Optimal orbits for a recycling station supporting in-orbit recycling

This paper proposes a method to find the location of optimal orbits for a recycling station. The goal is to find the orbital elements of an orbit that can be reached from the regions of interest, for example where components of non-active spacecrafts are located. The idea is to look at areas in the orbital parameter space that are reached by propagating trajectories from the selected regions. Varying all initial parameters, sets of possible orbits are obtained. The associated manoeuvre cost is computed and compared to the classical direct transfers. The long-term evolution of the obtained orbits is studied to assess if they remain inside the reachable set. The orbits that minimise the manoeuvre cost are selected

A transport network for in-orbit recycling exploiting natural dynamics

This paper proposes an initial step towards the construction of a transport network connecting different orbit regimes with a Geosynchronous orbit in the Laplace plane and the Geosynchronous orbit with the Moon. This transport network will be designed to exploit a combination of natural dynamics and impulsive manoeuvres. The methodology proposed starts from the identification of regions, in orbital parameter space, around the Earth, where third-body effects concur to modify favourably the orbital elements. A sequence of manoeuvres is then devised to exploit these natural effects and achieve the desired final orbit. Conversely, the cislunar region will be connected thanks to impulsive manoeuvres and invariant manifolds, peculiar to the Circular Restricted Three-Body Problem. Finally, a perturbed two-body model is also used to identify possible disposal orbits for the decommissioned modular space assets

Assembly and disassembly dynamics of modular solar power satellite

Managing the disposal of large-scale modular structures in space, like Solar Power Satellites (SPS), poses a complex challenge. The modularity of these systems facilitates the replacement of malfunctioning components via space robotics, offering the potential for extended operational lifespans. In this context, it is crucial to understand how such structures behave during nominal operations and when they are being assembled or disassembled. The aim of this work is to analyse the dynamics of a large-scale modular structure, like an SPS in Earth orbit, while it is subject to a range of forces and during the assembly and disassembly processes. The dynamical model representing a SPS-ALPHA like satellite is derived. The structure is modelled as a tethered satellite, with two masses at the edges of a rigid rod, one representing the system of reflectors intercepting sunlight, the other the primary array transmitting to Earth the energy in form of a microwave beam. The satellite is located in a Geostationary orbit and it is subject to Earth’s gravity, solar radiation pressure and to the reaction force resulting from the discharge of the microwave beam. The evolution of the attitude angles and the phase space associated to chaos indicators are derived and compared for different scenarios: nominal without non-conservative forces, nominal with solar radiation pressure and microwave beam forces and during the assembly and disassembly phases. These phases are simulated by varying the area and mass of the system of reflectors over time. This analysis provides valuable insights into the behaviour of tethered satellites in Earth orbit, and constitutes an important step in understanding how a peculiar structure like that of a SPS can respond to a range of operational conditions

Multidetector CT appearance of the pelvis after cesarean delivery: normal and abnormal acute findings

Abstract Cesarean section (CS) may have several acute complications that can occur in the early postoperative period. The most common acute complications are hematomas and hemorrhage, infection, ovarian vein thrombosis, uterine dehiscence and rupture. Pelvic hematomas usually occur at specific sites and include bladder flap hematoma (between the lower uterine segment and the bladder) and subfascial or rectus sheath hematoma (rectus sheath or prevescical space). Puerperal hemorrhage can be associated with uterine dehiscence or rupture. Pelvic infections include endometritis, abscess, wound infection, and retained product of conception. Radiologists play an important role in the diagnosis and management of postoperative complications as a result of increasing use of multidetector CT in emergency room. The knowledge of normal and abnormal postsurgical anatomy and findings should facilitate the correct diagnosis so that the best management can be chosen for the patient, avoiding unnecessary surgical interventions and additional treatments. In this article we review the surgical cesarean technique and imaging CT technique followed by description of normal and abnormal post-CS CT findings