Thursday, January 18, 2018

Japanese Epsilon Rocket Sends ASNARO-2 Radar Satellite to Orbit

Epsilon-3 launch on January 17. Credit: JAXA

A Japanese Epsilon rocket has successfully delivered the ASNARO-2 radar Earth observation satellite to orbit. The Epsilon rocket launched from Uchinoura Space Center at 6:06 Japan Standard Time on Thursday, or 21:06 UTC on Wednesday.

The Advanced New Satellite with New System Architecture for Observation (ASNARO) series of satellites are spacecraft created for the Japanese Ministry of Economy, Trade, and Industry (METI) by the Japan Space Systems company.

The launch of ASNARO-2 aboard its Epsilon rocket was originally scheduled for Nov. 12, 2017. However, it was delayed by an electrical problem. Additionally, bad weather prompted a delay from Jan. 16, 2018.

The first ASNARO satellite was launched on a Dnepr rocket in 2014 and carried an optical observation system with a resolution better than 6.5 feet (two meters) per pixel. ASNARO-2 carries an X-band Synthetic Aperture Radar (SAR) for terrain mapping.

A third satellite in the series is planned to carry a hyperspectral observation payload for imaging in optical and other bandwidths.

The ASNARO satellites are designed to be small, lightweight spacecraft with masses around 900-1,300 pounds (400-600 kilograms) with a common spacecraft bus largely built from commercial-off-the-shelf parts and interchangeable payload sections. This commonality is designed to reduce cost and simplify mission planning and preparation.

ASNARO-2 carries an X-band SAR weighing about 485 pounds (220 kilograms). The SAR has a resolution of better than 1.3 feet (one meter) per pixel, and has three observation modes: spotlight, stripmap, and ScanSAR. The narrowest, spotlight, has an image width of more than 6.2 miles (10 kilometers).

The common ASNARO bus weighs about 672 pounds (305 kilograms) without fuel and carries two gallium-arsenide solar array wings that together generate up to 1,300 watts of power. The bus also carries 100 pounds (45 kilograms) of hydrazine fuel for maneuvering, in addition to reaction wheels and magnetic torque rods for attitude control.

The Epsilon rocket has three solid-fueled stages and an optional Compact Liquid Propulsion Stage (CLPS) upper stage, which was used in the launch of ASNARO-2. In fact, of the three total Epsilon flights, this was the second to utilize a CLPS.

The Epsilon launch vehicle delivered the ASNARO-2 spacecraft to a polar, Sun-synchronous orbit with an inclination of 97.4 degrees and an altitude of about 313 miles (504 km). The three solid fueled stages completed their burns after about nine minutes, and the CLPS stage separated from the spacecraft after about four and a half minutes after third stage separation.

The next launch of an Epsilon rocket is expected later this year (2018) with a quartet of small satellites, including OrigamiSat-1, which will demonstrate the deployment and behavior of membrane structures in space, and AOBA-VELOX 4, a joint Japanese-Singaporan 2U cubesat to study Lunar Horizon Glow, the anomalous light possibly caused by dust around the edge of the Moon.

Written by: Christopher Paul
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