TOKYO - A rapidly advancing technology known as remote sensing—used to observe and analyze Earth from space—is opening new possibilities for predicting disasters and understanding environmental changes.
Remote sensing refers to technology that observes the Earth remotely using satellites, aircraft, or drones. By analyzing light, electromagnetic waves, and other signals captured by sensors, researchers can monitor environmental conditions across the planet. The technology is drawing increasing attention as a potential solution for a wide range of issues, from abnormal weather patterns to natural disasters.
At the forefront of this research is the Center for Environmental Remote Sensing at Chiba University. According to center director Katsumi Hattori, analyzing disturbances in the ionosphere—the layer of charged particles high in Earth’s atmosphere—may allow scientists to detect signs that earthquakes or tsunamis are about to occur.
If successful, such research could significantly strengthen disaster preparedness. In some cases, Hattori’s team believes it may be possible to identify signals indicating earthquakes of around magnitude 6 several days before they occur.
Remote sensing technology has evolved dramatically over the past century. Early forms of the technology involved attaching cameras to balloons to photograph distant areas, originally for military reconnaissance. Over time, observation platforms moved higher into the sky—from balloons to aircraft and eventually to satellites capable of monitoring the entire planet.
Today, remote sensing involves sensors mounted on satellites, aircraft, and drones that capture reflected sunlight, infrared radiation, and other electromagnetic signals. By analyzing these data, scientists can determine conditions on the ground, such as vegetation health, soil moisture, or atmospheric changes.
One major challenge for traditional satellite observation is that clouds or nighttime conditions can obscure the Earth’s surface. To overcome this limitation, researchers are increasingly using microwave-based radar technology. Because microwave signals can penetrate clouds and operate at night, satellites equipped with this capability can observe Earth in nearly all weather conditions.
This approach, known as synthetic aperture radar, allows satellites to send electromagnetic waves toward the Earth and analyze the reflected signals. As a result, researchers can observe ground conditions regardless of rain, darkness, or cloud cover.
Japan has been actively developing such satellites. While a single satellite typically passes over the same location only once every several days, deploying multiple satellites in orbit allows scientists to observe the same area much more frequently—sometimes every day.
This capability is particularly valuable after disasters. By comparing satellite images before and after an earthquake or heavy rainfall, researchers can quickly determine where landslides have occurred or how much the ground has shifted along a fault line.
Rapid access to this information can help authorities respond more effectively in the crucial hours after a disaster. Rescue experts often emphasize that the first 72 hours are critical for saving lives. Remote sensing data could help emergency teams understand the situation on the ground much sooner and deploy resources more efficiently.
Beyond disaster prevention, remote sensing is also being applied in agriculture. By monitoring plant conditions and soil moisture levels, satellites and drones can detect crop diseases, drought stress, or irrigation needs. These data allow farmers to better manage fields and predict harvest yields.
Satellite imagery can also reveal patterns such as heat distribution in cities, helping researchers analyze the causes of the urban heat island effect.
One key tool used by researchers at Chiba University is Japan’s Himawari weather satellite series. The Himawari-8 and Himawari-9 satellites operate together, with one serving as a backup to ensure continuous monitoring of weather conditions around Japan and across large parts of the globe.
Maintaining multiple satellites ensures that observation data are not lost if one system fails. Japan is responsible for monitoring a large region of the Earth from its geostationary satellite position, making reliable operation essential for global weather observation.
For Hattori, the motivation behind this research dates back decades. After watching news coverage of the Great Hanshin-Awaji Earthquake in January 1995, he was deeply shocked and decided to focus his research on technologies that could contribute to disaster prevention.
Today, advances in remote sensing are expanding the ability to observe Earth in unprecedented detail. By combining satellite data, radar technology, and advanced analysis, scientists hope to not only understand environmental changes but also anticipate future events that could affect human life.
As the technology continues to evolve, the “scientific eye in the sky” may become one of the most powerful tools for protecting both the planet and the people who live on it.
Source: テレ東BIZ
