It will be necessary to replace it with a spareunit.
有必要用一个备用部件来替换它。
2
For the STS-133 mission, Discovery carried supplies, spare parts, and the Permanent Multipurpose Module, a storage unit that's the final piece of the International Space Station.
On the base of the research of spare fill rate, we established mission availability models of multi combat unit when order and logical relation of mission is full collateral and parallel.