotated into position behind the telescope. Seven of the filters cover the ECAS system bands: ul, b, v, w, x, p, and zs. There is also a closeup lens (also v-filter) to be used during the sampling phase. After passing through the filter, the image falls on a frame-transfer CCD. The CCD is a back-illuminated multi-pinned phase type, 1024 x 1000 pixels. A single pixel sees 20 arcsec. 30 different exposure times ranging from 5.5 ms to 134 s are available, and there is a ~1 microsecond exposure time to correct readout smear. Four position-angle glass polarizers are mounted on one edge of the CCD chip covering 200 x 200 pixels each. These allow measurement of polarization of the asteroid in the v- and w-bands.

The associated electronics include a computer for data compression and image data processing. The electronics requires 9.5 W power compared to 6.8 W to run the camera. AMICA is body-mounted and cannot be pointed independently of the spacecraft. It is pointed approximately in the anti-solar direction for normal inflight conditions. Calibrations, health checks, and flat-field measurements will be performed intermittently during interplanetary cruise. First detection of the target astroid is expected at roughly one million km. At distances of a few hundred thousand km photometric measurements begin, with AMICA taking images of the asteroid every 20-30 minutes. These images will also be used for identification of the free nutation of the asteroid and the search for any natural satellites. Hayabusa will enter a station keeping postion roughly 10-20 km from the asteroid, from which global mapping will take place. This includes topographic and colorimetric mapping, profiling of overall shape and spin state, photometric and polarimetric behavior of the asteroid near opposition, and validation of ground-based observations. During the close approach and sampling phase, AMICA will be used for high resolution surface imaging.

Alternate Names

  • AMICA
  • Hayabusa/AMICA
  • urn:nasa:pds:context:instrument:amica.hay

Facts in Brief

Mass: 5.74 kg
Power (avg): 16.3 W

Funding Agency

  • Institute of Space and Aeronautical Science, U of Tokyo (Japan)

Discipline

  • Planetary Science: Geology and Geophysics

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Tsuko NakamuraPrincipal InvestigatorNational Astronomical Observatory of Japantsuko@cc.nao.ac.jp

Selected References

  • Nakamura, T., et al., Multi-band imaging camera and its sciences for the Japanese near-earth asteroid mission MUSES-C, Earth Planet. Space, 53, No. 11, 1047-1063, 2001.
  • Saito, J., et al., Detailed Images of Asteroid 25143 Itokawa from Hayabusa, Science, 312, No. 5778, 1341-1344, June 2006.
  • Ishiguro, M., et al., The Hayabusa Spacecraft Asteroid Multi-band Imaging Camera (AMICA), Icarus, 207, No. 2, 714-731, doi:10.1016/j.icarus.2009.12.035, Jun. 2010.
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