Status of the Sardinia Radio Telescope as a receiver of the BIRALET bi-static radar for space debris observations

Space debris are human-made objects, of variable sizes and shapes, that orbit the Earth or reenter the atmosphere. They represent a serious problem for every active spacecraft and satellite, due to the high risk of collision and consequently the generation of new debris. One of the main segments of the Space Situational Awareness program regards space surveillance and tracking activities, with procedures for tracking resident space objects, using a sensor network composed by radars, telescopes and lasers. In this way, it is possible to collect data in order to catalogue and perform orbit predictions of objects orbiting the Earth, with the aim of avoiding collisions between them. One of the Italian radars for space and surveillance tracking functions is represented by the BIRALET system, an acronym which stands for Bistatic Radar for LEO Tracking. This radar operates in P-band at 410-415 MHz, is a bi-static configuration composed of a transmitting 7-meter antenna and the SRT (Sardinia Radio Telescope) as receiver, with a baseline of about 20 km. The Sardinia Radio Telescope is a 64-meter fully steerable wheel-and-track antenna, located near San Basilio (Cagliari, Sardinia, Italy). It represents a flexible instrument used for radio astronomy and space science studies, developed to work in a wide frequency range between 300 MHz and 110 GHz. In this paper, we present a review of the status of the SRT for space debris observation. In particular, we describe three possible system configurations, in order to perform Doppler shift and range measurements. In particular, we present a simplified solution based on a spectrum analyzer as a back-end that permits only Doppler shift measurements. Another more complex solution for Doppler shift measurements, is based on the electronic Red Pitaya board. For the Red Pitaya we developed also a dedicated signal acquisition chain with a down-conversion circuit, in order to shift the received signal in the frequency range of the board. Finally, a more complex solution that allows range and range rate measurements, based on the National Instrument USRP board as a back-end. For future developments, we present the possibility to improve our system, using a C-band Phased Array Feed as a receiver

Terrestrial Laser Scanner and Close Range Photogrammetry point clouds accuracy assessment for the structure deformations monitoring

In this paper we show the results of several tests carried out using methods and instrumentation typical of an architectural survey, along with a set of metrological instrumentation, on a Reinforced Concrete (RC) beam subjected to increasing loads. The goal was to assess the accuracy in the displacements estimated by a medium quality terrestrial laser scanner (TLS) Focus 3d from Faro Technologies, and the low-cost digital camera Canon PowerShot S110 used in a Close Range Photogrammetry (CRP) survey. The software used for scan-data and point clouds processing was Reconstructor JRC Software v. 3.1.0, maintained by Gexcel Ltd, while the images processing was performed with the software Photoscan from Agisoft, which implements Structure from Motion (SfM) approach. Two processing strategies were used in the point clouds comparison: mesh2mesh and modelling the beam behavior fitting the contours of the beam with second order polynomials. Comparisons between the TLS and CRP techniques and the metrological equipment used in parallel highlighted the limits and potentialities of the two geomatic techniques used. It has been shown that modeling the behavior of the beam leads to significantly better results than using the mesh2mesh comparison. For the CRP the increase in accuracy was in the order of 40%, while for the TLS of 50%

Interactions between calliphoridae dipters and Helicodiceros muscivorus

This article reports on the experimental results of a research programme dealing with the reproductive strategies of Helicodiceros muscivorus (L. fil.) Engler(Araceae: Aroideae). In particular, the role played by the odorous mixture emanated by the vegetable species as olfactory information received by the insects, and the importance of that specific biological activity in governing the behavioural choices made by the pollinating insects is studied

GAIA,Progettazione, realizzazione e caratterizzazione della GAIA Board

GAIA,Progettazione, realizzazione e caratterizzazione della GAIA Board. In questo report viene illustrata la GAIA board implementata per fornire e monitorare il BIAS degli LNA (Low Noise Amplifier) installati nei ricevitore radioastronomici

Advantages of using a C-band phased array feed as a receiver in the Sardinia radio telescope for space debris monitoring

The population of space debris is continuously growing and it represents a potential problem for satellites and spacecraft. In fact, new collisions could exponentially rise the number of debris and so the level of threat represented by these objects. To prevent new collisions, the monitoring of space environment is necessary. For this reason, radar measurements are relevant, in particular to observe Space Debris in Low Earth Orbit. In recent years, the Sardinia Radio Telescope, a fully steerable wheel-and-track 64-m antenna, located in Sardinia (Italy), has been used as a receiver in a Pband bi-static radar for space debris monitoring purposes. In this paper the authors investigate the advantages of using a Phased Array Feed in C-band for space debris monitoring (e.g. improved sensitivity and gain, detection of the object trajectory allowed by multiple beams, improvement of the orbit determination of known and unknown debris), as a receiver of the Sardinia Radio Telescope compared to the already used mono-beam P-band receiver

Space Debris Detection in Low Earth Orbit with the Sardina Radio Telescope

Space debris are orbiting objects that represent a major threat for space operations. In this work a bistatic radar configuration named BIstatic RAdar for LEo Tracking (BIRALET) is used to detect a set of space debris. Signalto- Noise Ratios, Doppler shift measures as well as the frequency specters for each debris are presented

The control system of the 3 mm band SIS receiver for the Sardinia Radio Telescope

We present the control system of the 84-116 GHz (3 mm band) Superconductor-Insulator-Superconductor (SIS) heterodyne receiver to be installed at the Gregorian focus of the Sardinia Radio Telescope (SRT). The control system is based on a single-board computer from Raspberry, on microcontrollers from Arduino, and on a Python program for communication between the receiver and the SRT antenna control software, which remotely controls the backshorttuned SIS mixer, the receiver calibration system and the Local Oscillator (LO) system

Upgrading the Sardinia Radio Telescope to a bistatic tracking radar for space debris

In order to prevent the harmful impacts for spacecrafts deriving from the presence of space debris, many surveillance and monitoring programs of the space environment have been started in recent years. The Sardinia Radio Telescope is a new comer in such a scenario, but it has already showed its potential. However, since the actual receiving chain is not optimized for the reception of the echoes scattered from the debris, some modifications has been planned to upgrade the telescope and made it suitable for these types of observations

Safety and efficacy of direct-acting antivirals in transfusion-dependent thalassemic patients with chronic hepatitis C

Background: Hepatitis C virus (HCV) infection is a major cause of liver-related morbidity and mortality among thalassemic patients. New treatments based on direct-acting antivirals (DAAs) are highly effective and well-tolerated by patients; nonetheless, they have not been studied in thalassemic populations. In this study, we evaluated the safety and efficacy of these treatments in a cohort of Sardinian thalassemic patients with chronic HCV infection. Methods: We consecutively recruited thalassemic patients with HCV infection, who were eligible for DAA therapy at 3 liver units. Different drug combinations, depending on HCV genotype and hepatic disease severity, were used according to the current guidelines. Sustained virological response was assessed at 12 weeks posttreatment. Data regarding the side effects and transfusion requirements were also collected. Results: We recruited 49 patients, including 29 males (59.2%), with the mean age of 43 years (genotype 1, 55.1%). Twenty-one (42.9%) patients had a history of interferon-based treatment. Cirrhosis was detected in 28 (57.1%) patients; only 1 patient had ascites and hypoalbuminemia (Child-Pugh B7). On the other hand, 35 (71.4%) patients received a sofosbuvir-based regimen. Ribavirin treatment was reported in 26 (53.1%) cases. All the patients were followed-up for at least 12 weeks after therapy, and sustained virological response was observed in 98% of the patients. No treatment discontinuation was required due to adverse events. The most common side effects included fatigue (24.5%), headache (10.2%), and anaemia (77%), requiring further blood transfusion in patients receiving ribavirin. Conclusions: This prospective study showed that DAAs are safe and effective agents in thalassemic patients with advanced liver fibrosis, regardless of previous antiviral treatment responses

Preliminary Characterization of the Digitally Formed Beams of PHAROS2 Phased Array Feed

We describe the beamforming strategy and the preliminary laboratory characterization results of the beam pattern synthesized by the PHAROS2 Phased Array Feed (PAF), a 4-8 GHz PAF with digital beamformer for radio astronomy application. The PAF is based on an array of 10×11 dual-polarization Vivaldi antennas cryogenically cooled at 20 K along with low noise amplification modules (LNAs) cascaded with a multi-channel Warm Section (WS) receiver. We present the beamforming and test procedures used to, respectively digitally synthesize and characterize the PHAROS2 antenna array beam pattern at 6 GHz. The tests of the array were carried out at room temperature by directly connecting 24 antenna elements to the WS and iTPM digital beamformer in a laboratory measurement setup