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| Artists rendering of Juno approaching Jupiter credit: NASA/JPL-Caltech |
Travelling at speeds of 58 kilometers a second(making it the fastest spacecraft to enter orbit around a planet), Juno fired its onboard engine for a risky thirty-five minute burn(insertion maneuver) on time at 11:18 p.m.
“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.
The burn occurred at the spacecraft’s closest approach to Jupiter, and slowed it enough to be captured by the giant planet’s gravity into a 53.5-day orbit.
Following an initial capture orbit, Jupiter will begin recording scientific data on its third orbit of the planet by which point the spacecraft will have entered a more stable 14 day-orbit.
Flying from north to south, the spacecraft’s point of closest approach above the cloud tops varies with each flyby -- coming as close as about 2,600 miles (4,200 kilometers) and as far out as 4,900 miles (7,900 kilometers). As Juno exits over the south pole, its orbit carries it far beyond even the orbit of the Jovian moon Callisto.
After the main engine burn, Juno will be in orbit around Jupiter. The spacecraft will spin down from 5 to 2 RPM, turn back toward the sun, and ultimately transmit telemetry via its high-gain antenna.
Over the course of this historic mission Juno will complete thirty-seven orbits over the next twenty months before burning up in Jupiter;s atmosphere to bring the mission to an end in February 2018.
“Independence Day always is something to celebrate, but today we can add to America’s birthday another reason to cheer - Juno is at Jupiter,” said NASA administrator Charlie Bolden.
The main goals of the Juno mission include:
-To find out how much water is in Jupiter's atmosphere, which helps determine which planet formation theory is correct (or if new theories are needed).
-To look deep into Jupiter's atmosphere to measure composition, temperature, cloud motions and other properties.
-To map Jupiter's magnetic and gravity fields, revealing the planet's deep structure
-To explore and study Jupiter's magnetosphere near the planet's poles, especially the auroras – Jupiter's northern and southern lights – providing new insights about how the planet's enormous magnetic force field affects its atmosphere.
-The possible discovery of new Jovian moons.
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| Juno's view of a half-lit Jupiter and four of its moons before all scientific instruments were turned off prior to Jupiter Orbit Insertion(JOI) credit: NASA/JPL |
One of the main mission objectives is to discover how a giant planet like Jupiter came into being, and how it evolved. This cloudy world is a primary example of a giant planet, and can also give us clues as to how other giant gas planets(called "Hot-Jupiters") which we have discovered orbiting other stars, may have formed.
Juno will accomplish this by studying the planet's cloudy atmosphere and its overall composition. By the end of the mission it is hoped that we will be able to see how Jupiter was born, and how important of a role it played in the formation of other planets in the solar system.
Using the suite of scientific instruments aboard Juno, teams back on Earth will study the magnetosphere of Jupiter, which will tell us if Jupiter has a solid core, and how big or small it might be.
Why the name Juno?
In Greek and Roman mythology, Jupiter was the king of the gods, as well as god of the sky and thunder. Jupiter drew a veil of clouds around himself to hide his mischief, and his wife, the goddess Juno, was able to peer through the clouds and reveal Jupiter's true nature.
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More information on the Juno mission is available at: http://www.nasa.gov/juno
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