Question

Which type of satellite sensor captures data in various spectral bands, including visible, infrared and microwave?

• A. Lidar sensor
• B. SAR sensor
• C. Multispectral sensor
• D. Hyperspectral sensor

Hint:

• Multispectral sensors collect data in multiple (several to tens) discrete spectral bands, typically in the visible, near-infrared (NIR), and short-wave infrared (SWIR) regions. Some also have thermal infrared bands.
• Hyperspectral sensors collect data in many (hundreds) narrow, contiguous bands, providing a detailed spectrum.
• SAR sensors operate in the microwave region.
• LiDAR uses laser pulses (often NIR or green).
• No single common sensor type routinely captures imagery across visible, infrared, AND microwave regions simultaneously. The question likely has an error regarding "microwave" if "Multispectral sensor" is the intended answer for visible/infrared.

Answer 1

The Correct Option is C

Satellite sensors are designed to capture electromagnetic radiation reflected or emitted from the Earth's surface across different parts of the electromagnetic spectrum.

• Multispectral Sensor (option c): These sensors collect data in several discrete, relatively broad spectral bands. These bands are typically located in the visible, near-infrared (NIR), short-wave infrared (SWIR), and sometimes thermal infrared (TIR) portions of the spectrum. They do not typically operate in the microwave region. Examples: Landsat OLI, Sentinel-2 MSI, MODIS.
• Hyperspectral Sensor (option d): These sensors collect data in many (often hundreds) of very narrow, contiguous spectral bands. This provides a much more detailed spectral signature of the target. They also typically operate in the visible to infrared regions. Example: Hyperion.
• LiDAR (Light Detection and Ranging) sensor (option a): LiDAR is an active sensor that uses laser pulses (often in the near-infrared or green part of the spectrum) to measure distances and create 3D point clouds. It does not typically cover visible, infrared, and microwave.
• SAR (Synthetic Aperture Radar) sensor (option b): SAR is an active sensor that operates in the microwave region of the electromagnetic spectrum. It transmits microwave pulses and records the backscattered signal. It does not operate in the visible or infrared regions.

The question asks for a sensor that captures data in "visible, infrared and microwave". No single sensor type listed typically covers all three of these broad regions (Visible, Infrared, AND Microwave) simultaneously as its primary mode of operation for imaging.

• Multispectral/Hyperspectral sensors cover Visible and Infrared.
• SAR sensors cover Microwave.
• LiDAR uses specific laser wavelengths (often NIR or Green).

There might be an error in the question or options, as these regions are usually covered by different types of sensor technologies. However, if the question implies a satellite platform might carry different sensors, that's possible. But it asks for a "type of satellite sensor." Given the provided answer is (c) Multispectral sensor: This choice is correct for capturing "visible and infrared" bands. The inclusion of "microwave" in the question makes this problematic. If "microwave" was omitted, (c) would be clearly correct. Perhaps the question is flawed. If we assume "microwave" is an error in the question and it meant "visible and infrared", then multispectral is appropriate. If the question is strict about including microwave, then none of the passive optical/infrared sensors (multispectral, hyperspectral) fit. SAR is microwave only. LiDAR is laser-based. There isn't a common single sensor type for imaging that spans visible, infrared, and microwave. A satellite payload might have separate instruments. Assuming the question intended to ask about sensors that collect data across a wide range of the optical and infrared spectrum, then multispectral sensors are designed to do this in several broad bands. If the provided answer (c) is indeed correct, it implies either a misunderstanding in the question regarding "microwave" or a very broad interpretation where some specialized (but not common) multispectral concept might exist or the "and microwave" is ignored. For standard understanding, (c) fits "visible and infrared". \[ \boxed{\text{Multispectral sensor}} \]