1、 Recommendation ITU-R RA.1417-1(12/2013)A radio-quiet zone in the vicinity of the L2Sun-Earth Lagrange pointRA SeriesRadio astronomyii Rec. ITU-R RA.1417-1 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spe
2、ctrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunicatio
3、n Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent state
4、ments and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also a
5、vailable online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satell
6、ite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signal
7、s and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2014 ITU 2014 All rights reserved. No part of this publication may be reproduced, by any me
8、ans whatsoever, without written permission of ITU. Rec. ITU-R RA.1417-1 1 RECOMMENDATION ITU-R RA.1417-1 A radio-quiet zone in the vicinity of the L2Sun-Earth Lagrange point (1999-2013) Scope The L2Sun-Earth Lagrange point or L2point, some 1 500 000 km from the Earth, provides a radio-quiet environm
9、ent and stable orbits that are used for space-based radio astronomy and space research service (passive) missions. Some such missions are currently using the L2point, and more are planned. This Recommendation provides timely supporting information and reiterates the importance of preserving the radi
10、o-quiet environment of the L2point as a basis for future space-based radio astronomy missions. The ITU Radiocommunication Assembly, considering a) that radio astronomy observations from space offer important advantages owing to the absence of atmospheric attenuation and scattering and the possibilit
11、y of using very long interferometer baselines between antennas; b) that the low levels of spectral power flux-density in the vicinity of the L2point (see Annex 1) from transmitters operating on the Earth and in space between the Earth and the geostationary orbit permit highly sensitive radio astrono
12、my observations; c) that quasi-stable orbits having radii up to about 250 000 km exist in the vicinity of the L2point; d) that it is desirable for space-based radio astronomy stations in the vicinity of the L2point to be able to observe at all radio frequencies, in order to exploit the full scientif
13、ic potential of the L2 point; e) that viewed from the L2point almost all sources of radio interference will lie within a cone no more than 3.2 across as determined by the apparent diameter of the geostationary orbit, recognizing that space-based radio astronomy missions are currently operating in th
14、e vicinity of the L2 point and that future missions are being planned (see Annex 2), further recognizing a) that Earth-space and space-Earth transmissions to/from the vicinity of the L2 point are needed to control, communicate and relay data from space-based radio astronomy missions operating in the
15、 vicinity of the L2 point; b) that space research service missions, including space research (passive), not conducting radio astronomy observations may receive and transmit in the space-Earth or space-space directions either in transit or while operating in the vicinity of and beyond the L2 point; c
16、) that specific frequency allocations have been made to the space research service for the purposes of controlling, communicating and relaying data from space missions, recommends 1 that administrations should note the scientific importance of the L2 Lagrange point of the Sun-Earth system and take a
17、ll practicable steps to maintain the radio-quiet environment in its vicinity; 2 Rec. ITU-R RA.1417-1 2 that administrations, in making frequency assignments that may affect missions operating near the L2 point, should protect a volume of space of radius 250 000 km centred about the L2 point as a coo
18、rdination zone of low electromagnetic emission, where all radio transmissions originating in and passing through the zone are confined to frequency bands allocated to the space research service for the purpose of controlling, communicating and relaying data transmissions; 3 that administrations shou
19、ld mutually coordinate activities involving use of the L2 point so as to minimize interference to radio astronomy observations or space research (passive) missions in its vicinity. Annex 1 Vicinity of the L2 Sun-Earth Lagrange point The L2 Lagrange point of the Sun-Earth system lies 1.5 million kilo
20、metres from the Earth, in the anti-solar direction, on a line joining the barycentres of the Earth and Sun. There is an area around the L2 point where objects will execute orbits that are stable for long periods of time, and are suitable for long-term space missions (see Fig. 1). FIGURE 1 Typical ge
21、ometry of an L2orbit RA.1417-01EarthSun250 000 kmL27.51.5 10 km6150 10 km6Rec. ITU-R RA.1417-1 3 Annex 2 TABLE 1 Space-based radio astronomy missions operating or planned for operation near the L2Sun-Earth Lagrange point Mission/operator aperture Type of mission observing mode Dates of operation Obs
22、erving frequency bands (GHz) MAP/NASA 1.4 m 1.6 m Single dish continuum imaging of the cosmic microwave background Continuum 2001-2009 18-96 PLANCK/ESA 1.5 m 1.9 m Single dish continuum imaging of the cosmic microwave background Continuum 2009-2012 30 3 44 4.4 70 7 100 10 150 28 217 40 353 65.5 545
23、101 857 158.5 Herschel/ESA 3.5 m Single dish radio astronomy Spectral line and continuum 2009-2013 490-642 640-802 800-962 960-1 122 1 120-1 250 1 600-1 800 2 400-2 600 Millimetron/ ROSKOSMOS 12 m Single dish radio astronomy and space very long baseline interferometry (sVLBI) Spectral line and continuum 2015-2030 18-4 800 SPICA/JAXA 3.5 m Single dish radio astronomy/spectral line and continuum 2018 1 500-10 000
