Jupiter got a little less lonely today as NASA's Juno deep-space probe arrived after a five-year journey capped by a dramatic engine maneuver. The space agency's Deep Space Network has confirmed that the unmanned spacecraft successfully initiated a 35-minute course correction burn at 8:18 pm EDT (Earth Receive Time) that placed it in orbit around the Solar System's largest planet for a 20-month science mission.

According to NASA, Juno's final path to Jupiter orbit began about four days ago when the spacecraft received its final updates and reconfigured itself for the engine burn. All of the science instruments were powered down and some of the onboard computer's fault detection systems were taken offline to avoid interference with the maneuver. Instead, the computer was ordered to execute a quick shutdown/restart procedure in the event of trouble to prevent interrupting the engine burn.


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Two hours before the burn, the probe turned away from the Sun to position the main engine at the correct angle. From then until the end of the burn, Juno was on battery power. Half an hour before engine ignition the spacecraft stabilized its attitude and increased its rotation from two to five revolutions per minute.

Image of Jupiter and its moons sent back by Juno (Credit: NASA)

Because Jupiter is 540 million mi (869 million km) away, it takes 48 minutes and 19 seconds for signals to travel back to Earth, so the entire course correction was carried out entirely under autonomous control. As a jubilant mission control at the Jet Propulsion Laboratory monitored the flight, the burn completed at 8:53 p.m. PDT (Earth Receive Time). Juno shut down its main engine and reduced its rotation back to two RPM and pointed its panels back toward the Sun.

About 58 minutes after the start of the maneuver, Juno resumed telemetry transmission to Earth. The orbiter is programmed to switch its scientific instruments back on in about two days.

Named after the Roman goddess and wife of Jupiter, Juno is the first solar-powered spacecraft sent into the outer Solar System, the second spacecraft to orbit Jupiter, and the first to orbit its poles. With its giant solar panels, Juno is about as big as a basketball court and it has a specially hardened titanium vault to protect its avionics from Jupiter's intense radiation belts.

Juno lifted off from Space Launch Complex 41 at Cape Canaveral Air Force Station, Florida atop an Atlas/Centaur rocket on August 5, 2011. It arrived at Jupiter almost five years later after a roundabout orbit that sent it on a flyby of Earth in 2013 to build up speed to match orbits with Jupiter, resulting in a total distance traveled of 1.7 billion mi (2.8 billion km).

The Juno mission is tasked with returning the highest-resolution images of Jupiter in history with a special emphasis on the polar regions. It will look for clues regarding Jupiter's formation, determine the deep structure of the planet, and study its magnetic fields and the giant aurorae at the poles.

Currently, Juno is headed into a 53.5-day temporary orbit to conserve propellant. A subsequent burn in October will move the orbiter into its planned, highly eccentric 14-day orbit that will bring it within 2,600 mi (4,200 km) of Jupiter's cloud tops. Its scientific mission will continue for about 20 months, after which the local radiation will have degraded Juno's avionics. On February 20, 2018, it will make a controlled dive into the Jovian atmosphere, where it will burn up to avoid biological contamination of Jupiter's moons.

The animation below shows Juno arriving in Jupiter orbit.

Source: NASA

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