Landsat
The Landsat satellites are a series of civil earth observation satellites from NASA for remote sensing of the continental surface of the earth as well as the coastal regions.
They are mainly used to map natural resources and to record changes caused by natural processes and human activity. Since 1972, eight satellites (including one false start) of this series have been launched, which are divided into four series. The remote sensing platform uses various sensors to record so-called remote sensing data .
The Landsat program has its origins in the time of the Apollo moon landing missions in the 1960s, when images of the earth's surface were first taken from space. In 1965, the then director of the United States Geological Survey (USGS), William Pecora, suggested setting up a remote sensing satellite program to obtain data on the earth's natural resources. In the same year, NASA began methodical remote sensing of the earth's surface with the help of instruments placed on aircraft. In 1970, NASA finally got permission to build a satellite. Landsat 1 was launched just two years later and remote sensing could begin.
Satellite launches
- The “Earth Resources Technology Satellite-1 (ERTS-1)”, developed on the basis of a Nimbus weather satellite, was launched in 1972; in 1975 it was renamed Landsat 1. Instruments: RBV (Return Beam Vidicon) and MSS ( multispectral scanner ). In 1978 it went out of service.
- 1975: Landsat 2 started with the same instruments. 1983 out of service.
- In 1978 Landsat started 3. RBV panchromatic instead of multispectral, MSS with thermal band, 1983 out of service.
- 1982: Landsat 4 with MSS and TM ( Thematic Mapper ), due to problems early launch of Landsat 5, 1987 out of service.
- 1984: Landsat 5 with MSS and TM. Since about 2004 (?) No more pictures from Africa and South America. From Nov. 26, 2005 to Jan. 2006 problems with the servomotor for the solar panels. At just under 29 years, Landsat 5 holds the record for the longest service life of an earth observation satellite. After the failure of a replacement gyroscope, the end of the satellite was decided. The last command was sent to the satellite on June 5, 2013.
- 1986: With the French commercial , the Landsat series faced competition for the first time from another civilian operator of earth exploration satellites. LANDSAT 5 recordings cost around $ 80 to $ 500 in 1986.
- 1993: Landsat 6 with ETM, was lost at the start.
- 1999: Landsat 7 with ETM + ( Enhanced Thematic Mapper ), since the end of 2003 with significantly reduced image quality because the Scan Line Corrector failed.
- 2001: The experimental successor sensor ALI was started.
- 2008: Planning for the start of the Landsat Data Continuity Mission (LDCM) begins
- 2013: Landsat 8 launched.
- 2021 (planned): Launch of Landsat 9
Landsat 1 to 5 and 7 were launched with Delta missiles . Landsat 6 flew on a Titan 23G missile . The LDCM mission was launched on an Atlas V rocket.
Importance of remote sensing data
The Landsat program has provided basic knowledge of the earth's surface since its inception. The level of detail in the Landsat images enables researchers to make statements about urban growth, agricultural irrigation and tropical deforestation throughout the year, for example . The program also contributes significantly to a better understanding of the development of the coral reefs and the Antarctic glaciers.
In 1982, the Ocean Earth Construction and Development Corporation with branches in New York and Düsseldorf showed the world public through Landsat images of the Falklands War . Company founder Peter Fend sold the recordings to US and European TV stations. In 1983, John M. Miller, a geophysicist at the University of Alaska, published footage from Landsat showing an Arctic rescue operation in which Soviet Navy icebreakers attempted to free 50 trapped ships from the pack ice . In 1984 Miller published footage showing how Soviet submarines carried out novel missile tests in the Arctic near Wrangel Island . In an emergency, the nuclear weapons on board should be fired through openings in the pack ice. In March 1985, the New York Times reported that Japan was using Landsat footage to investigate military activities by the Soviet Union in Siberia and the Pacific. Landsat satellites also serve the goals of the International Charter on Space and Natural Disasters .
The knowledge gained is usually mapped. Paul Lowman drew the first map based on a Landsat photograph in 1972. Collected information also served as the basis for a series of maps of tectonic activities, the latter being dated to the year 2003. Most of the earth's surface in online map portals such as B. Google Maps (Earth), MSN Maps or Yahoo Maps is represented by processed Landsat 7 satellite images.
You can find out which image data is available from various sources (see also web links):
- Eurimage Einet contains data from Landsat TM and Quickbird with Quicklooks
- DESCW also contains older MSS data, albeit without Quicklooks, and other satellite systems
- USGS Earth Explorer also with Quicklooks
Landsat Data Continuity Mission
After the last of the seven Landsat satellites was put into orbit in 1999, plans for the so-called Landsat Data Continuity Mission (LDCM) have been in progress since 2008. The aim of this program is to keep data logging on the surface of the planet and it will continue the 40 year history of the Landsat missions under a new name. The LDCM is a collaborative project between NASA and the US Geological Survey (USGS).
The LDCM images will cover a resolution of around 15-100 meters and can be used primarily for the observation of land use change, the evaluation of land changes, e.g. B. after flood disasters as well as generally for the observation of water use worldwide. By continuing these activities, the LDCM enables the areas of geo and climate research to be supplied with analytical data. The new LDCM satellite thus represents the eighth Landsat satellite. It was launched on February 11, 2013. The satellite was brought into Earth orbit to an altitude of around 705 kilometers with an Atlas V-401 rocket.
The new Landsat satellite is equipped with two types of instruments:
- the so-called "Operational Land Imager" and
- a sensor for the detection of the electromagnetic radiation of the planet in the infrared range.
Compared to its predecessors, the “Operational Land Imager” has two more spectral ranges: While one is particularly suitable for tracking down cirrus clouds, the other is primarily intended to be used for observing coastal regions. The satellite's TIRS (Thermal Infrared Sensor) infrared camera works on two additional spectral ranges in the long-wave infrared range, which was previously covered by the Landsat satellites 4–7. As a further improvement compared to its predecessors, the LDCM satellite will send 400 images per day to the ground station and thus exceed the recording performance of the old Landsat satellites by up to 150 images per day. Last but not least, this increases the chance of obtaining cloud-free images of the earth's surface.
orbit
Landsat 1–3: 907–913 km, Landsat 4–7 705 km
orbit altitude
Quasipolar, sun-synchronized orbit with 99.2 ° inclination (Landsat 1–3) or 98.2 ° (Landsat 4–7). This means that each area is always overflown at the same time.
Equator crossing: 9:30 am local time (Landsat 1–5) or 10:00 local time (Landsat 7), i. H. Recording conditions that remain largely the same.
One orbit around the earth takes about 100 minutes, i.e. 14 cycles per day.
The observed strip of land has a width of 185 km, so that the same area is observed every 18 (Landsat 1–3) or 16 days (Landsat 4–7).
Instruments
RBV multispectral (Landsat 1, 2) :
band 1: 0.475-0.575 µm, blue-green
band 2: 0.580-0.680 µm, red
band 3: 0.690-0.830 µm, near infrared
resolution: 80 m
RBV panchromatic (Landsat 3) :
Volume A: 0.505-0.750 µm
resolution: 80 m
| LANDSAT 4.5 (1–3) | LANDSAT 4.5 | LANDSAT 7 | LANDSAT 8 | |
|---|---|---|---|---|
| Scanning system | Multispectral scanner
(MSS) |
Thematic mapper
(TM) |
Enhanced Thematic
Mapper Plus (ETM +) |
Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) |
| business | since 1972 | since 1982 | since 1999 | since 2013 |
| Pixel size | 79 × 79 m | 30 × 30 m | 30 × 30 m | 30 × 30 m |
| Spectral channels | 1 (4) 0.50-0.60 µm, green
2 (5) 0.60-0.70 µm, red 3 (6) 0.70-0.80 µm, near infrared 4 (7) 0.80-1.10 µm, near infrared |
1 0.45-0.52 µm, blue-green
2 0.52-0.60 µm, green 3 0.63-0.69 µm, red 4 0.76-0.90 µm, near infrared 5 1.55-1.75 µm, mid infrared 7 2.08-2.35 µm, mid infrared |
1 0.45-0.52 µm, blue-green
2 0.53-0.61 µm, green 3 0.63-0.69 µm, red 4 0.78-0.90 µm, near infrared 5 1.55-1.75 µm, mid infrared 7 2.09-2.35 µm, mid infrared |
1 0.433-0.453 µm, coast and aerosol
2 0.450-0.515 µm, blue 3 0.525-0.600 µm, green 4 0.630-0.680 µm, red 5 0.845-0.885 µm, near infrared 6 1.560-1.660 µm, mid infrared 7 2.100-2.300 µm, mid infrared 9 1.360-1.390 µm, Cirrus |
| Thermal channel | 6 10.4–12.5 µm (120 × 120 m) | 6 10.4–12.5 µm (60 × 60 m) | 10 10.30–11.30 µm (100 × 100 m)
11 11.50–12.50 µm (100 × 100 m) |
|
| Panchromatic canal | 8 0.52-0.90 µm (15 × 15 m) | 8 0.500–0.680 µm (15 × 15 m) | ||
See also
Web links
- NASA homepage
- Landsat Data Continuity Mission
- Landsat data University of Maryland
- USGS EarthExplorer
- DESCW (Display Earth remote sensing Swath Coverage for windows)
- EnMAP homepage
- Landsat 8 brochure (PDF; 509 kB)
Individual evidence
- ↑ Landsat 5 Sets Guinness World Record For 'Longest Operating Earth Observation Satellite. NASA, February 10, 2013, accessed February 22, 2013 .
- ↑ June 5, 2013 - Final command sent to Landsat 5th US Geological Survey, June 5, 2013, accessed June 12, 2013 .
- ↑ Upcoming ELaNa CubeSat Launches . NASA, accessed May 6, 2020.