Juice Aces Callisto Flyby Test

Implementation & Support

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What happened?

Seven years later, in April 2031, ESA's JUICE mission will fly past Jupiter's moon Callisto, giving scientists a stunning glimpse of the mysterious, cratered alien world.

That may seem far-fetched, but in the world of spacecraft operations, it's never too early to start production.

Teams at ESA's ESOC Mission Operations Center in Germany 'fooled' an engineering model of Zuss into thinking it was already on Callisto in order to test the mission's autonomous navigation software.

Why was this necessary?

Callisto's Juice Flyby (artist's impression)

When JUICE arrives at Callisto, the large communication delay between Earth and the Jupiter system means that if something goes wrong, it can't wait for a response from Mission Control.

Although we know exactly where Callisto will be in April 2031, we don't know its position well enough to guarantee that Jus's trajectory will line it up with proper high-precision through Callisto's gravitational field. Scientific measurements.

In the time it takes to send and receive messages between Jupiter and Earth, the direction in which JUICE points its remote sensing instruments could miss science, and critical mission objectives could suffer.

Even a small discrepancy can be terrifying for science, as some of Joos' instruments must be pointed at specific areas of Callisto within a fraction of a degree to make their measurements.

„We need Juice to operate with its own 'eyes' and its own 'brain,'” says Ignacio Danko, Juice's director of flight operations. „When Callisto appears in the field of view of its navigation camera, it can identify key features on the moon's surface, rotate itself to point its instruments at them, and then continue to rotate to keep them in view as it flies past.”

what did you do

Teams at ESA fly spacecraft to new and exciting places throughout the solar system. They use a one-of-a-kind replica on Earth to train for critical operations and diagnose and resolve problems experienced by the spacecraft millions of kilometers away. This 'engineering model' is an exact replica of the hardware, software, electrical systems and instruments that will be sent into deep space.

The JUICE engineering model is under ESA mission control

The Juice team is testing autonomous navigation software using its engineering model, which will track Juice in the Jupiter system.

They 'fooled' the moon into believing it was on Callisto by seeing how it would respond to a faithful replica of the spacecraft's navigation camera taking successive images of it.

These high-resolution images, generated by a computer model, depicted Callisto in the exact orientation and phase that Jupiter would see it seven years later.

„It's not as simple as preparing images in advance and playing a video in front of the navigation camera,” says Giulio Pinzan, the ESA spacecraft operations engineer who oversaw the operation.

„The navigation software has to react to these images. If it notices that it's approaching Callisto at the wrong angle or facing slightly the wrong direction, it has to try to correct these errors without our help.

„That means Callisto's vision has to react to the spacecraft's actions in real time. We've effectively attached a high-speed virtual reality headset to Zus's camera and allowed it to move around freely within this virtual space.

One of the computer-generated images of Jupiter's moon Callisto used to test Zuss' autonomous navigation software.

How did it go?

Teams from ESA and the spacecraft's manufacturer, Airbus, devoted three days to the Callisto flyby test. Spacecraft operators, scientists, and mechanical, electrical, and software engineers are all expected to spend days encountering and solving problems before Zus achieves a clean mission that performs exactly as they want.

To make this test even more challenging, they don't have access to one of the most important tools in the spacecraft's operating suite. Typically, before a complex test like this is run on a physical engineering model of the spacecraft, it is first run on a fully digital software simulator of the spacecraft with no physical components.

This is where most problems are encountered and solved, and tests are only run on a physical engineering model when operators already have a good idea of ​​what to expect.

Giulio Pinzan with the Juice spacecraft engineering model

„But this situation is so complex that it is currently not possible to simulate it with the JUICE software simulator,” says Giulio Pinzan. „We were flying completely blind in this experiment.”

Nevertheless, the team defied their expectations and won at the first attempt on the first day. Zus's navigation software locked onto the exact parts of Callisto, pointed its instruments directly, and safely maintained the correct path as it navigated the demanding flyby.

“We really have to commend our flight dynamics team, in particular,” says Giulio. „Their mathematical calculations enabled us to fly a clean plane on the first try despite our inexperience by testing the software simulator. Amazing, actually. They even surprised us.

„The Airbus team did a remarkable job setting up the engineering model in time for testing, while providing us with all the details needed to properly operate the autonomous navigation system.”

What happens next?

The Callisto flyby is one of the most demanding scenarios facing Juice, and one of the most difficult to set up and implement in the engineering model.

The model was transported from Airbus in France to ESOC in Germany in February. With this final test successfully completed, it is now fully set up, fully trained on how to use it and officially handed over to ESA crews.

Juice's team must now confirm that the aircraft model performs as well as the engineering model by conducting similar testing in space. However, the only opportunities to track a large object with Zus' navigation camera will come during its planetary flyby.

to come Lunar-Earth gravity assistance was not an option for this experiment in August this year. During this double trip, Juice will quickly pass the Moon and then the Earth 24 hours later to steal energy from both bodies. This is a very delicate maneuver that has never been attempted before and all hands must be ready to react to any anomaly at a moment's notice.

wait @esaoperations And @ESA_Juice On that day X April 14th for Juice's launch anniversary celebrations and news that Europa's Jupiter mission will briefly return to Earth in August 2024.

See how Jupiter's path will be changed by the first-of-its-kind double flyby of the Moon and Earth in August 2024

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