1、 Recommendation ITU-R RS.2064-0 (12/2014) Typical technical and operating characteristics and frequency bands used by space research service (passive) planetary observation systems RS Series Remote sensing systems ii Rec. ITU-R RS.2064-0 Foreword The role of the Radiocommunication Sector is to ensur
2、e the rational, equitable, efficient and economical use of the radio-frequency spectrum 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 t
3、he Radiocommunication Sector are performed by World and Regional Radiocommunication 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
4、Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements 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 pate
5、nt information database can also be found. Series of ITU-R Recommendations (Also available 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 (te
6、levision) F Fixed service M Mobile, radiodetermination, amateur and related satellite 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
7、service systems SM Spectrum management SNG Satellite news gathering TF Time signals 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, 2015 ITU
8、2015 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R RS.2064-0 1 RECOMMENDATION ITU-R RS.2064-0 Typical technical and operating characteristics and frequency bands used by space research service (passive) plan
9、etary observation systems (Question ITU-R 221/7) (2014) Scope This Recommendation provides typical technical and operational characteristics of space research service (passive) systems and frequency bands used by space research service (passive) planetary observation systems. The ITU Radiocommunicat
10、ion Assembly, considering a) that one application of the space research service (SRS) (passive) is for spacecraft to measure physical phenomena of extraterrestrial bodies; b) that SRS (passive) observation systems may receive emissions from transmitters operating in active radiocommunication service
11、s; c) that there are exclusive SRS (passive) allocations in which all emissions are prohibited by RR No. 5.340; d) that certain frequency bands are allocated to the SRS (passive) on a co-primary basis with active services; e) that studies considering protection for SRS (passive) systems may take pla
12、ce within ITU-R; f) that in order to perform compatibility and sharing studies concerning SRS (passive) systems, the technical and operational characteristics of these systems must be known; g) that the sensing of different physical properties requires the use of different frequencies; h) that simul
13、taneous measurements at a number of frequencies are often needed to distinguish between the various physical properties being measured, recommends 1 that the technical and operational parameters presented in Annex 1 of this Recommendation should be taken into account in studies considering SRS (pass
14、ive) systems operating in bands allocated to the SRS (passive); 2 that the frequency bands used for SRS (passive) sensing should be in accordance with Annex 2. 2 Rec. ITU-R RS.2064-0 Annex 1 Typical technical and operating characteristics used by space research service (passive) observation systems
15、1 Introduction The purpose of this Recommendation is to present typical technical and operating characteristics and preferred frequency bands of space research service (SRS) (passive) observation systems. The “decides” of Question ITU-R 221/7 Preferred frequency bands and protection criteria for spa
16、ce research service observations (passive), includes the studying of: 1) typical technical and operating characteristics of SRS (passive) observation systems; 2) preferred frequency bands for SRS (passive) observations; and 3) protection criteria for SRS (passive) observations. This Recommendation f
17、ocuses on the first two study objectives mentioned above. Annex 1 presents typical technical and operating characteristics of the spaceborne passive sensors in the SRS (passive) which have been flown or are planned to be used, and Annex 2 lists the preferred frequency bands along with missions assoc
18、iated with those frequency bands. 2 Specific missions with SRS (passive) systems The following sections describe various space research missions that have used or are using passive sensors (i.e., microwave radiometers). 2.1 Mariner 2 microwave radiometer at Venus Mariner 2 was a Venus flyby mission
19、in December 1962 where a microwave radiometer was used to determine the absolute temperature of the Venus surface and atmosphere. Mariner 2 approached Venus from 30 degrees above the dark side of the planet, and passed below the planet at its closest distance of 34 773 km on 14 December 1962. Simult
20、aneous measurements were made in two frequency bands at 15.8 GHz and 22.2 GHz with predetection bandwidths of 1.6 GHz and 1.5 GHz (Table 1). The microwave radiometer used a 48.5 cm diameter parabolic antenna with two reference horns looking 60 degrees away at space. The 3 dB beamwidths were 2.64 deg
21、rees and 2.2 degrees for the two frequencies, respectively. The microwave radiometer was of the crystal video type operating in the standard Dicke mode of chopping between the main antenna pointed at the target and a reference horn pointed at cold space. The planetary emissions were characterized by
22、 limb-darkening and confirmed the high temperature of Venus. The dual-channel microwave radiometer obtained three scans across the planet Venus. The peak temperature values supported a hot-surface model for the planet. The model best to match the limb-darkening ratios and temperature values measured
23、 at both frequencies pointed to a specular surface and an isothermal cloud-type layer at a temperature near 350 K. The magnitude of the relative dielectric coefficient of the surface varied between 3 and 4. Scientific discoveries made by Mariner 2 included a slow retrograde rotation rate for Venus,
24、hot surface temperatures and high surface pressures, a predominantly carbon dioxide atmosphere, continuous cloud cover with a top altitude of about 60 km, and no detectable magnetic field. Rec. ITU-R RS.2064-0 3 TABLE 1 Mariner 2 microwave radiometer characteristics Parameters Values RF centre frequ
25、ency 15.8 GHz 22.2 GHz Altitude Min 34 773 km Min 34 773 km RF predetection bandwidth 1.6 GHz 1.5 GHz Receiver noise figure 4 dB 4 dB Detectable delta temperature 4 K 7 K Number of scans 3 3 Duration/scan 220 s 220 s Antenna type Parabolic reflector Parabolic reflector Antenna diameter 48.5 cm 48.5
26、cm Antenna beamwidth 2.64 degrees 2.2 degrees Receiver noise figure 4 dB 4 dB 2.2 Cassini microwave radiometer at Titan The Cassini radar instrument was used in a passive microwave radiometer mode to map the microwave emission from Titan. These were the first resolved microwave emission measurements
27、 of an icy satellite. The measurement data provide crude composition maps of Titans surface, confirm equator-to-pole temperature gradients without the influence of the atmospheric effects, and provide some bistatic reflection measurements using the sun as a source to constrain roughness of ethane se
28、as. The Cassini spacecraft was launched in October, 1997, and arrived at Saturn in July 2004. Ninety-seven flybys of Titan occurred between July 2004 and January 2014. Flybys are planned monthly for the duration of the mission. The Cassini radar instrument uses a 4 m diameter antenna and operates at
29、 13.78 GHz as shown in Table 2. In the microwave radiometer mode, the incident microwave radiation is measured between echo pulses, hence the microwave brightness of targets in the beam. Microwave radiometry takes place throughout the Titan encounter and is the only mode for distant observations at
30、25 000-100 000 km. Internal calibrations are made with a noise diode and a resistive load of known characteristics. The microwave radiometer is linearly polarized either horizontally or vertically, depending on how the spacecraft antenna is oriented. TABLE 2 Cassini microwave radiometer mode charact
31、eristics Parameters Values RF centre frequency 13.78 GHz Altitude 1 000-100 000 km RF bandwidth 135 MHz Antenna type Parabolic reflector Antenna diameter 4 m Antenna beamwidth 0.35 degrees Antenna orientation Nadir Antenna polarization Linear H, V Receiver noise temperature 574 K 4 Rec. ITU-R RS.206
32、4-0 2.3 Magellan microwave radiometer at Venus The Magellan radar had a microwave radiometer mode which operated at 2.38 GHz and observed the radio emissivity of more than 91% of the Venus surface. The Magellan spacecraft was launched in May 1989 and arrived at Venus in August 1990. With an extended
33、 mission of two further mapping cycles, Magellan mapped Venus until September 1992. The microwave radiometer uses the 3.7 m diameter antenna which has a 2.1 degree beamwidth and uses horizontal linear polarization as shown in Table 3. This yields surface resolutions varying between 15 km and 85 km a
34、s the altitude varied from 280 km to 2 100 km. The microwave radiometer mode is enabled for 50 milliseconds at the end of each radar “burst” sequence, following either the altimeter or SAR observations. In the radiometer mode, the receiver is switched alternately from burst to burst between the high
35、 gain antenna and a dummy load as a reference. The microwave radiometer measurements show a global mean value of emissivity of 0.845 corresponding to a dielectric permittivity of 4.0 to 4.5, depending on the surface roughness, and is consistent with dry basaltic minerals composing the bulk of the Ve
36、nus surface. TABLE 3 Magellan microwave radiometer mode characteristics Parameters Values RF centre frequency 2.38 GHz Altitude 280-2 100 km RF bandwidth 10 MHz Horizontal resolution 15-85 km Antenna type Parabolic reflector Antenna diameter 3.7 m Antenna orientation Nadir Antenna polarization Linea
37、r H Antenna beamwidth 2.1 degrees 2.4 Juno MWR at Jupiter The Juno microwave radiometer on the Juno spacecraft, launched on 5 August 2011, is scheduled to arrive at Jupiter in 2016. This will be the second microwave instrument to explore the planets since the first observations from Mariner 2 of Ven
38、us in 1962. The microwave radiometer will operate in direct detection mode to quantify the distributions and abundances of water and ammonia in Jupiters atmosphere. After Jupiter orbit insertion, the 11 day orbit will have a perijove at 1.06 Jupiter radii and an apojove at about 39 Jupiter radii, pr
39、oviding 32 orbits over the nominal one year mission. This polar orbiting (inclination 90 degrees) instrument will probe deep into the atmosphere of Jupiter at six frequencies 0.6 GHz, 1.25 GHz, 2.6 GHz, 5.2 GHz, 10 GHz, and 22 GHz (Table 4). The six radiometers are to measure the planets thermal emi
40、ssions of ammonia and water in Jupiters atmosphere. Measurements at frequencies of 9.6 GHz and 23.1 GHz are for the ammonia NH3 clouds at 200 K at 1 bar pressure, and measurements at frequency of 1.2 GHz are for the water H2O clouds at 300 K and 8 bars pressure. The microwave radiometer has a 12 deg
41、ree beamwidth antenna. The six radiometers use direct-detect Dicke-style receivers with about 4% bandwidth. The six receivers are fed by a combination of patch array antennas at 0.6 GHz and 1.25 MHz; slot array antennas at 2.6 GHz, 5.2 GHz, and 10 GHz; and a horn antenna at 22 GHz. The primary acqui
42、sition of data occurs at 3 hours around perijove when the altitude varies between Rec. ITU-R RS.2064-0 5 4 200 km and 5 200 km. During the radiometer science passes, the microwave radiometer measurements are taken with the solar array plane of the spinning spacecraft passing through the centre of Ju
43、piter and the radiometer antennas aligned with nadir. TABLE 4 Juno microwave radiometer characteristics Parameters Values RF centre frequency 0.6 GHz 1.25 GHz 2.6 GHz 5.2 GHz 10 GHz 22 GHz Altitude 4 200-5 200 km RF bandwidth 24 MHz 50 MHz 100 MHz 200 MHz 400 MHz 900 MHz Antenna type Patch array Pat
44、ch array Slot array Slot array Slot array Horn Antenna beamwidth 12 degrees Receiver noise temperature 350 K 2.5 Change-1 microwave radiometer at the moon The Change-1 microwave radiometer was launched on the Change-1 spacecraft in October 2007. The microwave radiometer measures the natural radiatio
45、n emanating from the lunar surface at four microwave frequencies 3 GHz, 7.8 GHz, 19.35 GHz, and 37 GHz (as shown in Table 5). The objective is to profile the lunar regolith thickness and to measure the radiation brightness temperature with a resolution of 0.5 K. The instrument is expected to measure
46、 depths up to 30 m, 20 m, 10 m, and 1 m at the four frequencies. The circular orbit is at a low 200 km altitude with an inclination of 90 5 degrees and a period of 127 minutes. There are four horn antennas pointed at nadir, each diameter of which is scaled to the wavelength so that the four footprin
47、ts are co-aligned and overlapping. TABLE 5 Change-1 microwave radiometer characteristics Parameters Values RF centre frequency 3 GHz 7.8 GHz 19.35 GHz 37 GHz Altitude 200 km RF bandwidth 100 200 500 500 Ground resolution 56 30 30 30 Antenna type Horn Horn Horn Horn Penetration thickness 30 m 20 m 10
48、 m 1 m 2.6 Summary of SRS (passive) system characteristics The characteristics of the SRS (passive) systems in the previous sections are summarized in Table 6 below. 6 Rec. ITU-R RS.2064-0 TABLE 6 Summary of SRS (passive) microwave radiometer characteristics Parameters Mission Juno Juno Magellan Jun
49、o Change-1 Juno Change-1 Juno Cassini Change-1 Juno Change-1 Planet/Moon Jupiter Jupiter Venus Jupiter Earths Moon Jupiter Earths Moon Jupiter Titan Earths Moon Jupiter Earths Moon RF centre frequency 0.6 GHz 1.25 GHz 2.38 GHz 2.6 GHz 3 GHz 5.2 GHz 7.8 GHz 10 GHz 13.78 GHz 19.35 GHz 22 GHz 37 GHz Altitude 4 200-5 200 km 4 200-5 200 km 280-2 100 km 4 200-5 200 km 200 km 4 200-5 200 km 200 km 4 200-5 200 km 1 000- 100 000 km 200 km 4 200-5 200 km 200 km RF bandwidth 24 MHz 50 MHz 10 MHz 100 MHz 100 200 MHz 200 400 MHz 135 MHz 500 900 MHz 500 Antenna type Patch array Patc
