The power system is one of the fundamental systems required to operate any spacecraft. Many satellite engineers, who work on other systems, tend to take spacecraft power for granted. However, there have been many instances in which a mission is suddenly interrupted or terminated due to a loss of power. One case in point occurred last year - the power system failure of Amazonas 4A communications satellite.

This satellite experienced a power subsystem anomaly within three weeks of its launch, effectively reducing its communications capacity by 50%. Orbital Sciences built the satellite for Hispasat of Madrid, Spain, and launched it on March 22, 2014. It reached geostationary orbit shortly thereafter. It was supposed to enter full service by mid-year, but Hispasat detected the problem by mid-April. A few days later the anomaly was described as a "partial electrical system failure."

The planned useful lifetime was 15 years. Although the anomaly did not end the mission, if uncorrected it will cut the operational capacity in half. Fortunately, Hispasat had insurance that assured minimal economic impact on the company.

Amazonas 4A carries 24 Ku-band transponders to broadcast high-definition television over South America. Its weight at liftoff was nearly 6,500 pounds. Officials had hoped to have the satellite in service by June to increase communications capacity for the 2014 World Cup in Brazil. Hispasat did have contingency plans in place to avoid any disruption of service.

Orbital narrowed the problem to one of two highly likely causes of failure. One was specific to the Amazonas 4A satellite and one involved a well-known component with extensive flight heritage. In either case the cause was not characterized as potentially systemic to Orbital's product lines.

In summary, the problem was identified as a failed power subsystem. Clearly, there is much to be learned about the technology and design of spacecraft power systems. For space professionals who are involved in designing, developing, fabricating and testing spacecraft power systems, Launchspace offers an on-site focused three-day course, "Spacecraft Power System Design and Analysis."