The Cassini spacecraft is expected to reach its closest approach to Saturn´s giant moon Titan this morning.
The international spacecraft entered orbit around Saturn in June and is expected to reach the point of closest approach to Titan after 9 o´clock.
Scientists at the Jet Propulsion Laboratory in Pasadena expect to download pictures of Titan later this evening.
They hope the images will show whether the cloud-shrouded moon has a liquid or solid surface.
Titan is bigger than the planet Mercury and its atmosphere contains organic — or carbon-based — compounds much like those on Earth billions of years ago before life began.
Scientists say it´s unlikely life is found on Titan because it is too cold.
Cassini was launched in 1997 and has flown over two billion miles to reach Saturn.
The mission is funded by NASA, the European Space Agency and the Italian Space Agency.