As Intelsat’s Galaxy 15 satellite began to drift out of control along the geostationary-orbit arc in April, the satellite telecommunications industry itself entered into uncharted territory. Although Galaxy 15 is not responding to commands sent by Intelsat controllers, its C-band transponders remain active, giving it the potential to wreak radio-frequency havoc with other C-band satellites along its drift path, beginning with SES’s AMC-11. Industry officials say the situation is unprecedented.
To its credit, Intelsat appears to have pulled out all the stops to rein in the wayward craft, including taking the drastic step May 3 of attempting to shut down its transponders with an overwhelming radio-frequency blast from the ground. But so far, nothing has worked.
Intelsat also has kept SES apprised of the situation and coordinated closely with its competitor in devising interference mitigation plans. This consultation likely has required the sharing of proprietary technical data that companies, particularly rivals like Intelsat and SES, normally would prefer to keep close to the vest.
Although it is difficult to see anything good in the apparent loss of an expensive orbital asset and the threat of interference it now poses — Intelsat’s own satellites are next in the path of Galaxy 15’s eastward drift — the situation could have been worse. Galaxy 15 is a classic C-band fixed-satellite services platform, used mainly for delivering television programming to cable head ends — ground stations that receive and retransmit video over local cable networks. If Intelsat or SES has to move a satellite or redirect C-band transmissions to avoid interference, this can be accommodated much more easily on the ground than would be the case if the stricken satellite were, for example, a Ku-band direct-broadcast platform delivering programming directly to consumer households via small-dish antennas mounted on rooftops.
Secondly, if any two satellite companies have the wherewithal to manage a problem like this, they are Intelsat and SES, the world’s two biggest fleet operators. Both companies have cash resources and a wealth of experience and engineering talent, and keep plenty of spare capacity on orbit. Shortly after losing control of Galaxy 15, Intelsat was able to move another satellite to the failed craft’s operating location to take on the customers that otherwise could have suffered service outages. As Galaxy 15 passes through AMC-11’s orbital neighborhood, meanwhile, SES, in addition to maneuvering its satellite, should be able to reroute customer traffic over one or more of its ground teleports to avoid or minimize disruptions.
Fortunately, Intelsat and SES recognize the importance of working together, even if that means sharing data about their respective satellite systems that might be considered proprietary. It is worth noting that Intelsat and SES, along with mobile satellite services operator Inmarsat, are the founding members of the Space Data Association, a data-sharing cooperative that is representative of what industry needs to be doing to be a good steward of the orbital environment. The Galaxy 15 situation as it now stands might look completely different if it involved operators less willing to share information.
Finally, the fact that beyond AMC-11, Intelsat’s own satellites lie in the path of Galaxy 15 is a bit of good luck; although a problem for Intelsat, it is less of a problem than would be the case if other operators were involved. By the time Galaxy 15 passes through this Intelsat orbital neighborhood, it likely will have exhausted its power and thus no longer pose an interference hazard.
What this episode demonstrates, in addition to the fact that technology can never be considered infallible — something like this was bound to happen sooner or later — is that the geostationary-orbit arc and satellite broadcast frequencies are shared and finite resources. The more closely satellite operators, both commercial and government, are willing to work together, the more likely it is that incidents such as this can be managed with minimal damage.
