A very important class of satellite Earth' orbits for the hyge developments of industrial and commercial radiocommunications is the geostationary one. It may be worthy to note that its next decades equivalent in the lunar domain may very well be some of the lagrangian points, which also have interesting astronautical features. Use of Lfar should be strictly forbiden because it would ruin the radio pristine farside. It appears that Lprec would be the most suitable for future lunar telecommunications: it would give access to a whole sector covering one third of the farside, while preserving the pristine radio environment of the remaining 23 farside, including SAHA crater. Thus my proposal is 1) to use the West Third under a regime similar to the International Telecommunication Union one, 2) the Est Third to be left pristine and 3) for the time being, to leave the central far Third in a TBD regime for future discussions. Such a proposal would allow Very Low Frequency (VLF) radioastronomy to settle in the Est Third and Very Long Base Line Interferometry (VLBI) to set, as an extension of the SAHA crater proposal, a triangular network at three choice locations: craters SAHA, TSIOLKOVSKY and MENDELEEV.

In a previous paper I singled out a very specific farside lunar crater, Saha, as an excellent candidate for future high sensitivity radioastronomy, in particular for SETI. In order to initiate discussions on programmatic issues raised by this prospect for the coming decennies, I present here elements relative to transportations and communications with a main permanent base on the Moon.

In view of the incompatibility of high sensitivity radioastronomy with radio frequency interferences, I proposed that a well specified locale on the farside of the Moon be protected for the future generation scientific benefit of humankind. A careful study selected the 100 km diameter crater SAHA. Among the numerous questions raised by such a proposal in the technical, programmatic, astronautical, industrial, policy, legal, financial, political, sociological and ethical domains, the most urgent to be investigated are the Space Law ones. In order to ease the set up of a reasonable memorundum of understanding, we proposed to save just a small part of the lunar farside, but to ask for pristine conditions for all of classical radioastronomy frequencies. This is justified by astrophysical arguments based essentially on the expansion of the universe, on the unpredictability of eventual extraterrestrial artificial transmissions, on the impetus of radioastronomal science and technology and on our disastrous earthly experience with sidelobes and harmonics.

The aim of this review, whose title might as well be "Toward a dedicated lunar farside radio observatory", is to provide information for potential interested workers whom we invite to contribute to this multidisciplinary effort.First point: in view of the dramatic increase of radio interference due to the development of satellite-based human telecommunications, it will soon become impossible to conduct valuable high-sensitivity SETI observations from the terrestrial ground. It is why a few years ago I started an interdisciplinary and international endeavor to protect for the next 20/30 years a well specified lunar farside crater (Saha) which no Earth- or geostationary orbit-based radio emission could reach.After raising technical, programmatic, legal, astronautical, industrial, political, ethical issues at a number of conferences of international learned institutions, this enterprise is now of interest for the wider field of next generation high-sensitivity radioastronomy at large, from decametric to submillimetric waves.This last year, positive results were the creation of an IAA Sub-committee for "A Lunar SETI Study", the presentation of a Resolution to the IAU for the protection of a potential lunar radio observatory site, discussions at the IAA/IISL Scientific-Legal Roundtable on SETI & Society at IAF Congress in Torino, the organization of a half-day Scientific Event at next COSPAR Assembly in Nagoya and the initiation of an IAA Cosmic Study on the subject.We shall conclude by outlining the next efforts to be initiated up to a real Moon radio observatory. (C) 2000 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved.

The gravitational lens effect of the Sun would allow, by using a detector at one of its foci, to obtain a “telescope” with gigantic amplification and resolution powers opening extraordinary perspectives for the detailed study of extrasolar planets, particularly technologically advanced ones. But, astronautical challenges are raised by the necessity to align precisely and put in an efficient tracking and scanning mode the detector, necessarily modest in size compared to the dimensions of the planet images and ranges of orbital and rotational motions. In the frame of the FOCAL space mission submitted to ESA, we present the dynamical geometry of the images for two typical cases of observational wavelengths: 10 centimeters (radio) and 10 micrometers (infrared), for a solar-type stellar system 10 parsecs away. Plasma thrusters could provide interesting solutions for the control of the detector for tracking and scanning the focal images.

We present a swift survey of the recent aspects, and prospects, of SETI from diverse viewpoints such as bioastronomy, strategy, technology, searches,radio frequency interference, space law, diplomacy, sociology, culture, education.

AbstractWe conducted a search for narrowband artificial signals from the regions of stars around which planetary companions have been recently found: 51 Pegasi, Gliese 229, 70 Virginis and 47 Ursae Majoris. We used the large Nançay decimetric telescope, with a frequency resolution of 50 Hz, and we scanned over 0.64 MHz and 2.24 MHz respectively around the hydrogen and hydroxyl lines.

In case an extraterrestrial artificial signal is discovered, this will be immediate proof that civilizations are plenty in the cosmos and the odds: are that, with our freshly acquired experience, we shall readily unravel a dozen of them within a few years. Then the drive to investigate them, in all of their obligatory varieties, will get quite strong.Extrapolating the fact that, for the lest 30 years, the efficiency of our SETI detection systems doubled each eight months, a dramatic progression indeed, we shall get access to fainter and fainter extraterrestrial emitters. Unfortunately, the Earth or near-Earth man-made radio interferences will become a stronger and stronger obstacle to these investigations.It is why I recently proposed that a quite neatly singled-out locale on the farside of the Moon, the 100 km diameter crater Saha, be protected as a dedicated zone for SETI for the coming generation. Considering that it is a political end philosophical duty for humankind to provide for such a unique and limited protected lunar location, I suggested that international planning at the time scale of 20-30 years be started now at the level of programmatic, technical, legal and political issues.In the words of Ambassador Aldo A.Cocca: ''The reservation of a lunar zone for scientific activities (for) the common good of humanity, must be recognized and constitutes a precedent. The proposal must be supported with the legal framework it requires''.

In line with the concept of the galactic belt of advanced life, we evaluate the sky distribution of detectable artificial sources, using a simple astrophysical model. The best region to search is the median band of the Milky Way in the Vulpecula-Cygnus region, together with a narrower one in Carina. Although this work was done in view of a proposal to send a SETI probe at a gravitational focus of the Sun, we recommend these sky regions particularly for the searches of the sky survey type.

In view of future improvements of instrumental sensitivity in the search for extraterrestrial intelligence (SETI) and of the dramatic increase in radio frequency interferences generated by human technology, we stress the importance to initiate an international plan for a protected farside lunar-based SETI facility. For various simple reasons we propose to locate it in the Saha crater.

We use the three fundamental concepts of: the gravitational lens effect of the Sun; the solar sail propulsion of spacecraft; and the galactic belt of life to present extrasolar system missions aimed at an ultra-high gain investigation of the galactic centre (ASTROSAIL) and of the sky direction most likely to reveal extraterrestrial civilizations more advanced than ours (SETISAIL).

Without consideration of eventual specific points raised by an extraterrestrial message, we suggest that the best material to be sent as a first reply is a current encyclopaedia. It satisfies the reasonable criteria known to date.

One of us (J.H.) proposed a scheme to select preferred radio frequencies for SETI by using the rotational frequencies of pulsars and to test it in the field. The conversion from pulsar rotational frequencies to SETI frequencies in the 1–10 GHz galactic radio window is made in a very precise quasi-unique way by use of remarkable mathematical numbers. The selection of specific pulsars is made according to the types of SETI targets. We present the status of experimental observations made with the large Nançay (France) decimetric radiotelescope applied to the following typical searches: (1) target stars closer than 25 parsecs; (2) unknown targets in a globular cluster; (3) unknown targets anywhere in our galaxy closer than 2.5 kpc. In addition to stars with planet-like candidate companions, special emphasis was given to stars with candidate disks older than two billion years as these may have provided enough time for advanced life to appear. This experiment is a new step in a project of collaboration between Paris Observatory and NASA SETI Program Office started in 1981. It gives new insight to faint RFI relevant to SETI.

We apply our pulsar-aided SETI strategy to the particular case of the targeted search of the NASA SETI Program Office. We provide a list of weighted “preferred” search frequencies in the galactic radio window. They are precise to the hundred kilohertz level. The most preferred one is 2.65998 GHz, based on the pulsar PSR 1629 + 10, closely followed by 2.38093 GHz, based on PSR 0950 + 08. We also consider the case of cluster search and the sky survey case.

We apply our pulsar-aided SETI strategy to the particular case of the targeted search of the NASA SETI Program Office. We provide a list of weighted "preferred" search frequencies in the galactic radio window. They are precise to the hundred kilohertz level. The most preferred one is 2.65998 GHz, based on the pulsar PSR 1629 + 10, closely followed by 2.38093 GHz, based on PSR 0950 + 08. We also consider the case of cluster search and the sky survey case. .

S. GulkisSpace Physics and Astrophysics SectionF. Biraud and J. HeidmannObservatoire de ParisMeudon, FranceJ. TarterUniversity of California, Berkeley, CaliforniaThe SETI Institute, Los Altos, CaliforniaThe Nan_ay decimetric Radio Telescope (NRT) in Nan_ay, France, is described,and its potential use for SETI (Search for Extraterrestrial Intelligence) observationsis discussed. The conclusion reached is that the NRT is well suited for SETI obser-vations because of its large collecting area, its large sky coverage, and its widebandfrequency capability. However, a number of improvements are necessary in orderto take full advantage of the system in carrying out an efficient SETI program. Inparticular, system sensitivity should be increased. This can be achieved through aseries of improvements to the system, including lowering the ground pickup noisethrough the use of ground reflectors and more efficient feed design, and by usinglow-noise amplifer front ends.

Après un quart de siècle de percées en radioastronomie, exploration spatiale et biologie, la recherche d'intelligence extraterrestre (SETI) a obtenu le soutien des Académies Nationales des Etats-Unis et de l'URSS, de l'Union Astronomique Internationale et, de façon plus tangible, l'appui financier de la NASA. Si d'autres civilisations ont des posibilités techniques au moins comparables aux nôtres, il est possible de communiquer sur des distances dépassant mille années-lumières, les ondes radio étant les véhicules les plus efficaces connus pour la propagation d'informations à travers l'espace interstellaire. Un million d'étoiles sont alors à notre portée mais un problème formidable est créé par le nombre énorme des canaux possibles à explorer. Nous présentons les développements les plus récents faits par la Division des Recherches Extraterrestres de la NASA, nous concentrant sur ses deux volets principaux : l'analyse spectrale et la reconnaissanse de signaux. Nous présentons aussi une nouvelle stratégie SETI basée sur les pulsars. Puis nous évoquons l'intérêt de la collaboration internationale et présentons un projet d'obsevations SETI avec le grand radiotélescope de Nançay conjointement avec la NASA.

Clumpy irregular galaxies have been identified as giant irregulars with a clumpy structure. Investigations in the visible, UV, radio centimetric, X-ray and far infrared demonstrated that the clumps are hyperactive bursts of star formation, each equivalent to a hundred giant HII regions like 30 Doradus or NGC 604. In spite of their strong activity, their linear size is smaller than half a kpc, leading to an “olive jar” model with very peculiar physical conditions. These could be related to the non-detection of the 2.6-mm CO line and to our discovery in a clump of the first known case of a strong, compact, variable radio source which is not a galactic nucleus.