Descriptions of ERS Satellites
Specialists from “Samara” Data Acquisition and Processing Center receive and process data from the following spacecrafts:
1. Resurs-DK1 Satellite
2. Satellite Meteorological System NOAA (according to www.nasa.gov)
Satellites of NOAA series (National Oceanic and Atmospheric Administration, USA) have been operated from the early 70s at the altitude of about 800 km. The first satellite of these series, TIROS-M, was injected into orbit on the 23rd of January, 1970. The owner of the satellite is the USA.
Five satellites of these series are currently operated on orbit: NOAA 15 (May, 1998), NOAA 16 (September, 2000), NOAA 17 (June, 2002), NOAA 18 (May, 2005), NOAA 19.
The satellites are functioning on a sun-synchronous orbit; it means that every 24 hours the satellite flies over the certain territory at approximately one and the same local time.
The altitude of orbit is about 800 km with inclination of 990. The orbits lay close to the Earth poles, and due to wide swath it guarantees survey of any surface area with normal spatial resolution no less that 4 times in 24 hours by each satellite. The satellites are lofted into orbits in such a way that surveys made by different satellites are rather evenly sequenced in time. Orbital period of revolution round the Earth is 102 minutes.
Satellites of NOAA series are equipped with two sets of AVHRR (Advanced Very High Resolution Radiometer) instruments and a set of vertical sounding hardware. The main data content is transmitted by AVHRR scanning radiometer operating in 5 spectral bands:
|
Spectrum |
Spectral range, μm |
Typical usage |
1 |
visible |
0.58-0.68 |
Daylight survey of clouds and surface mapping |
2 |
visible |
0.725-1.10 |
Observation over water borders of land |
3 |
near-infrared |
3.55-3.93 |
Night survey of clouds, determination of water surface temperature |
4 |
infrared |
10.5-11.3 |
Night survey of clouds, determination of water surface temperature |
5 |
infrared |
11.5-12.5 |
Determination of water surface temperature |
Satellite spatial resolution is 1.1 km and swath is 3000 km.
TOVS (Tiros Operational Vertical Sounder) serves the purpose of vertical sounding of atmosphere. Sounder is a three-component system including:
· 4-spectrum Microwave Sounding Unit (MSU): observation over cloudy regions,
· 3-spectrum Stratospheric Sounding Unit (SSU): determination of stratosphere temperature,
· 20-spectrum High-resolution Infrared Radiation Sounder (HIRS/2): determination of vertical temperature profile, water vapour and ozone content.
NOAA operating band is 1670—1710 MHz.
Fields of data application:
Ecology:
· detection of large industrial emissions and monitoring of its further spreading;
· detection of polluting substances dumping to water reservoirs;
· detection of floods and assessment of disaster;
· monitoring of vast regions for the purpose of detection of hazardous sources of contamination;
· monitoring of dust storms.
Meteorology:
· restoration of vertical temperature profile and ambient air humidity;
· real-time forecast of intense cyclone formation;
· visualization of weather conditions and weather charts compilation;
· assessment and control of snow cover formation dynamics.
Agriculture and forestry:
· control of forest and plain fires origin and its spreading.
Oceanology and hydrology:
· assessment of ice conditions;
· real-time detection of flooded zones during snowmelt flood time and freshet.
3. EOS[1] series satellites
EOS (Earth Observing System) comprehensive program of NASA, aimed on Earth researching, includes three specialized satellites “TERRA” and “AQUA”, “AURA”, dedicated for earth, water and air researching respectively.
Specialists from “Samara” Data Acquisition and Processing Center receive and process data from “TERRA” and “AQUA” satellites of EOS series, equipped with MODIS spectroradiometer.
«TERRA»
EOS-AM1 (known as Terra) was launched on 18 of December 1999 within the frame of EOS program. The satellite has sun-synchronous polar orbit (altitude - 705 km, revolution period – 99 min, inclination - 98,2°; EOS-AM cross the Equator during flight from north to south at 10.30 on local time).
«AQUA»
“AQUA” Spacecraft was launched on 4 of May 2002 from Vandenberg Air Force Base (USA) and was carried into near polar sun-synchronous orbit 705 km altitude. Downlink from satellite is going on in continuous mode aside from five-minute pause when communication with ground station in Poker Flat (Alaska) and Spitsbergen (Norway).
“AQUA” equipped with complicated sounding system permitting troposphere temperature detection all aver the world with an accuracy up to 1°C and 1 km altitude resolution. Troposphere is the lowest layer of the atmosphere of the Earth; its comes to an end approximately at 10-15 km height depends on geographical location and contains most part of cloudiness.
Satellite orbital period and survey bandwidth (up to 2300 km) allow global Earth coverage with observed data with twice a day periodicity.
Main specifications:
Launch date: |
4 of May 2002 |
| |||||
Mode/port: |
1-2 |
3-7 |
8-19 |
20-25 |
26 |
27-36 | |
Spectral range (mcm): |
0,62-0,88 |
0,46-2,16 |
0,41-0,97 |
3,66-4,55 |
1,36-1,39 |
0,54-14,39 | |
Nadir spatial resolution: |
250 m |
500 m |
1000 m |
| |||
Survey bandwiwth: |
2300 km |
| |||||
Radiometric resolution: |
12 BPP |
| |||||
Survey periodicity: |
2 times a day |
| |||||
Orbital elements |
| ||||||
Eccentricity |
0.000921006 |
| |||||
Inclination |
98,2° |
| |||||
Synodic period |
98.4 min |
| |||||
Apogee |
686 km |
| |||||
Perigee |
673 km |
|
MODIS (Moderate-Resolution Imaging Spectroradiometer)spectroradiometer with average resolution is one of the key instruments of this series. MODIS, mounted on “TERRA” and “AQUA”, consist of two scanning spectrometers, one of them (MODIS-N) surveys in nadir and another one (MODIS-T) may has survey axis inclination. Spectroradiometer has 36 spectral channels with 12-bit radiometric resolution in visible, nearby, middle and distant IR range; dedicated for reflected spectral imaging from daytime part of the Earth and day/night emission in every point of the earth surface with spatial resolution:
· in two areas (620-670 и 841-876 nm) – 250 m,
· in five areas of visible and nearby IR range – 500 m,
· in another (range from 0,4 up to 14,4 mkm) – 1000 m.
Downlink from SC MODIS to ground station is in direct broadcasting mode. Due to continuous operation and broad survey band any territory within the station visible area is under survey once at least.
It allows usage of MODIS data for solving different tasks in regular monitoring of natural phenomena (ice conditions control, snow cover dynamic control, forest fire and spring flood monitoring etc.)
[1] information from www.ntsomz.ru