Smallsats are satellites that have a mass of 500 kg or less. They have many possible points of failure. Smallsats typically have dozens of microprocessors and related electronic circuitry. These components are used to control power management, solar cell operation, attitude control, telemetry, antennae pointing, propulsion systems, star trackers, sun sensors, earth sensors, cameras, and telescopes. A malfunction in any one of these systems can cause a smallsat to fail or partially fail so that only part of the mission can be completed. Considering the fact that most smallsats do not use radiation hardened electronic components, smallsat failure is not a rare occurrence.
The determination of the smallsat failure rate is not as straightforward as the launch vehicle failure rate. Whereas launch failures are difficult to hide, smallsat mission failure can be kept more private. For one thing, many organizations who desire to report mission successes through the publication of papers, don’t often treat mission failures in same way. Educational institutions in particular have a tendency to declare inoperative smallsats to be successful because they served to educate the students who built them. While that is a legitimate point of view, it obscures the answer to the question of how many smallsats fail to achieve their intended mission objectives.
Smallsats are classified as Successful Mission, Partial Mission Failure, or Mission Failure. Definitions are described below:
SUCCESSFUL MISSION: Smallsats are classified as successful missions as long as they transmitted the data for the intended life of their missions.
PARTIAL MISSION FAILURE: Smallsats experiencing component failures that prevent some objectives from being achieved are in this category. Smallsats that fail to operate after having operated successfully for a short period are in this category. For example, a smallsat may begin successful operations but then experience a failure of the power system after only a few hours or days. Whether or not that represents a mission failure or a partial mission failure depends on what objectives the smallsat was able to achieve before it stopped working.
MISSION FAILURE. These are the smallsats that failed to operate
altogether or completed very little of their stated mission objectives. Educational smallsats that achieve successful orbit but fail to transmit any signals are considered to be in this category. Even though the mission to “teach students lessons about smallsats” may have been achieved, the smallsats are electrically dead. Similarly, smallsats which only emit a beacon signal are considered mission failures unless that happened to be the only mission objective.
What the Data Says
Between the years of 2000 to 2016, 41.3% of all smallsats launched experienced total or partial mission failure. Of these, 6.1% were launch vehicle failures, 11% were partial mission failures, and 24.2% were total mission failures.
The smallsats failure data showed an increase in the failure rate with increased yearly launch rate.
The period 2000 to 2008 averaged 15 launches per year, for which an average of 28.6% of the smallsat missions failed or partially failed.
The period from 2009 to 2016 averaged 48 launches per year, for which an average of 42.6% of the smallsat missions failed or partially failed.
The launch vehicle failure rate for both periods adds another 6.1% to each period. This means that in 2009 to 2016, nearly one in two smallsats launched resulted in either total or partial mission failure.
If the partial mission failures are counted as successful, the failure rate is reduced, but only to 38.2% for the period 2009 to 2016.
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