(CNN) -- NASA's Mercury probe Messenger has become the first spacecraft to go into orbit around the closest planet to the Sun.

Confirmation of the probe entering Mercury's orbit was received Thursday evening.

"Achieving Mercury orbit was by far the biggest milestone since Messenger was launched more than six and a half years ago," said Messenger Project Manager Peter Bedini, of the Johns Hopkins University Applied Physics Laboratory.

"This accomplishment is the fruit of a tremendous amount of labor on the part of the navigation, guidance-and-control, and mission operations teams, who shepherded the spacecraft through its 4.9-billion-mile (7.9-billion-kilometer) journey."

The space agency is hoping to get the first pictures back from the Messenger probe in orbit by the end of the month. The primary science phase of the mission is scheduled to begin April 4.

"Despite its proximity to Earth, the planet Mercury has for decades been comparatively unexplored," said Sean Solomon, Messenger principal investigator.

"For the first time in history, a scientific observatory is in orbit about our solar system's innermost planet," he said. "Mercury's secrets, and the implications they hold for the formation and evolution of Earth-like planets, are about to be revealed."