For a long time astronomers (specifically radio astronomers) have wanted to place a telescope on the Moon. Now it seems that that desire is slowly becoming a possibility. NASA recently announced how it was backing a series of studies to investigate potential experiments for its ‘Next Generation Astronomy Missions’. Included in that backing is one proposal from the Massachusetts Institute of Technology to build a small radio telescope array on the Moon’s far-side.
Radio telescopes are really important tools for probing the Universe. All sorts of objects emit radio waves; quasars, very hot gas in the space between the stars, electrons rapidly whirring around in magnetic fields as well as planets to name but a few. On Earth radio astronomy has been at the forefront of astronomical research for decades. Indeed many of the great discoveries of modern astronomy have been made thanks to the use of radio telescopes; for example the radio telescope (MK1A) at Jodrell Bank Observatory in the UK discovered the first gravitational lens amongst its many great accomplishments.
But there is a problem with doing radio astronomy from Earth. Radio signals from astronomical objects are extremely faint; something that makes observing radio sources tricky even on a good day. But radio waves, of course, don’t just come from the sky. Radio stations, satellites, Wi-Fi networks and many other man-made sources all emit vast amounts of radio waves that are much more powerful than those coming from space. With this ubiquitous fog of radio waves often ‘spilling’ into the frequencies that astronomers observe in (combined with the fact that the Earth’s ionosphere blocks certain radio signals) it’s a wonder we can observe anything emitting radio waves in space; sorting the proverbial radio wheat from the chaff is no easy task.
What radio astronomers really need is something to block all the ‘noise’ coming from the Earth. Something like a massive shield…something like…the Moon. By locating radio telescopes (or groups of smaller telescopes called ‘arrays’) on the lunar ‘farside’ the telescopes are hidden from the radio noise from the Earth, since the farside is always in the radio ‘shadow’ of the Moon, plus they don’t have the Earth’s ionosphere to contend with!
MIT’s proposed telescope will consist of hundreds of small instruments set up across about 2 square kilometres to studio low frequency radio waves. The telescopes will be arranged by robotic machines and they don’t have to be that accurate since the wavelenghts that the array will study are fairly long. The array will probe some of the least well known periods of the Universe’s early history as well as looking at space-weather from the solar wind, radio emissions from the planets and possibly even galaxies too.
I’m going to be talking to Dominic King live on BBC Radio Kent at 10:30am tomorrow morning about the ambitious plans for these lunar observatories so if you are in south-east England tune in!
Above: ‘Farside’ radio telescopes will be able to tell us more about periods in the early Universe, earlier than the HUDF (pictured).
Credit: NASA, ESA, and S. Beckwith (STScI) and the HUDF Team