amica2isis

This application will import and convert a Hayabusa Asteroid Multiband Imaging Camera (AMICA) PDS image to an ISIS cube. The application reads and translates eight AMICA filters. See chart in AMICA Filters below for details on the different filters.

Requirements

• Detached header file (.lbl) (FROM)
• Raw image data (.fit) (specified in FROM label)
• Output ISIS file name (.cub) (TO)
• Users may need to override the target name (TARGET)

The input PDS formatted detached header file (.lbl) for the Hayabusa AMICA image must be used in the FROM parameter. This header contains a reference to a FITS formatted file ending in a .fit extension containing the image data. Both files must reside in the same directory or errors will occur.

When TARGET Parameter Should Be Specified

• When Hayabusa AMICA EDR labels contain an incorrect value for the TARGET_NAME keyword
• Define TARGET = "SKY" to later project the data with skymap.

Mission Overview

The Hayabusa spacecraft was launched on 9 May 2003. The AMICA instrument acquired more than 1,400 multispectral and high resolution images of the asteroid 25143 Itokawa beginning 12 September 2005 for three months. The primary goal of the mission was to land on the asteroid and return samples to Earth. The spacecraft safely landed on Itokawa in November 2005 and returned the samples to Earth in June 2010. Further information can be found in Ishiguro et al. (2010)

During the rendezvous phase with Itokawa, Hayabusa was designed to find its position relative to the asteroid autonomously using optical navigation cameras (ONC) and range data based on light-detection and ranging (LIDAR) technology. The ONC-T, a refractive telescope camera head, is referred to as the AMICA when used for scientific observations. Prior to "touch-and-go sampling", Itokawa was mapped by AMICA to select sampling sites free of serious obstacles such as meter-sized boulders and craters.

Instrument Overview

The AMICA instrument is a refracting telescope consisting of five lenses, each of which is cosmic-radiation-resistant and anti-reflection coated. A quartz optical parallel window is placed in front of the first lens for radiation protection. The SITe charge-coupled device (CCD) chip, developed and built by NEC TOSHIBA Space Systems, Ltd., is of the back-illuminated MPP (Multi-Pinned Phase) type. The CCD is kept below -10 degrees C in ordinary in-flight condition. The CCD dimensions are 1024 x 1000 visible pixels (full dimensions are 1024 x 1024) and the camera field of view is 5.83 x 5.69 degrees. The 12 columns on either side of the 1024 x 1000 pixel array are dark due to an obscuring mask. DNs in these areas were found to be dependent on both incident flux and wavelength, suggesting that the masks are not perfectly impermeable to light. Therefore, these pixels cannot be used for dark current correction. The remaining unobscured region has the dimensions 1000 x 1000.

AMICA is one of the ONCs comprised of three units: three CCD camera heads (ONC-T, ONC-W1, and ONC-W2), an analog signal processing unit (ONC-AE), and a digital signal processing unit (ONC-E). AMICA (ONC-T) and two wide-angle navigation cameras (ONC-W1 and ONC-W2) are controlled through ONC-E and ONC-AE, and the signals obtained are converted from analog to digital in ONC-AE. The digitized images are numerically processed by the ONC-E. The design of the AMICA camera head flight model is essentially the same as that of its prototype model. It is a CCD camera with a refractor telescope consisting of cosmic radiation-resistant and antireflection-coated lenses. The CCD device was configured in a frame-transfer architecture with an image area and a frame storage area. The depth of field (the distance between the camera and objects that are observed in focus) was designed to be 75 m to infinity.

AMICA has an eight position filter wheel, of which seven filters are nearly equivalent to the ECAS bands (Tedesco et al. 1982). Below is a table of the filters and their specifications:

AMICA Filters

The following table provides the specifications for each of the eight AMICA filters.

AMICA Filter Specifications

Name	Wavelength (nm)	FWHM (nm)
ul	381	45
b	429	108
v	553	72
w	700	70
x	861	81
p	960	75
zs	1008	66
WIDE	650	300

Data Archive

The Hayabusa AMICA data archive is located at several locations. The Japanese provide the data from the Japanese Hayabusa AMICA archive website. The data are also available from the NASA PDS Small Bodies Node and is the recommended source.

The file naming convention for ONC images is {T}{C}{nnnnnnnnnn}_{filter}.fits, where: {T} indicates the type of data ("S" for scientific data or "N" for navigation data), {C} identifies the name of the instrument (T, W1, and W2 for ONC-T (i.e. AMICA), ONC-W1, and ONC-W2, respectively); {nnnnnnnnnn} is the mission elapsed time when the images is generated in ONC-E; {filter} is the name of the filter (ul, b, v, w, x, p, and zs, respectively).

References

Ishiguro, Masateru, et al. "The Hayabusa Spacecraft Asteroid Multi-band Imaging Camera (AMICA)". Icarus 207.2 (2010): 714-731.
Tedesco, E.F., D.J. Tholen, and B. Zellner. The eight-color asteroid survey: Standard stars. Astron. J. 87, 1587-1592, 1982.