Neutral atomic hydrogen is the most abundant element in the Universe – astronomers call it HI.  The HI atom naturally emits radiation at a wavelength of 21 cm, making it detectable by MeerKAT.  Galaxies typically contain large reservoirs of HI, serving as the raw fuel for star formation. The exquisite sensitivity of MeerKAT will allow astronomers to study this important mass component of galaxies out to distances never before probed by radio telescopes.  

The LADUMA survey (Looking At the Distant Universe with the MeerKAT Array) aims use MeerKAT to study the cosmic evolution of the HI content of the Universe, for the first time.  It will do this by observing a small patch of sky – about the size of the full moon – for thousands of hours. Due to the way in which the telescope’s field of view naturally increases in size as we move to greater distances, the volume probed by LADUMA will be the shape of a vuvuzela.  

Astronomers know that when the Universe was about half of its current age, galaxies were producing stars at a rate about 10 times greater than they are today.  However, existing radio telescopes have never allowed us to probe the evolution of the HI (the fuel for stars) in galaxies. For the first time, MeerKAT will measure the neutral gas density of the Universe as a function of cosmic look-back time. 

See for more details.