When the Voyager space probes shot past Saturn, Uranus and Neptune on their 25-year journey into deep space, machines in the probe captured the whistles and chirrups the probes encountered, and transmitted them back to earth. Now composer Terry Riley has written a piece incorporating the sounds into a piece for the Kronos String Quartet and a 60-voice choir. “The string quartet was NASA’s idea, the product of an arts programme that, over the past 30 years, has commissioned work from artists including Andy Warhol and Robert Rauschenberg.”