Rosetta Camera to image ice and fire
7 January 2001Sophisticated spacecraft such as ESA's Rosetta comet chaser are designed to carry state-of-the art instrumentation into the depths of the Solar System. However, innovative technology that has been developed for exploration beyond the Earth can sometimes find unusual applications back on the ground.
One example of this "technology transfer" is a high-resolution CCD camera known as ROLIS, (Rosetta Lander Imaging System). Although the camera has been designed to send back the most detailed pictures ever obtained of an icy comet nucleus, specialists from DLR have recognised that it may also be an ideal tool for providing automated early warnings of forest fires.
The key to this dual usage is the camera's highly sensitive "MOSES" (Modular Sensor Electronics System) electronics package, which has been developed by the Institute of Space Sensor Technology and Planetary Exploration, part of the German Aerospace Centre (DLR) in Berlin-Adlershof. These electronics give the camera its high resolution (1024 by 1024 pixels) and high number of grey tones (over 16,000), and enable it to detect the smallest variations in light intensity.
The DLR Institute and several companies from Saxonia have used this technology to develop a system that may revolutionise the early recognition of forest fires. Supported by funds from the EU regional development programme and from the Organisation for Technology Marketing and Transfer, three prototype cameras were installed in the Cottbus region, one of the most fire-endangered areas of Germany, in March 1999.
The state of Brandenburg was particularly suitable for this pilot project since it is blanketed by 1.1 million hectares of forest. Despite posting guards in 133 watchtowers during the summer months, the state suffers from up to 1,000 forest fires per year, causing damage worth several tens of millions of Deutsch Marks.
The early recognition system developed by the DLR, together with the partner companies, INO vision GmbH (Possendorf), INO control GmbH (Dresden) and Hiersemann process automation GmbH (Chemnitz), works by providing automatic warning of smoke generated by forest fires.
Raised above the tree tops, the camera monitors the surrounding landscape and captures panoramic views of the surrounding woodlands. The digital images are sent via optical glass fibre cables to a control PC at the foot of the tower and then to a picture evaluation computer.
If a fire is discovered, the computer immediately transfers compressed pictures and additional information (time, fire co-ordinates) over ISDN lines or a mobile network (data communication via satellites is also possible) to a head office, where they are displayed on a local map.
The system detects smoke clouds that measure 10 metres across within a radius of 10 km, and is able to send a fire warning within 10 minutes of the smoke appearing. Using the camera's fine grey tone gradation, it is possible to detect the smallest of changes in the landscape. In this way, one person is able to keep watch over a large area and take further measures if a fire is detected.
Results from the pilot study show that 16 fires occurred in the monitored region of Brandenburg during 1999. The automated system detected all of them and issued alarms within the given time. The false alarm rate was less than one percent. As a result of these successes, considerable interest in the system has been expressed by other German States and forest authorities in Poland.
The technology could also be of value on a much larger scale - in Europe as a whole, up to 10,000 km2 of forest are destroyed by fire annually, and fires cause even more widespread damage in North America.
Other possible applications of this camera technology include the monitoring of industrial systems or use in automatic weather stations. In modified form, it could be used in many areas of safety monitoring.
ROLIS will be one of 10 instruments carried on board the Rosetta Lander spacecraft. The 100 kg Lander will become the first man-made object to make a soft touchdown on a comet nucleus when it reaches Comet Wirtanen in 2012.
The ROLIS CCD camera will play a major role in Rosetta's scientific investigation of the chemical and physical characteristics of the comet - the first in situ study of the surface and internal structure of one of these tiny ice worlds ever undertaken.
Black and white digital pictures of the landing site taken during the final stages of the spacecraft's descent will show details only a few millimetres across. ROLIS will subsequently obtain colour images of the ices below the Lander and stereo panoramic images of areas to be sampled by other instruments.