Event Report | A scientific marathon through the south of France

Event Report | A scientific marathon through the south of France

We took a lightning tour through southern France to visit some of the most famous scientific sites in the world. These included the 2m telescope at the Observatoire de Haute Provence (OHP) near Marseille that Mayor and Queloz used 20 years ago to discover the first exoplanet; the CEA and major ITER project at Cadarache; and finally the facilities at the Observatoire de la Cote d’Azur (OCA) near Nice on the plateau of Calern. The latter is where laser firing experiments to the moon take place to determine its distance from Earth. This was the prize of the three winners of the Cirta 7 Science Competition, which is organised  annually by Sirius Association of Astronomy for high school students.

Astronomy at the Observatory of Saint Michel

At the OHP’s two-meter telescope where the first exoplanet was discovered in 1995 (click to enlarge)

Prior to the main visit to the Observatoire de Haute Provence (OHP), we were received at the Saint Michel’s Observatory for some astronomical observations. This centre run by an astronomy association and dedicated to outreach and public engagement generously organized a full scientific program for our group. This started off by a long and clear night of observations using a 600mm telescope that allowed us to explore the wonders of the Haute Provence sky. The next morning, we moved on to observe the sun and its protuberances with a siderostat; this unique instrument for amateur astronomy is actually linked to an adjacent auditorium where the images captured from it are projected. That day, we could see a gigantic and detailed image of the solar disc of about 2m in diameter. We could also see two sunspots, and later on, a huge detailed picture of the solar spectrum, a great opportunity to introduce our young winners to spectroscopy.

Observatoire de Haute Provence: The birth place of extrasolar astronomy

The place where history was made twenty years ago. The discovery of the first exoplanete (click to enlarge) .

We then proceeded to an unforgettable afternoon visit to a historically significant place where the first exoplanet was discovered in 1995 by the two Swiss astronomers who worked at the OHP, M.Mayor and D.Queloz. It is a 2m telescope, the largest in Europe, and which, during the detection of the 51-Pegasi, used the Sophie detector conceived and built at OHP itself. Our guide, François Huppert, explained to us how the telescope operates and the observational techniques to catch exoplanets.

CEA Cadarache and ITER

Inside the Tore Supra building, in front of one of its main constitutive tore element (click to enlarge).

The next stop in our scientific program was a double feature: CEA Cadarache, a large scientific-military complex and the flagship of the French nuclear research, and the ITER fusion reactor nearby. The CEA Cadarache covers some 1,400 hectares of a military zone surrounded by electrified barbed wire fence and a triple-sound full alarm system. The scientific activities that take place within this complex are classified as sensitive. Entrance to the site was strictly controlled, but we had gone through rigorous procedures months in advance to gain access. This allowed us to visit a number of scientific installations and advanced technologies, including nuclear reactors, a unit for large scale production of solar power, and the Tore Supra, a nuclear fusion reactor, a sort of mini-ITER that holds the record for the longest controlled nuclear fusion of six minutes and 30 seconds.

For security reasons, we could not access the main CEA cafeteria so as to avoid contact with the researchers and personal at the site. But instead, we were invited to have lunch at a special annex dedicated to VIPs and management staff!

ITER, the $20 billion project

Getting expert explanations from Sylvie André-Mitsialis from ITER-France (click to enlarge).

We spent the reminder of the afternoon visiting the huge site of ITER (International Thermonuclear Experimental Reactor). The site is home to an international project with the ambitious goal of producing virtually free and abundant clean energy, one that does not generate radioactive waste, using nuclear fusion. This would thus represent a much more advantageous alternative to the traditional nuclear fission. The reactor weighting over 5000 tons – actually a Tokamak – is currently under construction, and is scheduled to be ready around 2027.

Few dozen meters from the pit where the Tokamak will become few years from now like a mini-Sun (click to enlarge).

Here too, security measures were drastic, though fairly less strict than those at CEA. We were allowed to take pictures, and with hard hats on, we crossed through the huge site stopping at the very site where the Tokamak will be installed. The huge pillars will support the reactor during its construction before it is lowered down into a gigantic pit. If everything goes as planned, energy will flow out of it, generated by the fusion of vaporised deuterium and tritium, circulating in its chamber and heated to a temperature of 150 million degrees. Powerful superconducting magnets will maintain this gas away from the walls of the reactor and energy production should be 10 times that used for producing and maintaining the gas in the plasma state. A miniature sun would have effectively been created, announcing the start of the post-oil era; countries who have not made their economic and technological transition will then be in trouble!

ITER, the latin for “way” or “journey”, is indeed a formidable technological challenge. The 11 years delay in its construction, together with the increasing cost of overheads testify to this; evidently, putting a Sun in a bottle is not an easy task!

Calern Plateau: reaching out to the moon through laser

We also carefully planned a visit to the exceptional astronomical site of Calern Plateau near Grasse, which is linked to the Observatory of the Cote d’Azur in Nice. We had to choose among the plethora of astronomical instruments available at this site, and we were of course highly interested in the Moon laser telemetry. The observatory itself extends over 350 hectares at an altitude of about 1300m and, since the 1970s, has been the site of many observations and research and development of instruments.

We started our visit with the Tarot, an automatic optical telescope dedicated to monitoring GRBs detected by warning satellites (GCN Network). GRBs are the most powerful explosions in the universe, much more powerful than supernova explosions, and they are detected mainly in the domain of gamma rays. This particular telescope has a modest diameter of 40cm, but its appearance hides something else. In effect, its remarkable mount allows it to revolve swiftly and be accurately directed towards GRB targets to obtain their light curves before they fade away.

Schmidt telescope

The dome of the 1.52m Schmidt telescope (click to enlarge).

We then visited the 1.52m diameter Schmidt telescope, with its discernible white dome located at the extreme end of the plateau, and which is used for wide field imaging of small objects. This is the largest Schmidt telescope in Europe and has been used to discover a number of supernovas, comets and asteroids, in particular the famous Toutatis asteroid. The principle behind this type of telescope is that it takes pictures using the Schmidt chamber to overcome field curvature that are typical of conventional telescopes.

Solar astronomy

On our way to explore laser telemetry, the final stop on this journey, was the ground segment of the Piccard space mission. There, we visited two particular instruments; SODISM2 and the French-Algerian Turbulence Monitor MISOLFA that is dedicated to solar astronomy and metrology. There is a replica of SODISM2 in orbit, and the two instruments allow for monitoring the temporal variations of the solar diameter and the effects of atmospheric turbulence, which has applications in cosmology, helioseismology and atmospheric studies.

Optical interferometry with the GI2T

The Optical Interferometer GI2T (click to enlarge).

One cannot visit the Calern Plateau without making a stop at the GI2T (Grand Interféromètre à 2 Telescopes), the famous pair of rail balls telescopes, a pioneer work in optical interferometry conceived by the brilliant astronomer Antoine Labeyrie and which were operational between 1974 and 2004. Some tourists make the journey here at Calern just for the view of these two telescopes, 1.52m in diameter each in the form of a jar within a concrete structure. An annexed part of the GI2T as seen on the picture is a surrealist permanent art installation by the artist Antti Lovag.

Group portrait with Grégoire (click to enlarge).

The two giant telescopes are connected by a tunnel whose distance can vary between 12 and 65 meters, making this a system equivalent to a telescope of a dozen meter in diameter. It allows for the study of stars, determining their diameter – based on the Doppler effect – as well as the distribution and the movements of neighbouring matter.

Laser telemetry

Our last stop on this visit was the station for shooting laser at the moon. Laser telemetry is the use a telescope to shoot short pulses of a powerful laser at the moon, to measure the precise instant when the few collected photons come back to Earth and so measure, very accurately the distance between our planet and the Moon.

Next to the laser beam then goes out as a 1.5m wide very slightly diverging huge pencil of light (click to enlarge).

The laser shots are aimed at one of the reflectors placed on the Moon by one of the Apollo or the Soviet missions. The shots must be accurately aimed because the laser beam, even though it starts off as a thin beam, reaches a diameter of one to two kilometers upon arrival to the Moon. This project has also allowed for determining the precise position of the Soviet space vehicle Lunokhod-1 on the Moon, which was deposed there by the spacecraft Luna 17 in 1970.

The Mont Gros Observatory: Heritage and history

The last segment of this scientific marathon was the historical observatory at Nice, which is located on top of mount Gros overlooking the city and facing the sea. Our tour of this site started off by a realistic session of practical astronomy using the software AstroJ. We used it to determine the rotation period of an asteroid based on a number of snapshots which was previously captured using a CCD camera, and we then reproduced the light curve associated with it. It took our team some 45 minutes to do this under the supervision of Olga Suarez, an astronomer at OCA.

Finding the rotation period and the shape of an asteroid from its light curve with Olga (click to enlarge).

We then visited the gigantic equatorial telescope of 76cm in its monumental dome, then the 1m50cm telescope dedicated to the study of double stars, and finally a historical tour of the city, with which we closed the visit. We then had to go back to Marseille, passing through the beautiful and geologically rich landscapes of Cote d’Azur.

Lasting memories will certainly stay anchored in the minds of our young winners who experienced a unique scientific and cultural adventure.

More photos here.

English translation by Oussama Metatla.