After a 4.9 billion-mile journey that required six years and some very tricky moves, NASA has put a spacecraft into orbit around Mercury for the first time ever. Researchers are eagerly awaiting their first extensive look at the solar system's smallest planet, AP reports. The Messenger probe will begin transmitting pictures and investigating the rocky planet's mysterious magnetic field next month.
Messenger arrived in its orbit 120 miles above the planet—which travels at an average speed of 106,000 mph—by taking a path that involved 15 loops around the sun and multiple fly-bys of various planets. "It was right on the money," said Messenger's chief engineer. "This is as close you can possibly get to being perfect. Everybody was whooping and hollering; we are elated. There's a lot of work left to be done, but we are there." (Read more outer space stories.)