Analysis and design of Cubesat constellation for the Mediterranean south costal monitoring against illegal immigration

Costal monitoring is focused on fast response to illegal immigration and illegal ship traffic. Especially, the illegal ship traffic has been present in media since April 2015, as the number of reported deaths of immigrants crossing the Mediterranean significantly increased. Satellite images provide a possibility to at least partially control both types of events. This paper defines the principal criteria to select the best satellite constellation architecture for maritime and coastal monitoring, filling the gaps of imagery techniques in term of real-time control. The primary purpose of a constellation is to obtain global measurement improving the temporal resolution. The small size and low-cost are the main factors, which make CubeSats ideal for use in constellations. We propose a constellation of 9 Cubesats distributed evenly in 3 different planes. This reduces the revisit time enhancing the coverage duration. In addition, it also allows observing fire, damage on building and similar disasters. In this analysis, the performance criteria were reported such as the revisit time, the vision duration and the area coverage.     

An interactive system for global ship monitoring

The US Navy has more than 300 ships equipped with over 500 PHALANX weapon systems. Ordalts (ordnance alterations) and casreps (casualty reports) are received frequently by Naval Ordnance. Ordalts are done when parts need replacing or a design is exchanged for an old. Casreps are an urgent request for parts or service. Information pertaining to ordalts and casreps is put into several databases, which are continually updated and used in reports among the PHALANX community. Ship locations are used for sending parts and/or assistance to the ship. The ordalt and casrep requests have been combined with the ship locations report to produce a more efficient manner in which to monitor ordalt requests, casrep requests and ship locations, using a sample database containing ordalt and casrep data and ship locations. The database is interfaced to a computer graphics program that monitors ship movement throughout the world and supplies information from the database whenever requested. The hardware and software used to implement the project are described     

Variation of the orbital elements for parabolic trajectories due to a small impulse using Gauss equations

Firstly we derive Gauss’ perturbation equation for parabolic motion using Murray–Dermott and Kovalevsky procedures. Secondly, we easily deduce the variations of the orbital elements for the parabolic trajectories due to a small impulse at any point along the path and at the vertex of the parabola.     

Didactic satellite based on Android platform for space operation demonstration and development

Space technology plays a pivotal role in society development. It offers new methods for telemetry, monitoring and control. However, this sector requires training, research and skills development but the lack of instruments, materials and budgets affects the ambiguity to understand satellite technology. The objective of this paper is to describe a demonstration prototype of a smart phone device for space operations study. Therefore, the first task was carried out to give a demonstration for spatial imagery and attitude determination missions through a wireless communication. The smart phone’s Bluetooth was used to achieve this goal inclusive of a new method to enable real time transmission. In addition, an algorithm around a quaternion based Kalman filter was included in order to detect the reliability of the prototype's orientation. The second task was carried out to provide a demonstration for the attitude control mission using the smart phone’s orientation sensor, including a new method for an autonomous guided mode. As a result, the acquisition platform showed real time measurement with good accuracy for orientation detection and image transmission. In addition, the prototype kept the balance during the demonstration based on the attitude control method.     

Optimization of Bi-Elliptic transfer with plane change—Part I

We introduce a more advanced analysis than that of Roth concerning the following two points of view: (1) We attempt to find an analytical solution of the optimization problem instead of Roth's iterative solution. That means a stress is operated on the analytical approach. (2) We consider the terminal orbits to be elliptic and not circular as Roth assumed. This is a generalization of the problem. We shall complete the solution of this Bi-Elliptic transfer with plane change problem in the second part of the present research paper (I).     

Impacts of the PAH size and the radiation intensity on the IR features of illuminated dust within the reflection nebulae

Interstellar dust grains are illuminated in the reflection nebulae. Under conditions of the PAH size and the intensity of the interstellar radiation field, we follow their impact on the PAH aromatic infrared bands using the numerical DustEM code. For a dust model consisting of PAH, amorphous C and amorphous silicate, the PAH size varies in a range from 0.31 to 4.9 nm while the radiation intensity varies by a scale factor from 0.1 to 10⁴. Various trends of the results show the effect of varying both the PAH size and the radiation intensity on the strength of the aromatic mid-IR bands. Through small PAH sizes less than 0.7 nm, the grain temperature distribution of PAHs shows a small variation within 2–3 K at low radiation intensity while it increases to 15 and 8 K for PAH⁰ and PAH⁺, respectively, at higher radiation intensity. In final the variability in these results reveals the evolution of the dust grains under the physical space conditions of the reflection nebulae. In the mid-IR region, the contributions of PAH⁰ and PAH⁺ in the total SED intensity agree with the proportions of these PAHs observed in some reflection nebulae having higher radiation intensities.     

The optimization of the orbital Hohmann transfer

There are four bi-impulsive distinct configurations for the generalized Hohmann orbit transfer. In this case the terminal orbits as well as the transfer orbit are elliptic and coplanar. The elements of the initial orbit a₁, e₁ and the semi-major axis a₂ of the terminal orbit are uniquely given quantities. For optimization procedure, minimization is relevant to the independent parameter e_T, the eccentricity of the transfer orbit. We are capable of the assignment of minimum rocket fuel expenditure by using ordinary calculus condition of minimization for |ΔV_A|+|ΔV_B|=S.We exposed in detail the multi-steps of the optimization procedure. We constructed the variation table of S(e_T) which proved that S(e_T) is a decreasing function of e_T in the admissible interval [e_Tmin,e_Tmax]. Our analysis leads to the fact that e₂=1 for e_T=e_Tmax, i.e. the final orbit is a parabolic trajectory.