CRAF Newsletter 1999/3

CRAF Newsletter 1999/3

July 1999

The European Science Foundation is an association of its 65 member research councils and academies in 22 countries. The ESF brings European scientists together to work on topics of common concern, to co-ordinate the use of expensive facilities, and to discover and define new endeavors that will benefit from a co-operative approach
The scientific work sponsored by ESF includes basic research in the natural sciences, the medical and biosciences, the humanities and the social sciences.
The ESF links scholarship and research supported by its members and adds value by cooperation across national frontiers. Through its function as coordinator, and also by holding workshops and conferences and by enabling researchers to visit and study in laboratories throughout Europe, the ESF works for the advancement of European science.

On behalf of European radio astronomers, the ESF Committee on Radio Astronomy Frequencies, CRAF, coordinates activities to keep the frequency bands used by radio astronomers free from interference.


1. Chairmans' Corner

Astronomers around the world were stunned by the news of the cable car accident at Plateau de Bure on 1st July. With 20 lives lost this was France's worst ever cable car disaster. The cable car provided the main access to the Plateau de Bure Observatory, IRAM's powerful mm-wave interferometer. The accident occurred as the morning shift set off to work from the village of St Etiene-en-Devouluy. Passengers included a construction team working on the track for the sixth antenna, cleaning and telecommunications workers, and IRAM technical staff. It appears that the cable car reached its point of steepest ascent before traction failed and it reversed back down to the pylon below, whereupon it crashed to the ground, killing all passengers. The cable car had undergone maintenance work only the day before. An enquiry has been set up to determine the cause of the accident.

The observatory plans to continue limited operations using helicopter access. The cable car was used to carry not only people, but also essential provisions for the staff, plus fuels, parts, liquid helium and so on for the equipment.

CRAF extends its heartfelt sympathy to all affected by this tragedy.

R. J. Cohen - Jodrell Bank

2. Report of 27th CRAF meeting (11-12 April 1999)

The 27th CRAF meeting was held at the Nicolaus Copernicus University, in Torun, Poland. The main items discussed during the meeting were the negotiations between CRAF and Iridium LLC towards an agreement for the period 1 May 1999 - 1 January 2006, the work in CEPT project teams, the preparations for the WRC-2000, and the work of the CRAF frequency manager.

* CRAF-Iridium LLC negotiations:

Since November 2nd, 1998, CRAF and Iridium LLC have met more than once a month to negotiate an agreement dealing with regulatory and technical details for the period between 1 May 1999 and 1 January 2006. Such an agreement was anticipated in the ESF-Iridium LLC Framework Agreement of 1998 which specified the regulatory details for the post-1 January 2006 period to protect European radio astronomy against harmful interference from the Iridium satellite system. The negotiations were completed by May 1999, after much hard work. A special edition of the CRAF Newsletter gives more details.

* CEPT project teams:

As usual, CRAF participates actively in CEPT project teams. Much progress was achieved on the issue of frequency allocations above 71 GHz (FM-PT33) in preparation of WRC2000. The progress in FM-PT34 on high density fixed(-satellite) service applications is rather slow because of a well-profiled position of Teledesic. For radio astronomy, the threat to the band 42.5-43.5 GHz from spaceborne transmissions in the band 40.5-42.5 GHz could not yet been resolved although CRAF made the radio astronomy requirements clear (also in SE-PT16 which addresses the technical aspects of this item). Other important frequency ranges considered by PT34 are ~22 GHz and ~11 GHz.

Progress in the study on spurious and out-of-band emissions (SE-PT21) is still very limited. The work in this project team is hampered by the position of some active users communities.

Project team SE-PT28 addressed as a new issue the protection of radio a stronomy from out-of-band emissions from Iridium aeronautical earth stations, AESs, on aircraft. Since currently no standard for such systems exists, CRAF is concerned that the proposals of Motorola remain verbal guarantees only. The developments of the AES standards must be monitored carefully.

* Preparations for WRC-2000:

The preparations for the World Radiocommunication Conferences are in full swing. Both regulatory conferences have great importance for the radio astronomy service. Much preparatory work is done in CEPT project teams, i.e. of the CEPT Working Group Frequency Management, WG FM. CRAF participates actively in this work at CEPT level. CRAF members participate in national preparations, as well as helping to prepare the European (CEPT) position. This work is done in close cooperation with IUCAF.

* Frequency manager:

The 1998 report of the frequency manager quantified his workload. The meeting discussed ways to achieve a better distribution of the work among CRAF members, to improve the overall efficiency CRAF and its frequency manager.

* other activities:

CRAF participated actively in the ERO Detailed Spectrum Investigation - Phase III which deals with the preparation of the European frequency allocation table for the frequency interval 862-3400 MHz. CRAF also contributed in the evaluation of the Green Paper on Spectrum Policy of the European Commission (for further info: see EC website).

T. A. Th. Spoelstra - Dwingeloo

3. Progress in Task Group 1-5

Task Group 1-5, the successor to TG1-3, was established to prepare, as an urgent matter, modifications to the two ITU-R recommendations dealing with out-of-band emissions (Rec 328) and intermodulation products (Rec 326). It was also charged, among other things, to pay particular attention to the protection requirements of the radio astronomy service and space services using passive sensors, and to improve the recommendation on spurious emissions (Rec 329) where necessary. These studies were called for at WRC-1997 in Recommendation 66, and some of the results will be presented to WRC-2000 under Agenda Item 1.2, which deals with spurious emissions.

TG1-5 met for the fourth time in Phoenix Arizona, in January this year, with sixty participants. The best news for radio astronomers is that the spurious emission limits for spacecraft, currently designated as design objectives, will be recommended for adoption by WRC-2000 without this qualification. The concept of design objectives was introduced in 1996 (in TG1-3) with no technical justification and removed in 1999 in the same way (after the launch of some 300 satellites). While the new limits do not satisfy all the needs of radio astronomy they are a lot better than no limits at all, and they provide a basis for further work. It is recommended that deep space space stations (defined as those further than 2 million km from Earth) be exempt from spurious emission limits. This should not be a problem for ground-based radio astronomy. Other changes to the spurious emission limits concern narrow-band transmitters (for which 250% of necessary bandwidth is still too small on account of phase noise!) and amateur earth stations.

The CPM text mentions that the passive and safety services do not receive adequate protection from unwanted emissions, in many cases, and that studies are continuing within ITU-R, to be reported at a future WRC. This is a reference to the band-by-band studies which are currently underway. Phase A of these studies will identify those bands where there is a major discrepancy, while Phase B will look at ways to close the gap between the protection requirements and the unwanted emission levels which are technically achievable. There was a lot of talk within TG1-5 of mitigation factors, with a clear hope that radio astronomy protection levels might be revised upwards in some bands to help close the gap. Clearly radio astronomers have some work to do explaining their needs to their separate national administrations.

TG1-5 is not making recommendations on out-of-band emissions to WRC-2000. The group is producing a preliminary draft new recommendation, however, which radio astronomers will need to study carefully. A key issue is the boundary between out-of-band and spurious emissions.

Other preliminary draft recommendations are being produced on the protection of safety and passive services from unwanted emissions. The preliminary draft recommendations discuss mitigation factors which can be adopted at the transmitter and at the victim receiver, to reduce the impact of interference from unwanted emissions. Problem bands will be identified, where even with all mitigation factors considered there is still a major gap between the needs of the passive/safety services and what is currently achievable for unwanted emissions. It will be vital for radio astronomers to make substantial contributions to these efforts.

Two further meetings of TG1-5 are proposed. One will be in August 1999 in the Netherlands, and the final meeting will be early in the year 2000, possibly in India.

R. J. Cohen - Jodrell Bank

4. Meeting of Working Party 7D (Radio Astronomy)

Working Party 7D met in Geneva from 3rd to 10th March with 20 participants from 11 countries, including for the first time a radio astronomer and an administrator from Brazil. The working party had a heavy agenda to deal with, which included major portions of text for the CPM report.

WP7D is the lead group on Agenda Item 1.4 and Resolution 128, Allocation to the Fixed Satellite Service (space-to-Earth) in the 41.5-42.5 GHz band and the protection of the Radio Astronomy Service in the band 42.5-43.5 GHz. The output text is on the whole favourable for radio astronomy. It includes discussion of the way that interference thresholds should be made more stringent for a number of simultaneously visible satellites. The difficulties of sharing for radio astronomy with FSS in the adjacent band are clearly set out in the text.

WP7D is also the lead group on Agenda Item 1.16, Passive Allocations above 71 GHz. A drafting group chaired by Tom Gergeley (USA) finished its worked on this, which was already well advanced in October 1998, and produced a well polished output. The text contains no proposed table of allocations, but it does contain a table of bands of interest to the radio astronomy service in the range 71-275 GHz, with the numbers of detected lines. The table of proposed allocations (and reallocations) was also discussed in the drafting group, but does not appear in the CPM text.

A small drafting group chaired by Venkat Subramani (NFRA and India) produced CPM text for Agenda Item 1.11, Res 219, concerning the impact of a proposed MSS downlink at 405-406 MHz on the radio astronomy service in the band 406.1-410 MHz. An attenuation of 94 dB would be required to meet the radio astronomy interference thresholds. This is considerably more challenging than the Iridium situation! Venkat was designated as the WP7D rapporteur for the MSS below 1 GHz issues (Agenda Item 1.11 and Res 214).

CPM text from JRG 7D-9D concerning Agenda Item 1.4 (HAPs) was also discussed briefly by WP7D, with further comments to be sent to Tom Gergeley.

A drafting group chaired by Klaus Ruf (Germany) continued to work on the x% issue. The preliminary draft new recommendation (PDNR) was developed further to include discussion of sky blockage by a single satellite. A figure of 5% emerges naturally as the fraction of sky around a the satellite where the radio telescope will have gain greater than 0dBi. This way of thinking leads to a tightening of the interference thresholds by 12.5logN dB for N satellites simultaneously visible above the horizon. Unfortunately all this good work was put on hold by a late torpedo from Canada, which asked on the last day for new material to be added to the PDNR, concerning mitigation factors. Canada was unable to explain why it had to insist on this change, which was not accepted by the group, and so the PDNR will be carried over to the next meeting.

The preliminary draft new recommendation on the protection of the Lagrangian L2 point was considered by a small drafting group chaired by Jim Cohen (UK) and was passed on to SG7 for approval. As a result of this success the corresponding question ITU-R 147/7 will be proposed for deletion. A draft new question on Protection and Sharing Criteria for Radio Astronomy Measurements from Space was also sent to SG7 for approval.

Liason statements were sent to TG1/5, to WP8D and to WP4A. Willem Baan was appointed the prelimiary draft new rapporteur to TG1/5, in place of Hans Kahlmann. Two liason statements were sent to TG1/5 and two were retained within WP7D for further consideration - these deal with the band-by-band studies and with mitigation factors. A late input from Russia resulted in a liason statement to WP4A on protection of the radio astronomy service in the band 15.35-15.40 GHz from FSS in the nearby band 15.43-15.65 GHz. This issue is not over yet, it seems.

A liason statement to WP8D dealt with the touchy matter of Res 127, the proposed MSS downlink at 1429-1432 MHz. The liason statement says that interference to the radio astronomy service can be avoided provided some very stringent conditions are met. It also expresses the concern of WP7D that satellite downlinks are being considered close to a band of paramount importance to the radio astronomy service.

The next meeting of WP7D (Radio Astronomy) will be held in January 2000, at a time and place still to be announced.

R. J. Cohen - Jodrell Bank

5. European Commission's Green Paper on Radio Spectrum Policy

On December 9th, 1998, the European Commission published its Green Paper on Radio Spectrum Policy. The objective pursued with this document is to identify how best to approach and implement Spectrum Policy at Community level. At the same time, the results from the Green Paper will also feed into several specific debates which are currently under way.

CRAF notes with appreciation that this strategy document also mentions scientific applications of radio frequencies including radio astronomy. In addition to this, CRAF has brought to the attention of the European Commission several observations and comments.

6. Statement from Vienna, IAU Symposium No. 196

The participants of the IAU-COSPAR-UN Special Environmental Symposium: "Preserving the Astronomical Sky" (IAU Symposium No. 196), held in Vienna July 12-16, 1999, as part of the Technical Forum of UNISPACE III,

recalling the paragraphs of the Draft Report of UNISPACE III (A/Conf.184/3) referenced in parentheses below,

and noting that:

1: Understanding the nature of the Universe is one of mankind's oldest and strongest fascinations, and of immense scientific, cultural and practical value for many centuries. Observations at all wavelengths of the electromagnetic spectrum, from the ground and from space, have been vital in the phenomenal progress in all areas of astronomy in the 20th century, from the exploration of the solar system to discoveries of the echo of the Big Bang and the beginnings of structure in the Universe (1,2,6,28);

2: The Space Treaties established by the United Nations have defined outer space and the space environment as "The province of all mankind", to be protected from harmful contamination and adverse changes of all kinds, and the exploration and peaceful use of which should be carried on for the benefit and in the interests of all mankind (313). This principle is strongly supported also by the IAU and COSPAR;

3: Nevertheless, continued scientific studies of the origin and evolution of the Universe and mankind's place within it are jeopardized worldwide by man-made environmental problems of rapidly growing severity. In space, interference at radio frequencies from telecommunications satellites and their ever-increasing demand for frequency space (158) cloud the future of radio astronomy and the operation of scientific satellites; space debris is a growing threat to scientific satellites and interferes with ground-based observations (70); and projects to launch bright objects into space for earth illumination, artistic, celebratory, or advertising purposes present a growing danger to observational astronomy against which no international protection now exists (73). On the ground, man-made light pollution has already made large areas of the world unsuitable for astronomical observations and is beginning to influence wildlife;

4: Space is not just another place to do business (273), but a finite natural resource common to all mankind and already showing inexorable symptoms of over-exploitation (70). The problems enumerated above are global in extent, and some are long-term or irreversible in time. Due to the extreme sensitivity of astronomical observations, science has been first to detect and suffer from these effects, but it will not be alone for long;

recommend that:

a: Member States should continue to cooperate, at the national and regional level, and with industry and through the ITU, to implement suitable regulations to preserve quiet frequency bands for radio astronomy (162), and to develop and implement, with urgency, practicable technical solutions to reduce unwanted radio emissions and other undesirable side-effects from telecommunications satellites;

b: Member States should cooperate to explore new mechanisms to protect selected regions of the Earth and space from radio emissions (radio quiet zones), to develop innovative techniques to optimise the conditions for scientific and other space activities to co-exist in radio frequency space as well as in physical space, also in the future;

c: Member States should cooperate, as a matter of urgency, to ensure that future space activities that would cause potentially harmful interference with the scientific research or natural, cultural, and ethical values of other nations (73) be subject to environmental impact assessment and international consultations before approval;

d: Member States should cooperate to ensure that the implementation of measures, at the international level, to preserve all aspects of the space environment in the long term, be included in the workplan of COPUOS and its Subcommittees (318-321). It is proposed that Article III (b) of the Vienna Declaration be formulated more adequately as follows, "To improve the protection of the near and outer space environment through further research in, and implementation of, measures to control and reduce the amounts of space debris and unwanted emissions at all wavelengths of the electromagnetic spectrum".

e: Member States should act to control pollution of the sky by light and by other causes, for the benefit of energy conservation, the natural environment, night-time safety and comfort, and national economy as well as science.

7. Abbreviations used in this Newsletter

AES = Aeronautical Earth Stations
CEPT = Conference of European Post and Telecommunication administrations
COSPAR = Committee on Space Research
CPM = Conference Preparatory Meeting (ITU-R)
CRAF = Committee on Radio Astronomy Frequencies (ESF)
ERO = European Radiocommunication Office (CEPT)
ESF = European Science Foundation
FM = ERC Working Group Frequency Management (CEPT)
FSS = Fixed Satellite Service (ITU-R)
HAPs = High Altitude Platforms
IAU = International Astronomical Union
IRAM = Institut de RadioAstronomie Millimetrique
ITU = International Telecommunication Union
ITU-R = ITU Radiocommunication Sector
JRG = Joint Rapporteurs Group (ITU-R)
MRC = Milestone Review Committee (ERC)
MSS = Mobile-Satellite Service
NFRA = Netherlands Foundation for Research in Astronomy (NL)
PNDR = Preliminary Draft New Recommendation (ITU-R)
SE = ERC Working Group on Spectrum Engineering (CEPT)
SG = Study Group (ITU-R)
WP = Working Party (ITU-R)
WRC = World Radiocommunication Conference (ITU-R)


Last modified: July 29, 1999