RazakSAT

RazakSAT® is a small Low Earth Observation (LEO) satellite orbiting the earth in uniquely Near Equatorial Orbit (NEqO) at nominal altitude of 685 km and 9 degrees inclination.  It carries the Medium-sized Aperture Camera (MAC) which is an electro-optical payload of a pushbroom camera type with 5 linear detectors (1 panchromatic, 4 multi-spectral).RazakSAT® operated through its ground segment in Malaysia, consists of a Mission Control Station (MCS) and an Image Receiving and Processing Station (IRPS). A team of satellite engineers operated the MCS and executing the RazakSAT® mission plan, command generation and telemetry receiving, archiving and analysis accordingly. The IRPS will receive and archive images for post processing and distribution to the users.

RazakSAT® satellite has a Panchromatic band (510 – 730 nm) and 4 Multispectral Bands: Band 1: Blue (450 – 520 nm); Band 2: Green (520 – 600 nm); Band 3: Red (630 – 690 nm) and Band 4: Near-Infrared (760 – 890 nm). The spatial resolution of 2.5 m and 5 m for Panchromatic and Multispectral, respectively, covers a swath width of 20 km at the 685 km nominal altitude. Data is being quantized into 8 bits of 256 brightness values to represent information. With the high spatial resolution of 2.5 m, RazakSAT® allows a maximum scale of 1:25000 for mapping product.   The following table summarizes MAC data characteristics.

Subsystems Specifications
Altitude 685 km
Inclination 9°
Payload (MAC) GSD : 2.5 m (PAN), 5 m (MS)
Swathwidth : 20 km @ 685 km
Attitude Determination & Control Subsystem (ADCS) Three-axis stabilization based on four reaction wheels
Pointing Accuracy : < 0.2° (2 s) Pointing Knowledge : 1 arcmin (2 s) Electrical Power Subsystem (EPS) GaAs/Ge solar cells on honeycomb substrate NiCd batteries (18 Ahr) Peak Power Tracking (PPT) & constant current control Solar Power : >300 W @ EOL
Command & Data Handling Subsystem (C&DH) Two on-board computers
Telemetry and command interface modules
Analog Telemetry channels : up to 90
Digital Telemetry channels : up to 120
Telecommunication Subsystem (TS) 9,600 bit/s / 1,200 bit/s S-band TT&C uplink
38.4 kbs / 9,600 bit/s / 1,200 bit/s S-band TT&C downlink
Payload Data Management 32 Gbit On-board solid-state memory
30 Mbit/s X band payload data downlink
Structure & Thermal Ø1,200 × 1,200 mm Hexagonal shape
Mass : 180 kg
Modular structure
Passive & Active thermal control
Mission Lifetime 3 Years

RazakSAT® potential applications

RazakSAT® was designed to produce Remote Sensing images which can be used in various applications such as cartography, land mapping, agriculture, forestry, oceanography and maritime industries.  This section elaborates the potential capability of RazakSAT® data  conducted by Universiti Malaysia Terengganu in selected applications including:

 

  1. Application Of RazakSAT®Satellite Imagery In Monitoring Shoreline Change
  2. Monitoring Land Reclamation Activities
  3. Water Quality Monitoring over Malacca Straits using RazakSAT®data.
  4. A Preliminary Assessment On The Capability Of RazakSAT®Imagery for Deriving Chlorophyll-a Map
  5. Soil and road network mapping
  6. Agriculture Mapping and Vegetation Indices (VI) Estimation over Kuala Terengganu
  7. Map Composition

 

 

Application 1: Application of RazakSAT® Satellite Imagery in Monitoring Shoreline Change.

Kuala Terengganu is a city located in coastal areas east of Peninsular Malaysia. This city well known for its sea turtle nesting places currently endangered due to coastal erosion. Coastal zone monitoring over Kuala Terengganu is an important task in a quest for sustainable development and environmental protection. Shoreline is one of the important linear features on the earth which display a dynamic nature. Coastline or shoreline extraction in various times is a fundamental work for coastal zone monitoring. RazakSAT® can play important roles for shoreline monitoring. The aim of this study is to monitor the shoreline change mapping for Kuala Terengganu coastal zone using RazakSAT® data and others high resolution sensor.

 

Figure 1 : Shoreline Map overlay on various temporal high resolution satellite data. (a) IKONOS data acquired on 2000, (b) IKONOS data acquired on 2002, c) SPOT data acquired on April,2009, and d) SPOT data acquired on Sept, 2009.

 

 

Figure 2: Shoreline determination using RazakSAT® data.

 

The high resolution satellite such as IKONOS from the United States of America, SPOT from France with multitemporal imagers and RazakSAT® from Malaysia were used in this study. Each image was geometrically and radiometrically corrected before shoreline determination applies. Based from RazakSAT® data through observation and investigation analysis, the shoreline comparisons show an accretion around 25m from year 2000 till year 2010.

 

Application 2: Monitoring Land Reclamation Activities at Kuala Terengganu.

RazakSAT® data can be used to detect certain degree of land reclamation activities. In this study, RazakSAT® data and other satellite such as IKONOS and SPOT from multitemporal data were used to identify the changes over the land. Each data was digitized and overlaid with same geometric projection. There were significant changes monitored from the year 2000 until 2010.

 

Figure 3: Land reclamation monitoring using multisatellite sensor and multitemporal data.

 

 

Figure 4: Land reclamation monitoring using multisatellite sensor and multitemporal data.

 

 

Application 3: Water Quality Monitoring over Malacca Straits using RazakSAT® data.

The multispectral band images data from RazakSAT® has been highly effective in acquiring information for water quality monitoring.  Existing floating substance content on the water can be precisely discriminated and classify with RazakSAT® data. As shown in Figure 7 the floating substance content were categorized into 4 types of substance levels such light, moderate, average and heavy floating substance. RazakSAT® data has the potential to be used for coastline mapping.

 

Figure 5 : Ocean Colour

 

Further application in relation to coastal area is Deriving Chlorophyll-a Map which is useful form of information for fishery application. The determination of the area is vital to assist the fishermen to increase their catch. One way of determining the potential area with fish is to use remote sensing methods.

Application 4 : A Preliminary Assessment On The Capability Of RazakSAT® Imagery For Deriving Chlorophyll-a Map

RazakSAT® data can be used for marine applications like suspended sediments/minerals monitoring and chlorophyll mapping. RazakSAT® multispectral band characteristics enable suspended sediments in water bodies to be monitored such as amount and spatial distribution.

It also enables the mapping of ocean colour that represents the different types of phytoplankton contain in the ocean with the distinct types of chlorophyll concentration. Detection of chlorophyll pigments in the water bodies can be used to identify the fishing ground. Mapping of chlorophyll concentration is essential for the study of ocean primary production, and others biological cycles as well as fishery research. Chlorophyll-a is a primary photosynthesis pigment in the phytoplankton. RazakSAT® data has been used for preliminary studies for deriving the Chlorophyll-a concentration over Kuala Terengganu coastline area.

 

Figure 6: Chlorophyll-a extraction from RazakSAT® data.

 

RazakSAT® data has been geometric corrected and resampled to the selected map projection before further enhancement process being made. The digital number of RazakSAT® spectral band was converted to reflectance values. Other areas such as land and cloud has been masked with no reflectance value and coloured in black to highlight specifically the water bodies feature in RazakSAT® image. An algorithm from Islam and Tat, 2001 has been applied on preprocessed RazakSAT® data for Chlorophyll-a extraction. Chlorophyll-a information obtained is shown in the map.

Application 5: Soil Road Network Mapping

 

Figure 7: Soil Road Network Mapping

 

RazakSAT® data has been utilized for extracting soil road features using simple spectral classification image processing. Figure 7 shows three types of features were extracted and classified from RazakSAT® multispectral data. Both agricultural areas and clouds were given the legend as white, while the soil road in red.

RazakSAT® data is applicable to feature extraction within main road and secondary road network extraction. Several methods of spectral classification were used as road extraction techniques and the final output of road extraction were mapped and compared with reference road network. Match filtering; Spectral Angle Mapping and Principal Component Analysis techniques were used for spectral classification to enhance the main road and secondary road features on RazakSAT® data.

 

Figure 8: Final result of road extraction derived from RazakSAT® imagery (a) and comparison with existing road network reference map using overlay technique (b).

 

Final result of road extraction was digitized using ArcGIS software and then compared with existing road network reference map. With the accuracy of 94.703% for main road extraction, the RazakSAT® data is suitable and potential source of remote sensing applications for features and road extraction.

Application 6: Agriculture Mapping and Vegetation Index.

 

RazakSAT® data is beneficial in land applications especially land usage or land cover mapping. Land usage meant that the land is being utilised for several activities such as agriculture, recreation, industrial and etc. On another hand, land cover refers to biophysical materials that are covering the land’s surface including water, vegetation, bare soil and etc. Land use/land cover information is required for many other applications such as population estimation, natural resource management, land development and etc. Figure 9 show the classification map which classify the land cover such as water body, coastal zone, and vegetation types.

 

Figure 9: Land Cover Mapping

 

The most common vegetation analysis using remote sensing data is the vegetation index estimation. Vegetation index is a single number that quantifies vegetation biomass in remote sensing image. The index is computed using several spectral bands that are sensitive to biomass plant. The higher values indicate the high biomass content in the plant.

 

Figure 10 : Determination of vegetation spatial distribution at Kuala Terengganu using several indices methods. (a) Normalized Difference Vegetation Index (NDVI). (b) Ratio vegetation Index (RVI). (c) Soil Adjusted Vegetation Index (SAVI). (d) Perpendicular Vegetation Index (PVI)

 

In this study, RazakSAT® multispectral data was used to estimate the vegetation indices using several indices methods over Kuala Terengganu area. RazakSAT® data was tested with the most common vegetation index, Normalized Difference Vegetation Index (NDVI). Comparison of reflectance values of RazakSAT® red and near infrared bands by using the following formula to estimate the NDVI:

RazakSAT® NDVI Estimation =NIR-RED/NIR+RED

RazakSAT® data also tested with several vegetation indices formula such as Ratio vegetation Index (RVI). Soil Adjusted Vegetation Index (SAVI and Perpendicular Vegetation Index (PVI). From the result presented in Figure 10, vegetation spatial features were well distributed over Kuala Terengganu area. Greener colour indicates the high density of vegetation feature. From this study, it shows that RazakSAT® multispectral data is a useful tool and suitable for vegetative analysis.

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