21.08.2024
Europe's Jupiter probe to stage daring lunar-Earth fly-by
Europe's JUICE Jupiter probe zooms by the moon in historic flyby (photos)
JUICE came within about 465 miles (750 kilometers) of the moon on Monday (Aug. 19).
An image of the moon taken by monitoring camera 1 on Europe's JUICE Jupiter probe. (Image credit: ESA/Juice/JMC; acknowledgement: Simeon Schmauß & Mark McCaughrean (image processing)
Europe's JUICE Jupiter probe swung by the moon for a "gravity assist" on Monday (Aug. 19), and it snapped some photos to commemorate the historic encounter.
JUICE (short for Jupiter Icy Moons Explorer) came within a mere 465 miles (750 kilometers) of the lunar surface on Monday evening, on the first leg of an unprecedented gravity-assist doubleheader. The second leg comes on Tuesday evening, when the probe flies by Earth.
JUICE chronicled Monday's lunar encounter with some imagery, which it captured using its two onboard monitoring cameras (which were designed to confirm the deployment of the probe's solar arrays and scientific instruments).
And the European Space Agency (ESA) shared these photos with the world as they came down to Earth, raw and unprocessed, via a live webcast that included commentary from some JUICE team members.
JUICE launched in April 2023, on a mission to study Jupiter and three of its four big Galilean moons — Ganymede, Callisto and Europa. All three are thought to possess oceans of liquid water beneath their icy shells, and Europa's is likely in contact with a rocky seafloor, making possible a variety of intriguing chemical reactions. (The seas of Ganymede and Callisto may be sandwiched between layers of ice.)
This week's moon and Earth flybys are historic; no other mission has ever performed a double gravity assist, according to ESA. The two maneuvers will set the probe on course for a similar encounter with Venus in August 2025, which will slingshot JUICE out toward the giant planet.
"Actually, this flyby is a braking maneuver, so we do not accelerate JUICE, in the sense of gaining speed relative to the sun," Ignacio Tanco, JUICE spacecraft operations manager, said during ESA's lunar flyby webcast.
"What we found is that by following this sequence of first Earth and then Venus, we manage to save about half a year of cruise time and arrive to Jupiter around July 2031," Tanco added. "This sort of counterintuitive approach of braking first, in fact, results ultimately in the shortest possible cruise phase."
To achieve the same change in velocity achieved by this week's two flybys via engine burns, the JUICE team would've had to use pretty much all the propellant in the probe's tanks, Tanco said.
JUICE team members say the assist worked perfectly. "It was a flawless maneuver! No fine-tuning or correction is needed before tonight's Earth flyby," ESA Operations posted to X on Aug. 20.
During its Earth flyby on Tuesday, JUICE will come within a mere 4,250 miles (6,840 km) of Earth. If all goes according to plan, closest approach will occur at 5:57 p.m. EDT (2157 GMT) over the North Pacific Ocean.
Amateur astronomers could theoretically see the probe through a telescope during the encounter, JUICE team members said — provided they're in Alaska or some other spot in or around the North Pacific.
There won't be another flyby-photo webcast during Tuesday's flyby, however. ESA's Pacific region telemetry-receiving stations are all in the Southern Hemisphere, so the JUICE team won't be able to communicate with the probe during the encounter, team members said on Monday.
Quelle: SC
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Update: 22.08.2024
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Juice rerouted to Venus in world’s first lunar-Earth flyby
ESA’s Jupiter Icy Moons Explorer (Juice) has successfully completed a world-first lunar-Earth flyby, using the gravity of Earth to send it Venus-bound, on a shortcut to Jupiter through the inner Solar System.
The closest approach to the Moon was at 23:15 CEST (21:15 UTC) on 19 August, guiding Juice towards a closest approach to Earth just over 24 hours later at 23:56 CEST (21:56 UTC) on 20 August.
As Juice flew just 6840 km above Southeast Asia and the Pacific Ocean, it snapped a series of images with its onboard monitoring cameras, and collected scientific data with eight of its ten instruments.
“The gravity assist flyby was flawless, everything went without a hitch, and we were thrilled to see Juice coming back so close to Earth,” says Ignacio Tanco, Spacecraft Operations Manager for the mission.
The purpose of the flyby was to reroute Juice’s path through space, using the gravity of first the Moon and then Earth to change the spacecraft’s speed and direction.
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.
Thanks to a flawless Ariane 5 launch back in April 2023, Juice has a little extra propellant in its tanks to get closer to Jupiter’s moon Ganymede than originally planned. The success of the lunar-Earth flyby has safeguarded this bonus science.
“Thanks to very precise navigation by ESA’s Flight Dynamics team, we managed to use only a tiny fraction of the propellant reserved for this flyby. This will add to the margins we keep for a rainy day, or to extend the science mission once we get to Jupiter,” adds Ignacio.
A first taste of science in space
Whilst the main goal was to alter Juice’s trajectory, the lunar-Earth flyby also provided an opportunity to test out Juice’s scientific instruments in space, with all ten switched on during the Moon flyby, and eight switched on during the Earth flyby.
We expect to publish images and spectra collected by some of Juice’s instruments in the next weeks, as they are downlinked from the spacecraft and evaluated by the instrument scientists. This includes high-resolution images on the Moon and Earth from Juice’s scientific camera, JANUS.
“The timing and location of this double flyby allows us to thoroughly study the behaviour of Juice’s instruments,” explains Claire Vallat, Juice Operations Scientist.
“It happens early enough in Juice’s journey that we can use the data to prepare the instruments for arrival at Jupiter. And given how well we know the physical properties of Earth, the Moon, and the surrounding space environment, it’s also the ideal location to understand how the instruments respond to a real target.”
Next step: Venus
This lunar-Earth flyby actually reduced Juice’s energy, redirecting it towards a meeting with Venus in August 2025. That Venus flyby will boost Juice back out towards Earth; the spacecraft will fly by our home planet again in September 2026 and January 2029, gaining two more boosts before arrival at Jupiter in July 2031.
Quelle: ESA
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Update: 26.08.2024
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First views from Juice’s science camera
Since ESA’s Jupiter Icy Moons Explorer (Juice) flew by the Moon and Earth earlier this week, we’ve seen images from its monitoring cameras and we’ve seen images from its navigation camera. Today we reveal the first images from its scientific camera, JANUS, designed to take detailed, high-resolution photos of Jupiter and its icy moons.
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.
The name JANUS comes from the Latin phrase 'Jovis, Amorum ac Natorum Undique Scrutator', or roughly 'Scrutiniser of Jupiter, and all his loves and descendants'. Jupiter's four largest moons – the main focus of Juice’s mission – are named after protagonists in the 'love affairs' of Zeus, the equivalent of Jupiter in Greek mythology.
JANUS will transform our knowledge of Jupiter’s icy moons, by capturing them with a resolution and coverage 50 times greater than previous cameras sent to the Jovian system. The camera is equipped with an onboard computer that manages all instrument functions, processes commands, and sends data back to Earth.
In imaging our own Moon, with no atmosphere, JANUS could test out how it will function at Ganymede, Callisto and Europa. In contrast, Jupiter itself has a huge, turbulent atmosphere; JANUS’s images of Earth can better simulate imaging the different layers and components of Jupiter’s atmosphere.
For more information, see the original press release from the Italian National Institute for Astrophysics (INAF).
Note: These images are preliminary and have not been processed to use for science
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Juice JANUS view of the Moon -
Juice JANUS view of the Moon -
Juice JANUS view of the Moon -
Juice JANUS view of the Moon -
Juice JANUS view of Earth -
Juice JANUS view of Earth -
Juice JANUS view of Earth -
Juice JANUS view of Earth
JANUS was developed by an industrial consortium led by Leonardo SpA, under the supervision of the Italian Space Agency (ASI) and in collaboration with the Italian National Institute for Astrophysics (INAF), which is responsible for instrument science, the German Aerospace Center (DLR), CSIC-IAA in Granada (Spain) and CEI-Open University in Milton Keynes (UK).
Quelle: ESA