The Laser Interferometer Space Antenna (LISA) Pathfinder mission was sent into space at the end of 2015 to help propel humanity's knowledge about gravitational waves, which are the ripples sent through space after massive objects like binary black holes collide with each other.
Despite how successful the LISA Pathfinder mission was, the European Space Agency officially ended the mission this week. LISA Pathfinder worked separately from Laser Interferometer Gravitational-Wave Observatory (LIGO), a ground-based gravitational wave detection method.
Researchers got everything they needed and more from LISA Pathfinder while it was active. The kill command helps ensure that LISA Pathfinder will no longer operate or transmit signals, which is imperative for ensuring the data we get from future missions isn't tainted with interference.
Gravitational waves are still a huge mystery to us, but with additional research, we may better understand how they happen and validate Albert Einstein's Theory of General Relativity.