A whisk broom or spotlight sensor, also known as an across-track scanner, is a technology for obtaining

satellite image Satellite images (also Earth observation imagery, spaceborne photography, or simply satellite photo) are images of Earth collected by imaging satellites operated by governments and businesses around the world. Satellite imaging companies sell i ...

s with optical cameras. It is used for passive

remote sensing Remote sensing is the acquisition of information about an physical object, object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring inform ...

from space. In a whisk broom sensor, a mirror scans across the

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

’s path (

ground track A satellite ground track or satellite ground trace is the path on the surface of a planet directly below a satellite's trajectory. It is also known as a suborbital track or subsatellite track, and is the vertical projection of the satellite's ...

), reflecting light into a single

detector A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a devi ...

which collects data one

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a Raster graphics, raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, p ...

at a time. The moving parts make this type of sensor expensive and more prone to wearing out, such as in the

Landsat 7 Landsat 7 is the seventh satellite of the Landsat program. Launched on 15 April 1999, Landsat 7's primary goal is to refresh the global archive of satellite photos, providing up-to-date and cloud-free images. The Landsat program is managed and ...

. Whisk broom scanners have the effect of stopping the scan, and focusing the detector on one part of the

swath width A swathe ( British English, rhymes with "bathe"; or swath American English, rhymes with "cloth") is the strip of cut crop made by a scythe or a mowing-machine. A mower with a scythe cuts a swathe along the mowing-edge leaving the uncut grass t ...

. Because the detector is only focused on a subsection of the full swath at any time, it typically has a higher resolution than a push broom design for the same size of scan swath. All sensors aboard the

Landsat The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to Lan ...

series of satellites used the whisk broom design until

Landsat 8 Landsat 8 is an American Earth observation satellite launched on 11 February 2013. It is the eighth satellite in the Landsat program and the seventh to reach orbit successfully. Originally called the Landsat Data Continuity Mission (LDCM), it i ...

which used a push broom sensor.

References

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External links

Earth Observing-1
(NASA), with animated whisk broom and push broom illustrations Image sensors Remote sensing

See also

References

External links