Portion of the Moon Mineralogy Mapper (M3) Instrument Electronics Assembly. The instrument was designed, built and tested at JPL in <24 months as part of NASA's Discovery Program. It will be launched aboard Chandrayaan-1, India's first mission to the Moon, in 2008.

Everything we sense consists simultaneously of both "signal" and "noise." When listening to a classical concert, the "signal" consists of complex tones generated by the strings, brass, percussion, and other instruments being played as the composer intended. "Noise" may include the person sneezing across the concert hall, the person next to you quietly scuffing their feet as they shift position, and the barely perceptible background of the ventilation system, and your own breathing. "Noise" appears on images we see, as in "snow" on a television screen superimposed on the program we are watching.

Because of the huge cost of getting equipment to our space destinations, instruments must be built as small as possible, and use as little electrical power as possible. Furthermore, our spacecraft are often remote from the phenomena they are intended to measure. Instead of being in the concert hall with the orchestra, imagine listening from a hilltop a few miles away for the bit of sound that leaks out the doors and roof, and trying to pick out this "signal" from all the surrounding "noise."

Our detectors typically measure the tiniest of signals, which must be amplified, filtered, and digitized to create an intelligible data stream, from which the original signal can be extracted and portrayed. All electronics, including the kind used to amplify small signals (think millivolts, microvolts and less), introduce noise of their own. We can ill afford electronics that introduce much noise.

Consequently, there is a whole art and science of creating "low-noise electronics" that operates and extracts signals from detectors and focal planes while introducing the very minimum of electronic noise itself. Sometimes this electronics runs at low temperatures. Careful grounding and elimination of "sneak circuits" are always part of the design, while meticulous workmanship ensures operation near ideal performance levels. People at JPL routinely apply decades of experience and a whole array of specialized techniques to design, build, test and deliver electronics where the amount of noise introduced is sometimes expressed as a few electrons on top of each tiny measurement.

Examples of recent and ongoing low-noise electronics include equipment for Mid-Infrared Instrument (MIRI) on the James Webb Space Telescope, the Moon Mineralogy Mapper, and the Optical Navigation Camera aboard Mars Reconnaissance Orbiter.