Which sensor is designated as ETM+?

The Enhanced Thematic Mapper Plus (ETM+) is specifically the name of the sensor that is onboard the Landsat 7 satellite, which was launched in 1999. ETM+ is an advanced version of the Thematic Mapper, which is designed to capture high-resolution imagery of the Earth's surface. This sensor features enhanced capabilities including improved spatial resolution and additional spectral bands compared to its predecessors, allowing for more detailed and accurate assessment of land cover and land use.

The main function of the ETM+ sensor includes capturing multi-spectral images that can be used in various applications, such as agriculture, forestry, land-use planning, and environmental monitoring. The inclusion of additional spectral bands makes it especially useful for analyzing vegetation, water bodies, and urban areas.

Other options do not correspond to any established satellite sensors or their functions. The Extremely Thermal Mapper, the Enhanced Time Mark sensor, and the Environmental Thematic Mapper for Landsat 8 are not recognized designations in the context of Earth observation satellites, which further emphasizes the correctness of identifying the ETM+ with Landsat 7.