Imprimir

astrophysics

In good company

The Soar telescope begins to work and places the country side by side with the best observation centers in the world

SOARTwo weeks ago, Alexandre Soares de Oliveira with his wife and three year old son, moved to Chile. Together with his colleague Eduardo Cypriano, also married but without any children, who had arrived there in January, Oliveira will form the Brazilian support team for Soar, a telescope funded by Brazilian and American institutions that began its working life this month. Still in the experimental phase, the telescope is installed on the top of a mountain in the Chilean Andes, at an altitude of 2,701 meters right the start of the Atacama Desert. The project and construction took ten years to come to fruition. The two young physicists Oliveira is thirty-four and Cypriano thirty know that they are getting involved in a historic project that represents a notable jump in quality for Brazilian astrophysics research.

In two or three months when it will be in operation, the Soar short for Southern Observatory for Astrophysical Research should provide images that are much more precise and abundant than those obtained up until now by the equipment in use in this country to study the Universe.

Set up with a main mirror of 4.2 meters in diameter, the Soar will be 1,600 times more powerful than the largest of the Brazilian telescopes with a mirror diameter of 1.6 meters, in operation since February of 1981 at the Pico dos Dias Observatory, in the municipality of Brasópolis, Minas Gerais, at an altitude of 1,860 meters.

Besides updating basic research instrumentation in this area in Brazil, which was ten years behind, the Soar telescope literally places the country at the side of the best astronomy observation centers in the world. On the same mountain at a distance of only 400 meters can be found the Cerro Pachon, one of the units of the Gemini Observatory, with one of the most powerful telescopes in the world, which began to operate about three years ago as a result of an agreement between seven countries, including Brazil, with a modest participation that gives it the right to at the maximum seventeen observation nights per year.

From this mountain of rocky soil, without any vegetation and with at least some days per year covered in snow, one can also see, about fifteen kilometers to the northeast, the Cerro Tololo Inter-American Observatory (CTIO), administered by the United States, dotted with almost a dozen telescopes the largest of them the same size as the Soar, but with the technological resources of forty years ago.

The telescope, which will start its operation on the 17th of this month at a ceremony with close to one hundred guests, is also equal in many aspects to the telescopes in space: its mirror is almost double the size of Hubble and the imaging is of equivalent quality. Due to a grouping of complementary mirrors, the Soar should eliminate the distortions of light caused by the earth’s atmosphere, from which Hubble manages to escape since it is in space at an orbit of 500 kilometers from the Earth an advantage obtained at a cost of approximately US$ 2 billion.

The Soar, evidently, cost a lot less: US$ 28 million. Brazil contributed US$ 12 million, divided between the National Council for Scientific and Technological Development (CNPq), which donated US$ 10 million to the project and FAPESP, which participated with US$ 2 million. As a consequence of their cost participation, the Brazilian researchers will have the right to 34% of the observation time, equivalent to 127 nights per year in an almost always clear, dry and clean sky another advantage over the three telescopes on the Pico dos Dias, subject to frequent rains during summer.

The other three partners are American: the National Optical Astronomy Observatories (Noao), the same institution responsible for the neighboring observatory on Cerro Tololo, which will have 33% of Soar’s observation time; the University of North Carolina (UNC), with 16% of the time; and Michigan State University (MSU), with 14%. Each participant will donate 10% of its available time to Chilean astronomers, in exchange for ceding their territory, common practice with almost a dozen foreign telescopes built in the Andes.

Complementary instruments
“With the start of Soar’s operation and access to Gemini, the Brazilian scientific community will be able to count upon a range of instruments that will permit the integration and the complementation of research projects”, says Albert Bruch, the director of the National Astrophysics Laboratory (LNA), the institution responsible for administering the three telescopes at Brasópolis that also manages the Brazilian participation at the Gemini and Soar telescopes. The Pico dos Dias Observatory, which helped to create the base of Brazilian astrophysics, will not be forgotten he assured: “we’re going to need all of our telescopes to satisfy the needs of astronomic research in Brazil”.

Built in order to attend to the needs of close to 200 Brazilian research groups in astrophysics, distributed through the universities of São Paulo, Rio de Janeiro, Rio Grande do Sul, Minas Gerais, Santa Catarina, Bahia, Rio Grande do Norte, Espirito Santo and Paraná, the Soar telescope, which Bruch defined as “a quantum leap for Brazilian research”, is going to investigate the sky from the wavebands of visible light to the start of infrared, in the wavelengths from 6,000 to 22,000 Angstroms (1 Angstrom corresponds to 1 billionth of a meter).

And this should be very useful, in the first place for the study of the origin of stars, galaxies and of the Universe itself. Also it should be useful for research into black holes celestial bodies that behave like archetypes of starving monsters, capable of swallowing everything that they find, even light.

Intensely investigated by teams from the states of São Paulo, Santa Catarina and Rio Grande do Sul, they seem to be more numerous than had been initially thought and are even capable of influencing the destiny of galaxies (see Pesquisa FAPESP Nº 96, February 2004). Another probable line of research are the Gravitational Lenses, as the galaxies that deviate the light emitted by other even more distant galaxies are called. Only after getting to know the effect of these gravitational lenses will it be possible to determine, with precision, the origin of the distortions of light that arrive on Earth.

The new telescope will be especially useful in research that demands continuous observations or of a wide area of the sky in large projects, such as the surveying of stars or of galaxies of one region, independently from the type to which they pertain. The Gemini, made up of two more powerful telescopes with mirrors of 8.1 meters one in Chile and the other in Hawaii at 4,220 meters in altitude, are going to complement the research, but it is unlikely that they will allow repetitive or wide covering observations, because its time is divided up for teams from the seven countries that funded its construction the United States, the United Kingdom, Canada, Chile, Australia, Argentina and Brazil.

Today it is common that the same research demands the use of more than one telescope. It was only possible to discover the star with lowest quantity of chemical elements with mass greater than that of hydrogen and helium the oldest yet discovered being between 12 and 15 billion years old because a multinational research team, which included the Brazilian Silvia Rossi, spread its research over four telescopes in the United States, Chile and Australia (see Pesquisa FAPESP No. 83, January 2003).

“The observations made through telescopes with mirrors of 2.2 or 4 meters select targets for more detailed observations than in the largest telescopes whose observation nights are sought after and expensive, such as the VLT (Very Large Telescope, in Chile) or the Gemini”, Dr. Silvia commented.

Pride and stress
“We have entered into the pro league of world research. Up until now we’ve had excellent players, but we stayed in the minor league”, celebrates the astrophysicist João Evangelista Steiner, a researcher at the University de Sao Paulo (USP) and president of the Consortium and the Board of Directors of Soar. The word truly is celebrate, since Steiner has been participating in the telescope project since 1993, “right from the very first ideas”, as he himself said.

Just over a decade later, at fifty-four years of age, after having helped to overcome the difficulties concerning logistics, design and contracts with companies and equipment, he now does not hide his satisfaction and pride of seeing the project finally concluded. “To build a telescope like this”, he states, “is the experience of a lifetime.” But clearly it has a price. In March of 1999, when the work on Soar was still only half way through, and what he calls “an indescribable quantity of problems” his habitual patience was eaten away and he was taken to hospital, a victim of severe stress.

In 1993, then with his health in order, Steiner was the Brazilian representative for the Gemini project during a meeting held in Tucson, Arizona, United States. During one of the breaks he presented to the astrophysicist Sidney Wolff – who was there in the name of Noao – the idea of building another telescope so as not to allow Brazilian research to drop further behind. “The Pico dos Dias Observatory was the base and the Gemini the top, but the body was missing that would attend to the future demands of research in Brazil”, Steiner tells. “It would not be possible to sustain the post-graduate programs in Brazil over the long term only with these telescopes.”

Sidney liked the idea. She had already carried out a similar project with anAmerican university, but had made no advances. Back in Brazil, Steiner set out arguments to convince the funding agencies of the importance of this new telescope for Brazilian research. “We did not include pre-existing projects, but we defined one starting from the needs of the research groups in Brazil and the American partners accepted the idea, because it also attended to what they wanted”, he says. “We didn’t give in to anything on the project’s design.” Once the pre-project and requests for funding were approved, we began building at the end of 1997.

The first task was to prepare the ground not that simple since it was a mountain top, 80 km distance from the closest town, La Serena, on the coast with the Pacific Ocean, with its own airport and daily flight to Santiago, the capital. For a year the tractors cut away the point of the cone, removing 13,000 m3 of rock and creating a flat area of 3,600 m2 .

Here the building with the telescope and the control rooms began to take shape, endowed with walls of steel Brazilian steel, by the way so as to avoid interference of heat sources in the light that comes from the stars, and, at the same time, to resist the variations in temperature that can oscillate from 25o C to + 30o , and even earthquakes. Above the metallic structure was positioned a ring of 20 meters in diameter and weighing 60 tons, manufactured by Santin, of Piracicaba, in the interior of the state of São Paulo, and milled by Metalúrgica Atlas, in the capital, and finally transported to the peak of Cerro Pachon in parts, at the one time, in four heavy trucks.

It was upon this ring that the cranes very carefully deposited the dome, a hemisphere of 14 meters in height, whose manufacture was coordinated by Equatorial, from the city of São José dos Campos. On the final Thursday of February, two days after Carnival, the main mirror of 4.2 meters in diameter and only 10 centimeters in thickness, manufactured and polished in the United States, was put in place on top of another metallic structure. This is a fascinating piece of equipment. In the form of a gigantic contact lens, and almost perfectly flat: the wrinkling is so insignificant that, if it were to be stretched out to an area equivalent to Brazil in total, the largest elevation would be no more than two centimeters.

Soar’s main mirror is so fine so as to avoid the dilatations and contractions of the glass that can interfere in the light that arrives from the stars, a problem common in other telescope mirrors, some with up to half a meter in thickness. By being so fine it is flexible, another equally undesirable characteristic, but countered by way of a 220 supports upon which the delicate piece of glass rests.

The supports attempt to secure, with admirable precision, the ideal setting of the mirror: the maximum that each of these points can move is equivalent to one hundred millionths of the thickness of a hair. This mirror is going to work in conjunction with two others, which can be adjusted, in search of a quality improvement in imaging, in accordance with a mechanism known as active optics.

There are still another two complementary mirrors capable of correcting the starlight from the distortions generated by the earth’s atmosphere. By way of this second pair of mirrors the so called adaptive optics, already in use in other telescopes such as the Gemini it is intended to achieve the same quality of imaging as the Hubble, which escapes from atmospheric interference simply by being in outer space. From next year onwards, Soar should also be able to count upon a piece of apparatus that decomposes and analyzes light a spectrograph, which is being built by an USP team and at the LNA, under a thematic project coordinated by Beatriz Barbuy and supported by FAPESP, with funding of close to US$ 1 million.

In accordance with the project, carried out under the technical supervision of Jacques Lepine, director of the Astronomy, Geophysics and Atmospheric Sciences (IAG) of USP, the final version of this spectrograph whose prototype is in operation since last year at Pico dos Dias there will be around 1,300 capture points, made up of optical fibers, which at each moment are going to demonstrate the variations in each frequency of light from the galaxies, conglomeration of galaxies and nebulae, among other astronomic objects.

Unpredictability on the horizon
The first Soar images will serve only for adjustments to the equipment, the mirrors and the computer programs, the so-called commissioning in which the two Brazilians already there will be working on, besides supporting the teams that will arrive and when possible looking after their own research. Only in two or three months is it that the observatory will begin to directly attend to research projects, according to the timetable that will be set by the LNA, depending upon the requests from physicists. According to Bruch, each year the Soar observatory should house close to fifty projects, half of the work at the Pico dos Dias, while the Gemini observatory attends to around 15 projects of Brazilian researchers.

Steiner, Soar represents the prospect of boosting, above all in quality, Brazilian scientific production, today responsible for 2% of worldwide astrophysics research, the equivalent of 250 papers. But there is something even more attractive: the prospect of discovering something that was never before imagined. “We are faced with the unpredictable”, he explains, “without the faintest idea of what could appear, and generally does appear, when a telescope with new technology begins to function.”

The Project
Soar Telescope; Modality Special Project; Coordinator João Steiner IAG/USP; Investment US$ 10 million (CNPq) and US$ 2 million (FAPESP)

Republish