The US National Radio Quiet Zone (NRQZ) is a rectangle of land, approximately thirty-four thousand square kilometres in area, that crosses into Virginia, West Virginia and Maryland and contains the National Radio Astronomy Observatory at Green Bank and the Sugar Grove Research Facility at Sugar Grove (part of the US Navy’s Information Operations Command and said to be an important part of the NSA’s ECHELON system).
The Green Bank Telescope, the world’s largest steerable radio telescope.
Within the NRQZ radio emissions are highly restricted; conventional television and radio transmitters do not operates and people who (incorrectly) believe that they are sensitive to electromagnetic emissions have flocked there in order to deal with their “problem”. Electric fences, electric blankets, car electronics and even radio-tagged animals have all caused problems in the NRQZ and all on-site vehicles must have diesel engines rather than petrol engines, as diesel engines use the heat generated by compressing petrol vapour rather than spark plugs to ignite their fuel.
The effectiveness of a telescope depends on its size; a larger telescope can gather more signals than a smaller one and therefore provide more information about the object being observed.
Since 1963 the 305-metre Arecibo Observatory has been the world’s largest and (therefore) most sensitive full-dish radio telescope.
But in March of this year China began construction of FAST, the Five Hundred Metre Aperture Spherical Telescope, in a natural depression in southwest China.
Costing $100m and due to be completed by the end of 2013, FAST will be unlike Arecibo in that the surface will be “adaptive”, able to change its shape to create 300-metre sub-dishes than can point up to 40° away from the vertical. Arecibo is only able to point vertically upwards and relies on the rotation of the Earth to sweep it across the sky.
I’m quite fussy about the time.
These are three of the clocks in my house. If you click on the image to enlarge it you’ll notice that they all show exactly the same time, to the second.
In the Cumbrian countryside there is a 17kW 60kHz radio transmitter operated by the National Physical Laboratory connected to three caesium fountain atomic clocks that constantly broadcasts the current time and date. Once a day, at night for some odd reason, each of the clocks in my house synchronises itself with the broadcast time signal, keeping them accurate to 1 second in 1000 years. My watch does the same thing.
Recently one of my other clocks fell off the wall and broke, so I took that opportunity to take it apart.
This is the part that drives the hands, a highly accurate stepper motor.
But this is the true heart of the clock: the radio receiver and the 60kHz antenna. The ribbon wire to the left of the image carries information from the receiver to the clock’s motors.
You can just about make out the tiny radio crystal in the bottom right-hand corner of the circuit board.