Anik‐E1 and E2 satellite failures of January 1994 revisited

Abstract

The consecutive failures of the geosynchronous Anik‐E1 communication satellite on January 20, 1994, and Anik‐E2 about nine hours later on January 21 (both incidents occurred on January 20 local time) received considerable publicity because the malfunctions of the satellites disrupted television and computer data transmissions across Canada, as well as telephone services to remote northern communities for hours. This often‐cited event is revisited here with materials not covered before. Using publicly available information, Anik‐E failure details, media coverage, recovery effort and cost incurred are first presented. This is then followed by scrutiny of space weather conditions pertinent to the occurrences of the Anik‐E upsets. We trace the space weather episode's inception on the Sun, propagation through interplanetary medium, and manifestation in magnetic field variations as well as in energetic electron flux increases, and its eventual impact on the Anik‐Es. The genesis of the energetic electron enhancements that have been blamed for the satellite malfunctions is thus traceable via high‐speed solar wind stream with Alfven wave fluctuations to a longitudinally wide coronal hole on the Sun. Furthermore, strong magnetic pulsations preceding electron flux peaks indicate Pc5 ULF (Ultra Low Frequency) waves as a probable acceleration mechanism for the energetic electron flux enhancement that resulted in the internal charging of the Anik‐Es. The magnetic fluctuations may even be possible triggers for the subsequent discharge that caused the satellites to malfunction. This incident illustrates that satellite operators should be on alert for elevated high‐energy electron environment that is above established thresholds, as specifications in satellite design may not render a satellite immune from internal charging.

On the predictive potential of Pc5 ULF waves to forecast relativistic electrons based on their relationships over two solar cycles

“…It was located at 80°W in January 1989 and at 119°W in January 1995, with a westward transition in between. It is of interest to note that by a fortuitous coincidence, GOES 7 happened to be located at 112°W in the proximity of Anik‐E1 (111.1°W) and Anik‐E2 (107.3°W) around the times of the Anik‐E failures in January 1994, rendering its in situ measurements beneficial to the Anik‐E failure study [ Lam et al ., ]. For the other GOESs, GOES 8 and GOES 12 were on the GOES East slot, while GOES 9 as well as GOES 11 were on the GOES‐West slot.…”

“…The short time delay can also be seen in the study by Lam et al . [] on Anik‐E satellite failures of January 1994 as it shows strong enhancements in relativistic electron flux a few hours after large increases in hourly Pc5 power. (The overall daily fluence for the high‐flux days for the Anik‐E event was at the extremely high fluence level of 10 9 .)…”

“…Relativistic electrons with energies >2 MeV measured at geosynchronous orbit (6.6 R E ) have been a subject of great interest not only because of their intrinsic scientific value but also because of their practical importance [ Baker et al ., ; Lanzerotti , ; Pilipenko et al ., ; Bodeau , ; Lam et al ., ], which arises from the fact that “swarms” of such electrons can put geostationary communication satellites at risk. Such relativistic electrons can result in the internal charging of satellites that leads to electrostatic discharge (ESD) [ Wrenn , ].…”

“…ESD not only causes satellite operational anomalies, which are a nuisance to satellite operators, but can also damage electronics and cause complete impairment of a satellite [ Lohmeyer et al ., ]. A notable example of satellite damage due to ESD is the consecutive outages of Telesat Canada's Anik‐E1 and Anik‐E2 geostationary communication satellites on 20 January 1994 that interrupted telecommunication and data transmission services across Canada for hours [ Lam et al ., ]. It is therefore prudent to pursue studies related to relativistic electron flux enhancements in order to help alleviate the space weather impacts of such events.…”

Realistic Worst Case for a Severe Space Weather Event Driven by a Fast Solar Wind Stream

“…These events pose a risk of satellite damage due to ESD as a result of internal satellite charging. For example, Intelsat K, Anik E1, and Anik E2 experienced anomalies on 20 January 1994 associated with a sustained high flux of relativistic electrons at geostationary orbit during a fast solar wind stream event (Baker, ; Lam et al, ). Fast solar wind streams also have the potential to disrupt ground‐based systems such as power grids since they cause multiple substorms.…”