Putting astronomy to work March 10, 2009Posted by Sarah in science.
Tags: adaptive optics, agriculture, astronomy, economist, politics
We astronomers often get asked about the point of our research. Why do we care about galaxies, about dark matter and dark energy? It happens at the best of times, but in these economic climes even more so – see my previous post. Phil Plait made a great video telling us exactly why astronomy, and scientific research in general, matters a great deal to everyone – even to those who think it is far removed from their beds. Watch it here.
This week’s issue of the Economist has the Technology Quarterly, where new technological developments are highlighted, and as usual it contains some really interesting stuff. One story in particular put a big smile on my face, as it’s applying astronomy research that I myself have worked on in the past, albeit indirectly, to a hugely relevant issue, both economically and environmentally: scientists in San Diego are using astronomical wavefront sensing technologies to determine when and how much fields need to be irrigated. Many modern telescopes use a technique called adaptive optics to remove the blurring effects of the turbulence in the atmosphere – the effect that causes the familiar twinkling of stars in the sky, from the light as it enters the instrument. By measuring the distortions in real time, several hundreds of times per second during every exposure, and feeding the information to a thin flexible mirror, the light can literally be bent back into shape. The process of measuring the blur of the light is called wavefront sensing.
The technique of adaptive optics (AO), including wavefront sensing originated in the military, where it was developed to obtain high-resolution satellite images of objects (or subjects?) on Earth and improved aiming of weapons. Following declassification of the original research, astronomers enthusiastically adopted the technology for improving the performance of infrared and optical telescopes – California, Arizona, France, the UK and Germany in particular have great centres of excellence for AO for astronomy. It has been applied successfully to several other industries, particularly ophthalmology and free space optical communication.
In this new application, a laser beam is shot across a field, and a wavefront sensing telescope continuously measures the amount of turbulence in the beam at the other side. As turbulence is highly affected by water vapour in the air, the amount of twinkling spotted in the beam is a measure of the amount of water evaporating from the soil. The farmer can use this information to see if he needs to turn on his sprinklers yet.
This is a super-cool application with a potentially big environmental impact, particularly in agricultural areas where water is naturally scarce, such as central California. I wonder how much such a device costs, and how much area one can cover? I presume given the potentially large market that many of the components can be mass-produced, which would help keep the cost down too.
So there you go. Astronomy: saving water, making agriculture more efficient.