Brazilian observatory is accredited by the International Astronomical Union

Installation is focused on research to monitor and characterize the properties of asteroids and comets that present a risk of collision with the Earth.

By Elton Alisson

Agência FAPESP – From the top of a mountain in the arid landscape of the Pernambuco community of Itacuruba, some 480 kilometers from Recife, Brazil’s second-largest astronomy observatory (the largest is in Minas Gerais State) sticks out like a sore thumb. It is OASI – a Portuguese acronym for the Astronomy Observatory of Sertão de Itaparica.

Built by the National Observatory of Rio de Janeiro and operating since 2011, OASI received its accreditation from the Minor Planet Center of the International Astronomy Union under the code Y28 OASI. With this accreditation, OASI became part of the official list of astronomy observatories recognized by the foremost astronomy body worldwide. 

“OASI received this designation [Y28] because we observe smaller objects discovered at other international astronomy monitoring sites and send their coordinates to IAU to better detail their orbits,” explained Daniela Lazzaro, a researcher at the National Observatory.

The researcher presented a summary of OASI activities during the 65th Annual Meeting of the Brazilian Society for the Progress of Science (SBPC), held July 21–26 in Recife, Pernambuco.

According to Lazzaro, OASI was conceived to serve the “The National Observatory Initiative to Monitor and Study Asteroids Neighboring the Earth” (IMPACTON).

Developed in collaboration with research astronomy institutions from abroad , the project is part of a network of international projects to search for and monitor small planets in the solar system – such as asteroids and comets – at risk of collision with the Earth.

Some of these celestial objects could collide with the Earth’s surface, opening craters and destroying small or large areas, depending on their size.

Among the challenges to detecting these objects through telescopes, according to Lazzaro, are that they are very small and do not emit their own light – they only reflect sunlight. Many of them are only observed when their orbits are very close to Earth or cross the Earth’s path – as occurred in February in Russia, when fragments of a meteor some 40 meters in diameter fell in a city in the south of the country, injuring more than 1,000 people.

Furthermore, although the nearly 1,000 asteroids that are large enough to cause the end of humanity if their orbits cross the Earth’s orbit are almost all mapped, scientists only know of 5,000 of the estimated 100,000 small celestial bodies in the solar system, stressed the researcher.

“The big problem is that there is an immense population of small objects that are still not detected. As the larger objects are greater and shinier, it is possible to observe them earlier. In the case of smaller objects, we cannot,” said Lazzaro.

Broader knowledge

To better understand the origins of these bodies and develop techniques to more precisely identify those that represent greater risks of collision with the Earth, in the last few years, new international programs have been initiated to search for and monitor small celestial bodies in the solar system.

IMPACTON is focused on monitoring, determining the orbit of and characterizing the rotational and physical properties of asteroids and comets.

The colors of asteroids, for example, can indicate whether they are composed of iron, rock or ice and whether their internal structures are dense or porous. These characteristics of the composition are factors in assessing the possible consequences of the damage that small celestial bodies could cause if they collide with the Earth’s surface, explained Lazzaro.

“If the internal structure of a celestial body is porous, it will fragment when crossing the atmosphere and reach Earth in smaller pieces. If the structure is very dense, it will fall to the Earth’s surface and the damage caused will be much greater,” she explained. Monitoring a small object allows researchers to more precisely determine its orbit and eventually evaluate the risk of its hitting the Earth.

In April 2011, for example, researchers using the OASI telescope observed an asteroid near the Earth travelling at a speed of 8 kilometers per second and determined that it had a rotation period of 7.33 minutes on its axis, whereas the average for an asteroid is 6 to 8 hours.

“The asteroid was extremely quick both in relation to the speed with which it passed near the Earth an in relation to its speed of rotation around its own axis,” explained Lazzaro.

The results of the observation of this asteroid were presented at the 2012 international astronomy conference in Japan. This presentation contributed to the IAU’s accreditation of OASI.

“For IAU, one must monitor at least 90% of these objects, but the majority of these are immediately lost soon after the discovery because the whole world hopes to discover asteroids and no one want to monitor them,” said Lazzaro. “We do the monitoring, although we also hope to discover some asteroids,” she explained.

Itaparica

According to the researcher, before the location for the astronomy observatory was chosen, a survey was conducted based on meteorological data to identify the regions of Brazil with the fewest rainy nights and latitudes as far south as possible because there are already many telescopes mapping celestial bodies in the Northern Hemisphere.

The researchers identified the region from northwestern Goiás State through Pernambuco and southern Piauí as the one that best met the meteorological and location criteria for the location of the observatory.

Sertão de Itaparica, however, ended up being chosen because, in addition to having many clear, dry nights, it has low atmospheric turbulence, low luminosity and pollution and is far from the sea. Furthermore, Itaruba’s City Hall made efforts to attract the observatory to the area.

“The city has an astronomy club, and the City Hall wanted to have a municipal observatory, open to the general public, to stimulate educational tourism in the region,” she commented.

“When they found out that we were looking for a place to install an observatory, the City Hall and several institutions in the region sought us out and sought a partnership, because although our project is scientific, it was also a form of attracting educational tourism. In addition, we offered the possibility of opening the doors of the observatory on some days for visitation,” she affirmed.

The first scientific images obtained from OASI’s telescope were taken on March 17, 2011. Built in Germany at a cost of R$1 million, the equipment can be remotely operated by researchers at the National Observatory in Rio de Janeiro. 

The observatory has a meteorological station that provides real-time data on the atmospheric conditions in Sertão de Itaparica that allow researchers to evaluate when they can leave the observatory’s dome open to capture images.

The telescope’s main mirror is one meter long – smaller than the telescope of the Observatory of Pico dos Dias (OPD) in Brasópolis, some 37 km from Itajuba in Minas Gerais, which has a 1.6-meter-long mirror.