A Trip to the Dominion Radio Telescope Observatory
While visiting a friend in the
Okanagan region of British Columbia, Canada region a few months ago (Nov 2016),
we drove by the Dominion Radio Telescope Observatory. Though it wasn’t open to the public that day,
we were allowed to go into the grounds on foot and look at the telescopes (from
a distance), as well as read some of the literature posted outside, describing
the research being done. It was a nice opportunity to look around the site, and
see some of these devices from fairly close up.
We also took a few pictures, which are reproduced in this blog.
It also fit in well with my own astrophysical
interests, and my son’s work during his PhD at McGill. His work focused primarily on X-ray
astrophysics (neutron stars, magnetars), but he often calibrated these results
with radio telescope results, and had co-authors on papers from the radio
astronomy world. And, as a finishing
touch, Dodecahedron Books will publish a humorous Science Fiction story later
this year, which prominently features the famous Arecibo Radio Telescope in
Puerto Rico, and touches on SETI and the Zoo Hypothesis.
Main Radio Telescope Dishes at the Dominion Observatory
First off, what is a radio
telescope, and what is radio astronomy (or astrophysics)? Basically, a radio telescope is just a large
reflective dish, that gathers long wave length electro-magnetic radiation, and
focuses it in a small detector region, which captures the signal, boosts it and
stores it for further analysis. (That’s
essentially what an optical telescope does as well, but at a shorter
wavelength.) The radio signal is then
analyzed for such features as the strength of the radio waves, the location in
the sky from which they emanate, the frequency spectrum of the signal, any
periodic features it might have, dispersion of the signal, and so forth. From
those results, the nature of the originating body and the medium through which
the radiation has travelled can be inferred.
Some Intelligent Life at the Observatory, though not SETI
Note that a lot of SETI (Search
for Extra Terrestrial Intelligence) research has been done via radio telescopes
– that’s probably what they are most famous for in the public mind, because of
books and movies like Carl Sagan’s “Contact” (good book, good movie, by the
way).
Close-up of a Radio Dish
Radio telescopes are big, because
radio waves are big. Radio waves can be
anywhere from millimeters to kilometers, so the radio telescopes must be
correspondingly big as well. After all,
a telescope that was smaller than the wavelengths it was meant to detect
wouldn’t be of much use (wouldn’t have resolving power). That’s also the reason that optical
microscopes can’t be used on very tiny things, like viruses, for which the much
more sensitive scanning electron microscope is used.
In addition to the issue of the
size of the wavelength requiring a large dish for resolving power, it is also
needed because a large wavelength doesn’t carry much energy. So, a big dish is needed to ensure that
enough energy is captured to produce a useful signal to noise ratio.
The biggest dish at this
observatory is 26 meters across. For
comparison, though, Arecibo is 300 meters in diameter, and there is now a
500-meter dish in China. However, the
dish at the Dominion observatory can move, and track objects in the sky. The really large dishes like Arecibo are stationary,
built into natural “bowl” land formations.
They are therefore limited to scanning only part of the sky –
essentially the part that happens to be above them at any time of the year
(though, over a solar cycle that can cover a lot of sky).
The 26-meter dish primarily
studies 21 cm radio waves. It “sees” an
area about the size of the full moon (half a degree or so). It is very useful for studying interstellar
gas clouds, such as those in star-forming nebulae. This helps us to understand the processes of
star formation, and therefore our own solar system’s origin.
Some of the photos above show
radio telescopes on railway tracks. There
are four of them (though Wiki says seven), each 9 meters in diameter, that they
can be moved on the tracks, relative to each other. This gives the effect of a
very large telescope, equivalent to one 600 meters in diameter, once some
clever electronics and digital signal processing is performed. This “aperture synthesis” telescope has been
used for various purposes, such as mapping large objects like the Andromeda
galaxy.
Linear Array of Cylindrical Antennae.
There is also something called
the 22 megahertz “T” antenna, which is reminiscent of the sort of dipole array
that was used by Jocelyn Bell to discover the first pulsar. It was used in the past for full-sky mapping.
There is also a small radio
telescope dedicated to solar observations.
That, along with a worldwide system of such scopes, helps to provide
predictions and warnings of solar events (bursts of high energy particles) that
can affect communication systems and other infrastructure on the Earth, or in
orbit.
Finally, there is an array of four
cylindrical reflector antennae, each 100 meters long and 20 meters wide. They are being used in an experiment to
measure the cosmological red-shift of the 21-cm line of neutral hydrogen, which
will give us a better idea of the history of the expansion of the universe
itself.
Note that the observatory is a
bit difficult to find, as it is somewhat off the beaten track. Also, you have to be very careful about stray
electromagnetic signals, even from objects as seemingly innocuous as a car
engine or a cell phone, if you visit.
After all, these are extremely sensitive instruments, and it doesn’t
take much to create a bit of radio interference that they can detect.
Sources:
Dominion Radio Astrophysical
Observatory:
Dodecahedron Books, field notes
and photos
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Now that you have read some real science
(astronomy and astrophysics), you should read some science fiction. Either of the Kati of Terra series or the
Witch’s Stones series would be excellent choices. Alternatively, you could try the short story
“The Magnetic Anomaly”, which has lots of physics, and even some Fourier analysis. :)
Kati of Terra
How
about trying Kati of Terra, the 3-novel story of a feisty young Earth woman,
making her way in that big, bad, beautiful universe out there.
The Witches’ Stones
Or, you might
prefer, the trilogy of the Witches’ Stones (they’re psychic aliens, not actual
witches), which follows the interactions of a future Earth confederation, an
opposing galactic power, and the Witches of Kordea. It features Sarah Mackenzie, another feisty
young Earth woman (they’re the most interesting type – the novelist who wrote
the books is pretty feisty, too).
The Magnetic Anomaly: A Science Fiction Story
“A geophysical crew went into the Canadian
north. There were some regrettable accidents among a few ex-military who had
become geophysical contractors after their service in the forces. A young man
and young woman went temporarily mad from the stress of seeing that. They
imagined things, terrible things. But both are known to have vivid
imaginations; we have childhood records to verify that. It was all very sad.
That’s the official story.”
