Optical observations for energetic characterization of in-orbit explosion: the FREGAT-SB case

Over the past years, the constant increase of space debris and inactive satellites is the root cause of catastrophic events, such as collision between a debris and active satellites. One of the events that might generate a large number of debris is the in-orbit explosion. Within this complex framework, it is of paramount importance to use a monitoring and surveillance system in order to understand the number and the distribution of fragments, in an area around the Earth extremely populated by man-made object. This entails a growing international interest in Space Surveillance and Tracking (SST), where optical observation reaches an interesting method to obtain information of orbital objects. In this paper, the Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) presents the results of an observative campaign focused on the energetical characterization of the explosion and the monitoring of the fragments, which have been generated by a low orbit explosion of the third Russian stage rocket FREGAT-SB (ID 37756). The event occurred on 08.05.2020 between 04:00 and 06:00 UTC time. Through the observatory system Sapienza Coupled University Debris Observatory (SCUDO) located in Collepardo (FR, Italy), a certain number of images have been collected. The observation strategy was focused on the orbital plane to try to estimate the number of these fragments and their distribution. Once the astrometry phase to retrieve the measures in terms of right ascension and declination was performed, a first analysis is carried on to understand whether or not the fragments are already present in the North American Aerospace Defense Command (NORAD) catalogue. The ones that are not catalogued could be FREGAT’s fragments. The next energetic characterization method is based on a tangential impulse assignment in agreement with isotropic explosion and the evolution of fragments’ cloud, where the important variations, to a first approximation, are on semiaxes and eccentricity. As a result of this procedure, an association between the impulse and the measure takes place. The analysis of the angular distance between original body and the fragments over the time is carried out, in order to validate this method. Moreover, a magnitude estimation procedure is shown. All these results are compared with those obtained with the NORAD assignment

A graphical method for the analysis of a satellite’s in-orbit breakup through optical observations

The incessant overcrowding of the space around the Earth with new operative satellites is a critical issue in the Space Traffic Management (STM) framework, especially in last years with the beginning of the new space economy. The operative life of the active satellites is seriously endangered by the numerous uncontrolled objects, i.e., the space debris, which populate the outer space. The consequence of an impact between these objects may be catastrophic, as proved by the events in the recent past. In this context, the in-orbit explosions both of dismissed satellites and rockets stages are one of the main causes of space debris generation. For this reason, a suitable observation and detection strategy of the fragments generated by these events is necessary, e.g., by means of optical systems. In this work, the Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) shows the results, by means of a graphical method, of the short-term analysis of the in-orbit explosions that involved the third stage of the Russian rocket FREGAT-SB and the fragmentation of the military Chinese satellite YUNHAI 1–02. In order to approach the study of a fragmentation event, an observation strategy and an analysis method have been developed. The research of fragments was focused on the orbital plane leading to estimation of fragments’ number and their distribution. The measurements obtained through the images were analyzed in order to understand if the objects present in the images are either included in the North American Aerospace Defense Command (NORAD) catalogue or not. The unknowns could be fragments. The next analysis follows the hypothesis of the isotropic explosion confined only on the tangential impulses. In first approximation, only semi-major axis and eccentricity change due to the impulse. Therefore, it is possible to generate a new Two-Line Elements (TLE) for each fragment leading to an association between the impulses and the affected TLEs. A new, simple, and fast analysis method was developed, specifically to improve the impulse association. It consists in a graphical method where it is possible to see the distribution of the fragments with respect to the original body using the angular distance trend between them

Image processing for geo detection

The space debris issue concerns anyone who decides to approach the space both for research and economic purpose. In fact, they have become a serious problem for the operative satellites, and regardless of their size, which goes from few millimeters to tenth of meters, the space debris are a threat both for the present and the future of the space missions. Nowadays, more than 28000 of orbiting object are placed around the Earth making their detection and recognition a primary issue in the space safeguard. The space debris affect all the orbital regime: from Low Earth Orbit up to the Geostationary region at about 36000 km. The Sapienza Space Systems and Space Surveillance Laboratory has been working for years in the field of the orbiting objects optical observations, and it is approaching the geostationary region monitoring by means an innovative optical system. In this paper the setup and the configuration of this system will be presented and, moreover, the image processing software for the geostationary object detection and recognition will be shown

Innovative observation systems for LEO and GEO orbiting objects state determination

The continuously increase in number of satellites launched, makes that the Space Traffic Management (STM) activities became a primary issue in the aerospace field. Even if the Low Earth Orbit (LEO) remain the most congested orbital regime, also the Geostationary orbit (GEO) begins to get crowded due to the alarming increase of space debris population. Several years of experience in the Space Situational Awareness (SSA) and Space Surveillance and Tracking (SST) framework characterize the Sapienza Space Surveillance and Space Systems Laboratory (S5Lab) research team. The space object observation is mostly based on Charge Coupled Device (CCD) technology pursuing the sidereal tracking observation strategy. This technology, however, doesn’t allow to obtain the measurements necessary to retrieve the so-called characterization information includes details about the attitude motion, shape and material of the space object. For LEO objects, a bistatic optical observations systems has been set up: REmote Space Debris Observation System (RESDOS) and Sapienza Coupled University Debris Observatory (SCUDO), thanks to last generation of scientific Complementary Metal-Oxide Semiconductor (sCMOS) sensors, permit to obtain a large number of synchronized measurements. These hardware are able to track the object during its passage above the observatory and allow to record the brightness variation over time, i.e., light-curves, of the objects itself useful for the attitude determination. For GEO ring monitoring, the fields of view (FoV) obtained with the system for LEO observation are too small. The large field of view requested, most of all in right ascension (RA) direction, has been satisfied with the SURveillance GEOstationary (SURGE) system. A digital cameras system, able to cover up to 120 in Ra, have been developed so that each camera points in a different area of sky vault focusing on the GEO ring. Since no moving parts are foreseen, the FoV of SURGE is fixed in sky vault. Its easy of transport, and its low cost makes SURGE a suitable system for the GEO ring surveillance. All these observation systems, which exploit different observation strategies, allow to obtain a huge amount of data for all the target objects retrieved thanks to fast imaging system. The continuous and fast increasing of satellite number makes that these advanced and innovative systems are required for the SSA and SST purposes. In this paper the development of these systems, the algorithms useful to process the obtained data, and the results of LEO and GEO objects observations will be shown

Hands-on education through nano-satellites development: Past, current and future projects at sapienza S5Lab

The Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) at Sapienza University of Rome is in the recent years carrying out a multiplicity of University nano-satellite projects, with the design, development, launch and operations of their CubeSats. The development of a satellite is a key-importance chance for University students to gain soft skills, practical knowledge and to follow a complete development cycle of a spaceborne object. Additionally, the development of a cycle with actual scientific objectives besides the educational aim addressed at students allow the involved participants to maximize their educational return by becoming mission specialists on specific scientific branches, when working on all the satellite subsystems. The paper describes the five current and past satellite projects (URSA MAIOR, 1KUNS-PF, LEDSAT, GREENCUBE, WildTrackCube-SIMBA). Every project is briefly described together with the scientific aim of the CubeSat and the main lessons learned related to the project

GreenCube: Microgreens cultivation and growth monitoring on-board a 3U cubesat

The in-orbit cultivation of vegetables, fruits, and edible plants is of paramount importance for the development of long-term manned space mission Environmental Control and Life Support Systems (ECLSS) and for the improvement of bio-regenerative systems. GreenCube is a 3U CubeSat mission aimed at demonstrating the functionalities of an autonomous cultivation laboratory that stems from a collaboration between the Sapienza University of Rome, the Italian Space Agency, University of Naples "Federico II", and ENEA. The satellite will cultivate microgreens in a pressurized vessel containing support systems and monitoring instrumentation for the plant growth. This paper describes the GreenCube mission and the instrumentation used for the growth support and monitoring