Elliptical low earth orbit (ELEO) satellite constellation

Abstract

An innovative Elliptical Low Earth Orbit (eLEO) Satellite Constellation combines the benefits of geostationary (GEO), middle Earth orbits (MEO) and low Earth orbit (LEO) satellites. This hybrid constellation aims to minimize latency and maximize coverage with fewer satellites, reducing capital and operational costs. The design features orbits with LEO-like perigee and extended apogee to optimize visibility and minimize collision risks, enhancing communication capabilities particularly over remote areas. The constellation offers flexible deployment options, including 24, 48 and 96 satellite configurations, tailored to different coverage and budgetary requirements. Strategic advantages include improved data transmission rates, enhanced satellite longevity, and robust support for both civilian and defense applications. This system represents a significant advancement in satellite communication technology, promising to meet diverse global communication needs efficiently.

Description

TITLE OF THE INVENTIONElliptical Low Earth Orbit (eLEO) Satellite ConstellationCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present patent application claims the benefits of priority of United States Patent Application No. 63 / 651,742, entitled “ELLIPTICAL LOW EARTH ORBIT (eLEO) SATELLITE CONSTELLATION”, and filed at the United States Patent and Trademark Office on May 24, 2024, the content of which is incorporated herein by reference.FIELD OF THE INVENTION

[0002] The present invention generally relates to satellite constellations and specifically to the optimal design and deployment of elliptical low Earth orbit (eLEO) constellations.BACKGROUND OF THE INVENTION

[0003] Conventional satellite orbits such as geostationary (GEO), medium Earth orbits (MEO), and traditional low Earth orbits (LEO) present challenges in terms of latency, dwell time, coverage, and collision risks. There has been a need to optimize these orbital designs to reduce costs and improve communication efficiency, particularly over sparsely populated areas.SUMMARY OF THE INVENTION

[0004] The shortcomings of prior art are mitigated by an eLEO satellite constellation that combines the benefits of MEO and LEO satellites, significantly reducing the number of satellites required while maintaining low latency, good dwell time and expansive coverage.

[0005] The invention encompasses a satellite constellation with an eLEO that maintains a typical LEO perigee and an extended apogee to optimize latency and minimize collision risks, while providing flexible and comprehensive coverage optimising path loss and dwell times.

[0006] Other and further aspects and advantages of the present invention will be obvious upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The above and other aspects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which:

[0008] Figure 1 is a schematic representation of the coverage map of a 48-satellite eLEO constellation, illustrating the regions where satellites are visible above 25 degrees elevation.

[0009] Figure 2 is a diagram of the ground track of the 48-satellite eLEO constellation, showing the paths traced by the satellites over the Earth's surface.

[0010] Figure 3 is a 3D model of the orbital planes and satellite positions for the 48-satellite eLEO constellation.

[0011] Figure 4 is a schematic representation of the coverage map of a 24-satellite eLEO constellation, displaying the coverage areas and visibility elevations.

[0012] Figure 5 is a diagram of the ground track of the 24-satellite eLEO constellation, demonstrating the orbital paths of the satellites.

[0013] Figure 6 is a 3D model of the orbital planes and satellite positions for the 24-satellite eLEO constellation.

[0014] Figure 7 is a 3D illustration of an example of inner and outer Van Allen belts.DETAILED DESCRIPTION OF THE INVENTION

[0015] A novel Elliptical Low Earth Orbit (eLEO) Satellite Constellation will be described hereinafter. Although the invention is described in terms of specific illustrative embodiments, it is to be understood that the embodiments described herein are by way of example only and that the scope of the invention is not intended to be limited thereby.

[0016] In the following description, similar features in the drawings have been given similar reference numerals, and in order not to weigh down the figures, some elements are not referred to in some figures if they were already identified in another figure.

[0017] The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and / or the specification may mean “one”, but it is alsoconsistent with the meaning of “one or more”, “at least one”, and “one or more than one”. Similarly, the word “another” may mean at least a second or more.

[0018] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as "comprise1and "comprises”), “having” (and any form of having, such as “have and “has”), “including” (and any form of including, such as “include and “includes”) or “containing” (and any form of containing, such as “contain” and “contains”), are inclusive or open-ended and do not exclude additional, unrecited elements.

[0019] As used herein the word “essentially” means “mostly, but not exclusively”.

[0020] It is also to be understood that the word “about”, “about” or “approximately” means an acceptable error for a particular value as determined by one of ordinary skill in the art, which depends in part on how the value is measured or determined. Insofar as it refers to percentages in the specification and claims, it means rounding up or down to the nearest whole number percentage. Insofar as it refers to other numbers in the specification and claims, it means plus or minus 10%.

[0021] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers, material percentages or ratios, reaction conditions, and other numerical values are also to be understood as modified by the term "about" in all cases.

[0022] Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending on the desired properties sought to be obtained. Without attempting to limit the application of the doctrine of equivalents to the claims, at a minimum each numerical parameter should be interpreted in light of the reported number of significant figures and by applying normal rounding techniques.

[0023] The present invention provides a novel satellite constellation characterized by an elliptical low Earth orbit (eLEO) designed to synergize the advantages of MEO (Medium Earth Orbit) and LEO (Low Earth Orbit) satellites, while mitigating their respective disadvantages. This eLEO constellation aims to achieve a balance between extensive global coverage and minimized latency for telecommunications and enabling new earth observation applications.

[0024] The constellation's increased dwell times significantly enhance its utility across multiple satellite operations including espionage, military reconnaissance, and life-saving drone coverage in hazardous airspace. Furthermore, this innovative configuration reduces the number of satellites required while maintaining high performance levels, thereby offering substantial cost advantages in terms of both deployment and data transmission. These features collectively enhance the constellation's competitiveness in both telecommunications and specialized applications such as radar and Earth reconnaissance, positioning it as a cost-effective solution in the evolving satellite technology market.

[0025] The eLEO can be defined as any orbit that features a LEO-like perigee of approximately 500 kilometers and an apogee that may extend up to about 36,000 kilometers, primarily constrained by commercially acceptable latency. The ideal orbit range for these eLEO satellites is proposed to be between about 1,200 kilometers and about 8,000 kilometers to circumvent space debris and mitigate potential exposure to the Kessler syndrome at perigee while minimizing the average latency to an acceptable level (preferably less than about 100 milliseconds) and allowing longer dwell times and improved look-angles at apogee. Data transmission occurs preferentially during apogee segments to provide increased dwell time.

[0026] In selecting an optimal orbit, the invention considers several key criteria and tradeoffs. These include the number of satellites necessary to cover a given surface area, the associated capital expenditure (CAPEX), latency, achievable fill rate, power density, lifetime of the satellites, scalability, and other technical variables. The paramount benchmark metric that needs to be optimized is the fill rate and lifetime-adjusted cost per bit at the lowest acceptable cost per bit. The satellite trajectories are chosen to reduce collision risk by avoiding crowded LEO shells.

[0027] Contrasting with satellites in MEO orbit, which are efficient in minimizing the number of satellites and related CAPEX, along with a high achievable fill rate and extended lifetime, LEO satellite constellations are more competitive regarding lower latency, higher relative power density, and scalability. The eLEO orbits benefit from the advantages of both MEO and LEO orbit types across all key success criteria, providing low latency and path loss similar to LEOs, while ensuring significantly better fill rates and a lower numberof satellites and related CAPEX, primarily due to higher dwell time compared to LEO orbits. This enables the eLEO constellation to address areas of market demand effectively.

[0028] The eLEO design also offers potential advantages for defense-related applications such as seamless coverage of the entire Arctic region, which is critical for vessels, submarines, and drones in a geographically contentious area. It proposes the capability for nearly 1-hour live tactical video earth observation via satellite with a minimum of about 25 degrees look-angle at apogee in unsecured airspace. Additionally, the flexibility to define the apogee of an eLEO orbit allows for reduced deployment times, given that eLEO- capable satellites are available for launch.

[0029] In terms of telecommunications, eLEO orbits present several benefits, including easier and fewer handovers, reduced Doppler shift, cost-effective user equipment (UEs), improved look-angles, easier integration with LEO, Medium Earth Orbit (MEO), and MEO constellations, optimized service delivery, and enhanced cost-performance metrics.

[0030] An improved space environment is another advantage of the eLEO orbits, including a benign radiation environment that avoids both Van Allen belts and generally reduced collision risk. The satellite trajectories are chosen to reduce collision risk by avoiding crowded LEO shells. The design strategically avoids traditional LEO orbits to also mitigate the risk of the Kessler syndrome, which is the snowball effect of increasing collisions due to space debris that could render LEO orbits unusable.

[0031] For example, the present invention can be implemented using a 48-satellite constellation, providing nearly global coverage with an emphasis on populated regions in the Northern and Southern hemispheres, or a more focused 24-satellite constellation. Any configuration which avoids hazardous zones such as the Van Allen radiation belts and optimize satellite visibility and communication efficiency could be used.

[0032] Highlighting an intrinsic redundancy, the eLEO constellation integrates hot in-orbit backup capability, ensuring that several satellites are usually visible at the same time over the targeted area of interest, thus avoiding single points of failure and enhancing service reliability.

[0033] Considering CAPEX, the invention significantly reduces expenditure by deploying a smaller constellation for example of 24 satellites, capable of covering half the globe with efficient operational costs compared to traditional models that may require a minimum of 460 satellites for complete global coverage at a relatively high altitude of approximately 1,200 kms. Indeed, global coverage is not required given 90 percent of the population lives in the Northern hemisphere. The invention enables an operator to focus on pockets of demand rather than being forced to adopt global coverage which in itself is not a commercial requirement.

[0034] The eLEO orbits employ an 'inclined elliptical' configuration, where the orbit's inclination and eccentricity offer distinctive advantages. This design is crucial for providing extended dwell times over a target area of interest at higher latitudes, a key differentiator from other satellite orbits which typically feature more uniform apogee and perigee. This allows to minimize the number of satellites required and capex whilst maximizing addressable Gross Domestic Product (GDP) over populated areas at the same time

[0035] In the embodiment of Figure 1, a 48-constellation coverage map displays the coverage areas of a 48-satellite eLEO constellation. Each outlined shape on the map represents the region on Earth where a satellite is visible above about 25-degree elevation angle, which is considered a threshold for good communication quality. The constellation parameters show that these satellites are distributed over 8 orbital planes with a specific inclination angle and eccentricity, completing 8.5 orbits per day.

[0036] Referring now to Figure 2, a ground track visualization shows the paths that the 48 satellites of Figure 1 will trace over the Earth's surface. There is one full orbit ground track depicted for an example satellite, and short ground tracks for all other satellites, indicating the path across the Earth's surface as the satellite moves in its orbit.

[0037] Referring now to Figure 3, an orbital plane representation of the 48-satellite constellation is shown.

[0038] Similarly to Figure 1, Figure 4 shows a constellation coverage map but for a smaller constellation of 24 satellites. The coverage regions are larger due to fewer satellites being used, which implies a trade-off between the number of satellites and the coverage area. Theconstellation parameters are adjusted accordingly, showing different values for eccentricity and orbits per day.

[0039] Referring now to Figure 5, a ground track map is shown that has a similar pattern to the 48-satellite map but with fewer lines, as there are only 24 satellites in this constellation. The individual satellite paths are spaced out, indicating a different coverage strategy that might prioritize certain areas or provide less frequent coverage.

[0040] Referring now to Figure 6, a 3D representation of the 24-satellite constellation's orbital planes is shown. It provides a perspective on the geometry and arrangement of the satellites in their respective orbits, emphasizing the spatial layout and the potential field of coverage.

[0041] Still referring to Figure 6, the eLEO constellation further excels in real-time singlepoint failure protection, enhancing service resilience significantly when compared to traditional GEO and global LEO systems. In this 24-satellite configuration, 16 satellites — 66% of the constellation — are dedicated to providing continuous coverage to the northern hemisphere. Should one satellite encounter a failure, another satellite in close proximity can seamlessly take over its service, virtually eliminating downtime. In contrast, a conventional GEO constellation, typically comprising just three satellites to cover similar regions, would suffer a loss of up to one-third of its coverage if a single satellite fails, necessitating the launch of a replacement which is notably costly — GEO satellites being 20-50 times more expensive than LEO satellites. Moreover, in global LEO constellations, which may require up to 460 satellites for comprehensive coverage, only a fraction directly serves significant landmasses such as the northern hemisphere. A failure in one of these satellites means there is no immediate backup available; realigning or adjusting the orbits of other satellites in the fleet is required to restore coverage. The eLEO constellation's design uniquely ensures that real-time, multipoint failure protection is achievable, a capability that other orbital configurations cannot match, often requiring new construction and launches for remediation. The number of satellites used for the invention can vary from about 24 to about 96.

[0042] Still referring to Figure 6, the engineered trajectory of the eLEO constellation ensures that satellites maintain prolonged exposure to sunlight, surpassing that of standardGEO or LEO orbits. This unique orbital design allows satellites to remain illuminated by the sun for extended periods, especially as they spend a significant amount of their orbit above the Earth's Arctic region. This continuous solar exposure facilitates a lighter and simpler satellite design, as the solar panels and onboard batteries can be smaller due to reduced energy storage requirements or alternatively, the extra power can be utilized for enhanced service capabilities. Additionally, the specific orbit minimizes the frequency and duration of eclipse phases that satellites encounter. Unlike LEO satellites, which experience eclipse phases about 50% of the time, and GEO satellites, which endure eclipse durations ranging from as little as about 10 minutes to up to about 70 minutes during equinoxes, eLEO satellites are less frequently obscured by the planet. This reduction in planetary shadowing further underscores the operational and energy efficiencies of the eLEO system.

[0043] While illustrative and presently preferred embodiments of the invention more spaced out, indicating a different coverage strategy that might prioritize certain areas or provide less frequent coverage have been described in detail hereinabove, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.

Claims

Claims:

1. An elliptical low Earth orbit (eLEO) satellite constellation comprising: a plurality of satellites deployed in inclined elliptical orbits, each orbit having a perigee altitude that is lower than its apogee altitude, wherein the orbits are configured to provide extended dwell time over selected regions of the Earth's surface for communication or observation purposes, and the constellation is further configured to maintain a minimum look-angle over said regions suitable for signal transmission.

2. The constellation of claim 1, wherein the perigee altitude is between about 500 kilometers and about 1,500 kilometers and the apogee altitude is between about 5,000 kilometers and about 36,000 kilometers.

3. The constellation of claim 1, wherein the perigee altitude is approximately 1,200 kilometers and the apogee altitude is approximately 8,000 kilometers.

4. The constellation of claim 1, wherein each satellite completes between 6 and 9 orbital revolutions per day.

5. The constellation of claim 1, wherein the orbital inclination is between about 45 and about 90 degrees.

6. The constellation of claim 1 , wherein the satellites are distributed in a set of 8 orbital planes.

7. The constellation of claim 1, wherein the satellite orbits are configured to provide uninterrupted coverage of the Arctic region.

8. The constellation of claim 1, further comprising onboard power systems sized to leverage extended solar exposure near apogee.

9. The constellation of claim 1, wherein the satellites operate outside of the inner and outer Van Allen radiation belts.

10. The constellation of claim 1, wherein the total number of satellites is between about24 and about 96.

11. The constellation of claim 1, wherein each satellite includes in-orbit failover capabilities to provide redundancy in coverage.

12. The constellation of claim 1, wherein the satellite spacing is optimized to minimize handover frequency during continuous coverage.

13. The constellation of claim 1, wherein the system is integrated with ground-based 5G or MEO / GEO infrastructure.

14. A method for providing satellite-based communication or observation, comprising: deploying a plurality of satellites in elliptical orbits, each orbit having a perigee altitude lower than its apogee altitude; orienting the orbits such that dwell time is increased over one or more predefined regions of interest; and transmitting data between the satellites and Earth-based terminals during extended dwell periods.

15. The method of claim 14, wherein the predefined region of interest includes a military conflict zone.

16. The method of claim 14, further comprising allocating satellite communication resources dynamically based on regional demand density.

17. The method of claim 14, wherein the satellite trajectories are chosen to reduce collision risk by avoiding crowded LEO shells.

18. The method of claim 14, wherein communication latency is maintained below about 100 milliseconds.

19. The method of claim 14, wherein data transmission occurs preferentially during apogee segments to provide increased dwell time.

20. The method of claim 14, further comprising reconfiguring the apogee altitude of at least one satellite to adapt to evolving coverage requirements.

Images