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Rosetta Langmuir Probe LAP

Rosetta Langmuir Probe's position at the spacecraft. Credit: ESA / IRFU-Sweden

One of the Rosetta Plasma Consortium's instruments is the Langmuir Probe (LAP), The Finnish Meteorological Institute developed and built the control electronics for this instrument and will participate as Co-Investigator in the analysis of the expected data.

A Langmuir probe is a device to measure weak electric currents flowing between the spacecraft and the surrounding space. "Empty space" is never empty: it always contains a tenuous gas of electrically charged particles, known as a plasma. By measuring the current to the Langmuir probe while varying its potential, we can find out quantities like the density, temperature and flow speed of the plasma. As pressure is density times temperature, we measure the three fundamental properties of all weather stations: temperature, pressure and wind speed: hence we sometimes call our instrument a "space weather station". For more details see the LAP home page