Northern Sky Research

Building Satellites amidst the TWTA Bottleneck

Jul 20th, 2011

Ideally an operator would like to have a satellite go from RFP to orbit in 25 to 30 months. However, the reality is that manufacturing satellites is far from an assembly line operation where every component is sourced with sufficient inventory support. Often the equipment onboard the satellite is highly specialized and vendors are few, which put constraints on delivery and in effect, time to market for satellite services.

So what issues keep satellite manufacturers up at night?

Undoubtedly, the most recurring theme when NSR spoke with satellite manufacturers, for the Global Satellite Manufacturing and Launch Markets study, was the issue of TWTA supply. Industry insiders were quick to point out that TWTAs are the first item to be ordered as soon as a contract is signed. Despite this, they can result in an extension to the manufacturing time by as much as 6 months.

Manufacturers also acknowledge that maintaining at least two suppliers for TWTAs (or any space-grade component) is required to ensure timely delivery. However, it seems that the likes of Boeing, Loral, Astrium, Lockheed and others often end up with longer manufacturing times at the bidding stage because of bottlenecks with the limited suppliers. A delay in closing the RFP process by a satellite operator results in a delayed order of these components and, subsequently, a delay in their arrival and integration. The issue takes on lesser importance for those manufacturers that focus on Government satellites or Earth Observation and Scientific missions as the requirements of their communication payloads are fairly straightforward. However, those looking at making an entry into the commercial GEO satellite manufacturing market recognize TWTA delays as an important item on the “critical path” that needs to be kept in check.



As communication satellites move from the traditional bent-pipe to the next generation of High Throughput Satellites (HTS), the issues become even more exaggerated as hundreds of TWTAs are required for the many spot beams that characterize such systems. Supply becomes scarce even as operators move from Ku-band to Ka-band as tubes for the latter are even more limited in supply. All this put together has kept Ka-band DTH satellites in the factory longer than initially anticipated.

Isn’t this too trivial an issue to be worried about?

Typically when a satellite is ordered, completing the beam patterns and thereby the antenna design is critical. Antennas are custom made, and a production lead time of 12 to 15 months is clearly a function of the design. TWTAs (on the other hand) are a function of demand and supply for a system that on-the-ground has long been replaced by solid state devices. Finally, manufacturers also have a host of other issues, not the least of which is factories that are typically overburdened with orders and a supply chain often distributed both politically and geographically.

Bottom Line
As with many aspects of the satellite manufacturing business, tubes can be termed a somewhat out-dated technology given that the terrestrial world has moved to solid state devices. The handful of space qualified tube manufacturers are also under pressure because this is not a volume business and hence cannot be a part of inventory. As a result, this natural bottleneck will continue to be passed on to the satellite operator for whom it becomes critical to close the RFP at the earliest. However, with satellite design driven increasingly by market forces and last-minute changes becoming commonplace, it seems like the issue of TWTAs will end up being just another challenge the industry will have to live with.

Information for this article was extracted from NSR's report Global Satellite Manufacturing and Launch Markets