2.9 Spacecraft Reliability
2.9.1 Requirements
Exhibit B
The reliability requirements for the spacecraft are defined as follows.
The spacecraft design is such that the probability of successfully being placed on station and oriented in the proper operational attitude, assuming successful launch and separation and allowing for up to 12 transfer orbits, shall exceed 0.95.
a
The spacecraft design life, electrical power capability and fuel shall Or the minimum of 9 years at either the 105.5° E permit operation for
It has been taken into consideration that the 116° E orbital locations. solar array has undergone degradation due to its previous orbital exposure.
2.9.2 General Conditions
The following general conditions shall be applied in the reliability assessment of the system based upon contractor compliance, where applicable, in the spacecraft design:
1) Any constraints placed on the operation of the spacecraft in orbit shall allow it to operate within the performance requirements
2)
specified.
To reduce the impact of a single part or unit failure in the system more of the communications that could cause loss of 50 percent or channels, the principle of redundancy or alternative operational modes shall be applied.
3)
to
Parts shall be protected against the expected radiation environment to maintain required
the specified spacecraft the extent performance for at least 9 years.
2.10 In-Orbit Standby
in a standby The spacecraft shall be capable of being maintained condition
its ability to perform within in orbit without degradation of its ability to specification within the 9 year mission fuel life after launch.
2.11
On-Ground Storage
The spacecraft (with the exception of batteries and the AKM) shall be capable of operating to the requirements of this specification after being in storage for up to 5 years in an environment controlled to a temperature range of 70°F 15° with humidity not to exceed 55 percent.
2.12 Lifetime
2.12.1 Design Life
The spacecraft
inherent
including design,
identifiable
wearout
mechanisms and excluding fuel capacity, shall ensure that it will continue to operate on station for a minimum design life of ten (10) years.
L.
B-4