The vehicle will be moving at a velocity of about 100,000 kilometers per hour when it completes the flyby, Dr. Scott Bolton of the Southwest Research Institute, the mission’s principal investigator, said.
Jupiter’s gravitational pull will accelerate Juno even more as it approaches in mid-2016, possibly to as much as about 165,000 kilometers per hour.
The spacecraft is so massive that, at the time of launch in Aug. 2011, there was not a rocket capable of moving it directly from Earth to Jupiter.
“When we launched, we had enough energy to reach out to the asteroid belt,” Bolton said. “It’s a big spacecraft and that capability wasn’t really there.”
At one point during today’s flyby Juno was about 500 kilometers above the Earth’s surface, with viewing most favorable from South Africa.
“That’s more or less the same sort of orbit the shuttle used to do, but Juno is moving much faster,” Bolton explained.
During the flyby Juno took photographs of Earth and the moon.
Bolton said that these images are the first opportunity humanity has had to view Earth and its moon together from such a distant vantage point.
The photography exercise is also necessary to calibrate Juno's instruments, he said.
Juno is scheduled to arrive at Jupiter on July 4, 2016. It will study the atmosphere of the solar system's largest planet.
“We’ll take a look at the interior structure to see whether there’s a core of heavy elements and also the water abundance,” Bolton said.