Sensors and Imagery 4

What type of sensor is Sentinel-1?

SAR (Synthetic Aperture Radar), an active sensor.

What is Sentinel-1's target wavelength?

C-band radar.

What is Sentinel-1's spatial resolution?

5 × 5 m, 5 × 20 m, 25 × 100 m, or 20 × 20 m.

What is Sentinel-1's temporal resolution?

~6 days global coverage.

How many satellites in the Sentinel-1 constellation?

Sentinel-1A, 1B, 1C.

What are Sentinel-1's main applications?

Land monitoring, maritime monitoring, and emergency management.

Why does Sentinel-1 have denser coverage near the poles?

Polar orbits overlap more at high latitudes, increasing revisit frequency.

What type of sensor is Sentinel-2?

MSI (MultiSpectral Instrument), a passive sensor.

What is Sentinel-2's target wavelength?

Visible to shortwave infrared.

What is Sentinel-2's spatial resolution?

10 m, 20 m, 60 m depending on the band.

What is Sentinel-2's temporal resolution?

5-10 days global coverage.

How many satellites in the Sentinel-2 constellation?

Sentinel-2A, 2B, 2C.

What are Sentinel-2's main applications?

Land monitoring, emergency management, security, and climate change.

What type of sensors are on Landsat 9?

OLI (Operational Land Imager) and TIRS (Thermal Infrared Sensor).

What is Landsat 9's target wavelength?

Visible to thermal infrared.

What is Landsat 9's spatial resolution?

30 m (multispectral), 15 m (panchromatic), 100 m (thermal).

What is Landsat 9's temporal resolution?

16 days global coverage.

What are Landsat 9's main applications?

Monitoring land use, vegetation health, water resources, agricultural forecasting, urban planning, environmental change detection.

What is the Harmonized Landsat-Sentinel (HLS) project?

A NASA project combining OLI (Landsat 8/9) and MSI (Sentinel-2A/B) to produce seamless reflectance records.

What is the revisit frequency of HLS at the equator?

Every ~3 days, more frequent at higher latitudes.

Who operates major Earth-observing satellites?

Large governmental agencies (e.g., NASA, ESA), usually providing free data.

What role do private companies play in the satellite ecosystem?

They launch satellites and typically sell data for a fee.

What is a major advantage of free satellite data?

Wider access and use in research, policy, and applications.

What trend is emerging in satellite technology?

Satellites are becoming lighter and smaller, enabling more frequent launches and wider coverage