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Spacecraft are man-made machines that operate in space. An orbiting spacecraft is normally referred to as a satellite, although it is manmade as opposed to a natural satellite like our moon. A spacecraft is typically subdivided into two major parts, the payload and the bus.
Where the mission can be defined as the purpose of the spacecraft and is usually identified as the payload part of the spacecraft (e.g. scientific instruments, communications). For Earth Observation (EO) applications, for example, the payload is the camera that is collecting the relevant data. For remote sensing satellites the payload will be the radar or other sensing equipment used to take readings.
The bus provides the structural body and primary system of a space vehicle, usually providing locations for the payload (typically space experiments or instruments). Although each spacecraft payload may be quite different from another, all spacecraft buses are similar in their makeup. A satellite bus or spacecraft bus is a general model on which multiple-production satellite spacecraft are often based.
The success of any spacecraft mission largely depends on the design, functionality, and reliability of the satellite bus. The satellite bus, also known as the spacecraft bus, serves as the backbone of a spacecraft, providing the necessary support and infrastructure for the mission’s payloads and other components.
In this article, we will explore the importance of satellite bus technology and how it impacts the overall success of a spacecraft mission.
What is a Satellite Bus?
A satellite bus is a fundamental component of a spacecraft that provides essential support and infrastructure. The satellite bus typically includes power systems, propulsion systems, attitude control systems, and communication systems. The payload, or scientific instruments, is integrated into the satellite bus, and the spacecraft bus is responsible for managing and controlling these instruments during the mission.
Satellite Bus Subsystems
The spacecraft bus consists of several different subsystems, each with a unique purpose. A bus typically consists of the following subsystems: Structures and mechanics subsystem (S&MS), Command and data handling (C&DH) system, Communications system and antennas, Electrical power system (EPS), Propulsion System (PS), Thermal control systems (TCS), Attitude control system (ACS), Guidance, navigation, and control (GNC) system, Structures and trusses and Life support (for crewed missions).
The Structures and mechanics subsystem (S&MS) provides the necessary mechanical structure to withstand launch loads by the launch vehicle, during orbital maneuvers, as well as loads imparted by entry into the atmosphere of earth or another planetary body. The structural subsystem consists of the primary structure of the spacecraft and supports all the spacecraft hardware, including the payload instruments. The structure, which can take various forms depending on the requirements of the particular mission, must be designed to minimize mass and still survive the severe forces exerted on it during launch and on its short trip to space.
The electrical power subsystem (EPS) provides the electrical power generation and distribution for various spacecraft subsystems. It provides power for the payload, as well as the rest of the bus. This is usually achieved through the use of solar panels that convert solar radiation into electrical current. The solar panels sometimes must be quite large, so they are hinged and folded during launch then deployed once in orbit. The subsystem also may consist of batteries for storing energy to be used when the spacecraft is in Earth’s shadow.
Another major subsystem is command and data handling, which consists of the computer “brain” that runs the spacecraft, and all the electronics that control how data is transported from component to component. All other subsystems “talk” to this subsystem by sending data back and forth through hundreds of feet of wiring carefully routed throughout the spacecraft bus.
The communications subsystem contains components such as receivers and transmitters to communicate with controllers back on Earth. Many operations the spacecraft must perform are controlled through software commands sent from Earth by radio signals.
Another important subsystem is the attitude control subsystem (ACS). This consists of specialized sensors able to look at the Earth, Sun, and stars to determine the exact position of the spacecraft and the direction in which it should point. Many operations spacecraft perform require very precise pointing, such as positioning imaging satellites that must point at specific spots on Earth. The ACS provides proper pointing directions for the satellite subsystems, such as sun pointing for EPS to the solar arrays and earth pointing for CS.
In order to adjust the orbit to maintain the spacecraft in orbit for many years, a propulsion subsystem (PS) is required. There are many types of propulsion systems, but most consist of various types of rocket thrusters, which are small engines that burn special fuel to produce thrust. The PS provides maneuvers necessary for altitude, inclination adjustment, and momentum management adjustments.
One additional crucial subsystem worth discussing is the thermal control subsystem (TCS) , which maintains the proper temperatures for the entire spacecraft bus and all its components. This is achieved through the use of small heater strips, special paints and coatings that either reflect or absorb heat from Earth and the Sun, and multi-layered insulation blankets to protect from the extreme cold of space. The TCS may also include active thermal control from electrical heaters and actuators to control temperature ranges of equipment within specific ranges.
For in-depth understanding on Spacecraft Bus technology and applications please visit: Mastering Spacecraft Bus Technology: From Mission Planning to Integration and Testing
Technology trends
The capability of combining subsystems into a compact spacecraft platform has advanced considerably. Commercial-off-the-shelf (COTS) assembled spacecraft buses enable secondary payloads on larger launch vehicles or via dedicated rideshare opportunities on a small spacecraft launcher, thus expanding the small spacecraft market. These buses provide modular platforms upon which a payload can be hosted and ready to fly in a comparatively short amount of time. Integrated platforms can be used for a wide variety of missions, and the integrated subsystems are operable in a range of environmental and mission conditions.
Two trends have emerged in the nanosatellite bus market: CubeSat component developers with a sufficiently diverse portfolio of subsystems offering package deals, and companies traditionally offering engineering services for larger bespoke platforms miniaturizing their subsystems.
Minisatellite (100 – 180 kg)
Adcole Space
The MagicBus platform is equipped with communications encryption, propulsive orbit maintenance capability, and an electro-optical imaging configuration featuring a 24 – 50 cm aperture telescope. The dimensions go up to 965 x 660 x 610 mm with a total system mass of 50 – 220 kg . The scalable payload dimensions are 221 x 190 x 99 mm to 210 x 221 x 190 mm with a total system mass of 50 – 220 kg. In collaboration with the U.S. Army Space, Missile Defense Command, and the U.S. Army Forces Strategic Command, the Kestrel Eye 1 spacecraft was based on the MagicBus platform that flew in 2017 for ten months.
University of Toronto Institute for Aerospace Studies Space Flight Laboratory (UTIAS SFL)
The Space Flight Laboratory (SFL) at the University of Toronto Institute for Aerospace Studies has extensive experience building integrated small spacecraft platforms and collecting on-orbit data for their various small satellite missions. The Nautilus (Nemo-150) bus offers up to 70 kg in payload mass and has an envelope of 600 x 600 x 600 mm. This bus also offers a separation service that provides propulsive capabilities of cold gas, resistojet, monopropulsion, and Hall Effect thrusters. This platform will be demonstrated on the nanosatellite for Earth Monitoring and Observation–High Definition (NEMO-HD) mission that is scheduled for launch with Arianespace in August 2020.
MAXAR 1300 CLASS
The world’s most popular spacecraft platform, the Maxar 1300 Class is designed to accommodate evolutionary advances in technology. This versatile platform seamlessly serves a variety of missions—from communications satellites to spacecraft for exploration. Maxar has built and launched more than 280 satellites with a combined 2,200 years of on-orbit service, and we have more than 90 1300-class satellites currently operating on orbit—more than any other company.
1300 Class features:
- lightweight, high-strength structure
- fuel-efficient attitude and station-keeping subsystems
- reliable, high-efficiency solar arrays and batteries
- advanced command and control subsystems
In March 2021, Maxar Technologies announced the delivery of the Solar Electric Propulsion (SEP) Chassis to NASA’s Jet Propulsion Laboratory (JPL) for the NASA Discovery Mission, Psyche. The SEP Chassis is based on Maxar’s 1300-class platform, the world’s most trusted spacecraft, which provided NASA the opportunity to budget, design and build the historic Psyche mission on flight-proven, commercially developed hardware.
The NASA Psyche mission is expected to launch in August 2022 to explore an asteroid orbiting between Mars and Jupiter, which is likely made largely of metal and may be core material from an early planet. The Psyche spacecraft will travel more than 1 billion miles and arrive at the asteroid in 2026, where it will spend 21 months orbiting the 140 mile-wide asteroid, mapping it and studying its properties.
The SEP Chassis built for Psyche is Maxar’s lightest and smallest graphite 1300-class spacecraft platform, roughly the size of a small car. It is combined with a medium-sized solar array, a high-gain antenna and Maxar’s latest solar electric propulsion system. The spacecraft has been specifically designed to function in a low-power environment because of the Psyche asteroid’s distance from the sun.
Microsatellites (10 – 100 kg)
AAC Clyde Space
AAC Clyde Space EPIC spacecraft platforms leverage decades of flight heritage. Available from 1U to 12U, the EPIC platform offers up to 9U in payload volume and a range of configurations. The 6U standard platforms have VHF/UHF transceiver with an in-house whip antenna, transceiver from CPUT/ETSE and a high-speed S-band transmitter with patch antenna for payload communications.
The payload volumes of the EPIC 12U and 12U PLUS are respectively 8U and 9U, a default data storage of 4GB, and 100 Mbps / 9.6 kbps data downlink and 8 Mbps / 6 kbps of uplink capability. The 6U platform was demonstrated as part of the NSLSat1 mission, which launched July 2019, and achieved mission success. The other platforms have also been flight proven.
Nanosatellites (1 – 10 kg)
Tyvak’s Trestles bus systems for CubeSats
In the early days of CubeSats, different companies specialized in developing various modular components. The idea was that the system could be built to integrate with anything developed by another company. But the technology is complicated, so the hardware didn’t always work together, and the software necessary to operate a customized system was difficult to write. So companies are adopting a vertical approach, providing full-service hardware, software, and even mission resources. This kind of all-inclusive support is an evolution that is of interest to NASA for its cost, schedule, and quality proposition while the mission team can focus more on the payload development, according to Santos.
Anyone can purchase a system and add payloads such as a camera for Earth imaging. The company also offers services to build the satellite, launch it, and manage mission operationsaccording to Marc Bell, CEO of Terran Orbital. “Nearly all Tyvak modules are manufactured in-house. This integration methodology acts as a form of risk reduction,” said Bell. This approach saves customers time and money, reduces the amount of documentation required to hitch a ride on a rocket, and mitigates potential delays in the supply chain that can disrupt a scheduled launch.
Numerous companies and government organizations use the Trestles technology – now an integral part of the company’s offering – for applications like communications activities, Earth observation, and more. Their customers can count on the successful integration of hardware such as radar systems, remote sensing imagers, telescopes, and technology demonstrations due in part to NASA’s support of the bus’ development, according to Bell.
AAC Clyde Space
The 1U and 3U EPIC nanosatellite platforms have payload volumes ranging from 0.2U – 4.5U and peak payload power from 15 W to 180 W. A ‘PLUS’ configuration for each platform is also offered that allows for more payload power and volume. The EPIC 3U bus has a VHF/UHF transceiver with an in-house whip antenna and a high-speed S-band transmitter with patch antenna; standard downlink capability is 2 Mbps and high-speed is up to 10 Mbps.
Blue Canyon Technologies
Blue Canyon’s XB3 Cubesat is its longest operating platform, continuing to provide data from the first XB3 which launched in 2016. The XB3 has continued to gain successful flight heritage on several nanosatellite missions since 2016 (e.g., RAVAN Mission, figure 2.10). The allocated payload mass is 2 kg in ~1.7U volume, and it uses in-house S-band SDR and antennas as the standard communications solution.
Blue Canyon Technologies
The full line of Blue Canyon buses provides flexibility for payloads in LEO to Geosynchronous Earth orbits, with kilowatt solar arrays on the X-SAT Saturn, and a range of propulsion options. Blue Canyon’s X-SAT Venus ESPA-class microsatellite platform has launched seven times carrying payloads from 10 to 90 kg. The X-SAT Venus carries 400 W solar arrays and optional electric propulsion for maneuvering and momentum management beyond LEO.
Blue Canyon’s XB6 and XB12 platforms have a maximum allocated payload volume of 4U and 10U respectively, and 4 kg and 8 kg payload mass. These larger cubesats and X-SAT microsats can be equipped with electric and chemical propulsion systems, have downlink capability up to 100 Mbps with in-house X-band and S-band SDR and antennas. Their platforms are compatible with UHF, S-band and X-band equipment, and have been integrated with several commercial as well as in-house radios. The XB6 has extensive flight heritage on several microsatellite missions since 2016 including Asteria, CubeRRT, HaloSat, and TEMPEST-D. The XB12 bus will be provided for two upcoming demonstrations, Link XVI and ASCENT, that are scheduled for launch in 2021.
Picosatellites
Picosatellites, also known as picosats or FemtoSats, are defined as spacecraft with a total mass of 0.1 – 1 kg. In this classification, the PocketQube has been defined as half the size of a 1U CubeSat in 5 cm3 dimensions, or 1P, where P = 1 PocketQube unit, one-eighth the volume of a CubeSat . The mass of these spacecraft vary from 0.15 – 0.28 kg and have been categorized as “1P,” “2P,” and “3P.”
Satellite Bus Market
The global satellite bus market grew from $11.22 billion in 2022 to $11.98 billion in 2023 at a compound annual growth rate (CAGR) of 6.7%. The Russia-Ukraine war disrupted the chances of global economic recovery from the COVID-19 pandemic, at least in the short term. The war between these two countries has led to economic sanctions on multiple countries, a surge in commodity prices, and supply chain disruptions, causing inflation across goods and services, and affecting many markets across the globe. The satellite bus market is expected to grow to $15.8 billion in 2027 at a CAGR of 7.2%.
The satellite bus market consists of sales of mini satellite buses, CubeSats, microsatellites, nanosatellites, and picosatellites. The main types of satellite buses include small satellites, medium satellites, and large satellites.The small satellite refers to a primary body and structural component used to hold the payload and scientific equipment in satellites weighing less than 500 kilograms.
It includes services such as leasing and maintenance and support, which are used for earth observation and meteorology, communication, scientific research and exploration, and other applications.
The increase in investment by governments & space agencies is significantly driving the growth of the satellite bus market.The government of different countries is allocating special budgets for exploration, development, testing, evaluation, procurement and operation, and conservation of satellites and associated factors.
The satellite bus market has been segmented into subsystem, application, satellite size, and region. By subsystem, the market is segregated into structures & mechanisms, thermal control, electric power system, attitude control system, propulsion, telemetry tracking command, and flight software. By application, it is segregated into earth observation & meteorology, communication, scientific research & exploration, surveillance & security, mapping, and navigation. By satellite size, it’s segregated into small, medium, and large. Region wise, the global satellite bus market has been studied across North America, Europe, Asia-Pacific and LAMEA.
Based on Satellite Size, the Satellite Bus Market can be classified into Cube Satellite [0.1 – 1 KG], Femto Satellite [0.01 – 0.1 KG], Large Satellite [2501+ KG], Medium Satellite [501 – 2500 KG], Micro Satellite [11 – 100 KG], Mini Satellite [101 – 500 KG], and Nano Satellite [1 – 10 KG].
The increasing demand for satellite applications for various purposes, such as communication, navigation, space exploration, and scientific purposes, earth observation, and experiments, is anticipated to generate demand for new satellites, which will subsequently generate demand for satellite buses. Miniaturization of electronic components enabled the creation of more lightweight and affordable satellite buses while providing the required advances in technological capabilities is anticipated to propel the growth of the market in the coming future.
The demand for smaller and more affordable satellite buses is also driving the growth of the market. Small satellite buses, also known as smallsats, have gained popularity in recent years due to their lower costs, shorter development time, and flexibility in mission planning. These satellites are commonly used for Earth observation, remote sensing, and communication applications.
Key Market Trends
Small Satellite Segment will Grow with the Highest CAGR During the Forecast Period. Recently, the number of small satellites deployed has increased due to their advantage to have similar capabilities to the conventional satellites, at a relatively smaller cost of manufacturing. Revolutionary technological advancements have facilitated the miniaturization of electronics, which has pushed the invention of smart materials, in turn, reducing the satellite size and mass over time for manufacturers. Hence, numerous space startups are being started currently, creating a market for small satellites and mini rockets, owing to the increasing pace of deployment of small satellites in the earth and celestial observation, space research, and communication applications.
For instance, companies like OneWeb, Amazon, Telesat, and SpaceX among others plan to launch more than 40,000 small satellites in the coming decade. Similarly, many new programs are in pipeline for the production and launch of small satellites for defense purposes. With growing investments into the launch of satellite constellations, the small satellite segment is anticipated to witness the highest growth during the forecast period.
Technological advancement is a key trend gaining popularity in the satellite bus market.Major companies operating in the satellite bus market are focused on bringing technological advancements in satellite buses to strengthen their position.
Some of the recently introduced technologies include electric propulsion technology, high-resolution cameras, advanced remote seeing technology, future generation GPS satellites, LIDAR technology, and others.These advanced satellite buses offer advanced payload, better visibility with advanced cameras, and reduce cost.
Some satellite bus examples include: Boeing DS&S 702, Lockheed Martin Space Systems A2100, Alphabus, INVAP ARSAT-3K, Airbus D&S, Eurostar, ISRO’s I-1K, I-2K, I-3K, I-4K, I-6K, and Indian Mini Satellite bus, NASA Ames MCSB, SSL 1300, Orbital ATK GEOStar, Mitsubishi Electric DS2000, Spacecraft Bus (JWST) (Spacecraft bus of the James Webb Space Telescope), SPUTNIX TabletSat, and SPUTNIX OrbiCraft-Pro
leading vendors and innovation profiles in the Global Satellite Bus Market including Advanced Solutions, Inc., Airbus Group, Ball Corporation, Boeing Company, Data Patterns (India) Pvt. Ltd., General Dynamics Corporation, Honeywell International Inc., Inovor Technologies, L3Harris Technologies Inc, Lockheed Martin Corporation, MAXAR Technologies Inc., Mitsubishi Electric Corporation, NanoAvionics Corp, ND SatCom GmbH, NEC Corp, Northrop Grumman Corporation, OHB SE, Raytheon Company, Sierra Nevada Corporation, Surrey Satellite Technology Limited, and Thales Group.
Importance of Satellite Bus Technology
The satellite bus is a critical component of any spacecraft mission, and its design and functionality can have a significant impact on the success of the mission. Here are some of the key reasons why satellite bus technology is crucial:
- Provides Necessary Support and Infrastructure
The satellite bus provides the necessary support and infrastructure for the spacecraft mission. It includes systems for power, propulsion, attitude control, and communication. The payload is integrated into the satellite bus, and the bus manages and controls the payload throughout the mission.
- Enables Standardization and Modularization
Satellite bus technology enables standardization and modularization of spacecraft design. By using a standard satellite bus, spacecraft manufacturers can reduce costs, improve reliability, and streamline the integration and testing process. This standardization also allows for the rapid development of new missions and the reuse of existing technology.
- Increases Mission Flexibility and Efficiency
Satellite bus technology increases mission flexibility and efficiency by providing a platform for multiple payloads and scientific instruments. This allows for the optimization of mission objectives and the efficient use of resources. It also enables the sharing of infrastructure and resources among different spacecraft missions.
- Improves Reliability and Reduces Risk
Satellite bus technology plays a crucial role in improving spacecraft reliability and reducing risk. The satellite bus includes redundant systems and backup mechanisms, which ensure that the spacecraft can continue to operate even in the event of a failure or malfunction. This redundancy and backup capability reduce the risk of mission failure and increase the chances of mission success.
- Enables Future Technology Advancements
Satellite bus technology enables the integration of new technologies and advancements, such as artificial intelligence and robotics, into spacecraft design. This allows for the development of more capable and advanced spacecraft, which can support more complex missions and scientific objectives.
Conclusion
The satellite bus is a critical component of any spacecraft mission, and its design and functionality can have a significant impact on the success of the mission. The importance of satellite bus technology cannot be overstated, as it determines the spacecraft’s capabilities, performance, and longevity.
Satellite bus technology provides necessary support and infrastructure, enables standardization and modularization, increases mission flexibility and efficiency, improves reliability and reduces risk, and enables future technology advancements. By understanding the importance of satellite bus technology, spacecraft manufacturers and mission planners can optimize mission objectives and improve the chances of mission success.
As the demand for satellite-based services continues to grow, the satellite bus market is expected to expand, providing new opportunities for innovation, collaboration, and growth in the space industry.
References and Resources also include:
https://www.nasa.gov/smallsat-institute/sst-soa-2020/complete-spacecraft-platforms
