The European Science Foundation is an association of its 62
member research councils and academies in 21 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
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.
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 May 26, 1999, the European Science Foundation, ESF, signed an agreement with Iridium LLC, providing a further degree of protection of radio astronomy in the important band 1610.6 - 1613.8 MHz from out-of-band emissions of the satellite transmissions of the Iridium system in the band 1621.35 - 1626.5 MHz for the period 1 May 1999 - 1 January 2006. This interim agreement arose from the ESF-Iridium LLC Framework Agreement of 1998 (see also CRAF Newsletter 1998-3).
The interim agreement was reached after 6 months of intensive and harsh negotiations. However, radio astronomers are not overjoyed about the results since they have significant impact on radio astronomy operations in the band 1610.6-1613.8 MHz in Europe and contain potential regulatory complications.
During the negotiations, CRAF made significant concessions and compromises necessary to reach this agreement. This attitude is a strikingly different from Iridium LLC's position which furthermore was not supported by experimental data such as measured data of the unwanted emission spectrum, measured data on antenna patterns, and real data on customer traffic. During the negotiations, the CRAF recommended to Iridium LLC to give priority to the GSM functionality of its mobile phones in Europe: GSM operates at frequencies sufficiently distant from radio astronomy frequencies. Such a priority would not have negative impact on the operational quality of the Iridium system including its satellite component (traffic to/from the satellites is done via the European gateway stations). Therefore, by setting this priority, the issue at stake could be alleviated in a very elegant way. However, Iridium LLC was not able to consider this option.
Nevertheless, CRAF appreciates that the new agreement guarantees that unwanted emissions from the Iridium satellite system from the band 1621.35-1626.5 MHz into the band 1610.6-1613.8 MHz is kept below the levels documented in Recommendation RA.769-1 of the International Telecommunication Union, ITU, for up to about 50% of the time. This should be noted.
T.A.Th.Spoelstra - Dwingeloo
Radio astronomy has a primary allocation in the frequency band 1610.6-1613.8 MHz which covers an
important spectral line of hydroxyl (OH), one of the simplest and most common interstellar
molecules.
The 1612 MHz line of OH is used by astronomers to investigate many astronomical processes,
including the birth and eath of stars, the evaporation of comets, and active nuclei in distant
galaxies. The hydroxyl emissions come from regions which are hidden from optical telescopes
by clouds of dust and gas. The OH 1612 MHz line is characteristic of a special
class of astronomical sources, the OH-IR sources, which can only be studied
through their hydroxyl and infrared emission.
Europe has world-leading facilities for studying hydroxyl sources:
The 100-m telescope at Effelsberg. Germany, is the largest fully steerable radio telescope
in the world, and the 76-m telescope at Jodrell Bank in the United Kingdom is the second
largest fully steerable telescope in the world operatimng at the frequency of 1612 MHz.
The MERLIN network of radio telescopes in the United Kingdom is the world's leading instrument
for imaging 1612 MHz sources. MERLIN images together with single-telescope monitoring observations,
such as those carried out at Nançay, enable astronomers to measure accurately the distances
of OH 1612 MHz sources, and may soon give our most accurate measurement of the size of the Galaxy
in which we live.
The Westerbork Synthesis Radio Telescope in the Netherlands is one of the most sensitive
instruments in the world for detecting new 1612 MHz sources and monitoring their emissions.
The European VLBI Network is the most sensitive very-long-baseline interferometer network in the
world for imaging the fine structure in OH 1612 MHz sources.
Between November 1998 and May 1999, CRAF and Iridium LLC worked in several
meetings towards an agreement for the period 1 May 1999 - 1 January 2006 as anticipated in
the ESF-Iridium LLC Framework Agreement which was reached on August 11th,
1998. CRAF represented the interests of the European radio astronomy community. The key issue
in the discussions was the protection of radio astronomy in the frequency band 1610.6-1613.8 MHz
from unwanted emissions from the Iridium satellite system
operating in the band 1621.35-1626.5 MHz and to define circumstances under which both European
radio astronomy stations and the Iridium system can operate during the indicated period.
The legal basis for these discussions formed the ESF-Iridium LLC Framework Agreement,
the ITU-R Radio Regulations, Recommedation ITU-R RA769-1 as well as the
European Commission's licensing directive (97/13/EC) and relevant CEPT(ERC/ECTRA) decisions and
recommendations.
The CEPT Milestone Review Committee delegated its chairman, secretary and two of its members
to observe the proceedings of the negotiations. In several instances they also gave advice to
both CRAF and Iridium LLC.
After difficult negogiations CRAF and Iridium LLC reached agreement on substance which is
formulated in the ESF-Iridium LLC Agreement for the period 1 May 1999 -
1 January 2006.
This agreement has no impact whatsoever on the protection of radio astronomy from 1 January
2006 as outlined in the ESF-Iridium LLC Framework Agreement
The Committee on Radio Astronomy Frequencies, CRAF, is an associated committee
of the European Science Foundation, ESF. The ESF in its parent role published a
press release where it explained the milestone reached.
The new European agreement guarantees radio astronomy low interference
levels for up to 50% of the year, thus allowing Europe's extensive
1612 MHz research programmes to continue, with operational restrictions.
Unwanted emissions from the Iridium satellites are expected to be lowest
during periods of low user traffic.
The clear times of low interference which Iridium LLC is prepared to
guarantee include overnight periods similar to
those negotiated elsewhere, and also weekends. The weekends are
particularly important as they cover 24 hours per day, thus allowing
radio astronomers to study objects in any part of the accessible sky.
CRAF is happy to note that the new agreement between ESF/CRAF and Iridium LLC is in many respects
better than similar agreements reached elsewhere in the world:
Nevertheless, the "Iridium case" has set a bad precedent in several respects, which could threaten the future
development of radio astronomy in particular and the acceptance of an international treaty as
the ITU-R Radio Regulations in general.
The allocation of the frequency band 1616-1626.5 MHz for space-to-Earth transmissions in the
Mobile-Satellite Service, MSS, was made at the World Administrative Radio Conference 1992,
WARC-92, of the ITU, before technical studies had been concluded on the possible harmful
effects on radio astronomy operations in the band 1610.6-1613.8 MHz.
In recognition of the danger, the WARC-92 explicitly added ITU-R footnote
S5.372 to protect radio astronomy. Thus radio astronomy had regulatory protection. Yet in
practice the radio astronomy measurements are now having to be squeezer into those times when
Iridium LLC is willing to guarantee low interference levels. In effect, radio astronomy is
time-sharing with the unwanted emissions (radio waste) of the Iridium satellites.
Given the explosive growth in satellite telecommunications and broadcasting, radio astronomers
are worried about the long-term 'threat' to their science from unwanted emissions of all these
satellites. 80% of frequency bands allocated to the radio astronomy service on a primary basis
are adjacent to a band allocated for space-to-Earth transmissions. The allocations are not
yet taken up, in most cases, which is fortunate for radio astronomy.
Some other points of attention are:
As was said in CRAF Newsletter 1998-3 CRAF shares the opinion that
it is difficult to understand that radio astronomers are expected to sacrifice quality of
observations, while the frequency channels from which the interference originates are outside
the radio astronomy band 1610.6-1613.8 MHz and protection is guaranteed by ITU-R Radio
Regulations footnote S5.372.
2. Radio Astronomy at 1612 MHz
The large radio telescope at Nançay is second in collecting area only to the
giant 300-m reflector at Arecibo, Puerto Rico. The Nançay radio telescope spends half of its
time observing hydroxyl sources. It has recently been upgraded to greatly improve its sensitivity.
3. ESF-Iridium LLC Framework Agreement
4. ESF Press Release
5. Evaluation
The situation in the USA is as follows
In India radio astronomers are protected for up to 6 hours of Iridium 'quiet time'. It should
also be noted that in Australia, there exists no agreement between radio astronomers and Iridium
LLC. In Canada, there agreement on the condition that from 1 January 2006 the levels for
detrimental interference as given in ITU-R RA769-1 must be respected by the Iridium system.
Iridium supports the interpretation that protection is needed only during actual
operations of the victim service. CRAF's view is that Iridium's opinion is not supported
by the ITU-R Radio Regulations and the ITU Constitution. Because of this faulty interpretation,
the USA agreements contain clauses that radio astronomy observations
should be scheduled avoiding peak traffic periods of the Iridium system. Arecibo has even the
obligation to show Iridium LLC its schedules. The new European agreement does not contain such
a clause: it is the responsibility of each individual radio astronomy station to do the
observations at the time it considers best to achieve the scientific goal.
the agreement is an implementation of a time-sharing scenario. However, it must be noted
that according to ITU-R definitions, one cannot speak of a sharing situation: the
frequency band of the victim service (i.e. radio astronomy) is 1610.6-1613.8 MHz and that of
the interferer is (i.e. the Iridium system) is 1621.35-1626.5 MHz. A sharing situation
occurs only when the victim services and the interfering service use rightly an allocation
within the same frequency band. CRAF's concern is that
a problem of interference due to unwanted emissions from a poorly designed transmitting system
is cured by an improper tool: in this case time-sharing with 'radio waste'. Regulatory
authorities should prevent such solutions in future to prevent improper evolution of the
interpretation and use of the ITU-R Radio Regulations.
following the ESF-Iridium LLC Framework Agreement, the new agreement contains a clause on
collaborative efforts to discuss before 1 January 2006
"ways to reduce the susceptibility of radio astronomy
observatories to interference from the Iridium Satellite System". In an annex to the agreement
an initial workplan is given. This workplan will be adjusted according to the technological and
scientific developments during the period of validity of the agreement.