NASA's Juno Mission Burns for Jupiter

A NASA spacecraft now has Jupiter more squarely in its sights ahead of its July 4 arrival at the solar system's largest planet.

A NASA spacecraft now has Jupiter more squarely in its sights ahead of its July 4 arrival at the solar system's largest planet.

NASA's solar-powered Juno probe performed an engine burn Wednesday (Feb. 3), consuming 1.3 pounds (0.6 kilograms) of fuel to change its speed by about 0.7 mph (1.1 km/h). Juno was roughly 51 million miles (82 million kilometers) from Jupiter when it conducted the maneuver, agency officials said.

PHOTO: Juno Looks Back, Photographs Earth-Moon System

"This is the first of two trajectory adjustments that fine-tune Juno's orbit around the sun, perfecting our rendezvous with Jupiter on July 4 at 8:18 p.m. PDT [11:18 p.m. EDT; 0318 GMT on July 5]," Juno principal investigator Scott Bolton, of the Southwest Research Institute in San Antonio, said in a statement.

The second of these engine burns is scheduled to take place on May 31, NASA officials said.

The $1.1 billion Juno mission launched in August 2011. Its main goal involves mapping Jupiter's gravitational and magnetic fields in precise detail, to help scientists learn about the gas giant's structure, formation and evolution, mission team members have said.

Juno will perform its science work from orbit. The nominal mission plan calls for the 4-ton spacecraft to zip around Jupiter 33 times, coming within just 3,100 miles (5,000 km) of the planet's cloud tops once every 14 days, NASA officials said.

ANALYSIS: Is Jupiter a Soggy Planet?

Juno carries three 30-foot-long (9 m) solar panels, which together hold a total of 18,698 individual solar cells. Such extensive light-collecting gear is necessary to power the spacecraft in the relatively dim environment around Jupiter, which orbits more than five times farther from the sun than Earth does.

Last month, Juno became the farthest-flung solared-powered probe in spaceflight history. The previous record was held by the European Space Agency's comet-chasing Rosetta spacecraft, which got a maximum of 492 million miles (792 million km) from Earth in October 2012.

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Artist's impression of NASA's Juno spacecraft in orbit around Jupiter.

As NASA's Juno mission speeds towards a July 2016 date with Jupiter, the spacecraft is already racking up milestones in space. Just this month it became the furthest-flying solar spacecraft ever, even surpassing the feat of the Rosetta spacecraft that is still operating well at Comet 67P/Churyumov–Gerasimenko. As a preview of this amazing mission to the solar system's biggest planet, explore some of the science and engineering tasks Juno will focus on during its mission.

PHOTO: Juno Looks Back, Photographs Earth-Moon System

We often speak about the water on the icy moons in the outer solar system, such as Jupiter's Europa. But what is not is well-known is Jupiter itself has quite a bit of water in it. The upper atmosphere is actually seeded with water from the Shoemaker-Levy 9 comet impact of 1994. The water was discovered in 2013 after the Herschel Space Observatory found water concentrated in areas close to where the comet fragments

slammed into the atmosphere

. Water in other parts of the atmosphere may have come about during Jupiter's formation, when icy planetesimals were abundant in the solar system. Looking at water and other elements within Jupiter will give us a sense of what the solar system used to look like, because Jupiter -- unlike our own planet -- is very close in composition to what it was when it was formed. (Earth gained a new atmosphere through plants and volcanic eruptions, among other factors.

ANALYSIS: LEGO Figures Hitch a Ride with NASA's Juno Mission

Image: Jupiter's water distribution in the stratosphere, mapped by the Herschel Space Observatory. White and cyan show high concentrations, and blue is lower concentrations. The map is overlaid on a visible-image picture of Jupiter taken by the Hubble Space Telescope.

Jupiter has an enormous and powerful magnetosphere, which is greatly apparent in the strength of its auroras. (This 2007 outburst is an example). The challenge is there are few long-term observations of faraway planets, which is where Juno will have an advantage over observatories such as the Hubble Space Telescope that can only check in from time to time. The key to Jupiter's strong auroras is hydrogen gas getting crushed in the planet's intense gravity. It becomes metallic hydrogen and this fluid is very conductive. Juno will look at Jupiter's charged particles and magnetic fields from up close, with the aim of making projections for other big planets in our solar system and other locations.

ANALYSIS: Is Jupiter a Soggy Planet?

Image: A 2007 X-ray view of auroras on Jupiter taken by the Chandra X-Ray Telescope (purple). The optical picture is from the Hubble Space Telescope.

Jupiter's immense gravity is a boon when we try to send spacecraft far out in the solar system. We've used the giant planet as a speed boost for missions such as Voyager and New Horizons. The bonus is during these maneuvers, investigators usually turn on the cameras and at least some instruments to add to our scientific knowledge of Jupiter. Juno's role will be to look at the gravity field in detail, to find out about any changes and how they may be caused. Fluctuations in gravity could point to changes in the planet's interior structure.

VIDEO: Juno's Epic Flyby View of the Earth and Moon

Image: A massive plume is visible on Io (foreground) in this montage picture of Jupiter based on New Horizons data obtained in 2007.

One of the atmospheric mysteries of Jupiter is why the Great Red Spot is shrinking. This feature has been a part of Jupiter for at least 400 years (as long as we have had telescopes), but it's getting smaller for reasons that are poorly understood. The rate of shrinking also changes from year to year. The Hubble image you see here also shows a rare wave structure that was only seen once before, in pictures from 1977 taken by the Voyager 2 mission. For its part, Juno will map how deep these colorful features in the atmosphere penetrate, and also track the motions of fluids below the cloud tops for the first time.

NEWS: Spacecraft Sets Sail For Jupiter

Image: A 2015 map of Jupiter taken by the Hubble Space Telescope, including the Great Red Spot (lower right).

While Juno is focused on the science, the spacecraft itself will also be a useful point of study to plan future long-term missions. Juno is actually the furthest-operating spacecraft to use solar power, a milestone it just passed this month. Improvements in energy efficiency for the instruments and spacecraft, as well as better solar-cell performance, made this possible. As with all missions, scientists will be looking at how well the spacecraft does over time. When something breaks (as it inevitably will), the team will try to figure out a way to fix it. They will also try to design the next generation of that part better so that it doesn't break on the next spacecraft.

PHOTO: Smile, Earthlings: Jupiter Mission Captures Flyby Portrait