WO2016113586A1 - Système de satellites - Google Patents

Système de satellites Download PDF

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Publication number
WO2016113586A1
WO2016113586A1 PCT/IB2015/000783 IB2015000783W WO2016113586A1 WO 2016113586 A1 WO2016113586 A1 WO 2016113586A1 IB 2015000783 W IB2015000783 W IB 2015000783W WO 2016113586 A1 WO2016113586 A1 WO 2016113586A1
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WO
WIPO (PCT)
Prior art keywords
satellites
satellite
earth
satellites according
orbits
Prior art date
Application number
PCT/IB2015/000783
Other languages
English (en)
Inventor
Nicolas Girault
Original Assignee
Agence Spatiale Europeenne
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Agence Spatiale Europeenne filed Critical Agence Spatiale Europeenne
Priority to PCT/IB2015/000783 priority Critical patent/WO2016113586A1/fr
Publication of WO2016113586A1 publication Critical patent/WO2016113586A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/10—Artificial satellites; Systems of such satellites; Interplanetary vehicles
    • B64G1/1085—Swarms and constellations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
    • B64G1/24—Guiding or controlling apparatus, e.g. for attitude control
    • B64G1/242—Orbits and trajectories
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/195—Non-synchronous stations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/10—Artificial satellites; Systems of such satellites; Interplanetary vehicles
    • B64G1/1007—Communications satellites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/10—Artificial satellites; Systems of such satellites; Interplanetary vehicles
    • B64G1/1021—Earth observation satellites

Definitions

  • the invention relates to a system of satellites and a communication system using such a satellite system.
  • systems of cooperating satellites have been designed and launched in order to improve the continuity of the service.
  • systems of cooperating satellites also called a constellation of satellites, it is understood a group of satellites which are designed to be operated together in order to fulfill a given mission.
  • the satellites may be identical or not, be placed on the same orbit or not...
  • the Northern hemisphere is more populated than the Southern hemisphere; and in this Northern Hemisphere, population can be found at very high latitude, higher than the Arctic Polar Circle (Canada, Norway, Russia%) when below the Antarctic Polar Circle can only be found the Antarctic continent (with the exception of the Antarctic Peninsula) and little or no population.
  • orbital plane whose position is fixed in space, this plane being characterized by:
  • the orbit is an ellipse, the center of the Earth being always a node of the ellipse, the shape of which is determined by:
  • eccentricity its eccentricity, noted e; the eccentricity of satellite orbits usually ranges from 0 (circular orbit) to about 0.30,
  • the Mean Anomaly noted M which relates at any time the position of the satellite moving on its orbit to the time elapsed since the last known Mean Anomaly.
  • the orbital period of a satellite, noted T, directly derives from the parameters of the orbit.
  • Cost also governs the placement of the satellites on their orbits.
  • the satellites are distributed on a small number of orbital planes because placing several satellites on a given orbital plane needs a single launch; in addition, changing a satellite from an orbital plane to another is costly because it needs a large impulsion. Therefore, in the so called "PxN satellites systems" of P orbital planes, each containing N satellites, P will be small and there will be a large number N of satellites on the same orbit.
  • the "PxN satellites systems" are not optimal for certain applications: - They require a high number of satellites for a full and continuous coverage over the Earth even though the desired coverage is small, -
  • the geometry of the inter-satellite links (ISL) between different planes is very variable and imposes constraints on the system, like steerable antennas, in order to support inter-plane communications.
  • miniaturized satellites or small satellites are developing quickly. These satellites have masses usually under 100 kg, and in some cases even less than 10 kg. In addition to being cheaper to build, they are also cheaper to launch; a single launch can send to orbit dozens of smalt satellites belonging to the same system. They also can be launched as "piggyback" with larger satellites, taking benefit of spare room and mass.
  • the main applications of these miniaturized satellites are communication and Earth observation systems. This concept allows for systems with a very large number of satellites, typically tens to hundreds of satellites.
  • the 03B ProjectTM aims at providing high speed internet links with a group of 12 satellites orbiting on the equatorial plane at an altitude of 8 063 km. Due to the equatorial orbits, the coverage of the Northern Hemisphere is limited in latitude.
  • the IridiumTM constellation aims at providing a communication system for mobile phones using 66 satellites (initially 77) distributed in 11 Low Earth Orbits (LEO) with an altitude close to 781 km and an inclination of 86,4°.
  • IridiumTM is a global system, intending to provide a communication service all over the world.
  • This constellation corresponds to a usual "PxN satellites system" with the above mentioned drawbacks.
  • a and B are positive integers different from 0,
  • K is a constant for all satellites of the system. K may vary in time, but at any given time, equation (1) is true for all satellites of the system.
  • - the Right Ascension of the Ascending Node (RAAN) ⁇ occasion and the mean anomaly M n may be respectively expressed as:
  • ⁇ ⁇ ⁇ + 360°*A*n/N, modulo 360°
  • M n Mo + 360°*B*n/N, modulo 360°, (2)
  • ⁇ 0 and Mo are constants for all satellites of the system.
  • the planes of orbits may have the same inclination relative to the equatorial plane
  • - B may be equal to 1.
  • - A may be equal to 1, in this case there is only one satellite by plane.
  • the orbits may share the same eccentricity and/or the same semi major axis and/or the same argument of the perigee.
  • the orbits may be circular.
  • the altitudes of the satellites may be in the range of 160 to 2500 km above the Earth; for satellites not having a circular orbit, the altitude of the satellite is defined as its altitude over the Earth at perigee.
  • each satellite may be smaller than 1000 kg.
  • the system may be sun-synchronous.
  • the system may comprise in addition a least one polar orbiting satellite and/or at least one equatorial satellite.
  • the invention also relates to a communication system or an Earth observation system using a system of satellites according to the invention.
  • the invention also relates to a method to provide a radio communication link between at least two ground stations of the Earth, or to provide observation data of an observation zone to a ground station of the Earth, the method using a system of satellites according to the invention.
  • the at least two ground stations may belong to a coverage zone between two latitudes not crossing the equatorial plane and in that the satellites always pass in the same consecutive order over said ground stations.
  • ⁇ ( ⁇ ) ⁇ 0 + 360°* A*x, modulo 360°
  • M(x) Mo + 360°*B*x, modulo 360°,
  • x is a real number between 0 and 1.
  • L curve is given in X, Y, Z coordinates, X, Y being in the plane of the equator and Z being in the direction of the North Pole, where satellites are assumed to be on circular orbits for the sake of simplicity:
  • satellites are numbered according to the plane p to which they belong and their rank r in the corresponding orbit, that is S p>r
  • the satellites are numbered in sequence on curve L, satellites S n and S braid + i not sharing the same orbital plane.
  • N A*P, P in this case being the number of orbital planes
  • ARAAN 360°*A/N.
  • the satellite system according to the invention can be called a 'twisted constellation", which can be seen as a non planar chain of satellites of identical period, linearly spread along the chain, such that any two consecutive satellites have a fixed angle between the Right Ascension of their Ascending Node (RAAN) and a fixed angle between their mean anomaly.
  • This chain of satellites is not fixed in space; it rotates around an axis, being preferably the North - South axis of the Earth.
  • the satellite system can be seen as one-dimensional, the satellites being distributed along the chain, which provides useful properties to the system.
  • the distances between satellites are smaller, therefore there is a better link budget.
  • the launch could be performed by a single launcher (or a small number of launchers) with a large number of satellites per launch, followed by changes in the altitudes of the satellites in order to benefit from the precession caused by Earth in inclined orbits; controlled precession of the orbit of each individual satellite will end up in the deployment of orbital planes separated by the same angular pitch, like the deployment of a fan. Then the satellite is brought at its final orbit. This spreading process could take no more than a few months following the launch of 30 satellites with a single launcher, which is small regarding the lifetime of the system.
  • Figure 1 is a view above a point within the zone of coverage of three satellites at two different moments
  • Figure 2 A and 2B are graphic representations of the relation between
  • figure 3C illustrates a chain of satellites with the same orbital parameters but with 120 satellites
  • Figures 4A to 4D are world maps illustrating three examples of a chain of 120 satellites with different values of parameters A and B,
  • Figures 5A to 5D illustrate properties of a chain of satellites as for distance, angle and Doppler shift between satellites
  • Figures 6A and 6B illustrate uses of the system of satellites.
  • Figure 1 represents a group of three consecutive satellites SI, S2, S3 of a constellation of N satellites according to the invention, seen from a point of reference O on the Earth at time to and the same satellites S'l, S'2, S'3 at a time to + At, At being a small amount of time compared to the period T of the satellites.
  • CO and C5 are respectively the 0° and 5° elevation circles for a satellite above the point of reference O. 5° is considered as the minimum elevation for the visibility of a satellite from the ground segment, because at 0° the link with the satellite is usually blocked by obstacles above the horizon.
  • Vectors VI, V2, V3 represent the displacement of the respective satellites between t 0 and t 0 + At.
  • Each satellite travels on its own orbit O1, 02, 03 fixed in space (not represented on figure 1 for the sake of clarity). It can be considered that each vector VI, V2, V3 is tangent to a respective orbit at time to- There is an angular relation between the orbital planes occupied by the satellites: their RAAN is separated by a constant value 360°*A/N, A being a positive integer.
  • the satellites SI, S2, S3 are placed on a virtual curve L.
  • the N satellites of the constellation are also placed on this virtual curve L.
  • the satellites travel on their own orbit, at any given time they also form a chain represented by curve L around the Earth.
  • the satellites are numbered 1, 2, 3... N along this chain.
  • Satellite S lactate will take the place of its predecessor on the chain after an interval of time equal to T*B/N. Therefore, any ground station located in the continuous zone of coverage will see the satellites passing in the same sequential order, which is usually not the case in a PxN system of satellites.
  • the rise in Mean Anomaly is 1/3 the RAAN, the gap in Mean Anomaly between two consecutive satellites being 12°, and the gap in RAAN between two consecutive satellites being 36°.
  • ⁇ and M are modulo 360°, which means that 360° is equivalent to 0°.
  • the RAAN and the Mean Anomaly vary from 0° to 360°. It shows that there are 10 orbital planes, the RAAN of which varies from 0° to 324°, and that there are 3 satellites per orbital plane; line P4 illustrates the fourth plane, to which belong satellites 4, 14 and 24. In this representation of the constellation, the satellites are aligned on three lines Dl, D2, D3.
  • figure 2C is the same representation for a classical PxN system of 30 satellites, with 3 orbital planes and 10 satellites per plane.
  • the satellites are aligned on three vertical lines PI, P2, P3 representing the orbital planes, separated in RAAN by 120°.
  • the satellites are numbered 1 to 30 along a curve L31, forming a chain of satellites.
  • figure 3A illustrates that the satellites belong to a curve L31 that wraps around the Earth four times.
  • This curve L31 has four "segments" which are connected one another so as to form a continuous chain of satellites twisted around the Earth:
  • Figure 3A shows that such a satellite system provides an excellent Earth coverage in the Northern hemisphere, as well as in the South hemisphere.
  • each satellite covers a disc on the Earth, which diameter is a function of the satellite altitude and of the minimum elevation angle of the ground stations.
  • the constellation therefore covers a strip of land comprised between two latitudes, including high Northern latitudes.
  • One advantage of the system of satellite according to the invention is that it is very easy to increase the width of this strip of land with a permanent coverage by increasing the number of satellites in the system by a small amount.
  • each satellite S n has taken the position its next satellite S n+1 .
  • N 120
  • the isometric view shows how this curve L31 twists around the Earth.
  • Figures 4A to 4D illustrate chains of 120 satellites for different values of A and B and same orbital parameters other than ⁇ and M:
  • a - 5 and B 2: the chain L52 exhibits seven segments, L521 to L527 linked together in this order; the coverage in the high latitudes is improved.
  • the satellites of a chain cover specifically a Northern and a Southern strip of land on Earth having the shape of a "ring", a "ring” being defined as a geographical zone of the globe situated within a range of latitude L m in to L max , for instance 45° to 55°.
  • the satellite system according to the invention can provide a continuous coverage of such a strip of land, the values of Lmin to L max , depending on the parameters A and B and on the orbital parameters of the orbits other than ⁇ and M.
  • Curve 1 of figure 5A shows, for each satellite S practice, the angular separation in degrees between the antenna pointing axis for the ISL with the next satellite S n+ i and the antenna pointing axis for the ISL with the previous satellite S react.i.
  • the angle varies from 45° to 52° across the 30 satellites
  • Curve 2 of figure 5B shows the distance in km between two consecutive satellites, numbered 1 to 30. The distance is smaller than what would be obtained in a classical constellation of PxN satellites, and it varies little, from 4 000 km to 5 600 km across the 30 satellites.
  • the properties of the satellite system according to the invention are close to the ones obtained in a single plane of a PxN system of satellites.
  • Curves 3 and 4 show the ISL distance as a function of the number of satellites in the constellation, respectively for a classical PxN constellation (dashed line) and a constellation according to the invention (continuous line).
  • Figure 5C can be read two ways:
  • delta(V)/V :
  • ⁇ It is typically up to ⁇ 1 for links between satellite and ground.
  • Figure 6A illustrates the use of a system of satellites according to the invention in a communication system.
  • the communications between ground stations GS1 and GS2 pass through satellites p, p+1... p+k, therefore k+1 satellites, GS1 and GS2 being able to be very distant from one another. It makes use of k inter satellites links and two satellite to ground links.
  • Figure 6B illustrates the use of a system of satellites according to the invention in an Earth observation system.
  • the satellites of this system possess Earth observation means: satellite p is represented observing a zone of observation ZO of the Earth.
  • the signal of observation is passed through k+1 satellites down to the ground station GS3 through k ISL and one down link.

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Radio Relay Systems (AREA)

Abstract

L'invention concerne un système de N satellites, N étant supérieur ou égal à 4, en orbite avec une période identique, caractérisé en ce que, pour tout satellite n, avec n = 1 à N, l'ascension droite du nœud ascendant (RAAN) Ωn de son orbite et son anomalie moyenne Mn sont reliées par l'équation suivante : B * Ωn = A * Mn + K, modulo 360° où Ωn et Mn sont exprimées en degrés, A et B sont des entiers positifs différents de zéro, A < N et B < N, K est une constante pour tous les satellites du système. En supposant que les autres paramètres orbitaux sont identiques pour tous les satellites, des satellites sont positionnés sur une courbe paramétrée (L) où Ω et M sont définis par les équations Ω(χ) = Ω0 + 360°*A*x modulo 360°, M(x) - M0 + 360°*B*x, modulo 360°, où x est un nombre entier entre 0 et 1.
PCT/IB2015/000783 2015-01-16 2015-01-16 Système de satellites WO2016113586A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107797130A (zh) * 2017-10-16 2018-03-13 中国西安卫星测控中心 低轨航天器多点多参数轨道上行数据计算方法
CN115396321A (zh) * 2022-10-28 2022-11-25 中国电子科技集团公司第十五研究所 一种星地一体网络态势可视化方法、服务器及存储介质
WO2024118425A1 (fr) * 2022-11-30 2024-06-06 SpinLaunch Inc. Répétition d'optimisation de suivi au sol

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Publication number Priority date Publication date Assignee Title
US4809935A (en) * 1985-07-31 1989-03-07 Analytic Services, Inc. Satellite continuous coverage constellations
US20010051521A1 (en) * 1995-03-24 2001-12-13 Virtual Geosatellite, Llc, A Delaware Corporation Elliptical satellite system which emulates the characteristics of geosynchronous satellites
US20040065781A1 (en) * 2002-04-29 2004-04-08 The Boeing Company Satellite constellations using nodally-adjusted repeating ground track orbits

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4809935A (en) * 1985-07-31 1989-03-07 Analytic Services, Inc. Satellite continuous coverage constellations
US20010051521A1 (en) * 1995-03-24 2001-12-13 Virtual Geosatellite, Llc, A Delaware Corporation Elliptical satellite system which emulates the characteristics of geosynchronous satellites
US20040065781A1 (en) * 2002-04-29 2004-04-08 The Boeing Company Satellite constellations using nodally-adjusted repeating ground track orbits

Non-Patent Citations (1)

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Title
DANIELE MORTARI ET AL: "The Flower Constellations", JOURNAL OF ASTRONAUTICAL SCIENCES [H.W. WILSON - AST], 1 January 2004 (2004-01-01), pages 107, XP055222895, Retrieved from the Internet <URL:http://mortari.tamu.edu/Flower-Constellations/AAS-03-274.pdf> [retrieved on 20151021] *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107797130A (zh) * 2017-10-16 2018-03-13 中国西安卫星测控中心 低轨航天器多点多参数轨道上行数据计算方法
CN115396321A (zh) * 2022-10-28 2022-11-25 中国电子科技集团公司第十五研究所 一种星地一体网络态势可视化方法、服务器及存储介质
CN115396321B (zh) * 2022-10-28 2023-01-10 中国电子科技集团公司第十五研究所 一种星地一体网络态势可视化方法、服务器及存储介质
WO2024118425A1 (fr) * 2022-11-30 2024-06-06 SpinLaunch Inc. Répétition d'optimisation de suivi au sol

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