DE29924577U1 - Hot temperature event detection has six satellites with forward and rearward pointing sensors for dual observation points - Google Patents

Abstract

The satellite system has six dual view satellites (2-7) at a height of 1670 Km. This results in an orbit period of 120 minutes and hence a satellite passing a given point every 20 minutes. The satellites have two sets of sensors, one pointing forward and one rearwards. The angles are such that the sensors view areas 3340 Km apart. This is also the distance between the rear sensor view of one satellite and the forward sensor view of the next satellite. Hence each area is viewed every 10 minutes.

Description

The present invention relates to generally a satellite-borne high temperature event (HTE) detection arrangement, a multi-spectral image sensor working in the visible and infrared wavelength range with double vision.

In particular, the present invention relates on a satellite-borne multispectral image sensor arrangement for data collection for the Quasi real-time detection of high temperature events on the earth's surface, such as e.g. Vegetation fire, volcanic eruptions, coal mine fires and Industrial disasters, should be used where early and reliable detection high-temperature events (HTE) has the highest priority. High-temperature events on the surface of the earth cause very often Environmental disasters.

A very important requirement for the determination the HTE parameter, e.g. Temperature, scope and location is the reliable satellite-based remote detection of high-temperature events as Heat Set goals.

Regarding their area concerns This invention employs techniques for remote detection of heat targets the earth's surface on the basis of system-corrected multispectral data from satellite-borne optoelectronic Image sensor systems used to capture co-registered radiometric Image scene data in the mid-infrared (MIR, e.g. 3-5 μm range), in thermal infrared (TIR, e.g. 8-13 μm) and in visible / near infrared (VNIR, e.g. 0.4 1.0 μm) are.

So far, have been satellite-borne multispectral and co-registered image sensor data for off-line detection and surveillance of devastating fires and other high temperature events (HTE) on the surface of the earth used. The data of the Advanced Very High Resolution Radiometer (AVHRR) sensor on the NOAA meteorological satellites or along the data Track Scanning Radiometers (ATSR) sensors on the ERS 1/2 satellites e.g. will be ongoing for the detection of forest fires used. The mentioned However, multispectral image sensors are not used for HTE detection used, but their data is currently operational.

The main problems with a reliable fire or remote heat target detection and analysis based on Optoelectronic satellite sensor data are:

• - the strong temporal and spatial Fluctuation within the heat target (fire),
• - it is a big Dynamic range of the sensor channels required about saturation to avoid,
• - blackout the hot spot through smoke and clouds,
• - changeable Radiation emission of the background near the heat target, and
• - various Types of false alarm candidate targets.

False alarm candidates are:

• - industrial Hot spots,
• - clouds,
• - sun glitter,
• - Surfaces with higher Albedo, and
• - extensive warm surfaces (heated by the sun).

A severe limitation of the both previously mentioned operational sensors is that their 3-5 μm channel, which is the most sensitive channel for HTE detection, one saturation suffers as soon as the temperature of a picture element (pixel) occupies Aim higher than 50 ° C is.

The scan cone axis of the ATSR sensor is down and facing forward in the along-track direction of the satellite, whereby a scan across the satellite orbit reaches in two areas becomes. An Advanced Along Track Scanning Radiometer (AATSR) with additional channels in the visible and near infrared (VIS / NIR) is on the European polar platform ENVISAT are flown. The main goal of the AATSR is to continuity of the ATSR-1 and ATSR-2 records establish the exact sea temperature (SST), which means that it is not also used for HTE detection.

A full circular / conical scan with two observation zones (regarding the nadir forward and backward) was in the MSU-K scanner realized on the Russian spacecraft (S / C) of the "Okean O" series in the years 1983 to 1986 was installed. The MSU-K had a spectral band in the 0.5-0.9 μm range and couldn't for HTE detection can be used.

Various proposals have been created since 1994 of suitable satellite-borne high-temperature disaster detection systems in Have been considered, such as:

• - the Fire detection system FIRES (Fire Recognition Satellite System), that was proposed by the German aerospace research institute DLR is
• - the Fire Sat system for determining the spatial and temporal distribution of burning biomass, proposed by NASA Langley Research Center,
• - the satellite-based forest fire detection system FUEGO for the Mediterranean region, proposed and exploited by a European consortium, one Re-visit time of 30 minutes is one of the most critical planning requirements is
• - A prototype of an intelligent infrared sensor system FOCUS, which was to be flown on the international space station ISS (International Space Station), was developed by the DLR of the European Space Agency (ESA) in response to an occasion Announcement of Opportunity proposed for an externally attached payload during the early use of the ISS.

Draw both FIRES and FOCUS the use of multispectral infrared image data, which from one forward looking Fore Field Sensor (FFS) for autonomous on-board detection of high temperature events (HTE) can be considered.

The sensor in demonstration technology for one bispectral IR detection BIRD (Bi-spectral IR Detection), which is mainly used for heat point detection and analysis to be used is now under development and was supposed to fly on a small satellite mission in 2000 become.

Both the operational unsuitable discussed Fire sensors (AVHRR, ATSR and AATSR) as well as the proposed ones and planned, suitable fire detection sensors (FIRES, FireSat, FUEGO, FOCUS or BIRD) do not prefer to use one in two Direction of view simultaneously working, multispectral infrared image sensor with permanent forward and backward observation direction into consideration.

Simultaneous forward and backward space image sensors are used to create earth observation data for digital terrain models (DTM; Digital Terrain Model). These are mostly panchromatic optoelectronic sensors are made from CCD (Charge Coupled Device) memory array built in the VIS / NIR wavelength range work below 1.0 μm. You can but because of the absence of channels in the middle and thermal infrared wavelength range not for HTE detection can be used.

It is accordingly an object of the present invention to define an optoelectronic satellite sensor arrangement, who are capable of it is to acquire multispectral infrared image data that is simultaneous in a forward and a backward-facing one Observation direction are recorded, being almost in both cases same pick-up strip widths (swath widths) covered which increases the rate of re-visits becomes.

 According to the present invention will for a Increase in the rate of observation visits by a satellite-borne High temperature event (HTE) detection arrangement provided that one in the Visible and infrared wavelength range working multispectral image sensor with double vision and is characterized by the following features:

• a) two sensor parts that a fixed forward and backward oriented Provide the direction of observation and have almost the same areas the same recording strip width (swath widths) twice either by optical-mechanical scanning accordingly the "whisk broom" scanner principle, through opto-electronic scanning according to the "push broom" scanner principle or cover by conical scanning;
• b) Means for simultaneous geometric registration of the multispectral Forward and image data of the looking back Sensor part, both on the surface of the earth at the same time Satellite track direction from each other about a thousand or more kilometers remote areas watch and covered everyone Recording strip (swath) twice during a time interval of a few minutes during an overflight perceive the satellite;
• c) the two sensor parts have identical spectral, radiometric and geometric resolution parameters on what is the use of identical hot spot detection and analysis algorithms for the multispectral image data allowed by the forward and backward oriented sensor part be preserved.

A possible hot spot detection and analysis algorithm is in European patent application EP-A-O 892 286 outlined.

A desired increase in hot spot detection reliability the satellite-borne high-temperature event (HTE) detection arrangement, the one according to the invention designed multi-spectral image sensor with double vision is achieved by two sensor parts, the two almost the same surfaces with very different angles between the image sensor viewing direction and cover the angle of the sun, what makes it possible false alarms related to sunshine due to the combined use of the recording strips (swaths) that are not disturbed by sunshine the forward and the backward To avoid image.

This arrangement is preferably characterized by sensor parts that have almost the same surfaces a big one Angles of about 50 - 90 ° between cover the two viewing angles, what is recognizing of high temperature events (HTE) in the case of partial cloud cover with a higher one Probability and reliability than in the case of HTE remote sensing across only one observation area to the satellite orbit track.

According to a further embodiment of the invention, a reduction in the re-visit observation time by a factor of two is ensured in a multi-satellite system consisting of N satellites which are equally spaced apart in an earth orbit, each of these satellites with a previously mentioned one that is permanently looking forwards and backwards Multispectral image sensor arrangement is equipped, compared to the achievable re-visit time for N satellites that are evenly spaced apart on the same orbit who have, but are equipped with sensors that only use an observation area.

The present invention is described below Reference to the attached Described drawings. Show it:

1 a projection of the orbit level of an example of a multi-satellite system comprising six satellites, and

2 an orbital segment of the in 1 shown six-satellite system.

It is now going on 1 Referenced in which the earth orbit 1 runs circularly with a height h of 1670 km above the ground. The six satellites 2 to 7 have on orbit 1 even distances from each other. The time period for a satellite orbit around the earth (earth radius R _E = 6378 km) is 120 minutes, which means that the time interval between satellite overflights 20 Minutes. The projection of the satellite speed vector onto the earth's surface 8th results in a ground speed of the satellite orbit track of 5.57 km / sec. The satellite projection moves down over a distance of 6680 km within 20 minutes. Half of this distance is achieved by a double-view sensor arrangement which is designed according to the invention and contains two sensor parts, one of which looks forward at 41 ° and the other looks back at 41 °.

An orbital segment of the six-satellite constellation example, which is equipped with sensor arrangements with a double view direction for satellite-borne fire detection, is shown schematically in FIG 2 shown. They are two consecutive satellites 2 . 3 the six in orbit 1 uniform distances to each other are shown satellites, each satellite being equipped with a line scanning multispectral image sensor arrangement with a double view direction. The re-visit time, ie the regularly recurring time interval between the overflights of the forward and the backward oriented admission strips (swaths; swaths) 9 and 10 on the surface of the earth 8th is 10 minutes. The average detection time achieved (= 50% of the re-visit time) for the six-satellite system with double vision is 5 minutes.

Claims (4)

Satellite-borne high-temperature event (HTE) detection arrangement, which has a multi-spectral image sensor with double-gaze direction, which operates in the visible and infrared wavelength range, characterized by the following features: a) two sensor parts which provide a fixed forward and backward-oriented observation direction and almost the same areas ( 9 . 10 ) with the same recording strip width (swath widths) twice either by optical-mechanical scanning according to the "whisk broom" scanner principle, by opto-electronic scanning according to the "push broom" scanner principle or by conical scanning; b) Means for the simultaneous geometric registration of the multispectral image data of the forward and backward-looking sensor part, both of which are simultaneously on the surface of the earth ( 8th ) observe areas lying about a thousand or more kilometers away from each other in the direction of the satellite track and perceive each covered recording strip (swath) twice during a time interval of a few minutes during an overflight of the satellite; c) the two sensor parts have identical spectral, radiometric and geometric resolution parameters, which allows the use of identical heat point detection and analysis algorithms for the multispectral image data obtained from the forward and backward oriented sensor part. Arrangement according to claim 1, characterized by two sensor parts that have two almost the same surfaces very different angles between the image sensor viewing direction and cover the angle of the sun, what makes it possible Sun-related false alarms due to the combined use the recording strips not disturbed by sunshine (swath; swath) parts of the forward and the backward To avoid image. Arrangement according to claim 2, characterized by sensor parts, the almost the same areas with a great Angles of about 50 - 90 ° between cover the two viewing angles, what is recognizing of high temperature events (HTE) in the case of partial cloud cover with a higher one Probability and reliability than in the case of HTE remote sensing in just one observation area across the satellite track. Multi-satellite HTE detection system consisting of N satellites ( 2 to 7 ) consisting of an earth orbit ( 1 ) have uniform distances from one another, each of these satellites being equipped with a permanently forward and backward-looking multispectral image sensor arrangement as claimed in claims 1 to 3, characterized by a re-visit observation time which is reduced by a factor of two compared to that which can be achieved Re-visit time for N satellites on the same orbit ( 1 ) have uniform distances from each other, but are equipped with sensors that only use one observation area.