Co-orbiting Laser Relay Satellite for High-Rate Data Downlink
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Solution Overview
Problem
Current satellite communication systems face limitations in data downlink capacity and frequency due to line-of-sight constraints, high capital investment requirements for ground stations, and interference issues with RF bandwidth, especially for low Earth orbit (LEO) satellites, which are not scalable with the growth of satellite infrastructure.
Innovation Solution
A dedicated communications relay satellite is placed in a quasi-orbit about a client satellite, passing between the client satellite and Earth, receiving data via a short-range low-power link and retransmitting it over an optical link to another satellite or directly to the ground, allowing for increased data rates and reduced infrastructure costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If satellites download data via space-to-ground radio-frequency links, then data can be transmitted from LEO satellites, but the communication is limited to line-of-sight with ground stations, restricting pass duration to less than ten minutes and pass frequency to three to five times per day
Solution Approach 1:
The patent introduces an intermediary satellite in a highly elliptical orbit to relay data between LEO satellites and ground stations. This intermediary acts as a mediator that extends the communication window beyond the brief line-of-sight passes of LEO satellites, allowing data to be stored and forwarded when the LEO satellite is out of direct ground contact.
Solution Approach 2:
The patent transitions from direct space-to-ground communication to a three-dimensional relay architecture where data passes through multiple orbital planes and altitudes. The highly elliptical orbit satellite provides a different dimensional pathway for data transmission, enabling communication during periods when direct line-of-sight is unavailable.
2Adaptability or versatility
If the number of ground stations is increased to overcome downlink constraints, then more satellites can be served, but capital investment requirements increase significantly
Solution Approach 1:
The patent makes a single ground station serve multiple LEO satellites through the intermediary satellite relay. The highly elliptical orbit satellite can receive data from multiple LEO satellites during its orbital passes and forward it to a single ground station, allowing that ground station to service multiple satellite constellations rather than requiring dedicated ground stations for each satellite.
Solution Approach 2:
The intermediary satellite in highly elliptical orbit performs self-service by autonomously managing data storage and forwarding operations. It collects data from multiple LEO satellites, maintains it in onboard storage during periods when ground stations are not visible, and automatically transmits the accumulated data when in communication range, reducing the need for multiple ground-based infrastructure elements.
3Productivity
If high data rates are achieved during limited contact time, then more data can be transmitted per pass, but high-power transmitters and high-gain antennas are required on the satellite, constrained by power and mass limitations
Solution Approach 1:
The patent replaces the mechanical/electrical high-power transmitter system with an optical communication system. Instead of using high-power radio frequency transmitters that consume significant electrical power and require large antennas, the system uses optical lasers for data transmission, which can achieve high data rates with lower power consumption and smaller form factors suitable for LEO satellites.
Solution Approach 2:
The patent changes the fundamental parameter of communication from radio-frequency to optical domain. This parameter change enables high data rate transmission with reduced power requirements, as optical communication systems can achieve higher bandwidth efficiency and require less transmit power compared to RF systems for the same data rate.
4Quantity of substance
If RF bandwidth is increased to accommodate more satellites, then more data can be transmitted, but RF signals from multiple satellites and ground stations interfere with one another
Solution Approach 1:
The patent substitutes optical communication for RF communication to eliminate spectrum interference issues. Optical wavelengths do not suffer from the same congestion and interference problems as RF bands, allowing multiple satellites and ground stations to operate simultaneously without mutual interference, thereby effectively increasing available bandwidth without the harmful interference characteristic of RF systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides higher data transfer rates, reduced capital expenditures, and improved scalability by utilizing a small, cost-effective relay satellite that can operate independently of the client satellite's attitude-control requirements, offering enhanced data security and availability.
Implementation Method 1
receiving data from a client satellite via a radio-frequency link and retransmitting the data using an optical link
Data Source
AI summary
A dedicated satellite to reduce the cost and increase the rate and reliability of data transmission from space to ground is provided. For each client satellite producing data in Earth orbit, a dedicated relay satellite is provided. The relay satellite may fly near the client satellite and receive data from the client satellite by RF communication. The relay satellite may transmit the data to a ground terminal or to another satellite using a laser communication system. Because the relay satellite is not physically connected to the client satellite, the attitude-control requirements of an optical communication system are not imposed on the client satellite. The relay satellite may also be deployed from the client satellite. The relay satellite may allow downlinking large amounts of data for new satellite operators without an existing ground network and for established satellite operators seeking higher data rates, lower latency, or reduced ground system operating costs.