hy

NOVEMBER LAUNCHING SCHEDULED.

There's a parkina snot rem
served for Canada 22,390
miles in space, and in Nover=
ber 550 Ibs. of electronic
equipment, solar cells, an-
tenna and rocket fuel is sch-
eduled to take occupancy.

Canada's first communica-
tions satellite, named Anik
and owned by Telesat Canada,
is to be launched from Cape
Kennedy by the U.S. tational
Aeronautics and Space Admin-
istration.

Assembly of the satellite
is expected to heain shortly
at the Huoahes Aircraft Co. in
California. A network of 34
qround stations is beina con-
Structed and ''mission con-
trol!’ in Ottawa is nearina
completion.

1f the launch qoes accord-
ing to plan, the satellite
will become the world's
first domestic communications
system in synchronous orbit,
a circular orbit 22,300 miles
directly over the equator.

In such an orbit, the sat-
elite will take 24 hours to
revolve around the earth,
Since the earth rotates on
its axis in the same period
Antik will appear to remain
Stationary over a single
point on earth - 114 dearees
west longitude, facing cent-
ral Canada.

The satellite will become
in effect, a relay tower
several thousand miles hiaqh,
which allows it to blanket
vast areas of land. And be-
cause it is qeostationary,
expensive fully steerable
antennas are not needed for
around stations. |

From its central location
Anik will cover all of Can-
ada with television and mes-
sade transmissions, Special

ASSEMBLY OF CANADA'S COMMUNICATION SATELLITE TO BEGIN SHORTLY

beamina techniques will aive
all points nearly uniform
sional strenath, while red-
ucing: the sianal beamed out-
side Canada,

The satellite has
nels -

12 chan-
10 for commercial use

and two for stand-by~each cap-

able of transmittina one
color TY sianal or up to 960
one-way telephone messaqes,.
The siqnals will be nicked up

by 34 special ground stations,

which can redistribute them
by conventional terrestial
means.

Everything, of course, de-
pends on a successful launch
and precise quidance of the
satellite into its slot - a
task not lacking in challenae
even after 1/4 years of world
wide experience with satel”
lites.

92% SUCCESS RATE

Anik's booster will be one
of NASA's thrust-auqmented
Thor-Delta rockets, which has
a success rate of 92%. .The $7
million launch will put Anik
into an alliptical orbit,
22,300 miles from earth at

its furthest point, or apoaee,

and.inclined to the equator
about 28 deqrees. NASA's res-
ponsiblityv ends when the ell-
iptical orbit is achieved;
all subsequent operations
will be handled by Telesat
from its control centre in
Ottawa.

The first tmportant step
is the transfer orbit needed
to circularize the elliptical
orbit at 22,300 miles and
move the satellite down to
the equator. To do this, a
small rocket on the satellite
will be fired at anoaee, be-
tween the third and fifth

time Anik comes around,

Should the aponee motor
fail to put Anik into the de-
sired synchronous orbit, sm
all on-board thrusters miaht
be used, but onlv at the ex-
pense of the lifetime of the
satellite. (The thruster fue!
is needed to maintain the
satellite's position in space
throughout, its ojected seven
year life)

The transfer orbit is cru-
cial, for if the satellite
is not precisely located, it
loses its value as a commun-
ications system. So Telesat
is takina special precautions,

Barry Murphy, executive -
assistant to Telesat presid-
ent David Golden, said !!uahes
Aircraft has been asked to
build a special trackina
Station at Guam in the Pac-
ific. This will provide pos-
itional data on the satellite
while it is still in the
Eastern Hemisnhere so it can
be more readily acquired as
it comes into the “estern
Hemisphere and Telesat pre-~
pares to fire the apocee
motor. °

Mr. Murphy said: ‘Je want
to fire the anoaee motor
early in the flight. There
are some limits on the numbe-

of clliptical orbits that

can transpire before you cir-
cularize the orbit.'' For
example, the inclination to
the equator aets worse with
each orbit, makina it rore
difficult to amet Anik into
the equatorial orbit,

Telesat has chosen not to
have an in-house comouter
capability to handle this
complex manoeuvre, so Com-
putel Systems Ltd. of Ottawa
will provide its cornuter
durina rehearsals and launch
operations.

A second computer will ao.
through the whole thina si-
miltaneously, so it can cut
in immediately if anythina
qoes wrong with the firse