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To: Jeff Vayda who wrote (3139)	2/26/1999 1:31:00 PM
From: blue_lotus	Respond to of 29987

'Why use a Iridium phone to call somebody, when it is cheaper to just fly there and talk to them in person.....' Date: Friday, February 26, 1999 Source: Financial Times, London Ed1 Financial Times, London Ed1 via NewsEdge Corporation : Tough talking Talking of mobiles, why bother to phone when it's as cheap to fly? The thought clearly never struck one of the first users of an Iridium phone, the hand-held mobile that can be used everywhere from the South Pole to the Sahara. The busy businessman hired the phone to go on holiday to Scotland, but on his return was gobsmacked to find he'd run up a phone bill for {GBP}6,000. Iridium calls cost between {GBP}3 and {GBP}5 a minute - and the executive had been on the blower for around 25 hours. "Not much of a holiday," mused Ed Staiano, Iridium chairman, recounting the story yesterday as he revealed that his company is about to begin talks with bankers over why so few have taken the Iridium service. Observer can't imagine why. Copyright Financial Times Limited 1999. All Rights Reserved. <<Financial Times, London Ed1 -- 02-26-99, p. 15>>

To: Jeff Vayda who wrote (3139)	2/26/1999 1:52:00 PM
From: Mr. Adrenaline	Respond to of 29987

That's a good question. There are essentially two things that will limit a satellites lifetime: fuel and mechanical wear out. You correctly stated that the satellites were designed to have a "expected" lifetime of 7.5 years. From both a fuel and mechanical wear out perspective. But all launch vehicles are not created equal. For the worst case launch injection, they have 7.5 years worth of fuel, but other launches a lot more. The "worst case launch injection" is the Soyuz and the Zenit. Both those vehicles were originally spec'ed to inject at an altitude of 900 km. So, if the G* satellites had been injected into a 900 km orbit with full tanks, they would then have 7.5 years of fuel left. But the Delta missions (the first 8) dropped them off at 1250 km, so they have a lot more fuel than 7.5 years worth -- a LOT more. Like 20+ years. They Soyuz, as it turns out, can actually do a tad better 900 km (920) so they will have a bit more fuel than 7.5 years worth. The mechanical design life is still 7.5 years, but that limit is a lot harder to predict. Quite often, the mechanisms go a lot longer than expected, but taken as a constellation average, the satellites are "expected" to last at least 7.5 years. There are numbers to the probabilities and expectations, but, I think you get the idea. Mr A