Nearly nine years ago, NASA sent its New Horizons spacecraft to Pluto. On Saturday, after all that time in transit, it will come out of hibernation for the last time as it finally approaches what was, at the time of the launch, the furthest planet in our solar system. Throughout the journey, New Horizons has sent weekly pings back to Earth to let the team know it was still alive, as it was in hibernation for most of the trip. Earlier this week, New Horizons sent its last ping ahead of Saturday’s wake up.
It took the spacecraft New Horizons, hurtling from Earth faster than any mission before it, a matter of hours to pass the moon’s orbit and a year to reach Jupiter’s gravity. Nine years into its journey, it’s finally approaching its destination: Pluto. Much has changed since scientists at the Johns Hopkins Applied Physics Laboratory in Laurel, Md., conceived the mission a decade and a half ago. Astronomers found two more moons orbiting Pluto, observed changes in its thin atmosphere, and determined the distant object wasn’t a planet, after all. But they expect those discoveries to pale compared to the observations New Horizons will record once they wake it from hibernation Saturday, and as it approaches an encounter with Pluto in July. They organized the mission to learn more about Pluto’s composition and characteristics, and how planets formed in the early universe.