Success! The Juno spacecraft is now orbiting Jupiter

After a five-year journey, the Juno probe has begun to orbit the giant planet
Jul 7, 2016 — 3:55 pm EST
Juno at Jupiter

NASA’s Juno spacecraft successfully arrived at Jupiter on July 4. It’s the beginning of the probe’s 20-month visit to the giant planet. 


On July 4, NASA’s Juno probe arrived safely at Jupiter. The spacecraft traveled for nearly five years and 2.8 billion kilometers (1.74 million miles) through space. Its mission? To investigate the gas giant’s deep interior.

Researchers want to know everything they can about what lies beneath the planet’s blanket of clouds. Juno’s instruments will help them find out how much water vapor is hiding there. They will map the planet’s internal structure. And they will probe Jupiter’s vast magnetic field while looking at its polar regions.

Juno is the ninth spacecraft to visit the largest planet in our solar system. It’s the second to orbit it. And it will now spend 20 months circling Jupiter before diving to its death into the massive planet’s depths.

During its approach, Juno came within 76,000 kilometers (47,000 miles) of the tops of Jupiter’s clouds. (That’s about one-fifth the distance between Earth and our moon.) At 11:05 p.m., the spacecraft completed a 35-minute firing of its main engine. This helped Juno slow down to about 209,000 kilometers per hour (130,000 miles per hour). The decreased speed allowed the probe to be captured by Jupiter’s gravity and slip into orbit around it.

Juno wasn’t able to take pictures to celebrate its arrival. That’s because all of its scientific instruments were switched off on June 29. Otherwise, the delicate equipment could have been damaged when the probe flew through the planet’s strong radiation field. Scientists won’t get an intimate look at their target until August 27. That’s when Juno will swoop in again with all of its instruments turned on.

From here, Juno will make a 53-day loop around Jupiter that will end in October. Then it will begin a series of 14-day orbits. These will take the spacecraft above the planet’s north and south poles, soaring just 5,000 kilometers (3,100 miles) above the tops of the planet’s stormy clouds.

“What a feeling,” said Geoffrey Yoder, after learning that Juno had arrived safely. He’s the acting associate administrator of NASA’s division overseeing science missions, in Washington, D.C. “A mission of this complexity, to accomplish tonight, is just truly amazing.”

Rick Nybakken is Juno’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Tonight, through tones, Juno sang to us,” he noted on the orbiter’s arrival. “And it was a song of perfection.”

This video shows the reaction of NASA officials and Juno’s project scientists when they learned that the spacecraft had successfully completed its 5-year journey to Jupiter.JPL-CALTECH/NASA



Power Words

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gas giant    A giant planet that is made mostly of the gases helium and hydrogen. Jupiter and Saturn are gas giants.

gravity  The force that attracts anything with mass, or bulk, toward any other thing with mass. The more mass that something has, the greater its gravity.

Jupiter  (in astronomy) The solar system’s largest planet, it has the shortest day length (10 hours). A gas giant, its low density indicates that this planet is composed of light elements, such as hydrogen and helium. This planet also releases more heat than it receives from the sun as gravity compresses its mass (and slowly shrinks the planet).

magnetic field   An area of influence created by certain materials, called magnets, or by the movement of electric charges.

National Aeronautics and Space Administration, or NASA    Created in 1958, this U.S. agency has become a leader in space research and in stimulating public interest in space exploration. It was through NASA that the United States sent people into orbit and ultimately to the moon. It has also sent research craft to study planets and other celestial objects in our solar system.

orbit     The curved path of a celestial object or spacecraft around a star, planet or moon. One complete circuit around a celestial body.

planet     A celestial object that orbits a star, is big enough for gravity to have squashed it into a roundish ball and it must have cleared other objects out of the way in its orbital neighborhood. To accomplish the third feat, it must be big enough to pull neighboring objects into the planet itself or to sling-shot them around the planet and off into outer space. Astronomers of the International Astronomical Union (IAU) created this three-part scientific definition of a planet in August 2006 to determine Pluto’s status. Based on that definition, IAU ruled that Pluto did not qualify. The solar system now includes eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

radiation   (in physics) One of the three major ways that energy is transferred. (The other two are conduction and convection.) In radiation, electromagnetic waves carry energy from one place to another. Unlike conduction and convection, which need material to help transfer the energy, radiation can transfer energy across empty space.

solar system   The eight major planets and their moons in orbit around the sun, together with smaller bodies in the form of dwarf planets, asteroids, meteoroids and comets.

vapors   Fumes released when a liquid transforms to a gas, usually as a result of heating.


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Further Reading

C. Crockett. “Wandering Jupiter could have swept inner solar system clean.” Science News. Vol. 189, April 2, 2016, p. 7.

C. Crockett. “How did Earth get its water?” Science News. May 6, 2015.

E. Sohn. “Strange Neptune.” Science News for Students. January 9, 2007.

Mission Juno webpage. Southwest Research Institute.

Jupiter fact sheet. NASA. Updated May 16, 2016.