RU2337372C2 - Method for space geodetic network creation - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: claimed method concerns space geodesy and can be applied in space geodetic network (SGN) creation and in defining orbit parametres of mobile space objects (SO). Object of invention is extension of functional capacities of the method by accurate and expedient defining of mobile space object parametres by space triangulation method. System for implementation of method includes two interacting geodetic medium-altitude spacecrafts (MSC), land surveillance points (SP) of space geodetic network, high-altitude spacecrafts (HSC) of global navigation systems GLONASS (Russia) and NAVSTAR (USA), mobile space objects (SO) and optical electronic devices (telescope assemblies) installed onboard of each MSC and CCD matrixes used as photocells.

EFFECT: extended functional capacities of method of space geodetic network creation.

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Description

The proposed method relates to the field of space geodesy and can be used to create a space geodetic network (CGS) and to determine the parameters of the orbits of moving space objects (KO).

Known methods for creating a space geodetic network and determining the orbits of moving space objects (RF patents Nos. 2,040.860, 2.059.423, 2.081.436, 2.107.928, 2.107.929, 2.124.217, 2.153.700, 2.174.092, 2.247.945; US patents Nos. 3,336.585, 3.803.610, 3.883.812, 3.984.071, 4.688.092, 4.837.699; UK patent No. 2.180.426; EP patent No. 0.763.714); Skubka R.A. et al. Satellite at the helm. - L .: Shipbuilding, 1989, p.168; Boykov V.V., Galazin V.F., Kaplan B.L. et al. Experience in creating a geocentric coordinate system P3-90. - F :. Geodesy and cartography, 1993, No. 11, pp. 17-21; Polovnikov V.I. et al. The practical application of stellar catalogs "FK-5" and "Hipparcos" in modeling subsystems of astronomical support, communication. IPA RAS No. 97, St. Petersburg, 1996, 28 pp .; J. Marsh, B. Douglas, S. Klosko Coordinates of tracking stations, determined from observations of outbreaks of "Geos-1 and 2" in the book Use of artificial satellites for geodesy. / Ed. S. Henriksen, A. Mancini, B. Chowitz. - M .: Mir, 1975, and others.

Of the known methods, the closest to the proposed is the "Method of creating a space geodetic network" (RF patent No. 2.124.217, G 01 S 5/00, 1997), which is selected as a prototype.

The known method provides an increase in the accuracy of assigning the origin to the center of mass of the Earth and determining the relative position of points of the space geodetic network by compensating for the uneven distribution of points on the Earth’s surface and the uneven distribution of measurements on long orbital arcs, but it does not allow determining the parameters of the orbits of moving space objects, t. e. does not fully realize its potential capabilities.

An object of the invention is to expand the functionality of the method by accurately and efficiently determining the parameters of the orbits of moving space objects using the space triangulation method.

The problem is solved in that according to the method of creating a space geodetic network, including rangefinder, Doppler and photographic measurements from points of the space geodetic network to the geodetic satellite and the adjustment of these measurements by the dynamic method of space geodesy with the division of the totality of all measurements into a group of measurements uniformly distributed over long orbital arcs for assigning the origin of the space geodetic network to the center of mass of the Earth, and to a group of measurements assigned and short orbital arcs to clarify the relative position of points of the space geodetic network, including short arcs as unknown elements of mutual transformation of solutions along long and short arcs, while performing additional range-finding measurements between the geodesic satellite and the satellite of the space navigation system to fill the gaps together measurements on long orbital arcs and rangefinding measurements from part of the points of the space geodetic network to space satellites navigation system, use the second geodetic spacecraft, orbited from the first geodetic spacecraft by a certain linear distance, and the coordinates of a moving space object are determined by the method of space triangulation, for which the aforementioned rangefinder, Doppler and photographic measurements specify the basis between geodetic spacecraft, bind a moving space object to catalog stars, the coordinates of which are precisely determined in the absolute coordinate system, and the angles between the basis and the directions “geodetic spacecraft - space object” are measured by the on-board optoelectronic equipment installed on board each geodetic spacecraft, the sides of the measuring triangle are determined from the measured values of the basis and two angles at the vertices of which the moment of measurement are two geodetic spacecraft and a space object, respectively, and thereby measure the distance between the geodetic spacecraft and the space object, which determine the radius vector of the space object in the inertial coordinate system at the time of measurement, differentiate in time the coordinates of the space object obtained in a series of measurements with a given step, thereby determining the velocity vector of the space object at a given point in time, according to the measured values of the radius vector and the velocity vector of the space object at a given point in time determine the parameters of the orbit of the space object.

The proposed method is practically implemented as follows.

Since the GLONASS (Russia) and NAVSTAR (USA) space navigation systems currently exist and function, for the implementation of the proposed method, it is sufficient to install on the geodetic spacecraft receivers of radio signals emitted from navigation high-orbit spacecraft (VKA), organize a periodic reset of the accumulated measurement information from the geodetic medium-orbit spacecraft (SCA) - (spacecraft - KAI meters) to ground-based points (NP) receiving this information and place on a part of the KGS points the rangefinders currently used for observations of the spacecraft from the control measuring points of the space navigation system.

Since the height of the orbit H of the navigation satellites is approximately 20,000 km, and the geodetic satellites are 1000-1500 km, 4-5 navigation satellites are visible from each geodetic satellite.

Thus, navigational spacecraft in this range perform the functions of additional mobile stations of the CSC, compensating for the uneven location of ground stations and filling gaps in the set of measurements covering the orbit of the satellite. Additional rangefinding measurements from a part of the CGS points to the RCA contribute to a better coordination of the coordinates of the CGS points and the parameters of the orbits of all satellites when adjusting by the dynamic method of space geodesy.

Measurements between SCA and SCA will be performed with higher accuracy due to the absence of atmospheric influence and weakening of the ionosphere. As the results of the TOPEX / POSEIDON project experiment showed (Nerem RS, Lerch FJ, Marshall JA et al. Gravity model development for TOPEX / POSEIDON: Joint gravity models 1 and 2. Jorn Geophys. Res. V.99, No. 12, 1994, pp.421-447) and other studies, such a two-tier construction of a space geodetic complex allows one to increase by an order of magnitude the accuracy of assigning the origin to the center of mass of the Earth and determining the relative position of CGS points.

для звезд, записанных в звездном каталоге, при условии получения изображения звезды с

на ПЗС-матрицах с заданной надежностью за время экспозиции Δt_Э на фоне шумов прибора и звездного неба. Каждый кадр, считанный с ПЗС-матрицы, представляет собой n пятен от точечных источников света (освещенных Солнцем КО и звезд),которые зафиксированы совместно с шумами ПЗС-матрицы и фоном звездного неба в приборной системе координат ПЗС-матрицы d_ПР, x_ПР, y_ПР.Optoelectronic devices (telescope assemblies) are installed on board each SCA in such a way that their fields of view form a double viewing zone (Figure 1), into which, when the SCA moves in orbit, the specified altitude regions of the near-Earth space enter where the spacecraft move in their orbits fixed on photodetectors (CCD matrices) of SKA if they fall into the double-vision zone in the form of points on the background of stars that are fixed point emitters of light. The gates of optoelectronic devices with a given frequency open simultaneously on both SCAs for the exposure time Δt _E <1 second, in order to avoid significant blurring of the image of point emitters on CCD arrays due to the angular displacement of SCAs and CO in their orbits. The sensitivity of CCD arrays of optoelectronic devices is determined by the maximum magnitude

for stars recorded in the star catalog, subject to the image of a star with

on CCD matrices with a given reliability for the exposure time Δt _E against the background of the noise of the device and the starry sky. Each frame read from the CCD matrix represents n spots from point light sources (KL illuminated by the Sun and stars), which are recorded together with the noise of the CCD matrix and the background of the starry sky in the instrument coordinate system of the CCD matrix d _PR , x _PR , y _PR

The primary processing of the measurement information is to determine the centers of the light spots obtained from the point light emitters on the CCD matrix against the background of the noise, i.e. determine the coordinates (x _SI , y _SI ) of each S-th radiation source at the time of measurement t _i in the coordinate system of the CCD matrix.

The coordinates (x _SI , y _SI ) obtained in each frame are of no value if they are not tied to the coordinate system in which the motion of the spacecraft is determined, and also if the researcher cannot distinguish the star from the moving spacecraft.

Stars are selected among all point light emitters in a series of consecutive frames taken from the CCD matrix, on the basis of the sign that all stars, unlike moving KOs, will move in frames of the series with the same angular velocities equal to the CCD angular velocity matrix fixedly mounted on the SKA, which moves with the same angular velocity in a circular orbit. In this case, the relative distances between the stars on the CCD will remain the same in all frames of the series. Naturally, due to the rotation of the CCD matrix together with the SKA in a series of frames, some new stars will be included in the next frame, and some stars previously fixed in the previous frames will come out of the next frame. Of all the stars selected in a particular frame from the series, it is necessary to determine catalog stars whose coordinates are known with great accuracy in the second equatorial coordinate system. The selection of catalog stars in each frame is possible only if, at the time t _i corresponding to the measurement of the frame, the direction of the optical axis of the telescope (assembly of telescopes) in the second equatorial coordinate system and the relative angular distances between the catalog stars recorded are known with a sufficient degree of accuracy on the CCD at the same time.

Since the coordinates of catalog stars (α _S - right ascension, δ _S - declination of the star) are determined in the second equatorial coordinate system, the direction of the optical axis of the telescope should be determined by similar angles (α ₀ , δ ₀ ) in the same coordinate system. This circumstance requires the determination of the coordinates of the moving KOs in time (α _KO , δ _KO ) also in the second equatorial coordinate system, i.e. receiving at the time t _i coordinates of the moving CW [α _KO (t _i ), δ _KO (t _i )] relative to the location of the catalog stars in the frame of the CCD matrix at the time of measurement t _i .

During the rotation of the SCA along the circular orbit of the axis of the instrument coordinate system, d _PR , x _PR , y _PR , rigidly connected to the CCD matrix and the SKA case, make a complete revolution in absolute space. In this regard, when conducting the binding of moving TOs to catalog stars, it is necessary to determine at the moment t _i the rotation angle φ _{P of the} vertical plane of the CCD matrix (d _PR , y _PR ) relative to the plane of the declination circle of the optical axis of the telescope d _PR (figure 2).

Therefore, for the current binding of moving FBs to determining the coordinates [(α _KO (t _i ), δ _KO (t _i )] to catalog stars with coordinates (α _Sj , δ _Sj ), it is necessary:

1. Determine the coordinates of the spot centers of all point radiation sources [x _S (t _i ), y _S (t _i )] in the instrument coordinate system d _PR ; x _PR , _PR .

2. In a series of consecutive frames, select stars among all point light emitters fixed on a CCD.

3. To determine with sufficient accuracy the direction of the optical axis of the telescope (assembly of telescopes) at the time of measurement t _i in the second equatorial coordinate system [α _О (t _i ), δ _О (t _i )].

4. Determine the angle of rotation φ _{P of the} vertical plane of the instrument coordinate system relative to the plane of the declination circle of the optical axis of the telescope at time t _i .

5. Determine the catalog stars and their coordinates α _S (t _i ), δ _S (t _i ) among all the stars that fell into the frame of the CCD matrix at time t _i .

6. Bind the coordinates of mobile radiation sources to catalog stars, ie get the coordinates of KO α _KO (t _i ), δ _KO (t _i ) that fell into the frame of the CCD matrix at time t _i .

This completes the processing of specific frames of the CCD matrix, the output of which is the coordinates α _KO (t _i ), δ _KO (t _i ) of mobile radiation sources in the second equatorial coordinate system. The rest of the information recorded in the frames of the CCD matrix at the time t _i (coordinates of all stars) does not matter for further processing of the measurement information, therefore it can be destroyed.

All these tasks must be solved onboard the SKA, and the centers of light spots of point radiation sources are determined using microprocessors built into the optoelectronic devices, and the coordinates of the moving optical sensors that are in the frames of the CCD matrix must be determined on a powerful on-board computer stored in information about technological data of SKA avionics, star catalog, current SKA coordinates in the absolute geocentric equatorial coordinate system, etc.

CKA ₁ (KAI ₁ ) and SKA ₂ (KAI ₂ ), creating a double-view zone (Figure 1), must have a permanent communication channel between them to transmit to the leading SKA ₁ pairs of coordinates KO α _KO (t _i ), δ _KO ( t _i ) received on the slave SKA ₂ at the time t _i .

Since the coordinates of the moving KO α _KO (t _i ), δ _KO (t _i ) are measured by the on-board equipment CKA ₁ and SKA ₂ against the background of different parts of the starry sky (relative to catalog stars), then the task that the KO should be solved on the leading CKA ₁ fixed at the same time t _i on the CKA-matrices CKA ₁ and СКА ₂ belongs to the double-view zone and allows to construct a measuring triangle C ₁ OC ₂ (figure 3), in which the sum of the angles

α ₁ + α ₂ + Δ = π,

и вектором дальности

между КАИ₁ и космическим объектом;where α ₁ is the angle between the linear measuring base

and range vector

between KAI ₁ and the space object;

и вектором дальности

между КАИ₂ и космическим объектом;α ₂ - the angle between the base

and range vector

between KAI ₂ and the space object;

и

при вершине измерительного треугольника, где находится измеряемый космический объект.Δ is the angle between the vectors

and

at the top of the measuring triangle, where the measured space object is located.

Thus, the proposed method in comparison with the prototype allows not only to increase the accuracy of assigning the origin to the center of mass of the Earth and determine the relative position of points of the space geodetic network by compensating for the uneven distribution of points on the Earth’s surface and the uneven distribution of measurements on long orbital arcs, but also provides accurate and operational determination of the parameters of the orbits of moving space objects by the method of space triangulation at short dimensional intervals (from yadka 10-20 seconds), which does not allow the method of the goniometric measurements of moving space objects from one geodetic spacecraft, thus the functionality of the known method expanded.

Claims (1)

A method of creating a space geodetic network, including rangefinder, Doppler and photographic measurements from points of the space geodetic network to a geodetic satellite and the adjustment of these measurements by the dynamic method of space geodesy with the division of the totality of all measurements into a group of measurements uniformly distributed on long orbital arcs to refer the origin of the coordinates of the space geodesic network to the center of mass of the Earth, and to a group of measurements assigned to short orbital arcs to clarify the reciprocal the position of the points of the space geodetic network, with the inclusion in short arcs as unknown elements of mutual transformation of solutions for long and short arcs, while doing additional range-finding measurements between the geodetic satellite and the satellites of the space navigation system to fill the gaps in the totality of measurements on long orbital arcs and rangefinding measurements from part of the points of the space geodetic network to the satellites of the space navigation system, characterized in that using the second geodetic spacecraft, orbited from the first geodetic spacecraft by a certain linear distance, and using the space triangulation method, determine the coordinates of a moving space object, for which the aforementioned rangefinding, Doppler and photographic measurements specify the basis between geodetic spacecraft, and the mobile space objects to catalog stars whose coordinates are precisely defined in the absolute coordinate system the distance, and the angles between the basis and the directions “geodetic spacecraft - space object” are measured by the on-board optoelectronic equipment installed on board each geodetic spacecraft, from the measured values of the basis and two angles determine the sides of the measuring triangle at the vertices of which at the time of measurement two geodetic spacecraft and a space object, respectively, and thereby measure the distance between the geodetic spacecraft and the space object , which determine the radius vector of a space object in an inertial coordinate system at the time of measurement, differentiate in time the coordinates of the space object obtained in a series of measurements with a given step, thereby determining the velocity vector of the space object at a given time, according to the measured values of the radius the vector and velocity vector of a space object at a given point in time determine the orbit parameters of a space object.

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