PASADENA, Calif. – Braving intense radiation, a NASA spacecraft reached Jupiter on Monday after a five-year voyage to begin exploring the king of the planets.
Ground controllers at the NASA Jet Propulsion Laboratory and Lockheed Martin erupted in applause when the solar-powered Juno spacecraft beamed home news that it was circling Jupiter’s poles.
READ MORE: Juno mission to Jupiter: What scientists hope to learn about solar system’s giant planet
The arrival at Jupiter was dramatic. As Juno approached its target, it fired its rocket engine to slow itself down and gently slipped into orbit. Because of the communication time lag between Jupiter and Earth, Juno was on autopilot when it executed the daring move.
“Juno, welcome to Jupiter,” said mission control commentator Jennifer Delavan of Lockheed Martin, which built Juno.
The spacecraft’s camera and other instruments were switched off for arrival, so there won’t be any pictures at the moment it reaches its destination. Hours before the encounter, NASA released a series of images taken last week during the approach, showing Jupiter glowing yellow in the distance, circled by its four inner moons.
WATCH: The moment NASA scientists knew the Juno mission had succeeded
Scientists have promised close-up views of the planet when Juno skims the cloud tops during the 20-month, $1.1 billion mission.
The fifth rock from the sun and the heftiest planet in the solar system, Jupiter is what’s known as a gas giant — a ball of hydrogen and helium — unlike rocky Earth and Mars.
With its billowy clouds and colorful stripes, Jupiter is an extreme world that likely formed first, shortly after the sun. Unlocking its history may hold clues to understanding how Earth and the rest of the solar system developed.
Named after Jupiter’s cloud-piercing wife in Roman mythology, Juno is only the second mission designed to spend time at Jupiter.
WATCH: Hubble captures brilliant aurora on Jupiter as Juno spacecraft nears
Galileo, launched in 1989, circled Jupiter for nearly a decade, beaming back splendid views of the planet and its numerous moons. It uncovered signs of an ocean beneath the icy surface of the moon Europa, considered a top target in the search for life outside Earth.
Juno’s mission: To peer through Jupiter’s cloud-socked atmosphere and map the interior from a unique vantage point above the poles. Among the lingering questions: How much water exists? Is there a solid core? Why are Jupiter’s southern and northern lights the brightest in the solar system?
WATCH: Juno’s journey to Jupiter
“What Juno’s about is looking beneath that surface,” Juno chief scientist Scott Bolton said before the arrival. “We’ve got to go down and look at what’s inside, see how it’s built, how deep these features go, learn about its real secrets.”
There’s also the mystery of its Great Red Spot. Recent observations by the Hubble Space Telescope revealed the centuries-old monster storm in Jupiter’s atmosphere is shrinking.
The trek to Jupiter, spanning nearly five years and 2.8 billion kilometres, took Juno on a tour of the inner solar system followed by a swing past Earth that catapulted it beyond the asteroid belt between Mars and Jupiter.
READ MORE: Juno’s mission to Jupiter: 7 weird and wonderful facts about this giant planet
Along the way, Juno became the first spacecraft to cruise that far out powered by the sun, beating Europe’s comet-chasing Rosetta spacecraft. A trio of massive solar wings sticks out from Juno like blades from a windmill, generating 500 watts of power to run its nine instruments.
In the coming days, Juno will turn its instruments back on, but the real work won’t begin until late August when the spacecraft swings in closer. Plans called for Juno to swoop within 5,000 kilometres of Jupiter’s clouds — closer than previous missions — to map the planet’s gravity and magnetic fields in order to learn about the interior makeup.
Juno is an armoured spacecraft — its computer and electronics are locked in a titanium vault to shield them from harmful radiation. Even so, Juno is expected to get blasted with radiation equal to more than 100 million dental X-rays during the mission.
Like Galileo before it, Juno meets its demise in 2018 when it deliberately dives into Jupiter’s atmosphere and disintegrates — a necessary sacrifice to prevent any chance of accidentally crashing into the planet’s potentially habitable moons.
3-2-1: A look at NASA’s Jupiter mission by the numbers
Since launching in 2011, NASA’s Juno spacecraft has been cruising toward the biggest planet in the solar system. On Monday, Juno performed a nail-biting move that placed it into orbit around Jupiter to explore its cloud-covered atmosphere and interior makeup.
Here are a few key numbers about the $1.1 billion mission:
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.
5,000 kilometres
That’s how close Juno will fly to Jupiter’s cloud tops. It’ll pass over the poles 37 times during the mission on a path that avoids the most intense radiation.
48 minutes, 19 seconds
That’s the time it took for radio signals from Jupiter to reach Earth. During the encounter, Juno fired its main engine for about a half hour to slow down. By the time ground controllers receive word, the engine burn was completed, placing Juno 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.