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

Author(s):  
Pablo Rodriguez Llorca

<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>

2003 ◽  
Vol 792 ◽  
Author(s):  
M. Chipara ◽  
D. L. Edwards ◽  
J. Zaleski ◽  
B. Hoang ◽  
B. Przewoski ◽  
...  

ABSTRACTThe effects of the space environment on polytetrafluorethylene and some fluorinated polymers, copolymers, and blends are critically reviewed. It is shown that in low altitude orbits such as Low Earth Orbit and Geostationary Orbit the presence of both ionizing radiation and atomic oxygen triggers a synergetic degradation of materials based on fluorinated polymers. The behavior is due to the lability of the in-chain alkyl radical to oxygen attack. It is concluded that fluorinated polymers should not be used as materials for space applications, as long as the mission implies low Earth orbits.


2020 ◽  
Vol 956 (2) ◽  
pp. 50-56
Author(s):  
I.N. Gansvind

Changes in space activities related to the practice of using small satellites are considered. The relatively low cost of development, production and launch in low Earth orbiting are explained due to transformation of small satellites into a mass product, available for using in the educational process, remote sensing, in meteorology, flight-testing new technologies, communication and internet distribution as well as space exploration. Small satellites constellations serve the need for systematic global imagery with minimal interval between observing any area of the Earth. Large constella- tions of satellites with radio-occultation equipment provide high-altitude profiles of atmospheric pressure, temperature and humidity for assimilation in weather models. Small satellites will find applications beyond low earth orbits. It is planned to launch 6U CubeSat Sky Fire in the vicinity of the moon to study its surface with new infrared hardware. The projected orbit for Lunar Orbital Platform Gateway will be checked using CubeSat to meet the design requirements.


Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 577
Author(s):  
Luca Schirru ◽  
Tonino Pisanu ◽  
Angelo Podda

Space debris is a term for all human-made objects orbiting the Earth or reentering the atmosphere. The population of space debris is continuously growing and it represents a potential issue for active satellites and spacecraft. New collisions and fragmentation could exponentially increase the amount of debris and so the level of risk represented by these objects. The principal technique used for the debris monitoring, in the Low Earth Orbit (LEO) between 200 km and 2000 km of altitude, is based on radar systems. The BIRALET system represents one of the main Italian radars involved in resident space objects observations. It is a bi-static radar, which operates in the P-band at 410–415 MHz, that uses the Sardinia Radio Telescope as receiver. In this paper, a detailed description of the new ad hoc back-end developed for the BIRALET radar, with the aim to perform slant-range and Doppler shift measurements, is presented. The new system was successfully tested in several validation measurement campaigns, the results of which are reported and discussed.


2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Francisco Miranda

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.


Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 433
Author(s):  
Dario Modenini ◽  
Alfredo Locarini ◽  
Marco Zannoni

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.


2013 ◽  
Vol 367 ◽  
pp. 270-274
Author(s):  
Guang Yan Xu ◽  
Jian Fu Luo

J2 perturbation has been widely studied for satellite formations in low earth orbit. However, the effects of some tiny aspherical gravitational perturbations such as high-order zonal harmonic perturbations, sectorial and tesseral harmonic perturbations are not negligible for long term formation flight. In this paper, after eliminating the effects of J2 perturbation which accommodating it, research these tiny perturbations uses numerical analysis and acquires some conclusions. High-order zonal harmonic perturbations may cause divergence in radial, in-track and cross-track direction, while the drift caused by sectorial and tesseral harmonic perturbations is larger than higher-order zonal harmonic perturbations about two magnitudes generally, and drift in cross-track direction is secular.


2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
J. C. Sampaio ◽  
E. Wnuk ◽  
R. Vilhena de Moraes ◽  
S. S. Fernandes

The increasing number of objects orbiting the earth justifies the great attention and interest in the observation, spacecraft protection, and collision avoidance. These studies involve different disturbances and resonances in the orbital motions of these objects distributed by the distinct altitudes. In this work, objects in resonant orbital motions are studied in low earth orbits. Using the two-line elements (TLE) of the NORAD, resonant angles and resonant periods associated with real motions are described, providing more accurate information to develop an analytical model that describes a certain resonance. The time behaviors of the semimajor axis, eccentricity, and inclination of some space debris are studied. Possible irregular motions are observed by the frequency analysis and by the presence of different resonant angles describing the orbital dynamics of these objects.


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