Exactly 10 years ago, on 21 November 2013, the first Polish astronomical scientific satellite named "BRITE-Lem", has been launched into space. Since then, it has completed more than 50 000 orbits around the Earth, travelling some 2.3 billion kilometres. During the six years of its scientific mission, it has observed twenty fields all over the sky and obtained more than 6 millions of scientific measurements of the brightness of over 200 stars. Lem has stopped its astronomical observations in May 2020 as it can no longer point to specific stars with the required accuracy, but it still communicates with the ground station at the Nicolaus Copernicus Astronomical Center, delivering data for technical use and is in good health otherwise.
Lem and the whole BRITE-Constellation have been a trailblazing mission in many aspects. It allowed Poland and its Center of Space Research to develop complicated space technology, and it showed for the first time that nanosatellites can be stabilized in their orbits sufficiently to obtain science-grade brightness measurements. The scientific legacy of Lem is so comprehensive - it made important contributions to research of binary stars, pulsating stars, hot stars, cool stars, magnetic stars, stars with winds, etc. - that it is hard to single out a single scientific highlight. Let it just suffice to say that Lem contributed to some 30 refereed scientific publications only by itself, and from its archival observations we expect several more to come. Happy Birthday, Lem!
