The view from Diwata

MANILA, Philippines – Diwata-1, the Philippines’ first microsatellite for scientific earth observation, again captured high-resolution images during the satellite’s test phase.

Diwata-1’s High Precision Telescope (HPT), one of four cameras onboard, obtained images with a ground resolution of 3m at nadir (or lowest point), the highest resolution attained so far by a microsatellite in the 50-kg class.

This was announced earlier this month by the Department of Science and Technology’s Advanced Science and Technology Institute (DOST-ASTI) and the University of the Philippines Diliman (UPD), which have been collaborating with Japan’s Hokkaido and Tohoku Universities for the operation of Diwata-1.  

Below is a comparison of the images taken by Diwata-1’s HPT and by the American earth observation satellite Landsat 8’s Operational Land Imager (OLI). The ground resolution of OLI is 30m. Landsat 8 has a launch mass of about 2,600 kg.

Left side photo of Figure 1 shows the RGB composite (normal color) images taken by Diwata-1’s HPT at 9:07 a.m. Philippine Standard Time (PHT) last May 19, 2016 and the photo on the right shows Landsat 8’s OLI at 10:06 on May 21 PHT. The images show portions of Dumingag, Zamboanga, a mountainous area in Mindanao. The OLI image with a 30m- ground resolution can identify only rough structures of the mountain but the detailed geographical features are unclear.  

On the other hand, the Diwata-1’s HPT image can clearly identify trees, rock surface, mountain paths, river and some man-made objects (Figure 1a). With a clearer photo from Diwata-1’s HPT camera, it will be easier to see which areas are affected by natural and even man-made disasters such as floods and fires. One of the missions of the HPT is to determine the extent of damage from natural hazards such as typhoons.

Figure 2 photos show a comparison of “false color” images of an urban area in Florida, United States, which were taken by Diwata-1’s HPT at 7:48 a.m. Eastern Daylight Time (EDT) last June 30 and by Landsat 8’s OLI, respectively. False color images are created to emphasize the difference between vegetation and other objects using three different bands. The photo on the left (Figure 2a) is an image constructed by stitching six successive images captured by Diwata-1’s HPT camera with one-second intervals.

As a successful demonstration of the target pointing capability of Diwata-1, the microsatellite was able to capture six images of the focused area with field-of-view of 2 km x 1.5 km even though it was orbiting the Earth with a velocity of ~7.7 km/s at an altitude of ~400 km. It can be seen that buildings and roads are clearly distinguishable from the vegetation in the HPT images (Figure 2a), while such features are very unclear in the OLI image (Figure 2b).

The ability of Diwata-1’s HPT camera to take pictures of places even outside the country is a good indication that through Diwata-1, the Philippines will be able to share and exchange images among a group or constellation of microsatellites with neighboring countries for mutual benefit. This is one of the objectives of the country’s microsatellite development program.  – S&T Media Service