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High-performance small radar satellite "ASNARO-2"

Observing the ground using radio waves

NEC’s high-performance small radar satellite "ASNARO-2", is lightweight with a mass of 570kg, with a high observing ability to identify objects on the earth’s surface up to 1m above ground.

Visualizing radio waves below clouds

It is great fun looking down at earth from the sky from an airplane. The spoiler of such fun are clouds. Modern airplanes fly at altitudes of 10,000m or higher, but in cloudy weather, only cloud waves will be visible.
The same goes for satellites flying in space. That the earth is always covered by clouds is evident by just seeing any satellite image used in weather forecasts. If the sky is cloudy, one cannot see the ground from satellites.
That's where radar satellites come in. Light is blocked by clouds, but radio waves can pass through clouds. Using radar satellites, you can observe the ground not only under clouds, but also under volcanic plumes and at night. In recent years, there has been an increased interest internationally in radar satellites.

On August 9, 2017, the aircraft of the radar satellite "ASNARO-2" developed by NEC was released at the NEC Fuchu Plant, Japan. ASNARO (Advanced Satellite with New System Architecture for Observation) is a project of Japan’s Ministry of Economy, Trade and Industry to develop small earth observation satellites that are globally competitive. NEC participated in the ASNARO program as a satellite manufacturer and developed the optical satellite "ASNARO-1" and the radar satellite "ASNARO-2".

ASNARO-1 was launched in 2014 and has been in orbit since 2017.
NEC developed ASNARO-2, and is in charge of total satellite operations including creating plans for satellite imaging to obtaining the actual images.

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ASNARO-2 model. In-orbit configuration with radar antenna and solar cell
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ASNARO-2. The solar array paddle and radar antenna are folded. The main body’s upper and lower half have different colors. The upper is the mission equipment part and the lower is the satellite bus "NEXTAR"

Making radar satellites smaller and lighter

Optical observation satellites that observe the earth's surface with visible light to infrared light, observe the surface illuminated by the sun. The light source is the sun, and the satellite itself does not illuminate the ground.
Radar satellites, on the other hand, emit their own radio waves and reflect back on the ground to obtain images. The larger the antenna, the higher the resolution of the radar image. But even if the antenna is small, processing the received data with a computer on the surface of the earth will produce a high-definition image equivalent to that received by a virtually large antenna. This is one of the features of the synthetic aperture radar technology.

The biggest advantage of radar satellites is that they can see the surface of the earth, whether cloudy or at night. The disadvantage is that the equipment is bulky. In order to emit radio waves, a transmitter must be installed, and electric power for operating the transmitter is also required. Satellites also need solar cells with a larger area because they get their power from solar cells. Therefore, the satellite becomes large. Currently, radar satellites operated by countries around the world have a mass of about 1.2 to 2 tons.
In comparison, ASNARO-2 is 570kg in weight, and small and light. Yet it can produce high-definition images that can identify even a 1m object on the ground.

About satellite bus "NEXTAR"

A satellite bus is a set of functions required for any satellite, such as power supply, communication system, attitude control system, and thermal control system. With a satellite bus, it is easier to manufacture satellites with various functions by installing mission equipment parts with different functions.
The ASNARO-2 satellite bus developed by NEC is called "NEXTAR". Various ideas are included so that it can be easily combined with various mission equipment sections. For example, when exchanging data between internal devices, it employs a mechanism that allows data to be exchanged just by connecting wiring, similar to a PC network. By simply connecting each device to the common wiring, data can be exchanged. ASNARO-1 uses the same "NEXTAR". By using NEXTAR, development of ASNARO-1 and ASNARO-2 was done in a short time and at low cost.

Internationally, the need for small radar satellites such as ASNARO-2 is expected to increase. This is because radar observations of the Earth includes monitoring natural disasters such as volcanic activity and landslides, grasping the changing land use of cities, resource surveys to examine the distribution of mineral resources, sea ice observation, and ship monitoring, and more.
To meet these needs, NEC provides not only satellite development to date, but also on-orbit operations for the ASNARO-2 project.
In the future, we aim to process the obtained images to extract and provide important information for customers, and to play a comprehensive role for society as a solution provider.