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Planetarium Highway
With
the nine planets of the solar system, a plinth was built along the 1,2 km main
street of Sutherland - each showing the size of the planet in relation to the
size of the sun and also the distance between the plinths are on scale to the
distance between the planets. The plinth was built by local people with stone
masons from the district..... the art of masonry still being alive and well in
Sutherland. We
belong to the cosmic family called The Solar System. The Sun is the head of this
gigantic group of Planets, Moons and countless Asteroids and Comets. The biggest
family members are the Planets. You can see five of the planets with the naked
eye because they shine so brightly in our sky. These planets are: Mercury, Venus
, Mars, Jupiter and Saturn. The other three planets - Uranus, Neptune and Pluto
- are so far away from the Sun that you need a telescope to see them.
Seven
of the planets aren't alone is space. They have companions called Moons.
Earth
has one. Saturn has the most - 18 in total. Only Mercury and Venus orbit around
the Sun without any moons.
Many other things belong to the Sun`s family. Millions
of Asteroids move in a belt between Mars and Jupiter. At the edge of the Solar
System, past Pluto, lie millions of ice balls. When one of these ice balls shoots
towards the sun, we see it as a Comet with a glowing tail of gas and dust. | Radar
Directional Beacon The
Sutherland enroute radar station was installed in 1991 on Swaarweerberg to fill
a gap between Bloemfontein and Cape Town in radar surveillance. It allows ATC
(air traffic control) to 'see' aircraft flying in the region on screens in Cape
Town and Johannesburg. This makes it possible for them to see exactly within a
few metres where each aircraft is, how fast, high, and what direction each aircraft
is flying.
Since the installation of this radar, air traffic controllers have
been able to monitor aircraft movement from takeoff to landing between Johannesburg
and Cape Town. This allows for quicker routing, and shorter travel times. This
site was chosen due to its high position, and relatively few obstacles around
it (mountains, hills, etc.) which could obstruct the radar signals. It unfortunately
also experiences some of the most severe weather in South Africa, with windspeeds
in excess of 100 km/h and temperatures of -16C having been measured there. The
radar station comprises 2 types of radar:
1) Primary radar - Very high powered transmitter (2 megawatt) which sends out
a radio pulse, reflects it off the metal body of the aircraft, the signal returns
to the radar station and the position of the aircraft is displayed on the screen.
This is old technology, not unlike the radar systems of the 2nd world war, except
much refined. It does not allow one to recognize which aircraft is which. Because
of the high power generated, it is very costly to operate. 2)
Secondary radar - Low powered transmitter (2 kilowatt) which sends a signal to
a transponder on board the aircraft. The aircraft then replies and supplies information
such as identity code and altitude. This is nowadays the more preferred system
because of the identity benefit, lower maintenance cost, etc. It is however dependent
on the transponder on the aircraft to be operational in order for the aircraft
to be seen. The
radar station is totally unmanned, all the signals are sent to Cape Town by satellite
link. The site gets monthly visits from the engineers at Cape Town International
airport. Full control and monitoring of the equipment can be done from Cape Town. Other
equipment at the site. Radio transmitters/receivers - to allow air traffic controllers
to talk to aircraft. The audio signals are sent to/from Cape Town via Telkom lines.
Telkom also has equipment housed in the building, the town's telephone lines
are all routed through here, by means of a microwave link to Matjiesfontein. It
is rumoured to be the longest Microwave link in South Africa. Although
dependent on Escom for electricity supply, the building has a back-up generator
to supply power in event of a failure. The generator is an 8-cylinder turbocharged
Cummins diesel, capable of generating 375 kW of power, and consumes a healthy
30 litres of diesel per hour! |
