GERMANY:

BIRD - A DLR Small 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 fr 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

  1. Test of a new generation of infrared array sensors adapted to earth remote sensing objectives by means of small satellites
  2. Detection and scientific investigation of hot spots (forest fires, volcanic activities, burning oil wells or coal seams)
  3. 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:

  1. More precise information about leaf mass and photosynthesis for the early diagnosis of vegetation condition and changes
  2. Real time discrimination between smoke and water clouds

 

The operational requirements are characterized by 

A sun-synchronous orbit fulfills these requirements best, but an orbit with an inclination of i 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: 

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

3.4-4.2m

8.5-9.3m

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

7mx7m

30mx30m

30mx30m

Pixel number

5184

2x512 staggered

2x512 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

 

tech_9_3.gif (44176 Byte)

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 

 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.

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Fig.3. BIRD mission architecture

 

 References 

[1] Jahn, H., K. Brie, 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.

 

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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 Brie, Herbert Jahn, H.P. Rser

Address:

Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e. V. (DLR)
Institut fr Weltraumsensorik
Rudower Chaussee 5
D - 12489 Berlin, Germany

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