Juno (spacecraft) facts for kids

Quick facts for kids
Juno

Artist's rendering of the Juno spacecraft
Names	New Frontiers 2
Mission type	Jupiter orbiter
Operator	NASA / Jet Propulsion Laboratory
Website	(NASA) (SwRI)
Mission duration	Planned: 7 years Elapsed: 13 years, 11 months, 25 days Cruise: 4 years, 10 months, 29 days Science phase: 4 years (in progress; extended until September 2025)
Spacecraft properties
Manufacturer	Lockheed Martin Space
Launch mass	3,625 kg (7,992 lb)
Dry mass	1,593 kg (3,512 lb)
Dimensions	20.1 × 4.6 m (66 × 15 ft)
Power	14 kW at Earth, 435 W at Jupiter 2 × 55-ampere hour lithium-ion batteries
Start of mission
Launch date	August 5, 2011, 16:25:00 UTC
Rocket	Atlas V 551 (AV-029)
Launch site	Cape Canaveral, SLC-41
Contractor	United Launch Alliance
Flyby of Earth
Closest approach	October 9, 2013
Distance	559 km (347 mi)
Jupiter orbiter
Orbital insertion	July 5, 2016, 9 years, 25 days ago
Orbits	76 (planned)
Orbit parameters
Perijove	4,200 km (2,600 mi) altitude 75,600 km (47,000 mi) radius
Apojove	8.1×10^6 km (5.0×10^6 mi)
Inclination	90° (polar orbit)
Juno mission patch New Frontiers ← New Horizons OSIRIS-REx →

Juno in launch configuration

The Juno spacecraft is a NASA space probe that orbits the giant planet Jupiter. It was built by Lockheed Martin and is operated by NASA's Jet Propulsion Laboratory. Juno launched from Cape Canaveral Air Force Station on August 5, 2011. It is part of the New Frontiers program, which sends probes to explore different parts of our Solar System.

Juno arrived at Jupiter and entered a special polar orbit on July 5, 2016. Its main job is to study Jupiter up close. Scientists want to learn about Jupiter's makeup, its gravity, its magnetic field, and the area around its poles called the polar magnetosphere. The mission also looks for clues about how Jupiter formed. This includes trying to find out if it has a rocky core, how much water is deep in its atmosphere, and how its strong winds move. These winds can blow at speeds of up to 620 kilometers per hour (about 385 miles per hour)!

Juno is the second spacecraft to orbit Jupiter. The first was the Galileo orbiter, which explored Jupiter from 1995 to 2003. Unlike many other spacecraft that travel far into the outer Solar System and use nuclear power, Juno uses solar panels. These are more common for satellites orbiting Earth or working closer to the Sun. Because Jupiter is so far from the Sun, Juno needed the largest solar panels ever used on a planetary probe when it launched. These huge panels help keep the spacecraft stable and provide all its power.

Why is it Called Juno?

Juno's name comes from Greek and Roman mythology. The god 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.

The name Juno comes from ancient Roman myths. In these stories, the god Jupiter would hide himself behind clouds. But his wife, the goddess Juno, could see through the clouds and discover his true self. This is like the spacecraft, which is designed to "see through" Jupiter's thick clouds to learn its secrets.

Sometimes, Juno is also called New Frontiers 2. This is because it's the second mission in NASA's New Frontiers program.

Mission Overview

Juno's interplanetary path.

Animation of Juno's journey from August 5, 2011.       Juno ·       Earth ·       Mars ·       Jupiter

Juno was chosen for the New Frontiers program on June 9, 2005. Before Juno, scientists really wanted to send a probe to Jupiter, but no missions had been approved for a while.

Juno took five years to travel to Jupiter, arriving on July 5, 2016. The spacecraft traveled about 2.8 billion kilometers (1.7 billion miles) to get there. It was designed to orbit Jupiter 37 times. This was originally planned to take about 20 months.

To get a speed boost, Juno used a gravity assist from Earth. This happened during an Earth flyby in October 2013, two years after its launch. When Juno reached Jupiter, it fired its engine to slow down and enter Jupiter's orbit.

The mission was originally set to end in February 2018. However, it has been extended multiple times. In January 2021, NASA extended the mission until September 2025. This allows Juno to study Jupiter's large moons: Ganymede, Europa, and Io. Juno flew very close to Ganymede on June 7, 2021, and Europa on September 29, 2022. It also had close flybys of Io on December 30, 2023, and February 3, 2024.

Journey to Jupiter

Juno ready for launch in 2011.

Launching into Space

Juno launched on an Atlas V rocket from Cape Canaveral Space Force Station in Florida. This happened on August 5, 2011, at 16:25 UTC. The rocket used a powerful main engine and five solid rocket boosters to lift off.

After the boosters fell away, a protective cover called the payload fairing separated. This cover kept Juno safe during its trip through Earth's atmosphere. Then, the Atlas V main engine shut off, and the Centaur second stage ignited. This stage fired twice, first putting Juno into a parking orbit around Earth, and then pushing it onto a path to escape Earth's gravity and head towards the Sun.

Before separating from the Centaur stage, Juno was spun up to 1.4 rotations per minute. This spin helps keep the spacecraft stable during its long journey. About 54 minutes after launch, Juno separated and began to unfold its large solar panels. Once the panels were fully open, Juno's batteries started recharging.

• 

  Atlas V on launch pad.

• 

  Lift-off.

Earth Flyby and Speed Boost

South America seen by JunoCam during its October 2013 Earth flyby.

After traveling for about a year, Juno fired its engine twice to change its path. This brought it back to Earth for a close flyby on October 9, 2013. This maneuver, called a gravity assist, used Earth's gravity to give Juno a huge speed boost. It increased Juno's speed by more than 3.9 kilometers per second (about 8,700 miles per hour), sending it on its way to Jupiter. This flyby also allowed the Juno team to test some of the spacecraft's instruments.

Arriving at Jupiter

Jupiter's strong gravity pulled Juno in, speeding it up to about 210,000 kilometers per hour (130,000 miles per hour). On July 5, 2016, Juno fired its engine for over 2,100 seconds. This slowed it down enough to be captured by Jupiter's gravity. The spacecraft successfully entered an elliptical, polar orbit around Jupiter.

Orbiting Jupiter

Juno's elliptical orbit and Jupiter's radiation belts.

Juno's orbit is very stretched out. It comes as close as 4,200 kilometers (2,600 miles) to Jupiter's cloud tops and then swings out as far as 8.1 million kilometers (5 million miles). This special orbit helps Juno avoid Jupiter's intense radiation belts. These belts can damage spacecraft electronics and solar panels.

To protect its sensitive electronics, Juno has a special "Juno Radiation Vault." This vault has 1-centimeter-thick titanium walls, which reduce the radiation by 800 times. Even with this protection, the radiation is very strong.

How Juno Works

Animation of Juno's path around Jupiter from June 1, 2016, to October 25, 2025.       Juno ·       Jupiter

Ganymede, photographed on June 7, 2021, by Juno during its extended mission.

Juno completed its first close flyby of Jupiter on August 26, 2016. It captured the first images of Jupiter's north pole.

On October 14, 2016, some of Juno's helium valves didn't open correctly. A few days later, Juno went into "safe mode." This means its computer detected a problem and powered down non-essential systems to protect itself. Because of this, no science data was collected during its second close approach. However, the mission team fixed the issue, and by December 11, 2016, most instruments were working again.

The mission was extended in June 2018 and again in January 2021. This allowed Juno to continue its studies until September 2025. During this extended phase, Juno has been making close flybys of Jupiter's largest moons: Ganymede, Europa, and Io. These flybys help scientists learn more about these fascinating worlds.

Planned End of Mission

NASA originally planned for Juno to intentionally crash into Jupiter's atmosphere after its mission. This is done to prevent any chance of the spacecraft accidentally hitting one of Jupiter's moons, especially Europa, which might have conditions suitable for life. This process helps avoid contaminating the moons with any tiny Earth microbes that might have survived on the spacecraft. However, with the mission extensions, the deorbit date has been pushed back.

The Juno Team

The Juno mission involves many talented people. Scott Bolton from the Southwest Research Institute is the main scientist in charge. The Jet Propulsion Laboratory in California manages the mission, and Lockheed Martin built the spacecraft. Many other scientists and institutions also help with the mission.

Mission Cost

The Juno mission was originally estimated to cost about $700 million in 2003. By 2019, the total cost for operations and data analysis through 2022 was projected to be $1.46 billion.

What Juno Studies

Jupiter imaged using the VISIR instrument on the VLT. Juno builds on these observations.

Juno's science instruments are designed to answer big questions about Jupiter:

• Water in Jupiter: It measures how much water is in Jupiter's atmosphere. This helps scientists understand how Jupiter and the rest of the Solar System formed.
• Jupiter's Core: It tries to figure out the mass of Jupiter's core. This also helps with theories about the planet's formation.
• Gravity and Mass: It precisely maps Jupiter's gravitational field. This shows how mass is spread out inside Jupiter, giving clues about its structure.
• Magnetic Field: It maps Jupiter's magnetic field to understand where it comes from and how deep inside the planet it is created.
• Atmosphere: It studies the different layers of Jupiter's atmosphere, including its temperature, clouds, and how its winds move.
• Polar Lights: It explores the 3D structure of Jupiter's polar magnetosphere and its amazing auroras (like the Northern and Southern Lights on Earth).

Science Tools on Juno

Juno carries nine special instruments to achieve its goals:

Microwave Radiometer (MWR)

Microwave Radiometer

This instrument has six antennas that measure microwave energy. Microwaves can pass through Jupiter's thick atmosphere. The MWR measures water and ammonia deep in the atmosphere, up to 500-600 kilometers (310-370 miles) deep. This helps scientists understand how deep the atmospheric circulation goes.

Jovian Infrared Auroral Mapper (JIRAM)

Jovian Infrared Auroral Mapper

JIRAM is a camera that sees in near infrared light. It studies the upper layers of Jupiter's atmosphere. It also takes pictures of Jupiter's auroras. By measuring heat from the atmosphere, JIRAM can see how clouds with water move beneath the surface. It can also detect gases like methane and ammonia.

Magnetometer (MAG)

MAG

The MAG instrument measures Jupiter's magnetic field. It helps map the field's strength and direction. This tells scientists about the inside of Jupiter and the structure of its polar magnetosphere.

Gravity Science (GS)

Gravity Science

This experiment measures Jupiter's gravity. Small changes in gravity affect Juno's speed as it orbits. By detecting these tiny speed changes using radio waves sent to Earth, scientists can create a map of how mass is distributed inside Jupiter.

Jovian Auroral Distributions Experiment (JADE)

JADE

JADE is a particle detector. It measures low-energy ions and electrons in Jupiter's auroras. This helps scientists understand the particles that create the stunning light shows at Jupiter's poles.

Jovian Energetic Particle Detector Instrument (JEDI)

JEDI

JEDI also detects energetic particles, but at higher energies than JADE. It measures ions and electrons in Jupiter's polar magnetosphere. This helps scientists study how these particles behave in Jupiter's powerful magnetic environment.

Radio and Plasma Wave Sensor (Waves)

Radio and Plasma Wave Sensor

This instrument has two antennas that detect radio and plasma waves. It helps identify the regions where auroral currents flow and how particles are sped up to create Jupiter's radio emissions and auroras. It also observes how Jupiter's atmosphere and magnetosphere interact.

Ultraviolet Spectrograph (UVS)

Ultraviolet Spectrograph

UVS records ultraviolet light. It provides images of the UV light coming from Jupiter's auroras in the polar magnetosphere. This helps scientists understand the processes that cause these lights.

JunoCam (JCM)

JunoCam

JunoCam is a visible light camera. It was originally included for public outreach, but it's now also used to study Jupiter's clouds, especially those at the poles. Even though it was expected to last only about eight orbits due to radiation, JunoCam is still working well after more than 55 orbits!

Where Juno's science instruments are located.

Juno's Design

Solar Panels

Illumination test on one of Juno's solar panels.

Juno is the first mission to Jupiter to use solar panels instead of nuclear power. Even though Jupiter is far from the Sun, solar panel technology has improved a lot. Juno has three huge solar panels, each about 2.7 by 8.9 meters (9 by 29 feet). Together, they have 50 square meters (538 square feet) of solar cells. These were the largest solar panels ever on a NASA deep-space probe when Juno launched.

At Jupiter, Juno receives only about 4% of the sunlight it would get at Earth. The panels generate about 435 watts of power. Two large lithium-ion batteries store power for when Juno passes through Jupiter's shadow.

Communication

Juno's high-gain antenna dish being installed.

Juno communicates with Earth using large antennas from NASA's NASA Deep Space Network. It sends data back using X-band radio waves. The spacecraft's computer can send about 50 megabits of instrument data per second.

Because of communication limits, Juno can only send back about 40 megabytes of JunoCam images during each 11-day orbit. This means it sends between 10 and 100 images per orbit, depending on how much they are compressed. The main focus is on sending back scientific data from the other instruments.

Propulsion System

Juno uses a main engine for big maneuvers, like entering Jupiter's orbit. It also has twelve smaller thrusters. These small thrusters are used to control the spacecraft's direction and make small adjustments to its path.

Special Items on Juno

Galileo Plaque and Minifigures

Galileo Galilei plaque.

Juno carries a special plaque dedicated to Galileo Galilei, a famous scientist. The plaque is made of aluminum and has a picture of Galileo. It also has text in Galileo's own handwriting from 1610. This text describes his observations of Jupiter's moons, which he was the first to see.

The spacecraft also carries three special Lego minifigures! These minifigures represent Galileo Galilei, the Roman god Jupiter, and the goddess Juno. The Juno minifigure holds a magnifying glass, showing her search for truth. Jupiter holds a lightning bolt. Galileo has his telescope. These special Lego figures are made of aluminum so they can survive the harsh conditions of space. They are part of a program to get kids interested in science, technology, engineering, and mathematics (STEM).

Discoveries and Results

Juno has already made many exciting discoveries about Jupiter. For example, it found new information about lightning on Jupiter, changing earlier ideas. It also gave us the first views of Jupiter's north pole and new insights into its auroras, magnetic field, and atmosphere.

In 2021, Juno helped scientists learn that the dust causing the Zodiacal light (a faint glow in the night sky) actually comes from Mars, not from comets or asteroids as previously thought.

Juno's findings are challenging existing ideas about how Jupiter formed. When it flew over Jupiter's poles, it saw stable clusters of cyclones. It also found that Jupiter's magnetosphere is uneven and chaotic. Using its Microwave Radiometer, Juno discovered that Jupiter's famous red and white bands extend hundreds of kilometers deep into the atmosphere. However, the inside of Jupiter is not evenly mixed. This has led to a new idea that Jupiter might not have a solid core. Instead, it might have a "fuzzy" core made of pieces of rock and metallic hydrogen. This unusual core might be the result of a collision that happened early in Jupiter's history.

In April 2020, Juno even detected a meteor impact on Jupiter!

Juno's studies of Jupiter's storms show they are much taller than expected. Some storms go 100 kilometers (60 miles) below the cloud tops. The famous Great Red Spot extends over 350 kilometers (200 miles) deep! By flying low over Jupiter's clouds, Juno could measure tiny changes in velocity. This helped scientists figure out that the Great Red Spot goes about 500 kilometers (300 miles) below the cloud tops. The new results also show that cyclones are warmer at the top and colder at the bottom, while anticyclones are colder at the top and warmer at the bottom.

Mission Timeline

Images for kids

Jupiter Views

• 

  Perijove 26 image.

• 

  Jupiter's southern polar region (August 27, 2016).

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  Jupiter's size changing as Juno approached and left (August 27, 2016).

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  Infrared view of Jupiter's southern aurora (August 27, 2016).

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  Southern storms of Jupiter.

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  Area of Jupiter where different atmospheric conditions meet (March 27, 2017).

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  Juno moving away from Jupiter (May 19, 2017).

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  Image taken from 16,535 km (10,274 mi) above the atmosphere (July 10, 2017).

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  Close-up of the Great Red Spot (July 11, 2017).

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  The Great Red Spot as seen by JunoCam (April 2018).

• 

  Jupiter viewed by Juno
  (February 12, 2019).
• 

  Photograph taken at the end of Perijove 15 (September 6, 2018).

Moon Views

• 

  Ganymede, taken by JunoCam during Juno's flyby on June 7, 2021.

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  Infrared view of Ganymede during the flyby by Juno.

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  View of Europa taken during Juno's flyby on September 29, 2022.

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  Low resolution view of Io captured by JunoCam (September 2017).

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  Io, as recorded by JunoCam
  (September 2, 2017).

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  Plume near Io's terminator
  (December 21, 2018).

• 

  Io, viewed by JunoCam
  Several Volcanos
  (October 15, 2023).

• 

  Io, viewed by JunoCam
  Volcanic plume
  (October 15, 2023).

• 

  Io, taken by the JunoCam instrument during Juno's flyby
  (December 30, 2023).

See also

In Spanish: Juno (sonda espacial) para niños