Global Carbon Inventory Satellite

Abstract

The present invention provides a global carbon inventory satellite, comprising: a frozen orbit unit, configured to set an orbital inclination, so that the global carbon inventory satellite operates on a frozen orbit, with the apogee of the frozen orbit frozen above the latitude of an area with intensive human activities; and a sun-synchronous orbit unit, configured to enable the global carbon inventory satellite to continue operating on the sun-synchronous orbit, so that the global carbon inventory satellite is always in an illuminated area when it operates to the apogee; wherein the relationship between the perigee orbit altitude and the apogee orbit altitude is obtained based on the value of the ascending node of the sun-synchronous orbit, the value of the orbital inclination, a first function, and a second function; the first function represents the relationship between the semi-major axis of the orbit and the perigee orbit altitude and the apogee orbit altitude; the second function represents the relationship between the orbital eccentricity and the perigee orbit altitude and the apogee orbit altitude.

Description

[0001] This application is a divisional application with application number CN2021800021203 and invention name “Orbital Design System for Global Carbon Inventory Satellite”. Technical Field

[0002] The present invention relates to the field of carbon emission technology, and in particular to a global carbon inventory satellite. Background Art

[0003] Quantitative monitoring and assessment of carbon emissions are crucial for achieving greenhouse gas reductions. Changes in atmospheric carbon dioxide concentrations reflect both anthropogenic carbon emissions and carbon absorption. Countries around the world are competing to develop space-based greenhouse gas monitoring systems to meet the critical need for global carbon inventory verification. Currently, the monitoring of anthropogenic carbon emissions is facing even higher demands, requiring timely monitoring of carbon emissions in areas with high human activity worldwide.

[0004] Currently, carbon monitoring satellites primarily use low-orbit, sun-synchronous orbits. While these satellites can achieve global coverage, their low orbital position, limited bandwidth, long target revisit periods, and relatively uneven global coverage prevent them from intensively monitoring key areas of high human activity, nor can they achieve the high-precision, high-efficiency monitoring of these areas required for global carbon inventories. Furthermore, high-orbit carbon monitoring satellites use geosynchronous orbits, stationed above a specific area. However, a single satellite cannot achieve global coverage and lacks global coverage capability. They can only observe within a range of ±50° in longitude and latitude, centered on a fixed location. Summary of the Invention

[0005] The purpose of the present invention is to provide a global carbon inventory satellite to solve the problem that the existing single carbon monitoring satellite orbit design is difficult to achieve high-precision and high-efficiency monitoring of global carbon inventory.

[0006] To solve the above technical problems, the present invention provides a global carbon inventory satellite, comprising:

[0007] a freezing orbit unit configured to set an orbital inclination so that the global carbon inventory satellite operates on a frozen orbit, wherein the apogee of the frozen orbit is frozen above the latitude of an area with dense human activities; and

[0008] a sun-synchronous orbit unit configured to keep the global carbon inventory satellite in a sun-synchronous orbit, so that the global carbon inventory satellite is always in the illumination zone when it reaches its apogee;

[0009] The relationship between the perigee orbit altitude and the apogee orbit altitude is obtained according to the value of the ascending node of the sun-synchronous orbit, the value of the orbital inclination, the first function and the second function;

[0010] The first function represents the relationship between the semi-major axis of the orbit and the altitude of the orbit at perigee and apogee;

[0011] The second function represents the relationship between orbital eccentricity and the orbital altitudes of perigee and apogee.

[0012] Optionally, the global carbon inventory satellite further includes:

[0013] The regression orbit unit is configured to keep the global carbon inventory satellite on the regression orbit and obtain observation conditions consistent with the previous regression period to ensure the periodic repeatability of the ground track;

[0014] Through coupling design, the orbital perigee and apogee heights are adjusted synchronously. While ensuring the orbit's sun-synchronous characteristics, the orbital period, orbital precession, and Earth's rotation speed are matched to find the regression orbit.

[0015] Observation conditions include the satellite elevation angle and solar altitude angle of the observation point.

[0016] Optionally, in the global carbon inventory satellite, the latitude of the human activity-intensive area is between 20° north latitude and 45° north latitude;

[0017] The synchronization parameters include orbital inclination, orbital semi-major axis and orbital eccentricity;

[0018] The observation conditions include the satellite elevation angle and the solar altitude angle of the observation point;

[0019] The orbital parameters of the Global Carbon Inventory satellite include:

[0020] The perigee orbit altitude ranges from 350km to 1000km, the apogee orbit altitude ranges from 6800km to 8300km, and the perigee argument ranges from 215° to 235°.

[0021] Optionally, in the global carbon inventory satellite, the inclination of the elliptical frozen orbit is selected as follows: affected by the Earth's oblateness, the apses of the elliptical orbit precess over time. When it is known that the orbital inclination satisfies specific conditions, the apses precession rate is 0, and the orbital apses are "frozen". At this time, the orbit is called a frozen orbit, and the corresponding inclination is the critical inclination. According to the magnitude of the critical inclination, the medium-orbit elliptical orbit is divided into a prograde elliptical frozen orbit and a retrograde elliptical frozen orbit. The orbital inclination of the prograde elliptical frozen orbit is 63.4°, and the orbital inclination of the retrograde elliptical frozen orbit is 116.565°.

[0022] According to the precession of the ascending node, the ascending node of the prograde orbit precesses westward by a certain angle every day, and the ascending node of the sun-synchronous orbit, which serves as the ascending node of the retrograde orbit, precesses eastward by a certain angle every day. The orbital inclination of the global carbon inventory satellite is selected to be 116.565°.

[0023] Optionally, in the global carbon inventory satellite, by jointly designing the orbital inclination, orbital semi-major axis, and eccentricity, the precession rate of the right ascension of the ascending node of the orbital plane is about 0.98° eastward per day, thereby achieving synchronous tracking of the sun;

[0024] This orbit can ensure that the apogee is always in the illuminated area, and the local time of the areas passed by different orbits remains consistent. The local time of the sub-satellite point within one orbit changes, thereby ensuring that the observation lighting conditions are relatively consistent, so as to achieve high-precision carbon dioxide column concentration inversion.

[0025] Optionally, in the global carbon inventory satellite, the precession angular rate of the orbital plane is

[0026]

[0027] in is the radius of the Earth, is the semi-major axis of the orbit, is the orbital eccentricity, is the orbital inclination;

[0028] The value of the ascending node of a sun-synchronous orbit satisfies the following conditions:

[0029]

[0030] The orbital inclination is 116.565°;

[0031] The first function is ;

[0032] The second function is ;

[0033] in is the perigee orbit altitude, is the apogee orbital height, R E is the radius of the Earth;

[0034] Substituting the orbital inclination, the first function and the second function, we can get the perigee orbital height. and apogee orbital altitude The combined equation of

[0035] The track height relationship curve is obtained based on the combined equation.

[0036] Optionally, in the global carbon inventory satellite, after one regression cycle, the sub-satellite point trajectory of the regression orbit overlaps with the sub-satellite point trajectory of the previous regression cycle:

[0037]

[0038] in is the number of orbits the satellite orbits the Earth in one regression cycle, is the number of ascending days in the regression cycle, is the traverse angle;

[0039] Synchronously adjust the perigee and apogee orbital altitudes to obtain the regression orbit by matching the orbital period, orbital precession, and Earth's rotation speed while ensuring the constraints of the sun-synchronous orbit.

[0040] Based on the Q value, points on the orbit altitude relationship curve are selected, and the parameters of the regression orbit are iteratively calculated within the range of a medium-orbit elliptical orbit with a perigee orbit altitude of 350km~1000km, an apogee orbit altitude of 6800km~8300km, and an orbital inclination of 116.565°.

[0041] Optionally, in the global carbon inventory satellite, by adjusting the argument of perigee, the apogee of the global carbon inventory satellite is set above a specific latitude in the Northern Hemisphere, so that the global carbon inventory satellite spends a longer transit time over areas with dense human activities in the Northern Hemisphere, thereby observing the Northern Hemisphere for a longer period of time;

[0042] Based on the proportional relationship between the argument of perigee and the latitude of apogee, the argument of perigee is determined, 35° north latitude is selected as the apogee position, and the argument of perigee of the global carbon inventory satellite is selected as 220°.

[0043] Optionally, in the global carbon inventory satellite, according to the operating characteristics of the global carbon inventory satellite, the operating arc of the global carbon inventory satellite payload is at the apogee of the northern hemisphere. Therefore, the flight direction of the satellite in the illumination area is ascending orbit, so as to achieve:

[0044] When the satellite is in the Earth's shadow, there is no sunlight, which consumes battery power. When it enters the illuminated area, the satellite is in the southern hemisphere, performing observation missions while charging the solar panels, preparing for long-term observations in the northern hemisphere.

[0045] After the satellite enters the illuminated area, the external heat flux reaches temperature equilibrium, and the satellite reaches a stable thermal equilibrium state before concentrated observations in the Northern Hemisphere to improve the data quality of the infrared channel.

[0046] Optionally, in the global carbon inventory satellite,

[0047] When the satellite is at different latitudes, the local time of the subsatellite point changes, and the corresponding solar elevation angle changes accordingly;

[0048] When the local time of the descending node is 0 o'clock, the local time curve of the subsatellite point at different latitudes is drawn. The horizontal axis is latitude, with south latitude as negative and north latitude as positive. From left to right is an orbit ascending process, and the vertical axis is the local time of the subsatellite point;

[0049] When the satellite is at the southern latitude, the local time is afternoon. When it passes the equator, the local time is 12 noon. When it is observed in the northern hemisphere, the local time is morning. The local time of a typical orbit near 35° north latitude is about 10:45 am.

[0050] If the ascending node's right ascension is actually shifted as needed, the local time will shift accordingly. The adjustment method is: for every 15° increase in the ascending node's right ascension, the corresponding subsatellite local time will increase by one hour.

[0051] In the global carbon inventory satellite provided by the present invention, the global carbon inventory satellite operates on a medium-orbit elliptical orbit. When the global carbon inventory satellite reaches the apogee, it is located above the latitude of areas with dense human activities. Since the apogee is at a high altitude and the flight speed is slow near the apogee, the global carbon inventory satellite can achieve long-term residence observation of areas with dense human activities in northern latitudes (including Asia, North America, and Europe).

[0052] The apogee of the global carbon inventory satellite in the present invention is frozen above the latitude of areas with dense human activities, which can ensure the maximization of the observation time of the Northern Hemisphere; when at apogee, it is always in the illuminated area, thereby ensuring that the lighting conditions of the observation are relatively consistent, which is conducive to the realization of high-precision carbon dioxide column concentration inversion.

[0053] This invention uses a coupled design to synchronously adjust the orbit's perigee and apogee altitudes, ensuring the orbit's sun-synchronous properties while matching the orbital period, orbital precession, and Earth's rotation speed to find a regressive orbit. This regressive nature of the orbit ensures periodic repeatability of the ground track, thereby achieving consistent observation conditions, such as the satellite elevation angle and solar altitude at the observation point, simplifying the design of satellite operating modes.

[0054] The global carbon inventory satellite in the present invention operates on a medium-orbit elliptical frozen sun-synchronous regression orbit, which can achieve global coverage, a high orbit position, a large width, and a short target revisit period; it can realize high-frequency scanning and encrypted observation of key areas with intensive human activities during transit. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Schematic diagram of the orbit of the global carbon inventory satellite in one embodiment of the present invention;

[0056] Figure 2 Schematic diagram of the correspondence between the perigee and apogee of the elliptical frozen sun-synchronous orbit of the global carbon inventory satellite in one embodiment of the present invention;

[0057] Figure 3 Schematic diagram of the sub-satellite point trajectory of the elliptical frozen sun-synchronous regression orbit of the global carbon inventory satellite in one embodiment of the present invention;

[0058] Figure 4 Schematic diagram of the corresponding relationship between the argument of perigee and the latitude of apogee of a global carbon inventory satellite in one embodiment of the present invention;

[0059] Figure 5 Schematic diagram of local time differences at different latitudes of subsatellite points of the global carbon inventory satellite in one embodiment of the present invention. DETAILED DESCRIPTION

[0060] In the present invention, each embodiment is only intended to illustrate the aspects of the present invention and should not be construed as limiting.

[0061] It should also be pointed out that within the scope of the present invention, the terms "same", "equal", "equal to" and the like do not mean that the two values ​​are absolutely equal, but allow a certain reasonable error, that is, the terms also cover "substantially the same", "substantially equal", and "substantially equal to".

[0062] In addition, the numbering of the steps of the methods of the present invention does not limit the order in which the steps are to be performed. Unless otherwise specified, the steps of the methods may be performed in different orders.

[0063] The global carbon inventory satellite proposed in this invention is further described in detail below, with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become more apparent from the following description and claims. It should be noted that the drawings are greatly simplified and not to exact scale, and are intended solely to facilitate and clarify the purpose of illustrating the embodiments of this invention.

[0064] The purpose of the present invention is to provide a global carbon inventory satellite to solve the problem that existing carbon monitoring satellites cannot achieve high-precision and high-efficiency monitoring of global carbon inventory.

[0065] To achieve the above-mentioned objectives, the present invention provides a global carbon inventory satellite, comprising: a long-stay unit in the northern hemisphere, configured to enable the global carbon inventory satellite to operate on a medium-orbit elliptical orbit, and to enable the global carbon inventory satellite to be located above the latitude of an area with intensive human activities when it reaches its apogee; a frozen orbit unit, configured to set a special orbital inclination, so that the global carbon inventory satellite can still operate on a frozen orbit, and the apogee of the frozen orbit is frozen above the latitude of an area with intensive human activities; and a sun-synchronous orbit unit, configured to set synchronization parameters, so that the global carbon inventory satellite can still operate on a sun-synchronous orbit, so that the global carbon inventory satellite can always be in the illuminated area when it reaches its apogee.

[0066] An embodiment of the present invention provides a global carbon inventory satellite, comprising a Northern Hemisphere long-dwell unit (LDU) configured to operate the satellite in a medium-orbit elliptical orbit (MEEO) and to position the satellite above latitudes of densely populated human populations at its apogee. Conventional low-orbit sun-synchronous orbits typically employ circular orbits with an altitude of 500 km to 1000 km and a flight speed of 7.3 km / s to 7.6 km / s, corresponding to a ground speed of 6.4 km / s to 7.1 km / s at the sub-satellite point. Due to their low altitude and high speed, the satellite's transit time over specific ground areas is short, making large-scale scanning and monitoring impossible. The global carbon inventory satellite in this embodiment, however, operates in a MEEO orbit with a higher apogee altitude and a slower flight speed near the apogee. By positioning the apogee above a specific latitude (e.g., 30° north latitude), it is possible to conduct long-term resident observations of densely populated northern latitudes (including Asia, North America, and Europe).

[0067] In one embodiment of the present invention, the global carbon inventory satellite further includes: a frozen orbit unit, which is configured to set a special orbital inclination so that the global carbon inventory satellite still operates on a frozen orbit, and the apogee of the frozen orbit is frozen above the latitude of areas with intensive human activities; the perigee argument of a general elliptical orbit will change with time, that is, it will precess, resulting in constant changes in the latitudes of the perigee and apogee, which cannot guarantee long-term resident observation of the northern hemisphere area where land and population are more concentrated. The carbon inventory orbit proposed in the present invention adopts a special inclination design so that the apogee is frozen above the northern hemisphere, which can ensure the maximization of the observation time of the northern hemisphere.

[0068] In one embodiment of the present invention, the global carbon inventory satellite further includes a sun-synchronous orbit unit configured to set synchronization parameters to maintain the satellite in a sun-synchronous orbit, ensuring that the satellite remains in the illuminated region when it reaches apogee. By jointly designing the orbital inclination, semi-major axis, and eccentricity, the right ascension (RAAN) of the orbital plane's ascending node (APN) precesses eastward at a rate of approximately 0.98° per day, achieving synchronous "tracking" of the sun. This orbit ensures that the apogee remains in the illuminated region and that local time remains consistent across the regions passed by different orbits (note that local time at the sub-satellite point within an orbit may vary slightly). This ensures relatively consistent illumination conditions for observation, facilitating high-precision inversion of carbon dioxide column concentrations.

[0069] In one embodiment of the present invention, the global carbon inventory satellite further includes a regression orbit unit configured to keep the global carbon inventory satellite on its regression orbit, obtaining observation conditions consistent with the previous regression period. Through a coupled design, the orbital perigee and apogee altitudes are synchronously adjusted to match the orbital period, orbital precession, and Earth's rotation speed while ensuring the orbit's sun-synchronous characteristics, thereby finding a regression orbit. The orbital regression characteristics ensure the periodic repeatability of the ground track, thereby obtaining consistent observation conditions, such as the satellite elevation angle and solar altitude angle at the observation point, which helps simplify the design of the satellite's operating mode.

[0070] In one embodiment of the present invention, in the global carbon inventory satellite, the latitude of the area with intensive human activities is between 20°N and 45°N; the synchronization parameters include orbital inclination, orbital semi-major axis and orbital eccentricity; the observation conditions include the satellite elevation angle and solar altitude angle of the observation point; the orbital parameters of the global carbon inventory satellite include: the range of perigee orbital altitude is 350km~1000km, the range of apogee orbital altitude is 6800km~8300km, the range of perigee argument angle is 215°~235°, and the orbital period is 3h.

[0071] In one embodiment of the present invention, the inclination of the elliptical frozen orbit of the global carbon inventory satellite is selected as follows: due to the influence of the Earth's oblateness, the apses of the elliptical orbit will precess over time. When the orbital inclination satisfies specific conditions, the apses precession rate can be reduced to 0, i.e., the orbital apses are "frozen." Such an orbit is called a frozen orbit, and the corresponding inclination is the critical inclination. Based on the critical inclination, the intermediate elliptical orbit is divided into a prograde elliptical frozen orbit and a retrograde elliptical frozen orbit. The prograde elliptical frozen orbit has an inclination of 63.4°, and the retrograde elliptical frozen orbit has an inclination of 116.565°. Considering the precession of the ascending node, the ascending node of the prograde orbit precesses westward by a certain angle each day, while the ascending node of the retrograde orbit precesses eastward by a certain angle each day. Sun synchronization requires the ascending node to move eastward by approximately 0.9856° each day. Therefore, based on the ascending node requirement of the sun-synchronous orbit, the orbital inclination of the global carbon inventory satellite is determined to be 116.565°.

[0072] In one embodiment of the present invention, in the global carbon inventory satellite, the relationship between the perigee orbit altitude and the apogee orbit altitude is obtained based on the value of the ascending node of the sun-synchronous orbit, the value of the orbital inclination, the first function and the second function; the first function represents the relationship between the semi-major axis of the orbit and the perigee orbit altitude and the apogee orbit altitude; the second function represents the relationship between the orbital eccentricity and the perigee orbit altitude and the apogee orbit altitude.

[0073] In one embodiment of the present invention, in the global carbon inventory satellite, the frozen characteristics of the elliptical orbit constrain the orbital inclination. Under specific orbital inclination conditions, the orbital semi-major axis and orbital eccentricity need to be jointly designed. Due to the influence of the non-spherical gravitational perturbation of the earth, the satellite orbit plane is constantly precessing in the inertial space. Only the harmonic terms are considered. The long-term perturbation of the term, the precession angular rate of the orbital plane is

[0074]

[0075] in is the radius of the Earth, is the semi-major axis of the orbit, is the orbital eccentricity, is the orbital inclination;

[0076] The value of the ascending node of a sun-synchronous orbit satisfies the following conditions:

[0077]

[0078] The orbital inclination is 116.565°;

[0079] The first function is ;

[0080] The second function is ;

[0081] in is the perigee orbit altitude, is the apogee orbital height, R E is the radius of the Earth;

[0082] Substituting the orbital inclination, the first function and the second function, we can get the perigee orbital height. and apogee orbital altitude According to the combined equation, the orbit height relationship curve is obtained, such as Figure 2 By traversing the perigee The altitude range is 350km~1000km, and the corresponding apogee orbit altitude can be obtained respectively. The relationship between the two is as follows: Figure 2 This is the design basis of the elliptical frozen sun-synchronous orbit. It can be seen that the higher the perigee altitude, the lower the apogee altitude.

[0083] Regression orbits are common in Earth remote sensing satellites. The satellite sub-satellite point trajectories in these orbits periodically overlap, ensuring consistent satellite elevation angles during transit. Combined with the orbit's sun-synchronous characteristics, this allows for consistent observation illumination angles and simplifies the design of satellite operating modes. In one embodiment of the present invention, in the global carbon inventory satellite, the sub-satellite point trajectory is a composite of the three motions of satellite flight, orbital plane precession, and Earth rotation. For a regression orbit, after one regression cycle, the sub-satellite point trajectory overlaps with the sub-satellite point trajectory from the previous regression cycle:

[0084]

[0085] in is the number of orbits the satellite orbits the Earth in one regression cycle, is the number of ascending days in the regression cycle, The longitude interval between consecutive adjacent trajectories on the equator, i.e., the traverse angle; synchronously adjust the perigee orbit altitude and apogee orbit altitude, and while ensuring the constraints of the sun-synchronous orbit, match the orbital period, orbital precession, and Earth's rotation speed to obtain the regression orbit;

[0086] Based on the Q value, points on the orbit-altitude relationship curve were selected, and the parameters of the regressive orbit were iteratively calculated within a range of intermediate elliptical orbits with perigee altitudes of 350 km to 1000 km, apogee altitudes of 6800 km to 8300 km, and an orbital inclination of 116.565°. Analysis revealed 14 orbits within this range that met the requirements of elliptical, frozen, sun-synchronous, and regressive orbits, as shown in Table 1.

[0087] Table 1 Design of elliptical frozen sun-synchronous return orbit

[0088]

[0089] The 8th group of orbits in the table is selected as the typical carbon inventory orbit, with a return period of 5 days. The subsatellite point trajectory for more than 5 days is as follows: Figure 3 shown.

[0090] In one embodiment of the present invention, in the global carbon inventory satellite, the adjustment of the argument of perigee will not affect the orbital period and the orbital plane precession rate, and thus will not affect the sun-synchronous characteristics and regression characteristics of the orbit. By adjusting the argument of perigee, the apogee of the global carbon inventory satellite is set above a specific latitude in the northern hemisphere, so that the global carbon inventory satellite will spend more time in the area with more intensive human activities in the northern hemisphere, so as to observe the northern hemisphere for a longer time; taking the 5-day regression ellipse frozen sun-synchronous orbit with a perigee altitude of 818.15km and an apogee altitude of 7199.32 as an example, the apogee latitudes corresponding to different arguments of perigee are as follows: Figure 4 As shown. Figure 4 As can be seen, the larger the argument of perigee, the higher the corresponding apogee latitude. Taking into account the latitude distribution of key countries, 35° north latitude was selected as the apogee position to enable longer-term observation of these key countries. Therefore, the argument of perigee for the Global Carbon Inventory satellite was selected to be 220°.

[0091] In one embodiment of the present invention, in the global carbon inventory satellite, according to the operating characteristics of the global carbon inventory satellite, the operating arc of the global carbon inventory satellite payload is at the apogee of the northern hemisphere. Therefore, the flight direction of the satellite in the illumination area is ascending (flying from south to north) to achieve:

[0092] The satellite is in the Earth's shadow area without sunlight, which consumes battery power. When it enters the illuminated area, the satellite is in the southern hemisphere and has fewer observation tasks. While performing observation tasks, the solar panels are charged to prepare for long-term observation in the northern hemisphere.

[0093] After the satellite enters the illuminated area, the external heat flow changes and it takes some time to reach temperature equilibrium. Raising the orbit in the illuminated area can ensure that the satellite reaches a stable thermal equilibrium state before concentrated observations in the northern hemisphere, thereby improving the data quality of the infrared channel.

[0094] Furthermore, in the global carbon inventory satellite, when the satellite is at different latitudes, the subsatellite local time changes, and the corresponding solar elevation angle changes accordingly; when the descending node local time is 0 o'clock, the subsatellite local time curves at different latitudes are drawn as follows Figure 5 As shown in the figure, the horizontal axis represents latitude, with south latitude being negative and north latitude being positive. A single orbit raising process is described from left to right, and the vertical axis represents subsatellite local time (24-hour system). When the satellite is at southern latitude, local time is afternoon. When crossing the equator, local time is 12:00 noon. When observed in the northern hemisphere, local time is morning. A typical orbit near 35° north latitude at apogee is approximately 10:45 a.m. If the ascending node's right ascension is shifted as needed, local time will shift accordingly. The adjustment method is: for every 15° increase in the ascending node's right ascension, the corresponding subsatellite local time increases by one hour. Following the above design steps, a set of satellite orbit designs suitable for global carbon inventory is obtained. Their orbital parameters and characteristics are shown in Table 2.

[0095] Table 2 Satellite orbit designs suitable for carbon inventory

[0096]

[0097] By analyzing the revisit and coverage capabilities of the orbit and comparing it with low-orbit sun-synchronous orbit satellites and geosynchronous orbit satellites, the global carbon inventory satellite provided by the present invention operates on a medium-orbit elliptical orbit. When the global carbon inventory satellite reaches the apogee, it is located above the latitudes of areas with intensive human activities. Since the apogee is at a high altitude and the flight speed is slow near the apogee, the global carbon inventory satellite can achieve long-term residence observation of areas with intensive human activities in northern latitudes (including Asia, North America, and Europe).

[0098] The apogee of the global carbon inventory satellite in the present invention is frozen above the latitude of areas with dense human activities, which can ensure the maximization of the observation time of the Northern Hemisphere; when at apogee, it is always in the illuminated area, thereby ensuring that the lighting conditions of the observation are relatively consistent, which is conducive to the realization of high-precision carbon dioxide column concentration inversion.

[0099] This invention uses a coupled design to synchronously adjust the orbit's perigee and apogee altitudes, ensuring the orbit's sun-synchronous properties while matching the orbital period, orbital precession, and Earth's rotation speed to find a regressive orbit. This regressive nature of the orbit ensures periodic repeatability of the ground track, thereby achieving consistent observation conditions, such as the satellite elevation angle and solar altitude at the observation point, simplifying the design of satellite operating modes.

[0100] The global carbon inventory satellite in the present invention operates on a medium-orbit elliptical frozen sun-synchronous regression orbit, which can achieve global coverage, a high orbit position, a large width, and a short target revisit period; it can realize high-frequency scanning and encrypted observation of key areas with intensive human activities during transit.

[0101] Although certain embodiments of the present invention have been described in this application, those skilled in the art will appreciate that these embodiments are provided by way of example only. Numerous variations, alternatives, and improvements will be contemplated by those skilled in the art in light of the teachings of this disclosure without departing from the scope of this disclosure. The appended claims are intended to define the scope of the disclosure and are intended to encompass methods and structures within the scope of these claims and their equivalents.

Claims

1. A global carbon inventory satellite, characterized in that: include: a freezing orbit unit configured to set an orbital inclination so that the global carbon inventory satellite operates on a frozen orbit, wherein the apogee of the frozen orbit is frozen above the latitude of an area with dense human activities; as well as a sun-synchronous orbit unit configured to keep the global carbon inventory satellite in a sun-synchronous orbit, so that the global carbon inventory satellite is always in the illumination zone when it reaches its apogee; The relationship between the perigee orbit altitude and the apogee orbit altitude is obtained according to the value of the ascending node of the sun-synchronous orbit, the value of the orbital inclination, the first function and the second function; The first function represents the relationship between the semi-major axis of the orbit and the altitude of the orbit at perigee and apogee; The second function represents the relationship between orbital eccentricity and the orbital altitudes of perigee and apogee; A northern hemisphere long-dwelling unit configured to place the Global Carbon Inventory Satellite in a medium-elliptical orbit and to place the Global Carbon Inventory Satellite at apogee above latitudes of areas with high human activity; The regression orbit unit is configured to keep the global carbon inventory satellite on the regression orbit and obtain observation conditions consistent with the previous regression period to ensure the periodic repeatability of the ground track; Through coupling design, the orbital perigee and apogee heights are adjusted synchronously. While ensuring the orbit's sun-synchronous characteristics, the orbital period, orbital precession, and Earth's rotation speed are matched to find the regression orbit. The inclination of the elliptical frozen orbit is selected as follows: due to the influence of the Earth's oblateness, the apses of the elliptical orbit precess over time. When the orbital inclination satisfies certain conditions, the apses precession rate is zero, and the orbital apses are "frozen." At this point, the orbit is called a frozen orbit, and the corresponding inclination is the critical inclination. Based on the critical inclination, the intermediate elliptical orbit is divided into prograde elliptical frozen orbits and retrograde elliptical frozen orbits. The orbital inclination of the prograde elliptical frozen orbit is 63.4°, and the orbital inclination of the retrograde elliptical frozen orbit is 116.565°. According to the precession of the ascending node, the ascending node of the prograde orbit precesses westward by a certain angle every day, and the ascending node of the sun-synchronous orbit, which serves as the ascending node of the retrograde orbit, precesses eastward by a certain angle every day. The orbital inclination of the global carbon inventory satellite is selected to be 116.565°.

2. The global carbon inventory satellite according to claim 1, characterized in that: The latitude of the area with intensive human activities is between 20°N and 45°N; Synchronization parameters include orbital inclination, orbital semi-major axis, and orbital eccentricity; The orbital parameters of the Global Carbon Inventory satellite include: The perigee orbit altitude ranges from 350km to 1000km, the apogee orbit altitude ranges from 6800km to 8300km, and the perigee argument ranges from 215° to 235°.

3. The global carbon inventory satellite according to claim 1, characterized in that: By jointly designing the orbital inclination, semi-major axis, and eccentricity, the right ascension of the ascending node of the orbital plane precesses eastward at a rate of 0.985612288° per day, achieving synchronous tracking of the sun. This orbit can ensure that the apogee is always in the illuminated area, and the local time of the areas passed by different orbits remains consistent. The local time of the sub-satellite point within one orbit changes, thereby ensuring that the observation lighting conditions are relatively consistent, so as to achieve high-precision carbon dioxide column concentration inversion.

4. The global carbon inventory satellite according to claim 3, wherein: The angular rate of precession of the orbital plane is in is the radius of the Earth, is the semi-major axis of the orbit, is the orbital eccentricity, is the orbital inclination; The value of the ascending node of a sun-synchronous orbit satisfies the following conditions: The orbital inclination is 116.565°; The first function is ; The second function is ; in is the perigee orbit altitude, is the apogee orbital altitude; Substituting the orbital inclination, the first function and the second function, we can get the perigee orbital height. and apogee orbital altitude The combined equation of The track height relationship curve is obtained based on the combined equation.

5. The global carbon inventory satellite according to claim 4, characterized in that: After one regression cycle, the sub-satellite point trajectory of the regression orbit overlaps with the sub-satellite point trajectory of the previous regression cycle: in is the number of orbits the satellite orbits the Earth in one regression cycle, is the number of ascending days in the regression cycle, is the lateral displacement angle; Synchronously adjust the perigee and apogee orbital altitudes to obtain the regression orbit by matching the orbital period, orbital precession, and Earth's rotation speed while ensuring the constraints of the sun-synchronous orbit. Based on the Q value, points on the orbit altitude relationship curve are selected, and the parameters of the regression orbit are iteratively calculated within the range of a medium-orbit elliptical orbit with a perigee orbit altitude of 350km~1000km, an apogee orbit altitude of 6800km~8300km, and an orbital inclination of 116.565°.

6. The global carbon inventory satellite according to claim 5, characterized in that: By adjusting the argument of perigee, the apogee of the Global Carbon Inventory satellite is set above a specific latitude in the Northern Hemisphere. This allows the satellite to spend more time over areas with dense human activity in the Northern Hemisphere, allowing for longer observations of the Northern Hemisphere. Based on the proportional relationship between the argument of perigee and the latitude of apogee, the argument of perigee is determined, 35° north latitude is selected as the apogee position, and the argument of perigee of the global carbon inventory satellite is selected as 220°.

7. The global carbon inventory satellite according to claim 6, characterized in that: According to the working characteristics of the global carbon inventory satellite, the working arc of the global carbon inventory satellite payload is at the apogee of the northern hemisphere. Therefore, the flight direction of the satellite in the illumination area is ascending orbit to achieve: When the satellite is in the Earth's shadow, there is no sunlight, which consumes battery power. When it enters the illuminated area, the satellite is in the southern hemisphere, performing observation missions while charging the solar panels, preparing for long-term observations in the northern hemisphere. After the satellite enters the illuminated area, the external heat flux reaches temperature equilibrium, and the satellite reaches a stable thermal equilibrium state before concentrated observations in the Northern Hemisphere to improve the data quality of the infrared channel.

8. The global carbon inventory satellite according to claim 3, wherein: When the satellite is at different latitudes, the local time of the subsatellite point changes, and the corresponding solar elevation angle changes accordingly; When the local time of the descending node is 0 o'clock, the local time curve of the subsatellite point at different latitudes is drawn. The horizontal axis is latitude, with south latitude as negative and north latitude as positive. From left to right is an orbit ascending process, and the vertical axis is the local time of the subsatellite point; When the satellite is at the southern latitude, the local time is afternoon. When it passes the equator, the local time is 12 noon. When it is observed in the northern hemisphere, the local time is morning. The local time of a typical orbit near 35° north latitude is 10:45 am. If the ascending node's right ascension is actually shifted as needed, the local time will shift accordingly. The adjustment method is: for every 15° increase in the ascending node's right ascension, the corresponding subsatellite local time will increase by one hour.

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