Hello From Jupiter!

On July 4, NASA scientists nervously gathered in a mission control room in Pasadena, California. They were waiting to find out if a spacecraft called Juno had reached Jupiter. At 8:53 p.m. Pacific Time, the scientists received a series of beeps. The control room erupted with cheers: The signal, broadcast by Juno, meant the spacecraft had made it. 

“We only had one chance to get it right,” says Steven Levin, Juno’s project scientist. “So I was really relieved when Juno arrived safely.”

On July 4, NASA scientists nervously gathered in a mission control room in Pasadena, California. They were waiting to find out if a spacecraft called Juno had reached Jupiter. At 8:53 p.m. Pacific Time, the scientists received a series of beeps. The control room filled with cheers. The signal came from Juno, and it meant the spacecraft had made it.

“We only had one chance to get it right,” says Steven Levin, Juno’s project scientist. “So I was really relieved when Juno arrived safely.”

Juno’s epic trip began five years ago, when it launched from Cape Canaveral, Florida, on August 5, 2011. Since then, it has traveled 2.9 billion kilometers (1.8 billion miles). The spacecraft is now in orbit, or following a curved path, around Jupiter (see Juno’s Journey). Juno will get closer to the planet than any other spacecraft in history. Its mission is to gather data that could answer some big questions about the massive and mysterious planet.

Juno’s long trip began five years ago. It launched from Cape Canaveral, Florida, on August 5, 2011. Since then, it has traveled 2.9 billion kilometers (1.8 billion miles). The spacecraft is now in orbit, or following a curved path, around Jupiter (see Juno’s Journey). Juno will get closer to the planet than any other spacecraft in history. Its mission: gather data that could answer some big questions about the huge, mysterious planet.

Jupiter is the fifth planet from the sun and the largest planet in our solar system. It’s so big that a thousand Earths could fit inside it. Jupiter, Saturn, Neptune, and Uranus are our solar system’s four gas giants—planets made of mostly hydrogen and helium gases. 

Red, brown, yellow, and white clouds cover Jupiter’s surface in bands, making Jupiter look striped. Winds gust across the planet at 640 km (400 mi) per hour—twice as strong as the most powerful hurricanes on Earth. These winds create one of Jupiter’s most famous features: its Great Red Spot. This giant storm is about twice the width of Earth. 

Jupiter is the fifth planet from the sun and the largest planet in our solar system. It’s so big that a thousand Earths could fit inside it. Jupiter, Saturn, Neptune, and Uranus are our solar system’s four gas giants. These planets are made mostly of hydrogen and helium gases. 

Red, brown, yellow, and white clouds cover Jupiter’s surface in bands. They make Jupiter look striped. Winds gust across the planet at 640 km (400 mi) per hour. That’s twice as strong as the most powerful hurricanes on Earth. These winds form one of Jupiter’s most famous features: its Great Red Spot. This giant storm is about twice the width of Earth. 

“Everything about Jupiter is bigger and more extreme than other planets,” says Levin. “It’s surrounded by intense storms, and traveling into its clouds would be deadly.”

Scientists have learned about many of Jupiter’s features thanks to seven spacecraft that have flown by the planet and one that has orbited it. But Juno will get much closer than any of these past missions, which weren’t designed to survive the dangerous conditions surrounding Jupiter.

“Everything about Jupiter is bigger and more extreme than other planets,” says Levin. “It’s surrounded by intense storms, and traveling into its clouds would be deadly.”

Scientists have learned much about many of Jupiter’s features. That’s because seven spacecraft have flown by the planet, and one has orbited it. But these past missions weren’t designed to survive the dangerous conditions around Jupiter. Juno will get much closer than any of them did.

The biggest obstacle to getting close to Jupiter is the intense radiation around it. The radiation comes from tiny charged particles emitted by the sun and Io—one of Jupiter’s 67 moons—and caught in Jupiter’s magnetic field. Jupiter’s field is much stronger than the similar force on Earth that moves compass needles. It accelerates the particles to incredible speeds (see Dangerous Radiation). 

It’s some of the most powerful radiation a spacecraft has ever encountered. Even though these particles don’t weigh much, they carry huge amounts of energy with them. These fast-moving particles can interfere with a spacecraft’s instruments or damage them permanently.  

The biggest problem with getting close to Jupiter is the strong radiation around it. The radiation comes from tiny charged particles sent out by the sun and Io—one of Jupiter’s 67 moons. The particles are caught in Jupiter’s magnetic field. This is similar to the force on Earth that moves compass needles. But Jupiter’s field is much stronger. It drives the particles to amazing speeds (see Dangerous Radiation). 

It’s some of the most powerful radiation a spacecraft has ever met. These particles don’t weigh much, but they carry huge amounts of energy with them. These fast-moving particles can interfere with a spacecraft’s instruments. They can even damage the instruments permanently.

Before Juno went into orbit, its star tracker was shut off to prevent interference. This device helps keep the spacecraft on course. Without it, the spacecraft was flying blind. “At that point, you just hold your breath and cross your fingers,” says NASA astrophysicist Jack Connerney. Juno was so far away that it took 48 nail-biting minutes for its communications to reach scientists and let them know that the spacecraft had arrived. 

Scientists still have to worry about radiation as Juno orbits Jupiter. To help protect the spacecraft, engineers designed Juno to follow an orbit that dips in and out of Jupiter’s radiation belt. That way Juno can avoid the most-intense patches of charged particles and limit the damage they are expected to cause. On this oval-shaped path, Juno soars from Jupiter’s north to south pole. As Jupiter rotates, Juno will get a close-up look at different parts of the planet with each flyby. There, it can snap amazingly detailed pictures and capture valuable data. 

Before Juno went into orbit, its star tracker was shut off to prevent interference. This device helps keep the spacecraft on course. Without it, the spacecraft was flying blind. “At that point, you just hold your breath and cross your fingers,” says NASA astrophysicist Jack Connerney. Juno was so far away that it took 48 nail-biting minutes for its signal to reach scientists. Then they finally knew that the spacecraft had arrived. 

Scientists still have to worry about radiation as Juno orbits Jupiter. They designed the spacecraft to follow a path that will help protect it. Along this orbit, Juno dips in and out of Jupiter’s radiation belt. That way, Juno can miss the strongest patches of charged particles. This will limit the damage they’re expected to cause. Juno soars on this oval-shaped path from Jupiter’s north to south pole. As Jupiter turns, Juno will get a close-up look at different parts of the planet with each flyby. There, it can snap pictures that are more detailed than ever before. It can also gather important data.