INAF - ISTITUTO DI RADIOASTRONOMIA

RadarVLBI Observational Project

Involved IRA scientists, technicians and collaborators: G. Tuccari, S. Buttaccio, I. Molotov, M. Nechaeva, G. Nicotra

Space debris (SD) is a new threat in the near-Earth space environment, and is a direct consequence of human activity in space. The current SD population (about 13,000  traceable objects and many more objects invisible from the Earth surface) represents a serious danger not only for manned orbital stations, rockets and operational satellites, but even for human life  and Earth  ecology. The monitoring project involves a European collaboration that was started under INTAS 2001-0669 with the NIS (New Independent States) radio telescope with systematic observational campaigns performed in one or more yearly sessions. Data products elaborated for SD research is the common denominator of Centers on collection, processing and analysis of space debris information of the Russian Academy of Sciences; Pulkovo cooperation of optical observers; VLBI radar sub-system of LFVN; LAPLACE analytical motion theory with model of explosions with optical and radar facilities to fulfill the multifaceted research about the status of pollution of GEO (Geostationary Earth Orbit), GTO (Geostationary Transition Orbit) and LEO (Low Earth Orbit) with small SD fragments. The project includes several participating teams from six European countries, which have a long experience in the study of space debris, have access to suitable observing facilities, and have already developed mutual collaborations.

The project uses a network of many optical telescopes placed from Siberia to Bolivia with aperture ranging from 0.6-m to 2.6-m, among them there is the unique Ukrainian radar RT-70 in Evpatoria. The project  uses also the VLBI network of radio telescopes in Ukraine, Italy, Russia, China and Latvia (LFVN).

Faint SD objects at GEO and GTO are discovered using optical telescopes with large FOV (Field Of View)  and then tracked with narrow FOV facilities. The follow-up photometry, spectroscopic, polarimetric, infrared and radar observations are arranged to clear up the material composition of fragments and their attitude motion. The area to search for SD fragments is specified with the help of the LAPLACE long-term analytical motion theory using models of GEO-object explosions. Another project activity is related to the statistical search of small-sized SD fraction at LEO using both optical and radar facilities. Such a kind of measurements will be improved with Irkutsk ionosphere radar,  and with the bi-static radar system Evpatoria RT-70 => Bear Lakes RT-64.

The preliminary analysis of the SD data is performed from the point of view of the solution of applied and fundamental problems. The results of the Project find their applications in scientific, technical, educational, social and economic fields. It will allow us to decrease the risk of SD collisions with operational satellites, to verify the existing spacecraft protection shields, to adjust the SD distribution models, to elaborate new mitigation measures to preserve the GEO region. The  SD catalogue may be used for many studies. For instance, it is used to improve the Earth gravity model and the orbital object motion theories, including the influence of the solar radiation pressure, and to analyze the upper layers Earth atmosphere density and the Earth’s magnetic field.

The Noto research team developed a VLBI acquistion and recording system well suited for RadarVLBI observations. Today many of these terminals are used at the radio telescopes belonging to the international RadarVLBI network.