After a journey of almost five years, NASA's Juno spacecraft has successfully entered orbit around Jupiter. Confirmation that one of the most critical parts of the mission was completed was received on Earth at 8:53 pm. PDT (11:53 p.m. EDT) Monday, July 4.
A 35-minute engine burn decreased Juno's velocity by 1,212 mph (542 meters per second) and allowed the spacecraft to be captured in an elliptical orbit around Jupiter. Juno's job will be to study Jupiter in great detail, the probe is expected to yield lots of data about the planet's composition, gravity field, magnetic field, polar magnetosphere and its radiation belts.
Scientists hope the $1.1 billion mission will be able to answer questions about how Jupiter formed, whether it has a rocky core and if there's water present in the deep atmosphere of the planet. Full details at NASA.
"The spacecraft worked perfectly, which is always nice when you're driving a vehicle with 1.7 billion miles on the odometer," said Rick Nybakken, Juno project manager from JPL. "Jupiter orbit insertion was a big step and the most challenging remaining in our mission plan, but there are others that have to occur before we can give the science team members the mission they are looking for."
Over the next few months, Juno's mission and science teams will perform final testing on the spacecraft's subsystems, final calibration of science instruments and some science collection.
"Our official science collection phase begins in October, but we've figured out a way to collect data a lot earlier than that," said Bolton. "Which when you're talking about the single biggest planetary body in the solar system is a really good thing. There is a lot to see and do here."
Juno's principal goal is to understand the origin and evolution of Jupiter. With its suite of nine science instruments, Juno will investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras. The mission also will let us take a giant step forward in our understanding of how giant planets form and the role these titans played in putting together the rest of the solar system. As our primary example of a giant planet, Jupiter also can provide critical knowledge for understanding the planetary systems being discovered around other stars.
As you can see on the image below, Juno was placed in a highly elliptical polar orbit. The probe gets as close as 4300km, but at it's farthest point, it's farther away from Jupiter than Callisto, which has a mean distance from Jupiter of 1.88 million kilometers. The highly elongated orbit minimizes radiation exposure and should also keep the craft's solar panels in sunlight.