New radio telescope in SA will also shed new light on the earliest moments of the universe: C-BASS South commissioning at Hartebeesthoek
27 March 2013
In the week that saw the release of the first results from the European Space Agency’s Planck satellite, astronomers at the Hartebeesthoek Radio Astronomy Observatory (HartRAO) near Johannesburg are working on a new radio telescope that will also shed new light on the very earliest moments of the universe.
The C-Band All-Sky Survey (C-BASS) is a project to map the sky in microwave (short-wavelength radio) radiation. Like Planck, it will survey the whole sky, mapping out how bright the sky is, and also the orientation of the waves (called polarization). While Planck observes very short wavelengths, C-BASS observes longer wavelengths that are actually easier to observe from the ground.
“Because we want to observe at these longer wavelengths, the C-BASS telescope has to be much bigger than the telescope on Planck,” explains South African C-BASS team member Charles Copley. “The C-BASS dish is over seven metres across – much too big to launch on a rocket.”
In order to observe the entire sky, C-BASS needs to use two different telescopes, one in the northern hemisphere and one in the southern hemisphere. The northern telescope is already operating in California, while the southern system is now undergoing final commissioning at HartRAO. After all the systems have been thoroughly checked out it will be moved to the SKA site in the Northern Cape, where the full survey will be done.
C-BASS is the latest in a long line of efforts to measure the properties of the oldest light in the Universe, the Cosmic Microwave Background (CMB). Tiny variations in the brightness and polarization of the CMB contain information about the conditions present in the early universe, only a few hundred thousand years after the Big Bang. The universe then was nothing like what we see today – there were no planets, stars or galaxies. However, the seeds of all the structures we see today can be seen in the CMB. Understanding these beginnings provides us with an insight into the universe today.
The recently released Planck results focus on the CMB brightness, providing more accurate measurements than previous experiments. However, possibly the most exciting data is yet to come, in a year or so when Planck releases their CMB polarization measurements. These measurements may tell us about the physics of the universe when it was a tiny fraction of a second old. However, in order to do this, the Planck mission is faced with a large problem – the Milky Way. Over a large fraction of the sky, any CMB polarization signal is completely obscured by radiation from our very own galaxy, the Milky Way. In order to be successfully measure the CMB polarization it is absolutely essential the astronomers understand this foreground radiation.
The article is taken from here.