ically have little vision of the ITU, to ensure that the owners of proposed new antenna gain. Links with satellites in low orbits would have signifi- geostationary satellite systems, and the national administrations cantly less loss; for example, for an orbit only 1500km above the under whose jurisdiction they fall, will meet with corresponding ground the loss would be about 28dB less, which would make a representatives of established geostationary systems belonging to great difference to the weight of batteries required in a pocket radio other countries, to make sure that interference problems will not telephone. For reasons such as these, low orbits are being seriously arise; this is called frequency co-ordination (ITU, 1990j). When considered for this application. frequency co-ordination has been successfully completed and the new system has been brought into operation, frequencies assigned 51.3.2 Launchers and launching to the satellite can be registered in the Master International Fre- quency Register, maintained by the ITU. Procedures intended to The classic procedure for launching a geostationary satellite falls deal systematically with the risk of interference between non-geos- into three phases. In the first phase (boost phase) a powerful two tationary satellites have not yet been developed. stage liquid propellant rocket (the booster) places the satellite and To keep within acceptable limits the interference which satellite the necessary upstage rockets in an orbit about 200km above the transmitters cause at the receiving stations of terrestrial radio links, ground. This orbit, called the 'parking' orbit, has a period of about upper limits have been placed on the spectral power flux density 100 minutes, it is direct (that is, the satellite revolves in the direction (PFD) which satellites, regardless of orbit, may set up at the Earth's in which the Earth rotates), it is approximately circular and the plane surface in frequency bands shared with terrestrial services (ITU, of the orbit is inclined to the p