Diagram illustrating the relative distances involved with the detection.

NASA conducted the Diffuse Infrared Background Experiment (DIRBE) using the Cosmic Background Explorer (COBE) from December 1989 to September 1999. The goal of the experiment was a survey of the diffuse infrared sky to get deeper knowledge on the population and evolution of early galaxies.

As the illustration shows we have already know a great detail of the modern universe, as well as of the Cosmic Microwave Background. However we still lack the deeper understanding of the Universe in the time period after the Cosmic Microwave Background.