The first-light image of the Hyperspectral Imager SUIte (HISUI)
September 28, 2020
Japan Space Systems
The Hyperspectral Imager SUIte (HISUI) developed by the Ministry of Economy,
Trade and Industry installed to the Kibo’s Exposed Facility on the International
Space Station (ISS) has acquired its first-light image as part of the initial checkout.

Jointly developed by the Ministry of Economy, Trade and Industry (METI) and the Japan
Space Systems, the Hyperspectral Imager SUIte (HISUI) was launched from the US
Cape Canaveral Air Force Base toward the International Space Station (ISS) on
December 6, 2019 (Japan time). On the 12th of December, HISUI was successfully
installed to the Kibo’s Exposed Facility and is currently undergoing an initial checkout.
Using the data acquired from the instrument commissioning, a demonstration
processing has been conducted and we are pleased to publish this as the first-light image.
Following the initial checkout as well as the sensor calibration, accuracy confirmation of
the imagery data, maintenance of ground data processing etc., it is scheduled to start
nominal operation observation from November 2020, and will begin its application
demonstration by March 2021.
HISUI's high-spectral resolution data enables precise identification of substances on thesurface of the earth. In the natural resources sector, it is possible to grasp thedistribution of many minerals that are important indicators for resource exploration.
Other applications include detailed classification of important forests and vegetation in
the environmental sector, grasping the state of crops and soil in the agriculture sector,etc. New information that is not available in the widely used multispectral data will beobtained, and it is expected to be used in a wide range of sectors.

Orbit of the ISS when
the first image wasacquired.

Figure 1: Natural color image over New South Wales, Australia captured by HISUI
Figure 1 is a natural color image acquired by HISUI over New South Wales, Australia
on September 4, 2020, the color of which has been processed to look as it would dothrough the human eye.

Figure 2: False color composite image by HISUI (left: taken on September 4) andSentinel-2 (right: taken on August 23)
Figure 2 is a comparison of false color image of the HISUI and that of the Sentinel-2
taken on August 23 in the same area. This band combination is often used in remotesensing image processing to understand the distribution of vegetation, because
vegetation reflects sunlight more strongly in the near-infrared region than in the visible
region. The color distribution such as vegetation in both images looks almost the same.

Figure 3: Differences in information extraction using bands from the visible region to
the short wavelength infrared region, which are unique to HISUI
Wavelengths used: (Left) All 185 bands, (Middle) 650 nm and 860 nm (Right) 857 nm
and 1241 nm
In remote sensing image processing, different information can be extracted by combining
data of various wavelengths. Multispectral data has 20 or less bands, but thehyperspectral sensor HISUI can acquire 185 bands, so it is expected that the spatial
distribution of various information can be grasped. Figure 3 is a diagram created byusing the HISUI data before radiometric correction etc. and using a method commonlyused in remote sensing analysis. The figure on the left is a land cover classification map
created by automatically grouping all 185 bands of HISUI based on spectral similarity.
From the figure, you can see that rivers, forests, urban areas, etc. are classified in thesame color. The figure in the center is a distribution map of an index called NDVI(Normalized Difference Vegetation Index), which shows the activity of vegetation, andwas created using the bands of 650 nm and 860 nm. It can be speculated that the redcolor has higher vegetation activity and the blue color has lower vegetation activity. Thefigure on the right is a distribution map of an index called NDWI (Normalized MoistureIndex), which shows the difference in water content of vegetation, and was created using
the bands of 857 nm and 1241 nm. It is used to evaluate vegetation moisture stress andfire risk.

<Overview of HISUI>
The HISUI system installed on the ISS consists of an

HISUI-Hyperspectral sensor

exposed payload system and an onboard data storagesystem.
●HISUI Exposure Payload SystemHISUI

isa

hyperspectral

sensorforspacedemonstration developed with the main purpose ofexploration of resources such as oil and gas for thestable supply of energy and resources in Japan. It has
the ability to identify substances on the surface of theBus partIncident lightearth with higher accuracy than existing multispectral（Observation the earth）

sensors. The bus section provides an environment for地球を観測）

the HISUI sensor to observe and transmits observation
data and telemetry.
〇 Number of bands: 185〇 Observation wavelength band: 0.4 – 2.5 ㎛〇 Observation width: 20km
〇 Spatial resolution: 20m to 30m〇 Mass: 550 kg●HISUI onboard data storage system
The HISUI onboard data storage system records the observation data and telemetrytransmitted from the HISUI exposure payload system on a hard disk and transmits
some of them to the ground.
A hyperspectral sensor is a sensor that acquires thelight reflecting from a substance on the ground as datathat is continuously observed for each wavelength.
Objects reflect light of most wavelengths, andtherefore by using a curve (spectral curve) that shows
the difference in reflectance for each wavelength, it ispossible to speculate the substance that exists in acertain location. The HISUI acquires information by

Examples of spectral curves that differ

dividing the visible region to the short wavelength

depending on the substanceinfrared region (400 nm to 2,500 nm) into 185 bands.
(The multi-spectral sensor "ASTER" developed by theMETI and still in operation acquires information in 9 bands in the same wavelength
range. The spectrum curve of vegetation acquired by each sensor is as follows. The shape

0.7
0.6
0.5
0.4
0.3
0.2
0.1
0Hyperspectral

0.5

1

1.5
2
Wavelength [μm]2.5Reflectance

Reflectanceis different.
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0Multispectral

0.5

1

1.5
2Wavelength [μm]2.5The spectral curves of the minerals that make up rocks,
especially those that are useful for energy and resource

Calciteexploration, show distinctive shapes, mainly from 2,000

Kaolinite

nm (2.0μm) to 2,500 nm (2.5μm). Based on theseMontmorillonite
Alunitecharacteristics, the minerals on the surface of the earth
are estimated, and the possibility of underground oil and

0.3

0.7

gas resources and metal mineral resources is estimatedfrom the geomorphological conditions.

2.0~2.5μm

Quartz

1.1

1.5

1.9

2.3

Wavelength (mm)Example of Spectral Curve

In the HISUI project, the Japan Aerospace Exploration Agency (JAXA) has provided
support, namely through the transportation of the HISUI to the ISS, installation of theHISUI to the "Kibo", initial checkout of the acquired data and the transmission to theground.

Contact :Japan Space Systems
E-mail : info-hisui※jspacesystems.or.jp※＝@2.7