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
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)
Feedback
Last modified: July 29, 1999
