Wired UK - 11.2019

STARRING

R O L E

‘Many waves come from pulsars.

Then there are mysterious Fast

Radio Bursts – brief flashes with

the power of 500 million SunsÕ

START 022

The radio-quiet zone begins about

half an hour’s drive from this desolate

spot in the Karoo desert, in South

Africa’s Northern Cape. The use of

mobile phones and laptops is strictly

forbidden. A few trees and shrubs dot

the ochre landscape; occasionally, a tiny

scorpion scurries away. What holds your

eye, though, are the giant dishes.

This is MeerKAT– 64 radio dishes

spread across eight square kilometres,

each 13.5 metres in diameter and as

tall as a five-storey building on their

supports. Together they form a single

radio telescope. MeerKAT means “more

KAT” (the Karoo Array Telescope was

its seven-dish forerunner), and astron-

omers use it to study strange but

little-understood objects in distant

space. Because phones and other gadgets

also emit radio waves, they are strictly

off-limits, to make sure these antennae

pick up only signals of cosmic origin.

MeerKAT is the precursor to what will

be the world’s largest radio telescope:

the Square Kilometre Array (SKA). In the

next decade, SKA will add another 133

dishes, working in tandem with as many

as 133,000 smaller antennae in Australia.

The aim is to observe how the universe

works – how hydrogen gas is assembled

into galaxies and gives birth to new stars

• and to track the sources of radio waves
  arriving on Earth. Many come from
  pulsars – the ultra-dense leftover cores
  of massive stars. Then there are myste-
  rious Fast Radio Bursts – brief flashes
  with the power of 500 million Suns.
  One of MeerKAT’s first tasks when
  it opened in June 2018 was to snap the
  clearest-ever image of our Milky Way’s
  galactic centre, home to the super-

Below: the clearest picture yet of the Milky Way, taken by MeerKat in June 2018. Radio waves glide right through the dust

How a MeerK AT

dish tracks radio

waves arriving

on Earth from

distant space

massive black hole Sagittarius A. Located some

25,000 light years away, it’s a region in space full of

interstellar gas and dust, so optical telescopes are

of little use – but radio waves glide right through.

MeerKAT’s picture (above) shows the black

hole like a volcanic eruption, but the red and

orange colours have nothing to do with heat –

they represent the brightness or intensity of the

radio waves picked up by the telescope. The visual-

isation could have been done in any colour, says

Fernando Camilo, the chief scientist at the South

African Radio Astronomy Observatory.

The round area just to the right of the

centre is the location of Sagittarius A.

Elsewhere, there are areas of star

formation (the bright spot to the right,

and the hourglass shape to the left),

and the remnants of supernovas – stars

that have exploded and died (far left).

The thin snaking lines, known as “fine

filamentary threads”, remain a mystery.

They have not been found anywhere else

in our galaxy, though, so may have some

connection to the black hole.

When the Square Kilometre Array is

fully operational (expected 2030) it will

be able to peer 14 billion years back to the

moments after the Big Bang, and provide

insights about supernovas, black holes

and the infant universe. Katia Moskvitch

PHOTOGRAPHY PREVIOUS SPREAD: ENRICO SACCHETTI. THIS PAGE: COURTESY OF MEERKAT

_ Incoming

radio waves

_ Primary parabolic

reflector surface (dish)

_ Subreflector

_Feed Horn

_Cables carrying

the signal from the

MeerKAT antenna

to the control room

for processing

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