CAPE CANAVERAL, Florida: For the first time in 20 years, a NASA spacecraft has traveled close enough to one of Jupiter’s moons to send back images.

The spacecraft, named Juno, flew past the icy Ganymede moon this week, coming within 645 miles of its surface.

In 2000, NASA’s Galileo spacecraft was the last spacecraft to fly close enough to a moon to photograph it.

NASA has released Juno’s first pictures, showing Ganymede’s craters and long, narrow features, which scientists said might have been tectonic faults. One picture depicts the moon’s dark side, opposite the sun.

“This is the closest any spacecraft has come to this mammoth moon in a generation,” said Juno’s lead scientist, Scott Bolton of the Southwest Research Institute in San Antonio. “We are going to take our time before we draw any scientific conclusions, but until then we can simply marvel at this celestial wonder the only moon in our solar system bigger than the planet Mercury,” as quoted in the Associated Press.

Ganymede is one of Jupiter’s 79 known moons. Ganymede was discovered by Italian astronomer Galileo in 1610, along with Jupiter’s three next-largest moons.

Juno, which has been orbiting Jupiter for five years, was launched ten years ago.