SPOT (satellite)
SPOT ( S ystems P robatoire d ' O bservation de la T erre later: S atellite P our L' O bservation de la T erre ) is the name of a satellite system, the French space agency CNES , developed in France, along with Belgium and Sweden. The SPOT constellation has been providing high-resolution optical images of large areas since 1986. SPOT 6 and SPOT 7 ensure data continuity until 2024. The data supplied will also be integrated into the Copernicus system .
Spot Image Astrium in Toulouse (France) markets the images with a resolution of 8 meters that SPOT can take from almost any point on earth.
Technical specifications
Satellites
The 1,800 kg earth exploration satellite SPOT 1 was launched on February 22, 1986 and took photos of the earth for the first time in an orbit at an altitude of 822 kilometers, which no civil satellite before it had sent to earth in this resolution. With two permanently working cameras, SPOT 1 registered objects on earth the size of a truck. This made the satellite superior to the US Landsat satellites that had been in use since 1972 . The corresponding images could be bought by agricultural experts, geologists , town planners, meteorologists , governments and other interested parties in 1986 from Spot-Image, a company founded in 1982, at a price of up to 1700 US dollars. The advantage of SPOT 1 with its moveable cameras compared to the then most modern Landsat 5 was that it was able to photograph the same desired target on earth again in 2 to 3 days, while LANDSAT 5 needed 2 weeks for this. For this, photos from LANDSAT 5 were available for 80 to 500 US dollars.
SPOT 2 followed on January 22, 1990 (which was already planned for 1988) and SPOT 3 on September 26, 1993 , both of which weigh around 1800 kg. SPOT 4 was launched on March 24, 1998, and the last time the 3,000 kg SPOT 5 was launched into orbit on May 4, 2002 was an Ariane 4 rocket . The dimensions of the satellites increased from 2 × 2 × 4.5 m for SPOT 1 to up to 3.1 × 3.1 × 5.7 m for SPOT 5.
All satellites orbit the earth at an altitude of 822 km in a quasi-polar, sun-synchronous orbit that is inclined 98.7 ° to the earth's axis, once in 101.4 minutes. They record the same area every 26 days. This repetition rate can, however, be increased because the recording direction can be inclined by ± 27 °. This means that stereoscopic recordings are also possible.
SPOT 2 was decommissioned in July 2009. Through several orbit maneuvers , the orbit was lowered so far that it will later burn up in the earth's atmosphere.
The launch of SPOT 6 took place on September 9, 2012 the identical SPOT 7 was launched into space on June 30, 2014. The satellites, which weigh around 710 kg, are based on the AstroSat-500 satellite bus from Astrium and are expected to remain in operation for 10 years . With an orbit height of 695 km and an orbit inclination of 98.2 ° (with the two Pléiades satellites in the same orbit), they provide images with a swath width of 60 km and a maximum resolution of 1.5 m. In total, SPOT 6 and SPOT 7 can record a total of 6 million km² per day at a repetition rate of one day. The two satellites are also very agile and can be maneuvered very quickly from their position to any point within a radius of 1500 km.
Sensors
All SPOT satellites had or have two identical sensors on board, each of which can be operated in different modes.
The sensors are:
- SPOT 1: (+) HRV with XS ( multispectral ) and P mode ( panchromatic )
- SPOT 2: (+) HRV with XS- (multispectral) and P-mode (panchromatic)
- SPOT 3: (+) HRV with XS (multispectral) and P mode (panchromatic)
- SPOT 4: (+) HRVIR with XI (multispectral) and M mode (panchromatic)
- SPOT 5: (+) HRG with HI- (multispectral), HX- (multispectral), HM- (panchromatic) and THR mode (panchromatic)
- SPOT 6 & 7: (multispectral) and (panchromatic)
(+) Satellite no longer in operation
| sensor | Frequency band | Spatial resolution in m | Wavelength in μm |
|---|---|---|---|
| SPOT 1 SPOT 2 SPOT 3 |
Panchromatic B1: green B2: red B3: near infrared |
10 × 10 20 × 20 20 × 20 20 × 20 |
0.50 - 0.73 0.50 - 0.59 0.61 - 0.68 0.78 - 0.89 |
| SPOT 4 | Panchromatic B1: green B2: red B3: near infrared B4: medium infrared |
10 × 10 20 × 20 20 × 20 20 × 20 20 × 20 |
0.61 - 0.68 0.50 - 0.59 0.61 - 0.68 0.78 - 0.89 1.58 - 1.75 |
| SPOT 5 | Panchromatic B1: green B2: red B3: near infrared B4: medium infrared |
2.5 × 2.5 or 5 × 5 10 × 10 10 × 10 10 × 10 20 × 20 |
0.48 - 0.71 0.50 - 0.59 0.61 - 0.68 0.78 - 0.89 1.58 - 1.75 |
| SPOT 6 SPOT 7 |
Panchromatic B1: blue B2: green B3: red B4: near infrared |
1.5 × 1.5 6 × 6 6 × 6 6 × 6 6 × 6 |
0.45 - 0.74 0.45 - 0.52 0.53 - 0.59 0.62 - 0.69 0.76 - 0.89 |
use of data
SPOT satellite images are a source of information for analyzing, monitoring, forecasting and managing resources and monitoring activities on Earth. Possible areas of application are, for example:
- Mapping for civil and military purposes
- Management of natural and man-made disasters
- Insurance
- Exploration of natural resources
- Land planning
- Agriculture
- Construction
- environmental Protection
- Maritime surveillance
- Geographic information systems
The satellites also provide data under the International Charter on Space and Natural Disasters .
Follow-up missions
Proba V can be seen as a supplement to the SPOT program and continues the tasks of the French satellite Spot-4 (mission: March 1998 to January 2013). Proba-V flies in the same orbit as Spot-5 (mission: since May 2002) and was supposed to replace it in 2014. However, in 2016, Spot-5 was still active. The more sophisticated Proba-V enables the data from the French satellite to be checked and supplemented with a much faster orbit and an enormous swath width of 2,250 km.
See also
Web links
- Astrium Geo
- CNES ( Memento of May 30, 2008 in the Internet Archive )
- EADS Astrium - Spot
Individual evidence
- ↑ Le CNES désorbite le satellite SPOT 2. Techno-Science.net, July 24, 2009, accessed on August 4, 2009 (French).
- ↑ Klaus Schmidt: Deorbitation of Spot 2nd International Space Fellowship, July 31, 2009, accessed on August 4, 2009 (English).
- ↑ http://www.thehansindia.info/News/Article.asp?category=1&subCategory=3&ContentId=80489 straight line | url = http: //www.thehansindia.info/News/Article.asp? Category = 1 & subCategory = 3 & ContentId = 80489 | date = 2018-11 | archivebot = 2018-11-30 16:31:13 InternetArchiveBot}} (link not available)
- ^ William Graham: India's PSLV successfully lofts SPOT 7 and companions. nasaspaceflight.com, June 30, 2014, accessed June 30, 2014 .
- ↑ a b SPOT 6 from Astrium is ready for launch campaign ( Memento from February 21, 2013 in the web archive archive.today )
- ^ Astrium: SPOT 6 & 7: Astrium GeoInformation Services
- ↑ SPOT 6 & SPOT 7 technical data sheet (PDF; 734 kB)
- ↑ ESA Earth Online SPOT. ESA, September 4, 2015, accessed March 13, 2016 .