Nasa's spacecraft Juno arrives safely at Jupiter after its epic 1.8BILLION mile journey

The solar-powered spacecraft which left Earth five years ago has finally reached its destination and entered into Jupiter's orbit.

Nasa's Juno spacecraft fired its main rocket engine at 4.18am BST, slowing itself down from a speed of 165,000 mph (265,000 kph) enough to drop into the gas giant's orbit.

The space station's mission control erupted with cheering and applause when the orbit was confirmed.

During its mission of exploration, Juno will circle the Jovian world a total of 37 times, soaring low over the planet's cloud tops.

The spacecraft will end its mission in 2018 when it takes a swan dive into Jupiter's atmosphere and disintegrates — a necessary sacrifice to prevent any chance of accidentally crashing into the planet's potentially habitable moons.

This image shows an Atlas V rocket carrying the Juno spacecraft lifts off from Space Launch Complex-41 in Cape Canaveral, Florida. It was the first step in Juno's 1.8 billion-mile voyage to the gas giant planet, Jupiter

JUNO'S MISSION IN NUMBERS 

— 1.8 billion miles (2.8 billion kilometres) 

That's the total distance travelled from launch to arrival. Juno's journey wasn't a straight shot. Because the rocket that carried Juno wasn't powerful enough to boost it directly to Jupiter, it took a longer route. It looped around the inner solar system and then swung by Earth, using our planet as a gravity slingshot to hurtle toward the outer solar system.

— 3,100 miles (5,000 kilometres)

That's how close Juno will fly to Jupiter's cloud tops. It will pass over the poles a total of 37 times during the mission on a path that avoids the most intense radiation, before it plunges into the planet's atmosphere.

— 48 minutes, 19 seconds

That's the time it takes for radio signals from Jupiter to reach Earth. During the encounter, Juno will fire its main engine for about a half hour to slow down. By the time ground controllers receive word that it started, the engine burn would have been completed, and if all goes as planned, Juno would be in orbit.

— 20 months

That's how long the mission will last. Because Juno is in a harsh radiation environment, its delicate electronics are housed in a special titanium vault. Eventually, Juno will succumb to the intense radiation and will be commanded to plunge into Jupiter's atmosphere to avoid any collision with the planet's moons.

— Nine

Juno carries a suite of nine instruments to explore Jupiter from its interior to its atmosphere. It will map Jupiter's gravity and magnetic fields and track how much water is in the atmosphere. Its colour camera dubbed JunoCam will snap close-ups of Jupiter's swirling clouds, polar regions and shimmering southern and northern lights.

— Three

Three massive solar wings extend from Juno, making it the most distant solar-powered spacecraft. The panels can generate 500 watts of electricity, enough to power the instruments

WHAT ARE JUPITER'S GREAT UNKNOWNS? 

 

Water 

Like the sun, Jupiter is a ball of mostly hydrogen and helium. It was probably the first planet to form. Jupiter is 11 times wider than Earth and with 300 times the mass. Juno will hunt for water in Jupiter's atmosphere, which may help explain how Earth got its water. Previous spacecraft found only a trace amount in Jupiter's atmosphere, but scientists think they didn't look deep enough. Juno carries an instrument that can pierce through thick clouds to measure the water content.

Great red spot 

A world of swirling clouds and colourful stripes, Jupiter's most prominent feature is the Great Red Spot, a fierce storm in the atmosphere larger than Earth that has lasted for centuries. In recent years, the spot has been mysteriously shrinking. Once an oval about 25,500 miles wide (41,036 kilometres) in the late 1880s, the spot shrank to its smallest observed size in 2014 — the shape of a circle about 10,250 miles across (16,495 kilometres). Juno will study how deep into the atmosphere the Great Red Spot extends in an effort to understand what may happen next to Jupiter's trademark.

Auroras 

Earth's dazzling southern and northern lights are dim compared to Jupiter's auroras, the brightest in the solar system. Earth's polar lights are triggered by solar storms, which occur when a cloud of gas from the sun slams into the planet's magnetic field. Jupiter's powerful auroras are sparked by the planet's own rotation. Jupiter is the fastest-spinning planet in the solar system, taking just 10 hours to complete a rotation. As Jupiter spins, it drags its magnetic field around with it. Juno will observe the light show and learn about the driving forces behind it.

Polar regions 

The first peek of Jupiter's poles came in 1974 when Pioneer 11 flew by en route to Saturn. Juno will get a more detailed look by passing over Jupiter's polar regions. During the next year, the spacecraft will circle Jupiter 37 times from pole to pole — a path that will cover the whole planet. At its closest approach, Juno will skim within 3,100 miles (5,000 kilometres) of Jupiter's cloud tops.

JUPITER'S GIANT AURORA 

Jupiter's auroras were first discovered by the Voyager 1 spacecraft in 1979. 

A thin ring of light on Jupiter's nightside looked like a stretched-out version of our own auroras on Earth. 

But later, astronomers discovered the auroras were best visible in the ultraviolet. Scientists also discovered the planet has X-ray aurora too.

Jupiter's aurora are larger than our entire planet and unlike those on Earth, occur almost continuously.

This suggests that the mechanism causing this light show is different from that on Earth.

While Earth's Northern and Southern lights are triggered by energetic particles from the sun slamming into gas atoms high in the atmosphere, Jupiter appears to have another source.

Scientists believe its powerful magnetic field accellerates charged particles from the space around it towards its poles, to cause similar interactions.

The volcanic moon Io spews oxygen and sulfur ions into Jupiter's spinning magnetic field, which sends them hurtling towards the planet below. 

Upon entering the atmosphere, their electrons are first stripped away by molecules they run into, but as they slow down they start grabbing electrons back. 

The 'charge exchange reaction' produces intense X-ray auroras.

Yet scientists have been baffled as to how Jupiter's magnetic field accelerates these particles. 

Note

Juno's name comes from Greek and Roman mythology. 

Jupiter, the father of the Roman gods, drew a veil of clouds around himself to hide his mischief.

 But his wife - the goddess Juno - was able to peer through the clouds and reveal Jupiter's true nature

Named after the Roman god Jupiter's cloud-piercing wife, Juno is only the second mission designed to spend time at Jupiter. 

Galileo, which launched in 1989, circled Jupiter for 14 years, beaming back splendid views of the planet and its numerous moons.

 It uncovered signs of an ocean beneath the icy surface of Europa, considered a top target in the search for life outside Earth.