SAR Satalites

1. Sentinel-1A and Sentinel-1B (Sentinel-1): Part of the European Space Agency's Copernicus program, the Sentinel-1 mission consists of a pair of SAR satellites (Sentinel-1A and Sentinel-1B) that provide continuous all-weather, day-and-night radar imaging.

2. TerraSAR-X and TanDEM-X: These are German radar satellites operated by the German Aerospace Center (DLR) in partnership with Airbus Defence and Space. TerraSAR-X and TanDEM-X work together to create high-resolution SAR images and generate precise digital elevation models of the Earth's surface.

3. RADARSAT-2: A Canadian SAR satellite operated by the Canadian Space Agency. It provides radar imagery for various applications, including environmental monitoring, disaster management, and maritime surveillance.

4. Cosmo-Skymed: An Italian constellation of SAR satellites designed for dual-use applications, including civil and military uses. It consists of four satellites: Cosmo-Skymed 1, 2, 3, and 4.

5. ALOS-2 (Advanced Land Observing Satellite 2): A Japanese SAR satellite operated by the Japan Aerospace Exploration Agency (JAXA). ALOS-2 is used for various applications, including disaster monitoring, forestry, and agriculture.

6. RADARSAT Constellation Mission (RCM): A Canadian SAR satellite mission consisting of three identical satellites: RADARSAT-2, RCM-1, and RCM-2. RCM provides frequent radar imaging of Canada and other regions.

7. ICEYE: A private Finnish company operating a constellation of SAR microsatellites. ICEYE's small SAR satellites are known for their agility and ability to provide rapid revisit times.

8. COSMIC-2 (Constellation Observing System for Meteorology, Ionosphere, and Climate-2): While primarily a mission for atmospheric and ionospheric studies, COSMIC-2 includes a GNSS-RO (Global Navigation Satellite System Radio Occultation) payload, which can be used for SAR processing to obtain information about surface properties.

Comments

Optical Sensors in Remote Sensing

1. What Are Optical Sensors? Optical sensors are remote sensing instruments that detect solar radiation reflected or emitted from the Earth's surface in specific portions of the electromagnetic spectrum (EMS) . They mainly work in: Visible region (0.4–0.7 µm) Near-Infrared – NIR (0.7–1.3 µm) Shortwave Infrared – SWIR (1.3–3.0 µm) Thermal Infrared – TIR (8–14 µm) — emitted energy, not reflected Optical sensors capture spectral signatures of surface features. Each object reflects/absorbs energy differently, creating a unique spectral response pattern . a) Electromagnetic Spectrum (EMS) The continuous range of wavelengths. Optical sensing uses solar reflective bands and sometimes thermal bands . b) Spectral Signature The unique pattern of reflectance or absorbance of an object across wavelengths. Example: Vegetation reflects strongly in NIR Water absorbs strongly in NIR and SWIR (appears dark) c) Radiance and Reflectance Radi...

Radar Sensors in Remote Sensing

Radar sensors are active remote sensing instruments that use microwave radiation to detect and measure Earth's surface features. They transmit their own energy (radio waves) toward the Earth and record the backscattered signal that returns to the sensor. Since they do not depend on sunlight, radar systems can collect data: day or night through clouds, fog, smoke, and rain in all weather conditions This makes radar extremely useful for Earth observation. 1. Active Sensor A radar sensor produces and transmits its own microwaves. This is different from optical and thermal sensors, which depend on sunlight or emitted heat. 2. Microwave Region Radar operates in the microwave region of the electromagnetic spectrum , typically from 1 mm to 1 m wavelength. Common radar frequency bands: P-band (70 cm) L-band (23 cm) S-band (9 cm) C-band (5.6 cm) X-band (3 cm) Each band penetrates and interacts with surfaces differently: Lo...

Thermal Sensors in Remote Sensing

Thermal sensors are remote sensing instruments that detect naturally emitted thermal infrared (TIR) radiation from the Earth's surface. Unlike optical sensors (which detect reflected sunlight), thermal sensors measure heat energy emitted by objects because of their temperature. They work mainly in the Thermal Infrared region (8–14 µm) of the electromagnetic spectrum. 1. Thermal Infrared Radiation All objects above 0 Kelvin (absolute zero) emit electromagnetic radiation. This is explained by Planck's Radiation Law . For Earth's surface temperature range (about 250–330 K), the peak emitted radiation occurs in the 8–14 µm thermal window . Thus, thermal sensors detect emitted energy , not reflected sunlight. 2. Emissivity Emissivity is the efficiency with which a material emits thermal radiation. Values range from 0 to 1 : Water, vegetation → high emissivity (0.95–0.99) Bare soil → medium (0.85–0.95) Metals → low (0.1–0.3) E...

Pre During and Post Disaster

Disaster management is a structured approach aimed at reducing risks, responding effectively, and ensuring a swift recovery from disasters. It consists of three main phases: Pre-Disaster (Mitigation & Preparedness), During Disaster (Response), and Post-Disaster (Recovery). These phases involve various strategies, policies, and actions to protect lives, property, and the environment. Below is a breakdown of each phase with key concepts, terminologies, and examples. 1. Pre-Disaster Phase (Mitigation and Preparedness) Mitigation: This phase focuses on reducing the severity of a disaster by minimizing risks and vulnerabilities. It involves structural and non-structural measures. Hazard Identification: Recognizing potential natural and human-made hazards (e.g., earthquakes, floods, industrial accidents). Risk Assessment: Evaluating the probability and consequences of disasters using GIS, remote sensing, and historical data. Vulnerability Analysis: Identifying areas and p...

Geometric Correction

When satellite or aerial images are captured, they often contain distortions (errors in shape, scale, or position) caused by many factors — like Earth's curvature, satellite motion, terrain height (relief), or the Earth's rotation . These distortions make the image not properly aligned with real-world coordinates (latitude and longitude). 👉 Geometric correction is the process of removing these distortions so that every pixel in the image correctly represents its location on the Earth's surface. After geometric correction, the image becomes geographically referenced and can be used with maps and GIS data. Types 1. Systematic Correction Systematic errors are predictable and can be modeled mathematically. They occur due to the geometry and movement of the satellite sensor or the Earth. Common systematic distortions: Scan skew – due to the motion of the sensor as it scans the Earth. Mirror velocity variation – scanning mirror moves at a va...

Vineesh V, Geography

Search This Blog