COBE Spacecraft Construction: In 1989, the Cosmic Background Explorer (COBE) spacecraft was launched into an Earth orbit to make a full sky map of the Cosmic Microwave Background (CMB) radiation. COBE found very subtle irregularities in the otherwise very uniform CMB, findings that are considered important evidence in support of the Big Bang theory.
Credit: NASA / COBE Science Team

The Cosmic Background Explorer (COBE) mission was led by John Mather. The COBE group was trying to figure out how to do measurements of the cosmic microwave background radiation. Even though the particular science I had been doing at Chicago was different, the techniques we had been using for infrared experiments were exactly what was needed to build the COBE. John developed a “theory of operation” for the detectors we were going to use on the COBE. This is basically a mathematical description of how the device should work. At the time, John’s wife was a ballet teacher in New York, and he would sit during her classes with a little programmable calculator (this was before there were laptops) to try to figure out the problem. This was a really different way of doing things, because people usually started by thinking about what detectors were going to be used, and what the different types of detectors were capable of doing, and where to buy them, and so on. But John was trying to develop a theoretical basis, so that you would understand how the performance of the detector could change if you modified the device in certain ways.

COBE All-Sky Map: The final COBE all-sky map of the apparent fluctuations in the cosmic background, thought to be the seeds of the large scale structure of the Universe.
Credit: NASA