Sat-ND, 18.10.1997 Well... how did I get here?
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DELAY OF THE DAY
Ariane 5: Anomaly detected, launch delayed
Some kind of take-over
Wired's trip to space
Wired or weird?
And here is the result of the Ariane 502 qualification assessment meeting I mentioned yesterday: the second launch of the new Ariane 5 rocket will not take place on October 28 as planned.
The French and European Space Agencies, CNES and ESA, said in a joint statement that "An anomaly has been identified on the Ariane launchers for flights 503 and 504 currently undergoing integration at Aerospatiale, Les Mureaux, France. The items concerned are the mountings of the Vulcain engine supply lines. It has therefore been decided to check the same items on the 502 launcher."
That will take some time, and so a new target launch date will be set during the course of next week. It is currently estimated that the delay will be a few days to a week. "The other actions under way have given satisfactory results," CNES and ESA said.
Yesterday I reported about speculations of an Internet news service that said "the most logical buyout has yet to come: A Hughes Electronics takeover of even more troubled AT&T."
Funny the Los Angeles Times today reports that "AT & T Corp. is expected to announce Monday that Los Angeles aerospace executive C. Michael Armstrong of Hughes Electronics Corp. will become its chief executive." Is that some kind of take-over, too?
For those interested: if you hurry, you can get the full story at http://www.latimes.com/HOME/NEWS/STATE/topstory.html
Over the past few months, Sat-ND has deliberately been trying to confuse you by reporting on a plethora of new satellite systems. Wired will de-confuse you. Will they?
Called Teledesic, Celestri, SkyBridge, Globalstar etc., they'll use different orbits and different technology. Their least common denominator is the provision of all kinds or wireless communications services such as Teledesic's "Internet in the sky."
Over the past four days, several interesting articles were published, which also cover related topics such as rivalling systems, satellite glitches, upcoming launch service providers, and space junk.
Wired describes Teledesic (in which billionaires Bill Gates and Craig McCaw hold a 30.1 percent stake respectively) as the upcoming major player of the satellite business: "the company is dictating the course this new global communications business will follow even before Teledesic launches its first satellite." True? Let's see.
First of all, ask yourself the question why Teledesic has to launch the record number of 266 satellites to get the complete system up and running (originally, thrice as many were planned before Boeing, Teledesic prime contractor and 10-percent shareholder, came up with a better solution.) No competitor needs either that vast number of spacecraft or the trifle of US$9 billion to build 'em and get 'em all up.
The enormous amount satellites needed for the Teledesic system arises from technical parameters such as the Low Earth orbit (LEO) and the frequency range used. Teledesic will utilise the Ka-band, meaning that uplink will take place in the range of 30 GHz, downlink at 20 GHz simply because that's where sufficient adjacent chunks of the frequency spectrum were still available for licensing a broadband service.
Low orbits, high frequencies
Even a Low Earth orbit does not exclude the influence of the atmosphere that tends to distort and diminish signals sent and received at such high frequencies. As a consequence, any signal will have to take the shortest path to a ground station in order to be received properly.
This is only the case when a satellite is visible at a high elevation angle, which means it's almost directly overhead but for each satellite, that's the case for just a short period of time. What's more, the Teledesic system layout calls for two satellites accessible for any user within the system's reach at any time.
"By being first to the punch, Teledesic has virtual reign over 500 MHz of Ka-band spectrum worldwide," says Wired true, but exactly because of that they also have to set up the largest satellite fleet ever at a record cost of US$9 billion. To my knowledge, the whole system still has to be financed somehow.
Besides, more advanced satellite systems utilising the Ka-band will rely on combinations of LEO and geostationary Earth orbits (GEO.) Teledesic propaganda to the effect that GEO satellites would be incapable of providing fast access to the World Wide Web, let alone other high-speed multimedia applications, has meanwhile been proven wrong.
On the other hand, Wired is absolutely right about one thing: Teledisc took some crucial regulatory hurdles during the past few years. The project was, for instance, strongly opposed by European governments at the International Telecommunications Unions (ITU) who feared the United States would dominate the market for satellite personal communications systems. The World Radio Conference (WRC) nonetheless allocated frequencies to Teledesic because the company had declared the developing countries a main target. Of course, those countries voted in favour of Teledesic. Back then, Teledesic chairman Russell Daggatt commented "We were betting the company on a vote. Good thing we won."
This trick is nothing new Iridium performed it, too. Once they had received the international licences they needed, they turned their main attention to wealthy businessmen and travellers in the industrialised countries' densely populated areas instead.
Total and equal coverage of all countries is not exactly in accordance with Teledesic's technical specifications anyway. They call for a link availability of 99.9 percent over most of the United States but just a 24-hour seamless coverage to over 95 percent of the Earth's surface whatever that may mean in real service availability figures outside the U.S.
From the beginning of its operation, the Teledesic satellite fleet will include a number of active in-orbit spares that amounts to ten percent of the active fleet. They will be used to repair the network whenever another satellite fails and has to be removed.
The fact that there will be such a large-scale redundancy has led critics to argue that Teledesic actually expects its satellites to drop out prematurely at a 10 percent rate. They may not have noticed that even for geostationary broadcast satellites it isn't unusual to carry a similar percentage of on-board spare transponders nowadays. Owing to the very nature of the Teledesic project, it's impossible to provide too much on-board redundancy, though.
Teledesic president Russell Daggatt said he expects a three percent failure rate within the system per year, but even that will still result in a quite respectable annual launch rate of replacement satellites.
Still true: "It could end up a catastrophic failure or a heroic success, or merge with another satellite scheme, or quietly disappear."
(Andrew Kupfer, FORTUNE)
Copyright 1997 by Peter C. Klanowski, pck@LyNet.De. All rights reserved.
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