Lesley Cowling
A new state-of-the-art telescope to be built in the Karoo will give South African astronomers a window seat on the furthest journey yet through southern skies.
The construction of the R100-million Southern African Large Telescope (Salt) at Sutherland, approved by Cabinet last week, means local cosmologists can now maintain their position at the forefront of international astronomy.
South African stargazers recently helped solve one cosmological conundrum – why certain stars appeared to be older than the universe itself – and contribute their research to such secrets of the universe as whether there is intelligent life out there, how the universe was created and what our neighbouring galaxies are like.
“But with the construction of bigger and better ground telescopes and specialised space-based telescopes, like Hubble, South Africa is losing its lead. It was this consideration that influenced the decision by Cabinet to commit R50-million towards building the telescope,” says Dr Khotso Mokhele, the head of the Foundation for Research Development (FRD).
Another R50-million will be raised from international partners.
The telescope will be managed by the South African Astronomical Observatory (SAAO), a national research facility of the FRD. At least 50% of the construction will be done by South African companies and is expected to take about five years.
Mokhele said he had experienced general enthusiasm at all levels of government, despite the expense. A close look at what the telescope can do makes the enthusiasm understandable: comparing Salt to South Africa’s older telescopes is like putting a spacecraft next to a hot-air balloon.
The southern hemisphere equivalent of Texas’s Hobby-Eberly Telescope, Salt “sees” out into the universe by collecting light on its 10m mirror. This means Salt can see five times further than its nearest local rival.
The implications are enormous: like all telescopes, Salt acts like a time machine. The light collected by telescopes has been travelling across the universe towards us for aeons and so the cosmic activity that astronomers are measuring is not happening at the time they are measuring it, but light years before.
Salt can take us nearer to that critical moment than any other single telescope in the southern hemisphere – within 10% of the age of the universe, according to the SAAO’s Dr Bob Stobie, about as far back as it is possible to go – adding a southern perspective to the data from large northern hemisphere telescopes.
Although most astronomers agree on the “big bang” theory, he says, data from Salt will help show how this happened.
Salt’s seeing eye will also help South African astronomers and their northern partners solve more mysteries, like the strange inconsistency of certain stars seeming older than the universe that existed until recently.
The inconsistency emerged because, as research by Professor Michael Feast and Dr Patricia Whitelock recently showed, the measurements used to establish distances in the universe were not precise enough.
Whitelock, Feast and their colleagues used data from pulsating stars to calculate the distance scale of the universe, and their calculations showed that stars and galaxies were further apart than previously thought. Since distance equals time in astronomy, that made the universe older – and solved the conundrum.
South African astronomers have been at the forefront of the study of pulsating stars, stars that vibrate, says Stobie.
Salt can scan the skies for changes in a star’s motion that indicate the stars out there that have planets. This would be a necessary first step in the quest, because life as we know it can only evolve on a planet, rather than a star.
But the research possibilities of Salt will have to be paid for – the R50-million pledged by the government will come out of the normal budgetary allocation to science and technology.
Unless the Department of Arts, Culture, Science and Technology finds a way, this will put pressure on research funding for other sciences.