The Spacecraft Bus for Webb

While telescopes and science instruments often grab headlines when spacecraft are launched, it is actually the bus that keeps it in orbit. Northrop Grumman mechanical design team employed creative design thinking techniques to construct Webb’s bus.

Rocket Lab’s small satellite bus solutions – Lightning and MAC-200 – are agile and versatile, featuring flight proven redundancies for mission critical subsystems.

It is a network of wires

Command, Control and Communication Architecture is an essential link between your mission operations and spacecraft. It consists of wired or wireless connections that transmit spacecraft signals between their spacecraft and mission control centers; as well as a communications subsystem responsible for collecting sensor and actuator data acquisition. However, such subsystems need significant power consumption as well as protection from radiation.

The Spacecraft Bus is a carbon fiber box which contains most of the major systems required for functioning of JWST telescope. Designed to last 12+ years in LEO with redundancies built-in for critical subsystems. Six modules mounted within an adjustable titanium frame resemble computer cards in terms of stackable frame architecture; all communicate via “SpaceWire.”

SmallSat market provides various spacecraft bus options that can be configured to meet the requirements of any particular mission. Some offer standard architecture and established interfaces for payloads; however, these may be less flexible than a custom designed spacecraft design.

It is a control system

The spacecraft bus is the primary control system that supports and carries the payload for satellites. It transmits command data to other subsystems while receiving telemetry data from them for downlink to ground/space-based communications antennas, senses changes in spacecraft orientation/stabilization, manages internal temperature using small heater strips, as well as reflect or absorb radiation from Sun and Earth radiation sources.

James Webb telescope engineers faced one of their greatest design challenges when creating its cryogenic cooler that cools the Science Instruments to very cold temperatures. To meet this objective, they utilized novel design thinking such as using heat pipes as structural support and insulation for this system.

Rocket Lab provides two comprehensive spacecraft bus solutions for small satellite missions – the microsatellite-class MAC-100 and nanosatellite-class MAC-200 platforms, carefully designed and tested to deliver maximum reliability and optimal mission performance, both of which include redundancies for critical systems.

It is a communication system

Spacecraft buses are systems used to transfer data and commands between all the components in a satellite, usually via controller area network (CAN). CAN has proven itself effective over three decades in harsh environments; its multi-master/multi-drop topology minimizes wiring requirements for communication purposes.

Many suppliers provide flight-qualified spacecraft buses, which can be customized for a specific mission and reduce overall costs, accelerate launch schedules and enhance design flexibility. Furthermore, using such systems can decrease data storage requirements on board.

Recent advances in satellite application technology have been driven by advances in spacecraft bus technology. These advances include precisely-oriented body-stabilized platforms capable of hosting high gain communications antennas, advanced Earth observation sensors and navigational payloads. For instance, one such groundbreaking spacecraft bus technology is the nano-class nDragonfly Bus which leverages validated avionics components for state of the art performance and reliability.

It is a power system

Spacecraft busses are standardized frames used to support satellite payloads and primary systems during launch and space conditions, including stresses associated with launch as well as power, attitude control and onboard data handling systems, communications channels and power supplies.

The power subsystem generates, stores, and distributes electrical energy. It relies on solar panels to convert sunlight into electricity for storage in batteries for times when solar panels don’t get direct sunlight; additionally it includes radiators and cryogenic coolers to maintain ideal bus and payload temperatures.

The Command and Data Handling system serves as both the “brains” of a satellite, as well as all associated electronics that ensure information flows smoothly from component to component. It receives and sends commands from ground control as well as monitors the status of its orbital mission, while controlling operation of Science Instrument sensors within telescope.