RU2535375C1 - Method of viewing surface of planet from space and space satellite system for implementing said method - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: group of inventions relates to information satellite systems (ISS) for various purposes, the tasks of which generally come down to scanning (continuously or periodically) a planet, particularly the Earth. In the disclosed ISS, satellites for scanning a region of a given latitude band with lower latitudes are taken to orbits with an inclination which is less than the inclination of the orbit to which satellites for scanning a region with higher latitudes are taken. High-latitude satellites also scan regions with said lower latitudes. Such an ISS design is preferable because scanning bands along adjacent satellite paths approach and overlap as the latitude rises. Satellite orbits can be selected close to circular with an average altitude which is different for high-latitude and low-latitude satellites. The essential condition of the ISS design is the equality between the regression velocities of the orbital nodal line for all satellites. This condition enables to maintain the structure of the ISS (given diversity of orbital planes on the longitude of the ascending node). Thus, the required number of satellites in the ISS and/or width of the scanning band is reduced. For a given number of satellites in the ISS and a fixed width of the scanning band, observation characteristics are improved (reduced scanning frequency, high accuracy of the navigation field etc.).

EFFECT: high efficiency of the ISS due to reduced non-uniformity on the width of conditions for scanning the surface of a planet with satellites.

10 cl, 4 dwg

Description

Technical field

The invention relates to the construction of information space satellite systems (SS) of a fairly wide class: monitoring, navigation, communication, etc.

Such SSs provide observation or review (continuous or periodic) of the surface of the planet, especially the Earth, with the aim of organizing the flow of information between ground objects (users) and SS. These objects should be in the field of view of the corresponding satellite equipment (like the satellites themselves - in the zone of visibility of objects).

Along the satellite paths, depending on the characteristics of their equipment and special requirements, more or less wide field of view of the planet’s surface are formed, many of which determine the type (continuous, periodic) and quality of observation (frequency of coverage, frequency of observation, etc.) of areas of a given latitudinal zone .

When optimizing SS observations (minimizing the number of satellites and / or the bandwidth of the field of view, as well as energy consumption for correcting their orbits), one should take into account perturbations of the Kepler satellite orbits due to, first of all (for low orbits ~ 100 ... 10,000 km), the off-center gravity field of the planet. One of the most significant disturbances, in the case of a flattened planet, is the secular change in the longitude of the ascending node (regression of the line of nodes), which is expressed in the precession of the orbital planes in the equatorial direction.

Different precession rates (Ω ′) of the planes of the orbits of satellites can lead to a change (destruction) of the structure of SS observations.

State of the art

Traditionally, the methods of observing the planet’s surface are carried out by SSs, in the construction of which the satellites display one or more of the orbits (with the same parameters a, e, i - the semimajor axis, eccentricity and inclination), distributing in some way the satellites along each of the orbits (usually circular), and the planes of the orbits along the equator, i.e. by the longitude of the ascending node.

Such methods and SS implementing them are described in the patents [1] RU 2076059 C1, [2] RU 2118273 C1, [3] RU 2075862 C1, [4] 2058917 C1, etc. In [1] - [4] multiple geosynchronous orbits were used , the inclination (i) of which depends on the periods of rotation of the satellites in orbit and the effective daily rotation of the Earth.

By the indicated choice of inclination and multiplicities of geosynchronous orbits, it is possible to optimize SS observations, as noted above. However, the following circumstance prevents the further improvement of the SS.

The relative position of the satellites with the orbits of the same inclination varies in latitude: at the equator, they are maximally distant from each other, and in the upper latitudes they approach each other (or even overlap). Thus, the critical value of the satellite span (or the critical number of satellites at a fixed span) selected at the lower latitude is redundant for the higher latitudes.

From geometric considerations, it is also clear that the viewing bands are located on the surface of the planet the denser (closer to each other), the smaller the inclination (i) of the orbits of the observation satellites - with a fixed width of the viewing band and the distributions of the satellites along the orbit and the planes of the orbits - along the equator. However, the quantity i is bounded below by the upper latitudes of the observed given latitudinal belt (φ _in ~ 70 ... 80 °), so that it is impossible to improve the situation solely due to orbits of small inclination.

Thus, a common drawback of the known methods and SS of observing the planet’s surface is the heterogeneity in the breadth of the observation conditions (coverage density) by the satellites of the planet’s surface, which prevents a decrease in the number of satellites in the SS and / or the viewing bandwidth.

The solution to the problem, as follows from the foregoing, can be the choice of the inclination of the satellite orbits depending on the latitude (φ) of the observation, i.e. i = i (φ), while ensuring the synchronization of the precession of the planes of all orbits: Ω ′ _j = const, where j = 1, 2 ... m is the number of orbit planes (the latter is to exclude unacceptable changes in the structure of the SS).

There are known “multi-tier” SSs whose satellites have orbits with different inclination and, accordingly, with different heights (more generally, different a, e) and the same regression speed of the node line - see, for example, patents [5] US 5999127 A , [6] US 5979832 A and [7] US 6892986 B2. However, CC data does not solve the problem of optimizing the observation of the planet’s surface by setting the inclination of satellite orbits depending on the latitude of observation.

The analysis of the prior art showed that as the closest analogues of the proposed inventions, the method and space-based CC observations of the planet’s surface from space [1] can be adopted, where artificial satellites are launched into non-zero inclined orbits and the given latitudinal belt of the planet’s surface is surveyed by these satellites using their airborne assets.

A disadvantage of the known method and CC [1] is, as noted above, the heterogeneity in the breadth of observation conditions (coverage density) by satellites of the planet’s surface, which limits the effectiveness of CC observation (in the sense of its optimality in the sense mentioned above).

SUMMARY OF THE INVENTION

The present invention is the creation of a method for observing the surface of the planet from space, devoid of the above disadvantages of the known similar methods (and implementing CC).

The technical result of the invention is to increase the efficiency of CC observation by reducing the heterogeneity in the breadth of the observation conditions by satellites of the planet's surface.

The solution of the problem with obtaining the specified technical result is achieved by the fact that, in contrast to the known method [1], the satellites for viewing the region of the indicated latitudinal belt with lower latitudes are put into orbits with an inclination less than the inclination of the orbits into which the satellites take out for viewing regions with higher latitudes, the last of the mentioned satellites also reviewing regions with the indicated lower latitudes, and the orbits of all satellites are selected with the same node regression speed at.

In practice, these regions with lower and higher latitudes are latitudinal belts from among those into which the specified predetermined latitudinal belt of the planet’s surface is divided.

In the simplest case, a given latitudinal belt of the planet surface can be divided into at least two adjacent latitudinal zones (from lower to middle latitudes and from middle to higher latitudes).

Moreover, as in the known methods, the planes of the orbits of the satellites for viewing at least one of these areas with lower or higher latitudes can be spaced along the longitude of the ascending node, and the satellites themselves are shifted along the orbits according to the latitude argument.

In a preferred embodiment, the satellite orbits can be selected close to circular, and satellites to view the region with lower latitudes have an average height of the orbits other than satellites to view the region with higher latitudes.

The solution of the problem with obtaining the specified technical result is also achieved by the fact that, in contrast to the known SS [1], the satellite orbits for viewing the region of the indicated latitudinal belt with lower latitudes have an inclination less than the inclination of the satellite orbits for viewing the region with higher latitudes and the orbits of all satellites are selected with the same regression speed of the line of nodes.

Preferably, all artificial satellites are provided with identical means of viewing a given latitudinal zone (although, generally speaking, these means can be differentiated by latitudinal regions).

The orbital planes of satellites for viewing at least one of the indicated regions with lower or higher latitudes can be spaced along the longitude of the ascending node, and the satellites themselves are shifted along the orbits according to the latitude argument.

The orbits of satellites can be chosen close to circular, and satellites to view the region with lower latitudes have an average orbit height different than satellites to view the region with higher latitudes.

In the simplest case, satellite orbits can be selected provided that the specified latitudinal belt of the planet’s surface is divided into two adjacent latitudinal belts, one of which is the region of higher latitudes (orbits of greater inclination), and the other - the region of lower latitudes (orbits of lesser inclination) .

The invention can be explained as follows.

First, the uniformity of the coating density of the indicated latitudinal regions (belts) is ensured by the choice of the inclination of the corresponding orbits indicated in the formula. Moreover, to cover high latitudes, sections of orbits of greater inclination, sufficiently distant from the equator, are used, and to cover low latitudes, they are used, in whole or in part, orbits of small inclination, as well as sections of orbits of greater inclination, less remote from the equator.

Secondly, the result of the uniform coverage density is a more effective “contribution” of each of the satellites to the coverage of latitudinal belts (areas) and, as a result, a decrease in the required number of satellites and / or the required satellite span.

Thirdly, with a given number of satellites and a fixed width of satellite viewing bands, ensuring a uniform density of latitudinal zones (areas) can improve the performance of information satellite systems - reduce the frequency of review for SS monitoring, increase the accuracy of the navigation field for navigation SS, reduce the average waiting time communication subscribers for SS communications, etc.

List of figures

Figure 1. A two-satellite space system constructed according to the traditional scheme, in accordance with known methods, in orbits with the same altitude values H = 3000 km and inclination i = 71 ° for both satellites: 1 - the orbit of the first satellite; 2 - the orbit of the second satellite; 3 - Earth; 4 - latitudinal belt 0 ... 70 °, covered by both satellites of the system.

Figure 2. View of flight paths on the Earth’s surface for two satellites of the system shown in FIG. 1, in geographical coordinates “latitude φ - longitude λ”: there is a high intensity of “overlap” of routes in the “upper” latitudes (40 ... 70 °) and , at the same time, low intensity of overlap at “low” latitudes (“holes” in coatings).

Figure 3. A two-satellite space system constructed in accordance with the proposed inventions in two orbits with different altitudes and inclinations selected from the condition of identical regression of the line of nodes of both orbits: 1 - an orbit with a height H = 3000 km and an inclination i = 71 ° of the first satellite participating in the coverage of the “upper” (40 ... 70 °) and “lower” (0 ... 40 °) latitudes; 2 - an orbit with a height of H = 5545 km and an inclination i = 41 ° of the second satellite participating in the coverage of only the “lower” (0 ... 40 °) latitudes; 3 - Earth; 4 - latitudinal belt 0 ... 40 °; 5 - latitudinal belt 40 ... 70 °.

Figure 4. View of flight paths on the Earth's surface for two satellites of the system shown in FIG. 3, in geographical coordinates “latitude φ - longitude λ”: a uniform intensity of overlap of the routes in the latitudinal belt 0 ... 70 ° is ensured.

Detailed description of inventions

The essence of the proposed invention is illustrated by the following detailed description of an example of their implementation.

Figure 1 shows a traditional system of two satellites placed in orbit with an altitude of H = 3000 km and an inclination of i = 71 °. The orbits of the two satellites are separated by the longitude of the ascending node. The system of these two satellites provides periodic (discontinuous) observation of the latitudinal belt 0 ... 70 °. Figure 2 shows the data paths of the satellites, formed during some, quite a long time of their operation. Figure 2 shows that while providing coverage for a given latitudinal belt 0 ... 70 ° in the upper latitudes of this zone, sufficiently remote from the equator, there is an intense overlap of satellite paths (and, consequently, of the associated viewing bands), while the lower latitudes of this belt, located in close proximity to the equator, overlapping paths (and lanes) has a significantly lower intensity, leading to the fact that there are “critical” cases of the survey, which determine the final total characteristics of the observation tions in all latitudinal zones.

At the same time, Fig. 3 shows a system of two satellites, designed to observe the same latitudinal zone 0 ... 70 °, but formed in accordance with the proposed invention. Namely, one of the satellites has the same characteristics as in the first case, H = 3000 km, i = 71 °, and the other satellite is placed in orbit with a higher altitude H = 5545 km and a lower inclination i = 41 °, synchronized with the first orbit in the longitude of the ascending node (the planes of both orbits precess the same way). From Fig. 4, corresponding to this satellite system and similar in content to Fig. 2, it can be seen that the use of the proposed method and the corresponding SS allows for a substantially more uniform distribution of the paths and the associated satellite viewing bands within the observed latitudinal zone 0 ... 70 ° . For this reason, the characteristics of observing the latitudinal belt in the proposed SS construction option will be significantly better compared to the analogue under consideration. This analysis is of a qualitative nature. The specific numerical values of the possible gains in the observation characteristics are given below.

The observation method, according to the invention, is carried out using the SS described in the following examples.

Example 1. The characteristics of the orbits of a traditional system of two satellites in circular orbits can be described by the same values of altitude H = 777.3 km and inclination i = 72 °. The phase structure of such a system is determined by the following values of the longitudes of the ascending nodes and the latitude arguments: Ω ₁ = 0 °, u ₁ = 0 °, Ω ₂ = 314.4 °, u ₂ = 339.7 °. When changing the parameters H, i of the circular orbit of one of the satellites in accordance with the proposed inventions, provided that the same precession of the ascending node of the orbit remains the same as for the first orbit, we can obtain the following values of altitude H ₂ = 2390.38 km and inclination i ₂ = 51 °. The phase structure of the system is preserved in the same form: Ω ₁ = 0 °, u ₁ = 0 °, Ω ₂ = 314.4 °, u ₂ = 339.7 °, as for the analogue. Modeling of the functioning of both systems shows that under equal conditions for observing the latitudinal belt of 10 ... 70 ° with a viewing angle β = 49.73 ° for system satellites, the frequency of the review provided by the traditional SS is τ = 32.5 h, and for the SS constructed in accordance with the proposed invention, τ = 12.8 hours. The gain in the frequency of observation of a given latitudinal belt is Δτ = 19.7 hours.

Example 2. The characteristics and phase structure of a traditional two-satellite system are as follows: H = 852.0 km, i = 64 °, Ω ₁ = 0, u ₁ = 0, Ω ₂ = 181.9, u ₂ = 26.4. Similarly to Example 1, in accordance with the proposed inventions, a system is formed with the same phase structure as that of the analogue and the following parameters of the satellite’s circular orbits providing the same precession of the node line: H ₁ = 852.0 km, i ₁ = 64 °, H ₂ = 1633.15 km, i ₂ = 51 °.

Modeling of the functioning of both systems shows that under equal conditions for observing the latitudinal belt 10 ... 64 ° with a viewing angle β = 52.18 ° for system satellites, the viewing frequency for a traditional SS is τ = 23.1 h, and for a SS constructed in accordance with the proposed inventions, τ = 10.8 hours. The periodicity gain here is Δτ = 12.3 hours.

Industrial applicability

To implement the present invention does not require fundamentally new developments in the field of rocket and space technology; traditional and well-tested tools and methods typical of satellite systems can be used.

Claims (10)

1. A method of observing a planetary surface from space, including launching artificial satellites into near-planetary orbits with non-zero inclination and viewing the given latitudinal belt of the planet surface by these satellites using their on-board means, characterized in that the satellites for viewing the region of the indicated latitudinal belt with lower latitudes display into orbits with an inclination smaller than the inclination of the orbits into which the satellites take to view areas with higher latitudes, the last of which They also provide an overview of regions with the indicated lower latitudes, and the orbits of all satellites are chosen with the same regression speed of the node line. 2. The method according to claim 1, characterized in that said regions with lower and higher latitudes are latitudinal zones from among those into which said specified latitudinal belt of the planet surface is divided. 3. The method according to claim 2, characterized in that the predetermined latitudinal belt of the planet surface is divided into at least two adjacent latitudinal zones. 4. The method according to any one of claims 1, 2, 3, characterized in that the planes of the orbits of the satellites for viewing at least one of these areas with lower or higher latitudes are spaced along the longitude of the ascending node, and the satellites themselves are shifted along the orbits along latitude argument. 5. The method according to any one of claims 1, 2, 3, characterized in that the orbits of the satellites are selected close to circular, and the satellites to view the region with lower latitudes have an average height of the orbits other than the satellites to view the region with higher latitudes. 6. Space satellite system for observing the planet’s surface from outer space, including artificial satellites in near-planet orbits with non-zero inclination, equipped with means for viewing a given latitudinal belt of the planet’s surface, characterized in that the satellite orbits for viewing the region of the indicated latitudinal belt with lower latitudes have an inclination less than the inclination of the satellite orbits to view the region with higher latitudes, and the orbits of all satellites are selected with the same regression speed of the link s. 7. The space satellite system according to claim 6, characterized in that all artificial satellites are equipped with identical means of viewing a given latitudinal zone. 8. The space satellite system according to any one of claims 6, 7, characterized in that the planes of the orbits of the satellites for viewing at least one of these areas with lower or higher latitudes are spaced apart in longitude of the ascending node, and the satellites themselves are shifted along the orbits in latitude argument. 9. The space satellite system according to claim 6, characterized in that the orbits of the satellites are chosen close to circular, and the satellites to view the region with lower latitudes have an average altitude of the orbits other than the satellites to view the region with higher latitudes. 10. The space satellite system according to claim 6, characterized in that the orbits of the satellites are selected provided that the specified latitudinal belt of the planet’s surface is divided into at least two adjacent latitudinal belts, one of which is the region of higher latitudes, and the other is the region of more low latitudes.

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