It's been 12 years in the making but the space craft Rosetta's mission has finally come to an end.
Here is what you need to know about it.
What is Rosetta?
Rosetta is the space probe built by the European Space Agency which was launched on the 2nd March 2004 from the Guiana Space Centre in France.
The spacecraft was designed to perform a detailed study of a particular comet, 67-P/Churyumov-Gerasimenko - also known as "space duck" due to its shape.
During its journey to the comet, the spacecraft flew by Mars and two asteroids.
When Rosetta came into orbit of the comet, it launched its lander module Philae.
This robotic machine performed the first successful landing on a comet - though its battery power ran out two days later.
Why are scientists crashing Rosetta into the comet?
Scientists are deliberately guiding the spacecraft into the comet because the ball of ice and gas is moving so far from the sun that the spacecraft will soon be unable to recharge its solar batteries.
Rosetta crashed into the comet at a walking pace today at around 11.40am.
Scientists controlling the spacecraft from Darmstadt in Germany, hope its last few minutes of life will feed back the most up-close revealing photos of the comet yet.
Why land on a comet?
Comets hold the secrets to the building blocks of the Solar System.
The more scientists can learn about them, the more they can learn about the origins of life.
Made of a combination of ice, rock particles and dust it is believed that comets brought the first water to Earth.
Rosetta has orbited the comet analysing the gases of the tail, testing its interior and measuring dust grains as well as sending back over 100,000 images.
Were there any problems with the mission?
Yes, the lander module Philae landed in the shadow of a cliff on the comet because its harpoons did not fire on landing.
This meant the craft lost power just days after landing as its solar panels were not exposed to enough sunlight.
The lander did however manage to send back some images from the surface of the comet before running out of power on November 14 2014.