PARIS — Iridium Satellite LLC Chairman Matt Desch said the company has been assured by independent technical consultants that the current Iridium constellation will stay healthy until 2013-2014, in time to begin launching a second-generation system.
Addressing a topic that has long been a subject of debate among satellite-industry specialists, Desch said the current constellation — 66 operational satellites and nine in-orbit spares — has been managed to husband resources and use software uploads to minimize the effects of component failure.
“Let me give just one example of what we did when we had issues with the satellites’ momentum wheels, which keep the spacecraft stable,” Desch said in a Feb. 16 interview. “We found a way to use the surplus of fuel on the Iridium satellites to compensate for momentum-wheel failure. We use short firings of the motor, and thank God Motorola had put so much more fuel than needed into these spacecraft.”
The Iridium satellites, launched into low Earth orbit between 1997 and 1999, were designed by Motorola to operate for five years in a near-polar orbit of about 780 kilometers in altitude.
When Motorola left Iridium, Desch said, some of the engineers most familiar with the system moved to Boeing Satellite Operations and Ground Systems of Leesburg, Va., to manage the constellation.
Desch said one change that was made in operations has been to switch off some of the satellites as they fly over the North and South poles, regions of low utilization and high concentrations of daily satellite passes. This saves fuel and wear on some components with virtually no effect on customers. “It’s one of many things we have been able to do. Motorola also designed the satellite software to be very upgradable, and we have taken advantage of that.”
Iridium competitor Globalstar of Milpitas, Calif., announced in early February that the Globalstar spacecraft appear to be degrading more quickly than expected in orbit under the daily exposure to high radiation levels at Globalstar’s operating altitude of around 1,414 kilometers.
Desch said Iridium’s orbit exposes its satellites to one-tenth the Globalstar radiation doses and helps explain why the company is in no rush to contract a second-generation system.
The constellation continues to deliver better than 99 percent call-completion rates, Desch said. Iridium on Feb. 15 introduced a service guarantee for new subscribers, offering to issue credits if a customer encounters uncompleted or dropped calls or gaps in coverage.
The company has begun canvassing possible future users of a second-generation Iridium system, including those interested in what a 66-satellite constellation might provide in terms of low-resolution Earth observation, weather monitoring and satellite navigation to supplement the U.S. GPS network in medium-Earth orbit.
Desch said no decisions have been made on a payload suite for the second generation, and the company is talking with several potential satellite manufacturers.
He said one decision on the second-generation system has been made: Its architecture of 60-odd satellites in low orbit, connected by intersatellite links to reduce the need for an elaborate network of ground gateways, will be maintained for the second generation.
“Part of the reason is backward compatibility, to assure continuity for users between the first and second generations,” Desch said. “Part of it is because we have begun to find all these new communities that think they can make real use of a global constellation like ours.”
Bethesda, Md.-based Iridium on Feb. 14 reported that as of Dec. 31, 2006, it had 175,000 subscribers, a 23 percent increase over a year earlier. Subscribers in 2005 had also increased by about 23 percent.
Revenues for 2006 were $212.4 million, with EBITDA, or earnings before interest, taxes, depreciation and amortization, at $53.9 million, or 25 percent of revenues.
Iridium said 2006 was its second straight year of profitable operations. It did not report specific 2005 financial results, but said 2005 revenue represented a 55 percent increase over 2004.