According to information provided by public databases in the United States, there are over 8,000 man-made objects in orbit around the Earth (excluding American military satellites, which is very confidential information). A number of these spacecraft fly over France every day, providing a potential danger to national security. It is therefore vital that the position of these orbiting objects should be known. ONERA's teams have designed and developed the GRAVES space surveillance system to establish and maintain a database of satellites flying over France at altitudes of less than 1,000 kilometers.
copyright © ONERA 1996-2006
GRAVES Space Surveillance System: the receiving antennas.
(DCSP)
Transmitting antennas emit a continuous low-frequency signal towards a given angular section of space. The receiving site, located nearly 400 kilometers away, houses a large number of omnidirectional antennas. Based on the elementary signals picked up by these antennas, a narrow-lobe beam is produced. The direction of this lobe provides an angular measurement of the object detected, while the frequency shift between the emitted signals and the received signals measures its radial velocity.
Based on this brand-new concept, the GRAVES radar network provides angular and radial velocity measurements. These are fed into the orbital processing algorithms developed by ONERA's researchers to calculate the orbital parameters of the detected satellites.
copyright © ONERA 1996-2006
GRAVES Space Surveillance System: the four transmitting panels.
