BIRD: A DLR Small Satellite Mission for the Investigation of Vegetation Fires and Vegetation Condition (IFFN No. 16 – January 1997)
GERMANY:
BIRD – A DLRSmall Satellite Mission for the Investigation
of Vegetation Fires and Vegetation Condition
(IFFN No. 16 – January 1997)
Starting from their FIRES proposal [1] the DLR (Deutsche Forschungsanstalt für Luft- und Raumfahrt) makes a new approach in the design of a small satellite mission dedicated to hot spot detection and evaluation: the BIRD mission. The new approach is characterized by a strict design-to-cost philosophy. A two-channel infrared sensor system in combination with a Wide-Angle Optoelectronic Stereo Scanner (WAOSS) shall be the payload of a small satellite (80kg) considered for a piggyback launch. The launch is not a main cost driver as for other small satellite missions with dedicated launchers. The paper describes the mission objectives, the scientific payload, the spacecraft bus, and the mission architecture of a small satellite mission dedicated to the investigation of hot spots (forest fires, volcanic activities, burning oil wells or coal seams), of vegetation condition and changes and of clouds. This report presents some results of a phase A study and of the progressing phase B.
Introduction:
A certain number of important questions on the status of the natural environment on earth and the global and local changes are related to hot spot events. For such occurrences as forest and vegetation fires, volcanic activity or burning oil spills and coal seams a dedicated space instrumentation does not exist. Other sensors are used for the observation of these events but they have some drawbacks because they are not designed for hot spot investigation.
For the near future a few missions with a new generation of infrared array sensors are planned which are appropriate for the tasks above. These sensors consist of cooled infrared arrays with a high need for electric power for cooling. The proposed missions like IRSUTE (France) [2] and FIRES (Germany) [1] are small satellite missions following a design-to-science philosophy, and FUEGO (Spain and other) [3] is more a service-oriented small satellite mission. These missions are characterized by 3axis stabilized satellites with a mass in the order of 300kg and by a dedicated launch strategy. This is one of the main cost drivers of these missions. As opposed to these mission proposals the BIRD mission follows strictly a design-to-cost philosophy. This means that the feasibility of a low-cost piggyback launch strategy drives the development of the satellite and mission conception. The mission is not optimized related to the objectives but related to the cost-performance relationship. The orbit is not only selected by scientific requirements but also by the launch opportunity in the proposed launch year.
Mission Objectives and Requirements:
The primary objectives of the planned BIRD mission are summarized in Table 1.
Tab.1. Mission objectives of BIRD
BIRD – Mission Objectives
- Test of a new generation of infrared array sensors adapted to earth remote sensing objectives by means of small satellites
- Detection and scientific investigation of hot spots (forest fires, volcanic activities, burning oil wells or coal seams)
- Thematic on-board data processing, test of a neuronal network classificator in orbit
The unique combination of a stereo camera and two infrared cameras gives the opportunity to acquire:
- More precise information about leaf mass and photosynthesis for the early diagnosis of vegetation condition and changes
- Real time discrimination between smoke and water clouds
The operational requirements are characterized by
- an operational lifetime of 1 year
- duty cycles of 10 minutes in a orbit mainly over land regions
- on-board processing of data
- raw scientific data downlink to a dedicated payload ground station (Neustrelitz and others)
- short mission or payload command access at the next possible uplink, possibility of payload control by scientific users and experiment team.
A sun-synchronous orbit fulfills these requirements best, but an orbit with an inclination of i ³ 53° should be acceptable as well.
The Scientific Payload: The payload is designed to fulfill scientific requirements under small satellite conditions. It consists of the following main parts:
- Wide-Angle Optoelectronic Stereo Scanner WAOSS
- Infrared sensor system for hot spot recognition
- Payload data handling with a mass memory
- Neural network classificator.
Figure 1 shows the structure of the smart multi-sensor system. The characteristics of the sensor system are summarized in Table 2. The infrared sensor system is designed for hot spot detection and investigation from a small satellite platform. It is described in more detail in [4]. More information concerning the neural network experiment for on-board classification of data (see Fig.1) is given in [6].
Tab.2. BIRD multi-sensor system parameters (altitude 450km)
WAOSS
MWIR
LWIR
Wavelength
(forward) 600-670nm (nadir, bw.) 840-900nm
3.4-4.2µm
8.5-9.3µm
Focal length
21.7mm
46.6mm
46.6 mm
Field of View
80°
19°
19°
F# number
4.5
2.0
2.0
Pixel size
7µmx7µm
30µmx30µm
30µmx30µm
Pixel number
5184
2×512 staggered
2×512 staggered
Quantization
11bit
16bit
16bit
Ground pixel size
145m
290m
290m
Swath width
753km
148km
148km
Net data rate
(with compres.) 597kbps
420kbps
420kbps
WAOSS – Wide-Angle Optoelectronic Stereo Scanner
MWIR – Medium Wave Infrared Sensor
LWIR – Long Wave Infrared Sensor
Fig.1. Scientific payload of BIRD
CMD Command MWIR Medium Wavelength Infrared CCW Coded Command Word LWIR Long Wavelength Infrared COBT Coded On-Board Time S/C H/K Spacecraft Housekeeping PDU Power distribution Unit I/F Interface ACS Attitude Control System SIF Serial Interface
The Spacecraft: The satellite (Fig.2) consists primarily of
- a spacecraft bus service segment
- an electronics segment
- a remote sensing payload segment, and
- fixed and deployable appendages.
The main spacecraft characteristics are given in Table 3. More detailed information is given in [5].
Fig.2. Spacecraft in flight configuration
Tab.3. Satellite characteristics
Baseline
Spacecraft mass
72kg
Payload mass
24kg
Power av.
40W
Stabilization method
3-axis stabilized
Pointing accuracy
4 per axis
Pointing knowledge
0.5 per axis
Communication
S-Band (& UHF?)
Planned launch date
1999
Life span in orbit
1 year
The Mission Architecture
The mission and communication architecture are depicted in Figure 3. Besides the main ground stations in Weilheim and Neustrelitz (Germany) a mini ground station should be implemented in Berlin-Adlershof for experimental purposes. This ground station should be an example of a low-cost ground station with the possibility of scientific data reception and housekeeping and uplink of commands (in experimental mode).
The science team organizes field experiments for validation and for support of interpretation of the remote sensing data by airplane experiments and ground truth measurements.
Fig.3. BIRD mission architecture
References
[1] Jahn, H., K. Brieß, A. Ginati. 1996. FIRES – A small satellite mission for fire detection from space. Proc. IAA Symp. on Small Satellites for Earth Observation, Berlin 1996, IAA-B-905P.
[2] Seguin, B. et al. 1996. IRSUTE – A small satellite for water budget estimate with high resolution thermal imagery. Proc. IAA Symp. on Small Sat. for Earth Obs., Berlin 1996, IAA-B-901.
[3] Gonzalo, J. 1996. FUEGO programme. Proc. IAA Symp. on Small Sat. for E. O., Berlin 1996, IAA-B-902.
[4] Skrbek, W. et al. 1996. HSRS – An infrared sensor for hot spot recognition, Proc. IAA Symp. on Small Satellites for Earth Observation, Berlin 1996, IAA-B-410P.
[5] Stelter, C., and I. Walter. 1996 Concept of microsatellite bus for cooled infrared sensors, Proc. IAA Symp. on Small Satellites for Earth Observation, Berlin 1996, IAA-B-1209P.
[6] Halle, W. 1996. Neuronal network application on-board the micro-satellite BIRD. Proc. IAA Symp. on Small Satellites for Earth Observation, Berlin 1996, IAA-B-607P.
Fig.4. Field test and validation experiment of the FIRES/BIRD Wide-Angle Optoelectronic Stereo Scanner (WAOSS), July 1995 near Freiburg, Germany. Small fires set at the edge of a pine forest stand near Freiburg (Germany). Photo: Courtesy Max Planck Institute for Chemistry, Fire Ecology and Biomass Burning Research Group.
From: Klaus Brieß, Herbert Jahn, H.P. Röser
Address:
Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e. V. (DLR)
Institut für Weltraumsensorik
Rudower Chaussee 5
D – 12489 Berlin, Germany
