During fly-by Juice snaps picture of Earth’s radiation belts

Juice image of Earth's radiation belts
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During its fly-by of Earth on August 19-20, the European Jupiter orbiter Juice used its NASA instruments, designed to study the radiation environment around the gas giant, to snap a false color image of the Earth’s radiation belts, as shown in the graphic to the right. From the caption:

On Aug. 19, JENI and its companion particle instrument Jovian Energetic Electrons (JoEE) made the most of their brief 30-minute encounter with the Moon. As Juice zoomed just 465 miles (750 kilometers) above the lunar surface, the instruments gathered data on the space environment’s interaction with our nearest celestial companion. It’s an interaction scientists expect to see magnified at Jupiter’s moons, as the gas giant’s radiation-rich magnetosphere barrels over them.

On Aug. 20, Juice hurled into Earth’s magnetosphere, passing some 37,000 miles (60,000 km) above the Pacific Ocean, where the instruments got their first taste of the harsh environment that awaits at Jupiter. Racing through the magnetotail, JoEE and JENI encountered the dense, lower-energy plasma characteristic of this region before plunging into the heart of the radiation belts. There, the instruments measured the million-degree plasma encircling Earth to investigate the secrets of plasma heating that are known to fuel dramatic phenomena in planetary magnetospheres.

The dotted line shows the trajectory of ESA’s Juice spacecraft during its lunar-Earth gravity assist, with the white rings indicating equatorial distances of 4 and 6 Earth radii. The colors indicate the strength of the energetic neutral atoms detected by the instruments, and show the million-degree hot plasma halo that circles the Earth.

The data proved that the instruments are functioning as intended, and will thus be able to achieve their main goal, studying the much more active and energetic radiation belts of Jupiter.

First high resolution images released from Juice’s fly-by of the Earth & Moon

Juice's high resolution view of the Moon
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The Italian science team that runs the high resolution camera on the asteroid probe Juice have now released that camera’s first images, taken to test its operation during the spacecraft’s close fly-by of both the Moon and then the Earth a week ago.

The picture to the right, cropped, reduced, and sharpened to post here, shows the Moon’s surface during that close fly-by, which got within 435 miles. The camera is dubbed Janus, and was developed by Italy and operated by the Italian National Institute for Astrophysics.

JANUS will study global, regional and local features and processes on the moons, as well as map the clouds of Jupiter. It will have a resolution up to 2.4 m per pixel on Ganymede and about 10 km per pixel at Jupiter.

The main aim of JANUS’s observations during the lunar-Earth flyby was to evaluate how well the instrument is performing, not to make scientific measurements. For this reason, JANUS took images with various camera settings and time intervals – a bit like if you’re going out to test a DSLR camera for the first time. In some cases, researchers intentionally ‘blurred’ the images so that they can test out resolution recovery algorithms. In other cases, they partially saturated the image to study the effects induced on the unsaturated areas.

As can be seen by the sample image above, the test images appear to have demonstrated that Janus will function as planned when Juice arrives in orbit around Jupiter in 2031 in order to study that gas giant’s upper atmosphere as well as its larger icy moons, Ganymede, Calisto, and Europa.

Juice completes Earth fly-by, heads for Venus fly-by

Earth as seen by Juice
Earth as seen by Juice during fly-by.
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The European probe Juice yesterday successfully completed a close fly-by of the Earth and was thus successfully slingshoted on its way to its next fly-by, of Venus, on its way to Jupiter.

This fly-by was actually a double event. First Juice zipped past the Moon the day before, coming within 435 miles. Then, only one day later it passed the Earth at a distance of 4,230 miles, thus completing the first dual fly-by of the both the Earth and the Moon.

The flyby of the Moon increased Juice’s speed by 0.9 km/s relative to the Sun, guiding Juice towards Earth. The flyby of Earth reduced Juice’s speed by 4.8 km/s relative to the Sun, guiding Juice onto a new trajectory towards Venus. Overall, the lunar-Earth flyby deflected Juice by an angle of 100° compared to its pre-flyby path.

The inherently risky flyby required ultra-precise, real-time navigation, but is saving the mission around 100–150 kg of fuel. In the month before the flyby, spacecraft operators gave Juice slight nudges to put it on exactly the right approach trajectory. Then they tracked Juice 24/7 between 17–22 August.

The Venus fly-by will occur in August 2025, followed by additional Earth flys in September 2026 and January 2029. The spacecraft will finally arrive in Jupiter orbit in July 2031, where it is designed to study the large icy moons (Europa, Gandymede, and Calisto) of that gas giant.

Juice completes fly-by of Moon

Juice's view of the Moon
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Europe’s Juice probe to Jupiter yesterday successfully completed its close fly-by of the Moon, shifting its path as it prepares for a close fly-by of the Earth today.

The picture to the right, cropped, reduced, and sharpened to post here, was taken during yesterday’s flyby. At its closest approach Juice was only 435 miles above the lunar surface. It will pass the Earth today at a distance of 4,230 miles.

If the Earth fly-by today is successful, Juice will then do flybys of Venus in August 2025, Earth in September 2026, and Earth again in January 2029, arriving in Jupiter orbit in July 2031, where it is designed to study the large icy moons (Europa, Gandymede, and Calisto) of that gas giant.

ESA’s Juice probe to Jupiter prepares for first Earth+Moon slingshot fly-by

Graphic showing Juice's upcoming duel fly-by
Graphic showing Juice’s upcoming duel fly-by.
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The European Space Agency’s (ESA) first mission to Jupiter, dubbed Juice (Jupiter Icy Moons Explorer) is about to do the first ever back-to-back fly-bys of the Moon and then the Earth immediately afterward in order to slingshot it forward on its long journey to the gas giant.

The graphic to the right, cropped and reduced to post here, shows the plan. Juice will first fly past the Moon, shifting its path slightly, and then zip past the Earth one day later, its trajectory then under-going a much larger change.

The lunar-Earth flyby will see Juice pass just 700 km [435 miles] from the Moon’s surface at 23:16 CEST on 19 August and 6807 km [4230 miles] from Earth’s surface almost exactly 24 hours later at 23:57 CEST on 20 August.

Using the gravity of the Moon to slightly bend Juice’s trajectory first will improve the effectiveness of the much larger gravity assist at Earth. However, the dual flyby requires extraordinarily precise navigation and timing, as even minor deviations could send Juice in the wrong direction.

The engineering teams have already been doing simulations to make sure they get this complex maneuver right. If all goes right, the spacecraft will then do flybys of Venus in August 2025, Earth in September 2026, and Earth again in January 2029, arriving in Jupiter orbit in July 2031.

Engineers free stuck radar antenna on Juice probe to Jupiter’s big moons

Engineers have successfully freed the 52-foot wide radar antenna on the Juice probe to Jupiter, shaking it enough to release a pin that was blocking deployment.

The pin was freed by employing “back-to-back jolts”. Imagine when you roll your car back and forth to get it freed from mud or snow. It appears this is what they did with the pin.

Juice will arrive in Jupiter orbit in 2031, where it will make numerous fly-bys of Europa, Calisto, and Ganymede, and then settle into an orbit around Ganymede alone. The radar antenna was essential for probing the ice content of these worlds, below the surface.

Hat tip to reader Mike Nelson.

Radar antenna on Europe’s JUICE probe to Jupiter stuck

European Space Agency officials revealed yesterday that the 52-foot radar antenna on its JUICE probe to Jupiter has failed to deploy as planned, and that they are attempting to shake what they think is a small pin free that is in the way.

Engineers suspect a tiny pin may be protruding. Flight controllers in Germany plan to fire the spacecraft’s engine in hopes of shaking the pin loose. If that doesn’t work, they said they have plenty of time to solve the problem.

Juice, short for Jupiter Icy Moons Explorer, won’t reach the giant planet until 2031. It’s taking a roundabout path to get there, including gravity-assist flybys of Earth and our moon, and Venus.

The radar antenna is needed to peer beneath the icy crust of three Jupiter moons suspected of harboring underground oceans and possibly life, a major goal of the nearly $1.8 billion mission. Its targets include Callisto, Europa and Ganymede, the largest moon in the solar system.

If this antenna cannot be freed, it will prevent JUICE from doing one of its prime missions.

Arianespace launches JUICE mission to Jupiter

Arianespace early today used its Ariane-5 rocket, on its next-to-last launch, to send the European Space Agency’s (ESA) JUICE mission on its way to Jupiter to study its large moons.

It will take eight years for JUICE to get to Jupiter, using flybys of the Earth, Moon, and Venus along the way. This journey might also include a flyby of an asteroid, depending on orbital mechanics and the spacecraft’s condition.

Once at Jupiter it will, from ’31 to ’34, do thirty-five flybys of the Ganymede, Callisto, and Europa, and then enter orbit around Ganymede for most of 2035, before being sent to crash onto the planet to end its mission.

Ariane-5 meanwhile has one more launch, in June. After this Arianespace will not at present have an active large rocket, as its Ariane-6 replacement is not yet flying, its maiden flight presently scheduled for the fourth quarter of this year.

This was also Europe’s first launch in 2023, so it does not get listed on the leader board. The leaders of the 2023 launch race are as follows:

23 SpaceX (with a launch scheduled for tonight)
15 China (with a launch scheduled for tomorrow)
6 Russia
3 Rocket Lab

American private enterprise still leads China 26 to 15, but is now tied with the entire world combined 26 all.

1st water vapor in Ganymede’s atmosphere, detected using data from Hubble

Using Hubble data, astronomers have detected the first evidence of water vapor in the atmosphere of Jupiter’s largest moon, Ganymede.

Though larger than the blistering planet Mercury, the Jovian moon Ganymede is no place to go sunbathing. Located ½-billion miles from the Sun, the water ice on its surface is frozen solid in frigid temperatures as low as minus 300 degrees Fahrenheit. This makes the ice as hard as rock. Still, a rain of charged particles from the Sun is enough to turn the ice into water vapor at high noon on Ganymede.

This is the first time such evidence has been found, courtesy of the Hubble Space Telescope’s spectroscopic observations of aurora on Ganymede spanning two decades. The auroras are used to trace the presence of oxygen, which then is linked to the presence of water molecules sputtering off the surface. Ganymede has a deep ocean located an estimated 100 miles below the surface. That’s too deep for water vapor to be leaking out.

This detection has a margin of uncertainty, but it provides a baseline for the up close observations planned for Europe’s JUICE orbiter, set to launch in ’22 and arrive in Jupiter orbit in ’29. JUICE’s study focus will be the three Galilean moons that appear to have lots of ice, Ganymede, Calisto, and Europa.

Europe has decided to build a probe, dubbed JUICE, to study Ganymede, Callisto and Europa, Jupiter’s big icy moons.

Europe has decided to build a probe to study Ganymede, Callisto and Europa, Jupiter’s big icy moons.

Known as JUICE, the Jupiter Icy Moons Explorer, the probe will enter orbit around the gas giant planet in 2030 for a series of flybys of Ganymede, Callisto and Europa. JUICE will brake into orbit around Ganymede, Jupiter’s largest moon, in 2032 for at least one year of close-up research.