Huge telescopes give a better picture of our solar system

Photo: DRAO

The CHIME Telescope, located at the Dominion Radio Astrophysical Observatory near Penticton.

Radio astronomy became an important branch of astronomy in the years following the Second World War.

In those days, the technology followed closely what was used in radar and communications. A typical radio telescope consisted of the biggest dish that available funds could provide, in order to collect as much of the weak cosmic radio emissions as possible. The dish focused the captured radio energy onto a small antenna, usually referred to as the “feed", which fed it to the radio receivers.

Systems like that were very useful for measuring the radio brightness and positions in the sky of cosmic radio sources, but were less useful for imaging. Basically, those radio telescopes were one-pixel cameras and making an image required scanning over the area of sky of interest, building up the image bit by bit.

That sort of imaging, or mapping, took a long time, and with intense competition by researchers for access to the larger, more sensitive radio telescopes, the large chunks of time needed for mapping projects were hard to get. If those projects got observing time at all, it was often on older, less-sensitive radio telescopes, for which the user-demand was less intense.

Fortunately, thanks to the dramatic advances in digital electronics over the last decade or two, the situation has changed dramatically. Now we can make radio telescopes that can take radio images of large areas of sky in a single operation and collect a wide-enough range of information to make it possible to collect data for multiple observing projects at the same time.

Of course, evolving from seeing the universe through a keyhole to having the whole picture was going to result in a lot of cosmic surprises.

The CHIME (Canadian Hydrogen Intensity Mapping Experiment) radio telescope at the Dominion Radio Astrophysical Observatory, near Penticton, was developed for studying the youth of the universe, when the primordial material from the Big Bang was organizing itself into the first stars and galaxies. To do that required an instrument that could observe large areas of sky simultaneously. That resulted in some entirely unexpected science surprises.

Some time earlier, the large, single-dish radio telescope at Parkes, Australia, just happened to be pointed in the right direction to detect a short, milliseconds duration intense pulse of radio emission from a source millions of light years away.

Such a short pulse means a small source, which in turn means a concentrated release of energy that is extremely large.

The CHIME radio telescope has now detected many thousands of those events. Such discoveries underline the importance of large, sensitive instruments that can observe large patches of sky with high sensitivity and has led to the current construction of a new, major instrument at Dominion Radio Astrophysical Observatory. It is called CHORD, the Canadian Hydrogen Observatory and Radio-transient Detector (the concoction of flashy acronyms is an important part of today's scientific research).

It will comprise a closely packed array of 512 sic-metre diameter dishes—rather like a giant insect's compound eye. There are other projects around the world, involving large numbers of relatively small antennas. The most ambitious is the Square Kilometre array, which will consist of thousands of antennas spread over South Africa and Australia. Canada is a partner in that project.

Although instruments like those are constructed with certain astronomical problems in mind, as we have found, their capabilities will open new avenues of research. Therefore, the data is recorded in as untouched a form as possible.

To ensure its accessibility to as large a research community as possible, and for it to be preserved for future use, it is stored in data centres, such as the Canadian Astronomy Data Centre.

•••

• The planetary line-up is nearly complete. Over the next few days Mercury will be sneaking up into the after-sunset glow, with Saturn close by. Moving to the left, (eastward) find brilliant Venus, then Jupiter, almost as bright and Mars, conspicuously red.

• The moon was be new yesterday (Feb. 27)

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.