Concept:The commissioning phase of a satellite is the period after launch when all systems are tested and calibrated before full scientific operations begin.
Explanation:For NISAR, the commissioning phase starts 1 year after launch.
This extra time is needed because NISAR has a complex dual-frequency radar (L-band and S-band) that requires thorough calibration and validation.
Immediately after launch, only basic health checks and orbit stabilisation happen.
After ~90 days, initial calibration may occur but not full commissioning.
After 6 months, some systems are still being fine-tuned.
Therefore, the correct timeline is after 1 year post-launch.
Answer:After 1 year (Option C)