scholarly journals Alternative Transfers to the NEOs 99942 Apophis, 1994 WR12, and 2007 UW1 via Derived Trajectories from Periodic Orbits of Family G

2009 ◽  
Vol 2009 ◽  
pp. 1-12 ◽  
Author(s):  
C. F. de Melo ◽  
E. E. N. Macau ◽  
O. C. Winter
Keyword(s):  
Periodic Orbits ◽  
The Earth ◽  
Low Earth Orbits ◽  
Heliocentric Orbits ◽  
Sphere Of Influence ◽  
Three Body ◽  
The Cost ◽  
Earth Orbits ◽  
Interplanetary Missions ◽  
Near Earth Objects

Swing-by techniques are extensively used in interplanetary missions to minimize fuel consumption and to raise payloads of spacecrafts. The effectiveness of this type of maneuver has been proven since the beginning of space exploration. According to this premise, we have explored the existence of a natural and direct link between low Earth orbits and the lunar sphere of influence to get low-energy transfer trajectories to the Near Earth Objects (NEOs) 99942 Apophis, 1994 WR12, and 2007 UW1 through swing-bys with the Moon. The existence of this link is related to a family of retrograde periodic orbits around the Lagrangian equilibrium point L1 predicted for the circular, planar, restricted three-body Earth-Moon-particle problem. The trajectories in this link are sensitive to small disturbances. This enables them to be conveniently diverted reducing so the cost of the swing-by maneuver. These maneuvers allow a gain in energy sufficient for the trajectories to escape from the Earth-Moon system and to stabilize in heliocentric orbits between the Earth and Venus or Earth and Mars. Therefore, the trajectories have sufficient reach to intercept the NEOs' orbits.

scholarly journals Resonant Orbital Dynamics in LEO Region: Space Debris in Focus

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
J. C. Sampaio ◽  
E. Wnuk ◽  
R. Vilhena de Moraes ◽  
S. S. Fernandes
Keyword(s):  
Collision Avoidance ◽  
Frequency Analysis ◽  
Space Debris ◽  
Semimajor Axis ◽  
Orbital Dynamics ◽  
Accurate Information ◽  
The Earth ◽  
Low Earth Orbits ◽  
Line Elements ◽  
Earth Orbits

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.

scholarly journals Managing multiple satellite architectures by spatial grasp technology

2021 ◽  
Vol 1 ◽  
pp. 3-16
Author(s):  
P.S. Sapaty ◽  
Keyword(s):  
Strategic Defense Initiative ◽  
The Earth ◽  
Space Projects ◽  
Strategic Defense ◽  
Low Earth Orbits ◽  
Cruise Missiles ◽  
High Level ◽  
Space Architecture ◽  
And Control ◽  
Earth Orbits

The paper reviews some advanced space projects oriented on many satellites moving around the globe in low Earth orbits, and investigates how to organize their collective operation for solving important world problems, especially those related to global security and defense. It analyzes the application of the developed Spatial Grasp model and Technology (SGT), successfully tested on numerous applications, for simulation and management of multiple satellite architectures. Of particular interest is the latest Space Development Agency Next-Generation Space Architecture that uses a great number of cooperating satellites organized on different layers, which appears to be much more advanced than the known Strategic Defense Initiative project of the eighties. SGT is based on mobile recursive scenarios in a special high-level Spatial Grasp Language (SGL) which can self-navigate and self-match distributed environments while leaving throughout them powerful spatial infrastructures capable of solving any distributed problems. Providing basics of the latest SGT version, the paper describes examples of solutions in it of such problems as distributed tracing and elimination of complexly moving cruise missiles and hypersonic gliders, organization of effective custody layer which will be able to observe not only localized dangerous objects on the Earth but also any distributed terrestrial infrastructures as a whole. It also shows how to introduce a higher virtual layer for satellite constellation which may simplify formulation and solution of many problems in both terrestrial and celestial environments, including advanced command and control of complex national and international operations and campaigns from space.

Satellites Again

2021 ◽  
pp. 289-294
Author(s):  
Laszlo Solymar
Keyword(s):  
Human Life ◽  
Satellite Networks ◽  
Geostationary Satellites ◽  
The Earth ◽  
Useful Life ◽  
Low Earth Orbits ◽  
Earth Orbits

The total number of satellites ever launched is about 2000. The operation of satellite networks, Iridium in particular, is described. Iridium has 66 satellites in orbit, enabling it to send messages from any point on Earth to any other point. Satellites past their useful life are disposed of in graveyard orbits. Geostationary satellites do not move relative to the Earth but being far away have the disadvantage of delaying the signal they process. Low Earth orbits have no noticeable delay but each one is available for relaying information for no more than 15 minutes. There was a disaster when launching one of the satellites when all three astronauts died instantly. Another notable accident was a collision between two satellites. No human life was lost but it resulted in debris that has since posed further threats to orbiting satellites.

Small satellites in space activities

2020 ◽  
Vol 956 (2) ◽  
pp. 50-56
Author(s):  
I.N. Gansvind
Keyword(s):  
Atmospheric Pressure ◽  
New Technologies ◽  
Low Cost ◽  
Educational Process ◽  
Small Satellites ◽  
The Earth ◽  
Design Requirements ◽  
Low Earth Orbits ◽  
Earth Orbits ◽  
Space Activities

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.

scholarly journals Orbital Perigee Deviation under Inclination Window for Sun Synchronized Low Earth Orbits

2019 ◽  
Vol 4 (10) ◽  
pp. 127-130
Author(s):  
Shkelzen Cakaj ◽  
Bexhet Kamo
Keyword(s):  
Orbital Plane ◽  
Earth Observation ◽  
Gas Content ◽  
The Sun ◽  
Orbital Inclination ◽  
The Earth ◽  
Low Earth Orbits ◽  
Earth Observation Satellites ◽  
Earth Orbits ◽  
Earth’S Oblateness

Data processing related to the Earth’s changes, gathered from different platforms and sensors implemented worldwide and monitoring the environment and structure represents Earth observation (EO). Environmental monitoring includes changes in Earth’s vegetation, atmospheric gas content, ocean state, melting level in the ice fields, etc. This process is mainly performed by satellites. The Earth observation satellites use Low Earth Orbits (LEO) for their missions. These missions are accomplished mainly based on photo imagery. Thus, the relative Sun’s position related to the observed area, it is very important for the photo imagery, in order the observed area from the satellite to be treated under the same lighting (illumination) conditions. This could be achieved by keeping a constant Sun position related to the orbital plane due to the Earth’s motion around the Sun. This is called Sun synchronization for low Earth orbits, the feature which is applied for satellites dedicated for the Earth observation. Nodal regression is the phenomenon which is utilized for low circular orbits providing to them the Sun synchronization. Nodal regression refers to the shift of the orbit’s line of nodes over time as Earth revolves around the Sun,  caused due to the Earth’s oblateness. Nodal regression depends on orbital altitude and orbital inclination angle. For the in advance defined range of altitudes stems the inclination window for the satellite low Earth orbits to be Sun synchronized. For analytical and simulation purposes, the altitudes from 600km to 1200km are considered. Further for the determined inclination window of the Sun synchronization it is simulated the orbital perigee deviation for the above considered altitudes and the eventual impact on the satellite’s mission.

scholarly journals Earth’s albedo time series reveals low radiative energy input in December 2020

2021 ◽  
Author(s):  
Antti Penttilä ◽  
Karri Muinonen ◽  
Olli Ihalainen ◽  
Elizaveta Uvarova ◽  
Mikko Vuori ◽  
...  
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
Radiative Energy ◽  
Series Data ◽  
Radiation Balance ◽  
The Sun ◽  
The Earth ◽  
Important Input ◽  
Low Earth Orbits ◽  
Earth Orbits

Abstract The Earth’s spherical albedo describes the ratio of light reflected from the Earth to that incident from the Sun, an important input variable for the Earth’s radiation balance. The spherical albedo has been previously estimated from satellites in low-Earth orbits, and from light reflected from the Moon. However, neither of these methods can produce continuous time series of the entire planet. We developed a global method to derive the Earth’s spherical albedo using the images from the Earth Polychromatic Imaging Camera (EPIC) on board NOAA’s Deep Space Climate Observatory (DSCOVR). The satellite is located in the Lagrange 1 point between the Earth and the Sun and observes the complete illuminated part of the Earth at once. The method allows us to provide continuously updated spherical albedo time series data starting from 2015. This time series shows a systematic seasonal variation with the mean annual albedo estimated as 0.295±0.008 and an exceptional albedo maximum in 2020, attributed to unusually abundant cloudiness over the Southern Oceans.

scholarly journals On the use of a continuous thrust to find bounded planar trajectories at given altitudes in Low Earth Orbits

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Allan Kardec de Almeida ◽  
Jhonathan Orlando Murcia Piñeros ◽  
Antonio Fernando Bertachini de Alme Prado
Keyword(s):  
Nonlinear Dynamics ◽  
Solar Radiation ◽  
Drag Force ◽  
Radiation Pressure ◽  
Solar Radiation Pressure ◽  
The Moon ◽  
The Earth ◽  
Low Earth Orbits ◽  
Earth Orbits ◽  
Different Altitudes

Abstract In this work, it is shown how a spacecraft equipped with a thrust and subjected to a drag force can be bounded at specific altitudes as function of the parameters of the thrust. It is used nonlinear dynamics tools to find attractors, which bound the motion of the spacecraft. For a specific set of parameters of the thrust, the spacecraft is bounded to a given altitude. Several forms for the thrusts are proposed in order to bound the altitude of the spacecraft. The influence of several forms of perturbations in the altitude of the spacecraft is also investigated in this work, like the solar radiation pressure, gravity of the Moon and oblateness of the Earth. Finally, nonlinear dynamics tools are also used to investigate transfers among the bounded orbits in different altitudes.

scholarly journals Experimental and numerical heat transfer from vortex-injection interaction in scramjet flowfields

2020 ◽  
Vol 124 (1280) ◽  
pp. 1545-1567
Author(s):  
J.R. Llobet ◽  
K.D. Basore ◽  
R.J. Gollan ◽  
I.H. Jahn
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Management ◽  
Numerical Heat Transfer ◽  
Performance Requirements ◽  
Air Mixing ◽  
Low Earth Orbits ◽  
The Cost ◽  
Earth Orbits ◽  
Good Agreement

ABSTRACTAir-breathing propulsion has the potential to decrease the cost per kilogram for access-to-space, while increasing the flexibility of available low earth orbits. However, to meet the performance requirements, fuel-air mixing inside of scramjet engines and thermal management still need to be improved.An option to address these issues is to use intrinsically generated vortices from scramjet inlets to enhance fuel-air mixing further downstream, leading to shorter, less internal drag generating, and thus more efficient engines. Previous works have studied this vortex-injection interaction numerically, but validation was impractical due to lack of published experimental data. This paper extends upon these previous works by providing experimental data for a canonical geometry, obtained in the T4 Stalker Tube at Mach 8 flight conditions, and assesses the accuracy of numerical methodologies such as RANS CFD to predict the vortex-injection interaction.Focus is placed on understanding the ability of the numerical methodology to replicate the most important aspects of the vortex-injection interaction. Results show overall good agreement between the numerical and experimental results, as all major features are captured. However, limitations are encountered, especially due to a localised region of over predicted heat flux.

Atmosphere density changes caused by the motion of spacecrafts in low Earth orbits

2009 ◽  
Vol 15 (1) ◽  
pp. 13-18 ◽  
Author(s):  
A.I. Maslova ◽  
◽  
A.V. Pirozhenko ◽  
Keyword(s):  
Atmosphere Density ◽  
Low Earth Orbits ◽  
Earth Orbits
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