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Forbes ASAP, October 10, 1994
Ethersphere
New
low earth orbit satellites mark as decisive a break in the history of
space-based communications as the PC represented in the history of computing.
Pay attention to much-maligned Teledesic. Backed by Craig McCaw and Bill
Gates, it is the only LEO fully focused on serving computers.
“They’ll Be Crowding The Skies.”
THUS STEVEN DORFMAN, president of telecommunications and space operations
for GM Hughes_the colossus of the satellite industry_warned the world
of a new peril in the skies. Planning to launch 840 satellites in low
earth orbits, at an altitude of some 435 miles, were
a gang of cellular phone jocks and computer hackers from Seattle going
under the name of Teledesic. Led by Craig McCaw and Bill Gates, they were
barging onto his turf and threatening to ruin the neighborhood.
You get the image of the heavens darkening and a new Ice Age looming as
more and more of this low-orbit junk_including a total of some 1,200 satellites
from Motorola’s Iridium, Loral-Qualcomm’s Globalstar and Teledesic,
among other LEO projects_accumulates in the skies. Ultimately, from this
point of view, you might imagine the clutter of LEOs eclipsing the geostationary
orbit itself, the so-called Clarke belt, some 21,000 miles farther out.
Named after science-fiction guru Arthur C. Clarke, the geostationary orbit
is the girdle and firmament of the Hughes empire.
In an article in Wireless magazine in 1945, Clarke first predicted that
satellites in orbit 22,282 miles (35,860 kilometers) above the equator,
where the period of revolution is 24 hours, could maintain a constant
elevation and angle from any point on Earth. In such a fixed orbit, a
device could remain for decades, receiving signals from a transmitter
on the earth and radiating them back across continents.
The Clarke orbit also posed a problem, however_the reverse square law
for signal power. Signals in space attenuate in proportion to the square
of the distance they travel. This means that communications with satellites
22,000 miles away typically require large antenna dishes (as much as 10
meters wide) or megawatts of focused beam power.
Now, however, a new satellite industry is emerging, based on gains in
computer and microchip technology. These advances allow the use of compact
handsets with small smart antennas that can track low earth orbit satellites
sweeping across the skies at a speed of 25,000 kilometers an hour at a
variety of altitudes between 500 and 1,400 kilometers above the earth.
Roughly 60 times nearer than geostationary satellites, LEOs find the inverse
square law working in their favor, allowing them to offer far more capacity,
cheaper and smaller antennas, or some combination of both. Breaking out
of the Clarke orbit, these systems vastly expand the total available room
for space-based communications gear.
It is indeed possible to “crowd” the Clarke belt_a relatively
narrow swath at a single altitude directly above the equator. But even
this swath does not become physically congested; collisions are no problem.
The Clarke belt becomes crowded because the ability of antennas on the
ground to discriminate among satellites is limited by the size of the
antenna. Spaceway and Teledesic both plan to use the Ka band of frequencies,
between 17 gigahertz and 30 gigahertz, or billions of cycles per second.
In this band, reasonably sized antennas 66 centimeters wide can distinguish
between geostationary satellites two degrees apart. That’s some 800
miles in the Clarke belt. Thus no physical crowding. But it means that
there are only a total of 180 Clarke slots for Ka band devices, including
undesirable space over oceans.
LEOs, however, can be launched anywhere between the earth’s atmosphere
and a layer of intense radiation called the Van Allen Belt. The very concept
of crowding becomes absurd in this 900 kilometer span of elevations for
moving orbits that can be 500 meters apart or less. Thus the 21 proposed
orbital planes of Teledesic occupy a total of 10 kilometers of altitude.
At this rate, 70 or more Teledesic systems, comprising some 65,000 satellites,
could comfortably fit in low earth orbits.
Nonetheless, it was clear that the LEOs, one way or another, were crowding
Hughes. Hughes commands satellite systems or projects that compete with
every one of the LEOs. Hughes responded to the threat of Teledesic by
announcing the expansion of its Spaceway satellite system, then planned
for North America alone, to cover the entire globe. Then, invoking the
absolute priority currently granted geostationary systems, Hughes asked
the Federal Communications Commission to block Teledesic entirely by assigning
Spaceway the full five gigahertz of spectrum internationally available
in the Ka band.
On May 27, Dorfman summoned the upstarts, Craig McCaw and Teledesic President
Russell Daggatt, to Hughes headquarters in Los Angeles for a talk. Busy
with Microsoft_the Redmond, Wash., company that in 1993 temporarily surpassed
the market value of General Motors_Teledesic partner Bill Gates did not
make the trip. But as the epitome of the personal computer industry, his
presence haunted the scene.
Together with Spaceway chief Kevin McGrath, Dorfman set out to convince
the Seattle venturers to give up their foolhardy scheme and instead join
with Hughes in the nine satellites of Spaceway. Not only could Spaceway’s
nine satellites cover the entire globe with the same services that Teledesic’s
840 satellites would provide, Spaceway could be expanded incrementally
as demand emerged. Just loft another Hughes satellite. Indeed, Spaceway’s
ultimate system envisaged 17 satellites. With “every component proprietary
to Hughes,” as Dorfman said, the satellites only cost some $ 150
million apiece. By contrast, most of the $ 9 billion Teledesic system
would have to be launched before global services could begin.
Nonetheless, the new LEOs marked as decisive a break in the history of
space-based communications as the PC represented in the history of computing.
Moreover, Teledesic would be the only LEO fully focused on serving computers_the
first truly “global Internet,” as McCaw’s vice president
Tom Alberg depicted it. It brings space communications at last into the
age of ubiquitous microchip intelligence, and it brings the law of the
microcosm into space communications.
If you enjoyed the New World of Wireless on the ground with its fierce
battles between communications standards, technical geniuses, giant companies,
impetuous entrepreneurs and industrial politicians on three continents_you
will relish the reprise hundreds and even thousands of miles up. Launching
Teledesic, McCaw and Gates were extending bandwidth abundance from earth
into space. Observers, however, often did not like what they heard.
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