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Environmental Regulation
Published in Francis Lyall, Paul B. Larsen, Space Law, 2016
Various orbital configurations are in regular use. To repeat data from Chapter 9, most satellites are in low Earth orbit (LEO) (c. 100–500 km/65–310 miles), taking some ninety minutes for each orbit. These vary from tracks more or less over the equator to polar orbits. Such orbits are roughly circular, their low and high points (perigee and apogee) being comparable. These orbits are lower than the Van Allen radiation belts. A highly elliptical Earth orbit (HEO) has a wide variation between perigee and apogee. Such orbits in their apogee phase remain visible from a point on Earth for up to twelve hours, and are used inter alia by communications satellites (e.g. the Russian Moliyna series). A medium Earth orbit (MEO) or intermediate circular orbit (ICO) is between 2,000 km and 35,000 km (1,240–21,750 miles) and a satellite in MEO takes anything from two to twelve hours to complete an orbit. MEOs are used mainly for global positioning satellite configurations, though they are also used for some communications satellites.88 A geosynchronous orbit is one in which a satellite returns to the same position each day. Of these the most well-known is the geostationary orbit (GSO), an eastwards circular orbit some 35,786 km/22,236 miles above the equator. The GSO is used for communications and remote sensing (mainly meteorological) satellites.89 A ‘parking orbit’ may be in LEO or MEO and is used temporarily after launch before a satellite or space probe is put on its final trajectory. Finally, a ‘graveyard’, ‘disposal’ or ‘junkyard’ orbit is normally higher than the geostationary. It is used for satellites that have reached the end of their useful life, and which it would be too expensive or difficult to de-orbit to Earth. As noted above, defunct satellites with radioactive power sources on-board are to be placed in a ‘sufficiently high’ orbit to remove them from causing problems in the immediate future.90 ITU Radiocommunication Sector Recommendation S.1003-1 (01/04) ‘Environmental Protection of the Geostationary-satellite Orbit’ would have states ensure that at the end of their useful lifetime geostationary satellites are relocated to a ‘supersynchronous graveyard orbit’ which does not intersect with the GSO.91
Environmental regulation
Published in Francis Lyall, Paul B. Larsen, Space Law, 2017
Various orbital configurations are in regular use. To repeat data from Chapter 6, most satellites are in low Earth orbit (LEO) (c. 100–500 km/65–310 miles), taking some ninety minutes for each orbit. These vary from tracks more or less over the equator to polar orbits. Such orbits are roughly circular, their low and high points (perigee and apogee) being comparable. These orbits are lower than the Van Allen radiation belts. A highly elliptical Earth orbit (HEO) has a wide variation between perigee and apogee. Such orbits in their apogee phase remain visible from a point on Earth for up to twelve hours, and are used inter alia by communications satellites (e.g. the Russian Moliyna series). A medium Earth orbit (MEO) or intermediate circular orbit (ICO) is between 2,000 km and 35,000 km (1,240–21,750 miles) and a satellite in MEO takes anything from two to twelve hours to complete an orbit. MEOs are used mainly for global positioning satellite configurations, though they are now also used for some communications satellites.110 A geosynchronous orbit is one in which a satellite returns to the same position each day. Of these the most well-known is the geostationary orbit (GSO), an eastwards circular orbit some 35,786 km/22,236 miles above the equator. The GSO is used for communications and remote sensing (mainly meteorological) satellites.111 A ‘parking orbit’ may be in LEO or MEO and is used temporarily after launch before a satellite or space probe is put on its final trajectory. Finally, a ‘graveyard’, ‘disposal’ or ‘junkyard’ orbit is normally at least 300 km/250 miles higher than the geostationary. It is used for satellites that have reached the end of their useful life, and which would be too expensive or difficult to de-orbit to Earth. Defunct satellites having radioactive power sources on board are to be placed in an orbit ‘sufficiently high’ to remove them from causing problems in the immediate future.112 ITU Radiocommunication Sector Recommendation S.1003–2 (01/04) ‘Environmental Protection of the Geostationary-satellite Orbit’ asks states to ensure that at the end of their useful lifetime geostationary satellites are relocated to a ‘supersynchronous graveyard orbit’ which does not intersect with the GSO, but this seems to have been dropped from the current (2016) ITU-R Recommendations.113
Decoding Mission Design Problem for NTP Systems for Outer Planet Robotic Missions
Published in Nuclear Technology, 2022
Saroj Kumar, L. Dale Thomas, Jason T. Cassibry
The initial parking orbit of the NTP injection stage and spacecraft is 2000 km circular with an inclination of 28.5 deg. During the first segment of the spacecraft Earth escape phase, the NTP engine burn for the trans-Neptune insertion (TNI) maneuver imparts the required ∆V of 9.5 km/s. The thrust vectors are along the velocity vector in the VNC(Earth) reference frame, and the total engine burn duration to complete the maneuver takes 30.2 min and consumes total LH2 propellant of 13 711 kg. The spacecraft states at the beginning and the end of the TNI are provided in Table V (Fig. 4).