Separate mission endings and data life

SANSA’s December 2021 account dates the last primary-function data to 14 September 2011 and describes later engineering telemetry. Its February 2022 retrospective confirms atmospheric reentry on 10 December 2021. These are different milestones. A voltage measurement received after routine imaging ended does not establish that the main camera service continued for the same duration.

Other summaries use different image counts or rounded operating durations. SANSA’s later retrospective specifically counts 1,128 usable images. A downloaded frame count, usable-scene count and catalogue-item count need not be identical. Before comparing totals, identify what each source counted. Likewise, an earlier component-damage date and a later final-data date can describe separate events rather than competing answers to one question.

NASA distinguishes cumulative radiation effects from single-event effects in electronics. Total ionizing dose can gradually change device behavior; displacement damage affects the semiconductor material. A single particle passing through a sensitive region can cause an upset or permanent damage. These categories are not simply “low energy is temporary” and “high energy is destructive.” Orbit, parts and circuit design all matter.

Error correction can help recover particular corrupted memory values, and a reset can recover some interrupted states. Neither repairs every damaged component. Redundancy helps only when the backup remains available and the switching arrangement works; a shared vulnerable supply can affect both paths. These are general engineering principles, not a claim that a particular unreported remedy would have saved SumbandilaSat. A reliable failure account needs device and operating evidence.

Record different mission lifetimes

The agency describes later telemetry used to study components and support command-link and ground-operation development. Such records can inform engineering even after a primary imaging service stops. SANSA also lists historical Sumbandila observations in its Earth-observation portfolio. An archive entry indicates preserved material, not a satellite still acquiring new scenes.

An old image can support a new study when its date, processing history and limitations fit the question. Reprocessing may improve calibration or mapping while leaving the original observation date unchanged. A repository update is not a new spacecraft measurement. Preserve the observation, its provenance and the methods used to interpret it: those are the parts of the mission that later researchers can continue to test.