NASA’s solar-powered Juno spacecraft successfully entered Jupiter’s orbit on Tuesday after a five-year journey from Earth, in a giant step to understand the origin and evolution of the king of planets and the solar system. “We’re there. We’re in orbit. We conquered Jupiter,” Juno chief scientist Scott Bolton said during a post-mission briefing.
As America celebrated its Independence Day, mission controllers at NASA’s Jet Propulsion laboratory (JPl) erupted in cheers when the $1.1 billion Juno spacecraft sent home the news of successfully executing a 35-minute engine burn that put the probe into the planned orbit around Jupiter. With its suite of nine science instruments, Juno will study 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 auroras on our solar system’s largest planet.
In the weeks leading up to the encounter, Juno snapped pictures of the giant planet and its four inner moons dancing around it. Scientists were surprised to see Jupiter’s second-largest moon, Callisto, appearing dimmer than expected. The spacecraft’s camera and other instruments were switched off for arrival, so there weren’t any pictures at that key moment. Scientists have promised close-up views of the planet when Juno skims the cloud tops during the 20-month mission.
The mission also will let us take a big 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, NASA said. As our primary example of a giant planet, Jupiter also can provide critical knowledge for understanding the planetary systems being discovered around other stars. The Juno spacecraft was launched on August 5, 2011 from Cape Canaveral Air Force Station in Florida.
“With Juno, we will investigate the unknowns of Jupiter’s massive radiation belts to delve deep into not only the planet’s interior, but into how Jupiter was born and how our entire solar system evolved,” said NASA administrator Charlie Bolden.
Confirmation of a successful orbit insertion was received from Juno tracking data monitored at the navigation facility at JPl in California, as well as at the lockheed Martin Juno operations centre in Colorado. The telemetry and tracking data were received by NASA’s Deep Space Network antennas in the US and Australia.
The burn of Juno’s main engine began at 8.48 am IST, decreasing the spacecraft’s velocity by 542 metres per second and allowing Juno to be captured in orbit around Jupiter. Soon after the burn was completed, Juno turned so that the Sun’s rays could once again reach the 18,698 individual solar cells that give Juno its energy.
“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 the mission they are looking for,” said Nybakken.
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.
Juno is only the second mission designed to spend time at Jupiter. 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 is to peer through Jupiter’s cloud-socked atmosphere and map the interior from a unique vantage point above the poles. However, there are the lingering questions: How much water existsIJ Is there a solid coreIJ Why are Jupiter’s southern and northern lights the brightest in the solar systemIJ
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 braved a hostile radiation environment to reach Jupiter. Engineers prepared by housing the spacecraft’s computer and electronics in a titanium vault. 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 will meet 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.