In late 2017, a European space telescope called CHEOPS will be launched - short for CHaracterising ExOPlanets Satellite. It'll hunt for Earth-like planets outside our solar system, by looking for dimming as those planets cross their stars.
But to spot that dimming taking place, it needs a reference point - a highly stable light source that stars can be compared with.
The satellite can measure the brightness of a star with an accuracy of 0.002%, meaning that the light has to be guaranteed to be ten times more stable than that.
Swiss engineers have now built that light source, and it's officially the most stable ever made. Developed at the University of Geneva, it uses a "mobile finger" to adjust in real-time to fluctuations in light intensity.
"We presented our instrument to the US group responsible for the TESS mission, another satellite researching exoplanets, and they were so interested that they asked us to build them a copy," said François Wildi, an engineer who worked on the instrument.
Having been tested in the lab, the lamp will now be tested under "space conditions" at a simulation tank at the University of Berne, where its suitability for the mission will be confirmed.