scholarly journals Small Satellites Constellations and Their Impact on CBRNe Management in Africa

2021 ◽  
Vol 11 (4) ◽  
pp. 387-395
Author(s):  
Donato Morea ◽  
Giacomo Primo Sciortino
Keyword(s):  
Optical Quality ◽  
Low Earth Orbit ◽  
Space Technology ◽  
Demand Model ◽  
Small Satellites ◽  
Relative Pricing ◽  
Ground Segment ◽  
User Terminal ◽  
Space Economy ◽  
International Astronautical

A wave of small satellites massive constellations, in the range of hundreds of units each, is progressively populating the Low Earth Orbit (LEO) with a low-price, and varied, offer of Telecom (speed band) and Earth Imaging services (Starlink, Planet, One Web, etc.). It is a market - driven trend based on new satellite interlocking technologies, which cut down the supplier costs of launch and in orbit operations compared to the traditional technology based on big (and much heavier) geostationary satellites operating at high altitudes. This is a disruptive phenomenon especially for the developing world, where such vital services have always been hard to access, and their use therefore remained scarce, not consolidated, or even completely missing. Among these, Emergency management is definitely crucial. The geographical focus of this study is Africa and it deals not only with Institutional PRS users but with a wider potential context (corporations, private subjects, etc.). It clearly appears that a general degree of “Country readiness” toward Space technology and organization is necessary for these initiatives to take place. This can be achieved through certified international cooperation. The authors then, based on an estimated demand Model for services with their relative pricing corresponding to a cost-designed constellation of small microsatellites, presented already, among other, at several International Astronautical Federation(IAF)Symposia on Space Economy, simulate the resulting type of services available: TLC by band types and relative upload and download rates, Earth imaging by refresh rates and optical quality and resolution, Ground segment configuration for signal backhauling and user terminal receiving.. This info isapplied to a specific African Country case (Nigeria) whose significance emerged over other Countries after the application of comparative grids. Finally, an insight on the specifically configuration of services for Chemical, Biological, Radiological, Nuclear, and Explosive (CBRNe) like management by local users, both maritime and land, with the relative costs, is offered. This is consequently left open for follow ups and discussion, due to the customer – design, project financing approaches of this Model programme.

scholarly journals Preliminary Study of Launch and Orbit of a CubeSat Using a Modified VSB-30 Launcher Vehicle

2020 ◽  
pp. 62-79
Author(s):  
Artur Gustavo Slongo ◽  
André Luís da Silva ◽  
Deniel Desconzi Moraes ◽  
João Felipe de Araújo Martos ◽  
Lorenzzo Quevedo Mantovani ◽  
...  
Keyword(s):  
Low Earth Orbit ◽  
Sounding Rocket ◽  
Space Technology ◽  
Sounding Rockets ◽  
Small Satellites ◽  
Mass Insertion ◽  
Orbital Decay ◽  
Launch Site ◽  
Suborbital Flights ◽  
Preliminary Study

During the last decade, the world faced the mass insertion of small satellites in the space technology scenario. Every year, the number of micro and nanosatellites launched increases and gets more attention from players in the space market. Despite the lack of a national launcher, the Brazilian Space Program is known for some successful development in the last century, including its space assets, such as a privileged launch site near the equator, a family of flight proven and reliable sounding rockets for suborbital flights and microgravity experiments and universities with established small satellites programs. Thereby, the present work proposes a modification of the Brazilian VSB-30 sounding rocket in order to allow the launch and insertion in low Earth orbit (LEO) of small satellites fulfilling the gap of a national launcher. It also presents a CubeSat orbital decay simulation and orbital insertion simulation with the modified rocket launched from the Alcântara Launch Center as a matter of verifying the potential of national missions using this modified launcher.

scholarly journals Guidance Stabilization of Satellites Using the Geomagnetic Field

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Francisco Miranda
Keyword(s):  
Geomagnetic Field ◽  
Technological Development ◽  
Low Cost ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Small Satellites ◽  
Attitude Stabilization ◽  
Short Period ◽  
Low Earth Orbit Satellite ◽  
Games Theory

In the last years the small satellites have played an important role in the technological development. The attractive short period of design and low cost of them and the capacity to solve problems that are usually considered as problems to big and expensive spacecrafts lead us to study the control problem of these satellites. Active three-axis magnetic attitude stabilization of a low Earth orbit satellite is considered in this work. The control is created by interaction between the magnetic moment generated by magnetorquers mounted on the satellite body and the geomagnetic field. This problem is quite complex and difficult to solve. To overcome this difficulty guidance control is considered, where we use ε-strategies introduced by Pontryagin in the frame of differential games theory. Qualitative analysis and results of numerical simulation are presented.

scholarly journals Attitude Sensor from Ellipsoid Observations: A Numerical and Experimental Validation

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 433
Author(s):  
Dario Modenini ◽  
Alfredo Locarini ◽  
Marco Zannoni
Keyword(s):  
Experimental Validation ◽  
Attitude Determination ◽  
Closed Form Solution ◽  
Infrared Camera ◽  
Form Solution ◽  
Low Earth Orbit ◽  
Preliminary Design ◽  
Small Satellites ◽  
Attitude Sensor ◽  
Rms Errors

The preliminary design and validation of a novel, high accuracy horizon-sensor for small satellites is presented, which is based on the theory of attitude determination from ellipsoid observations. The concept consists of a multi-head infrared sensor capturing images of the Earth limb. By fitting an ellipse to the imaged limb arcs, and exploiting some analytical results available from projective geometry, a closed form solution for computing the attitude matrix is provided. The algorithm is developed in a dimensionless framework, requiring the knowledge of the shape of the imaged target, but not of its size. As a result, the solution is less sensitive to the limb shift caused by the atmospheric own radiance. To evaluate the performance of the proposed method, a numerical simulator is developed, which generates images captured in low Earth orbit, including also the presence of the atmosphere. In addition, experimental validation is provided due to a dedicated testbed, making use of a miniature infrared camera. Results show that our sensor concept returns rms errors of few hundredths of a degree or less in determining the local nadir direction.

scholarly journals LATLAUNCH AIR-LAUNCH SYSTEM FOR LOW-COST LAUNCHING OF SMALL SATELLITES INTO LOW EARTH ORBIT

Aviation ◽  
2021 ◽  
Vol 25 (2) ◽  
pp. 73-78
Author(s):  
Aleksandrs Urbahs ◽  
Sergey Kravchenko ◽  
Margarita Urbaha ◽  
Kristine Carjova ◽  
Natalja Panova ◽  
...  
Keyword(s):  
Low Cost ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Competitive Advantages ◽  
Characteristic Velocity ◽  
Small Satellites ◽  
Aerial Platform

The paper presents the air-launch system enabling the delivery of small satellites into low Earth orbit. One of the most important advantages of the concept is its cost. Generally, the paper proves that launching a carrier from an aerial platform (a movable launch pad) provides the whole range of competitive advantages. In particular, the total losses during the launch from an aerial platform will reduce by 20–35%, and the characteristic velocity of the maneuver will reduce by 4–7%.

Security issues in space-based operations: the need to control the orbit´s overpopulation to ensure a safe access and use of space

2021 ◽  
Author(s):  
Pablo Rodriguez Llorca
Keyword(s):  
Low Earth Orbit ◽  
Minimum Size ◽  
Population Increase ◽  
Economic Losses ◽  
Private Company ◽  
Space Applications ◽  
Final Disposal ◽  
Small Satellites ◽  
The Earth ◽  
Low Earth Orbits

<p>The development of the technology used for space applications, along with the decreasing investment that is needed, has fostered the inclusion of new actors in the space business in what is known as the “New Space”. The number of participants in the market is growing exceptionally fast and one finds a poor, if any, regulation for very complex activities in space that might produce irreversible effects if all their phases, from the design to the final disposal and including several potential contingencies, are not considered and do not follow a set of rules.</p><p>Overpopulation of the common orbits, especially in low Earth orbits, increases the probability of collisions between satellites which, were it to happen, would pollute the orbit with small sized fragmentation debris. The cloud of fragmented parts becomes a hazard for other satellites sharing the same or nearby orbits, forcing to perform more collision avoidance manoeuvres. This situation arises new problems. On the one hand, there is an increasing number of small satellites (i.e. cubesats) with no capability to manoeuvre. Their propulsion system might not be able to react early enough as to avoid a potential collision. With the satellites population continuously growing, the situation is getting worse. On the other hand, the debris tracking systems can trace particles down to a minimum size, but smaller pieces cannot be monitored. These ones might result in the total loss of the spacecraft if a collision were to occur and their population increase needs to be avoided. Polluting the orbits increases the risk of economic losses, because a satellite could be totally damaged, but also because the orbit might become inaccessible for other users and their business could not be developed. Last but not least, there is a fundamental interest in certain orbits for Earth’s resources and environment monitoring, and a safe continuation of such activities must be ensured, as they represent a need for our civilisation.</p><p>The satellite traffic needs to be regulated and the final disposal activities ensured. Small satellites in low Earth orbit are likely to disintegrate during the re-entry in the atmosphere, although some parts, especially in bigger spacecraft, can reach the surface of the Earth. The probability of causing any damage is very low, but the growing number of satellites increases the chances of satellite residues producing damages. The disposal requires a reliable technology that performs the deorbit in a controlled way, and over a region of the Earth with minimum possibility of causing any damage. Higher orbits have designed disposal orbits were non-operational spacecraft are being stored, and that should also follow a regulation in order to avoid future problems.</p><p>This talk describes the problematics that are associated with the operations of the space market in different orbits and the need of a set of rules that any actor, regardless of being a space agency or a private company, is required to follow.</p>

DESIGN, IMPLEMENTATION AND TESTING OF A FLEXIBLE FULLY-DIGITAL TRANSPONDER FOR LOW-EARTH ORBIT SATELLITE COMMUNICATIONS

2014 ◽  
Vol 23 (10) ◽  
pp. 1450148 ◽  
Author(s):  
DANIELE DAVALLE ◽  
RICCARDO CASSETTARI ◽  
SERGIO SAPONARA ◽  
LUCA FANUCCI ◽  
LUCA CUCCHI ◽  
...  
Keyword(s):  
Power Consumption ◽  
Satellite Communications ◽  
Intermediate Frequency ◽  
Scientific Data ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Hardware Complexity ◽  
Digital Radio ◽  
Small Satellites ◽  
Control Configuration

This paper presents a flexible Telemetry, Tracking & Command (TT&C) transponder for Earth Observation (EO) small satellites. The proposed device adds to the state-of-the-art EO TT&C transponders the possibility of scientific data transfer thanks to the high downlink data-rate (up to 40 Mbps) and in-flight reconfigurability via Telecomand (TC). The integration of these features in one single device represents a considerable optimization in terms of mass budget, which is important for EO small satellites. Furthermore, in-flight reconfigurability of communication parameters via TC is important for in-orbit link optimization, which is especially useful for Low-Earth Orbit (LEO) satellites where visibility can be as short as few hundreds of seconds. The proposed transponder is a digital radio unit working at 70 MHz intermediate frequency (IF). A new custom and configurable hardware accelerator was developed to cover intensive radio DSP functions at IF. The custom hardware is integrated in a single FPGA with a space-compliant processor core, for control, configuration and interface with the other satellite subsystems. All the quantization parameters were fine-tailored to reach a trade-off between hardware complexity and implementation loss (IL). The IF RX/TX ports require eight bits and seven bits, respectively. The IL is 0.5 dB at BER = 10-5 for the RX chain. A system proof-of-concept was implemented on the Xilinx Virtex 6 VLX75T-FF484 FPGA. The total device occupation is 82%. The power consumption of the design fitted in FPGA is less than 2 W. The power consumption of the whole demonstrator board is less than 9 W.

scholarly journals Attitude Analysis of Small Satellites Using Model-Based Simulation

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Samir A. Rawashdeh
Keyword(s):  
Attitude Control ◽  
Magnetic Hysteresis ◽  
Space Station ◽  
Low Earth Orbit ◽  
Gravity Gradient ◽  
Simulation Tool ◽  
Shape Modelling ◽  
Small Satellites ◽  
Magnetic Stabilization ◽  
Aerodynamic Torque

CubeSats, and small satellites in general, being small and relatively light, are sensitive to disturbance torques in the orbital environment. We developed a simulation tool that includes models of the major environmental torques and small satellite experiences in low Earth orbit, which allows users to study the attitude response for a given spacecraft and assist in the design of attitude control systems, such as selecting the magnet strength when using passive magnetic stabilization or designing the shape of the spacecraft when using aerodynamic attitude stabilization. The simulation tool named the Smart Nanosatellite Attitude Propagator (SNAP) has been public in precompiled form and widely used since 2010; this paper accompanies the release of SNAP’s source code with the inclusion of new models for aerodynamic torque and other new features. Details on internal models are described, including the models for orbit propagation, Earth’s magnetic field, gravity gradient torque, spacecraft shape modelling and aerodynamic torque, permanent magnetic dipole torque, and magnetic hysteresis. A discussion is presented on the significance of aerodynamic torque and magnetic hysteresis on a magnetically stabilized 3-unit CubeSat in the orbit of the International Space Station, from which many small satellites are deployed.

scholarly journals Optimizing the Communication Capacity of a Ground Station Network

2019 ◽  
Author(s):  
Rogerio Atem de Carvalho
Keyword(s):  
Low Earth Orbit ◽  
Field Of View ◽  
Lead Times ◽  
Small Satellites ◽  
Physical Constraints ◽  
Ground Station ◽  
Communication Capacity ◽  
Communication Time ◽  
Total Communication ◽  
Synchronization Procedure

Small satellites are growing in use for educational, scientific, and commercial purposes, usually in Low Earth Orbit (LEO) flights, given their lower costs and associated risks, as well as smaller lead times for assembling and testing. However, the typically short periods of LEO passes bring the need to find ways of optimizing the communication between the ground and space segments. In that direction, several projects have relied on ground station networks to increase the total time of contact with the satellites. In this type of arrangement, the stations agree in monitoring one or more satellites in such a way that, as the spacecraft exits one station’s field of view, another station assumes its tracking, extending the total communication time and compensating the short passes. This type of solution, while very efficient in terms of costs, on the other hand demands a good synchronization procedure, so that all constraints present in its operations are taken into account and the network can operate effectively. This paper aims at describing a model implemented for orchestrating ground station networks that optimizes the communication capacity of the ground network, while taking into account physical constraints not usually considered in other models currently proposed.

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