'It's amazing': U of A scientist excited as Juno probe reaches Jupiter

Earthlings are getting an unprecedented view of Jupiter now that a NASA probe has arrived inside the planet's orbit for a peek behind the clouds. 

A sequence of tones beamed back Tuesday confirmed the Juno satellite had successfully manoeuvred its way into the planet's gravitational pull, five years after it departed Earth.

The trip took nearly five years and covered 2.8 billion kilometres. It was only one second off its estimated arrival time. 

"It was really exciting and it was a big relief that it got into orbit," said Moritz Heimpel, a physics professor at the University of Alberta who has been studying Jupiter's jet streams and anti-cyclones for years.

"It's amazing the windows that they have. They travel for five years and then they only have minutes or seconds to hit their targets. And they did it." 

The probe will spend 20 months circling Jupiter, peering behind the thick cloud cover and studying the planet's gravity and magnetic fields.

No other spacecraft has flown so close to the massive planet. The radiation from the belts that surround the planet can destroy unprotected instruments in seconds.

Heimpel said a lot could have gone wrong when the probe fired a rocket engine to slow its approach into orbit.

"You never know, if the booster doesn't fire, this thing can keep hurtling out into space," Heimpel said during a Tuesday interview on CBC Edmonton's Radio Active. "But everything appears to have gone as planned.

"So now we're just going to wait until the data starts coming in." 

For scientists and sky watchers, it will feel like a long wait. The data won't start beaming back to Earth in earnest until late fall.

The satellite will first make a 53-day orbit around the planet. After that, a second burn of the engine in mid-October will shorten its orbit to just 14 days. 

And that's when it can start truly measuring and documenting the planet as it passes, again and again, just a few thousand kilometres above the surface.

Unlike its predecessor, the Galileo probe that orbited Jupiter's equator from 1995 to 2003, Juno will orbit the poles, giving it a more expansive view of the planet's turbulent surface.

Juno's instruments will measure the surface storms, the planet's gravitational pull, and search for clues of remnant water sources. 

Heimpel  is particularly intrigued by the Great Red Spot, a massive anti-cyclonic storm. 

"There are also these big storms on Jupiter, and we don't know how deep they go," said Heimpel. 

"We don't know how deep the bands go, and we don't know how do they interact with the part of the planet that's generating its magnetic field." 

The probe will seek to answer many questions that have long puzzled scientists, including whether the planet has a solid or gaseous core.

"We don't even know if there is a rocky core, if there is a solid part to Jupiter at all. It may be a completely fluid planet. So with all the gravity data and beautiful instruments that Juno has, we'll get a much better idea as to whether these things are true or not."