308
9 OBDH Technology of Lunar Lander
(3) The data bus was used to realize data transmission between the terminals so
as to reduce the internal harness of spacecraft, and make spacecraft integrated
with separate modules and tested as separate modules.
(4) The real-time multi-task operating system was used to support the parallel
structure of multi process software. It had the characteristics of layered structure and modularization. It was easy to cut, expand, reuse, and easy to maintain
running on orbit, while following the open and rolling design guidelines.
(5) The use of data bus (sometimes multi-layer data bus or computer network)
provided channels for information exchange between subsystems, which could
not only facilitate the rapid exchange of large amounts of information between
subsystems, but also provide the interaction support between computers and
between ground station and spacecraft.
(6) The OBDH subsystem could support all level tests from component, software
and subsystems to the spacecraft system as a comprehensive system.
(7) Targeting at light-weight design of the lunar lander, on the basis of reliability,
comprehensive methods were taken from various aspects, such as function
integration of equipment, selection of parts and components, selection of shell
material, design of shell, internal and external connectors, so as to achieve
miniaturization requirements.
9.4.2 System Architecture and Configuration
The architecture of OBDH subsystem was up to the size and complexity of the spacecraft, mission, orbit, lifetime, survivability, function and performance requirements of
TT&C, support for other subsystems, other additional requirements such as number
and distribution of TT&C channels, information exchanged and date rate between
subsystems and parts, design constraints such as lifetime and corresponding radiation resistance and reliability, safety requirements, constraints of volume, mass and
power consumption. The scale and complexity of OBDH subsystem was determined
by all above factors.
The bus in the distributed architecture connected all the processor units with a
common data bus (or network). Compared with other distributed architectures, it had
many advantages such as modularity, easy extension, fault tolerance and simplicity.
It was currently widely used in spacecraft electronic systems.
A typical diagram of integrated electronic system based on bus structure is shown
in Fig. 9.1.
The system network was composed of a middle/low speed serial data bus and the
terminals connected to the bus to realize allocation of uplink tele-commands, control
of spacecraft, onboard time generation and management, the collection, packaging
and formatting of telemetry data, and sending to ground station. At the same time,
it supported handling of failure and emergency. In addition, the platform data was
transmitted to the multiplexer through the low speed data bus. The communication
network was composed of high speed data interface, payloads, data multiplexer,
9 OBDH Technology of Lunar Lander
(3) The data bus was used to realize data transmission between the terminals so
as to reduce the internal harness of spacecraft, and make spacecraft integrated
with separate modules and tested as separate modules.
(4) The real-time multi-task operating system was used to support the parallel
structure of multi process software. It had the characteristics of layered structure and modularization. It was easy to cut, expand, reuse, and easy to maintain
running on orbit, while following the open and rolling design guidelines.
(5) The use of data bus (sometimes multi-layer data bus or computer network)
provided channels for information exchange between subsystems, which could
not only facilitate the rapid exchange of large amounts of information between
subsystems, but also provide the interaction support between computers and
between ground station and spacecraft.
(6) The OBDH subsystem could support all level tests from component, software
and subsystems to the spacecraft system as a comprehensive system.
(7) Targeting at light-weight design of the lunar lander, on the basis of reliability,
comprehensive methods were taken from various aspects, such as function
integration of equipment, selection of parts and components, selection of shell
material, design of shell, internal and external connectors, so as to achieve
miniaturization requirements.
9.4.2 System Architecture and Configuration
The architecture of OBDH subsystem was up to the size and complexity of the spacecraft, mission, orbit, lifetime, survivability, function and performance requirements of
TT&C, support for other subsystems, other additional requirements such as number
and distribution of TT&C channels, information exchanged and date rate between
subsystems and parts, design constraints such as lifetime and corresponding radiation resistance and reliability, safety requirements, constraints of volume, mass and
power consumption. The scale and complexity of OBDH subsystem was determined
by all above factors.
The bus in the distributed architecture connected all the processor units with a
common data bus (or network). Compared with other distributed architectures, it had
many advantages such as modularity, easy extension, fault tolerance and simplicity.
It was currently widely used in spacecraft electronic systems.
A typical diagram of integrated electronic system based on bus structure is shown
in Fig. 9.1.
The system network was composed of a middle/low speed serial data bus and the
terminals connected to the bus to realize allocation of uplink tele-commands, control
of spacecraft, onboard time generation and management, the collection, packaging
and formatting of telemetry data, and sending to ground station. At the same time,
it supported handling of failure and emergency. In addition, the platform data was
transmitted to the multiplexer through the low speed data bus. The communication
network was composed of high speed data interface, payloads, data multiplexer,