by Although it is still seven years from achieving Jupiterthe SU the mission is progressing apace — and a recent test run envisioned the mission’s spacecraft flying past the icy Jovian moon, Callisto.
After leaving the European spaceport in French Guiana a year agothe Icy Moons Explorer Jupiter, called JUICE for short, still in the interior Solar system, is preparing for a series of gravity assists that will throw it on a path that will allow it to rendezvous with Jupiter in 2031. Callisto will be the first stop of the planet’s farthest moon, Callisto. This will mark the first of 35 planned flybys of the gas planet Callisto’s moons, Ganymede and Europebefore the spacecraft settles into orbit around Ganymede.
At the European Space Operations Center (ESOC) in Germany, the mission team is already preparing for this first flight, but using the engineering model of the spacecraft. This is an exact replica of the flight model currently traveling through space, with the same hardware, software and instruments. The only difference is that it is located in a clean room in Darmstadt.
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The problem facing SUUS, and indeed any mission to Jupiter, is a time delay – how long it takes for radio signals to reach the spacecraft from Earth and vice versa. This relay can take 33 minutes when Jupiter is closest to Earth (opposition) and 54 minutes when it is on the other side of the solar system. Therefore, JUICE is programmed with software that can think and plan independently without waiting for orders.
One example where JUICE’s autonomy will be critical is when observing Callisto’s surface features during flybys. Because we cannot know JUICE’s exact position when it passes through Callisto’s gravitational field, however, the onboard computer must take the spacecraft’s orientation and fine-tune it so that it can focus on individual surface features with its instruments to the accuracy of a fraction of a degree. .
“We need JUICE to be able to respond with its own ‘eyes’ and its own ‘brain,'” said Ignacio Tanco, who is JUICE’s Director of Flight Operations, in the European Space Agency. press release. “When Callisto appears in the field of view of its navigation camera, it must be able to identify important features on the lunar surface, rotate itself to focus its instruments on them, and then continue to rotate to keep them in view as he flies by. .”
The ESOC team had to convince the engineering model that it was actually in space and flying over Callisto by projecting computer-generated images of Callisto into the model’s navigation camera. The images mimicked the orientation and phase Callisto will be in when JUICE makes the flyby in 2031.
Giulio Pinzan, who is a Spacecraft Operations Engineer at the European Space Agency, compared it to attaching the engineering model to an immersive virtual reality headset and letting it move around that virtual space.
“The navigation software had to respond to these images,” said Pinzan. “If he noticed that he was approaching Callisto at the wrong angle or facing slightly in the wrong direction, he had to try to correct these errors without our help.”
Three days were set aside for testing at ESOC, and it was not expected to be a simple launch — the point of running these practices is to fix the connections. Due to the complexity of the task, it was not possible to test in a software simulator first, where most of the gremlins could be solved. Instead, the JUICE team expected to endure a lot of trial and error, as well as rewriting software, to get it to work.
However, the engineering model succeeded on the first day, successfully focusing on the images of Callisto and keeping it locked on locations on the icy surface of the moon as it made a virtual flight, rolling to the moon keep in sight.
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“We really have to commend our Flight Dynamics team,” said Giulio. “Their mathematical calculations were spot on and enabled us to do a trip through clean flight on the first attempts despite the lack of experience they would normally have from trying the software simulator. It was amazing, really . They even surprised us.”
The IS the next step JUICE’s real-world mission is Lunar-Earth Gravity Assist, or LEGA for short, in August. First, SÚ will fly over our moon and steal some of its orbital momentum, and less than 24 hours later passing the Earth and receiving additional gravitational assistance to increase its velocity. This is the first time this kind of double gravity assistance has ever been attempted, but because JUICE is one of the largest interplanetary spacecraft ever launched, it needs more help to move between planets. In 2025, JUICE will receive additional gravitational assistance from Venusand then two more flybys from Earth in 2026 and 2029 will give the spacecraft enough speed to climb out of the sun’s gravity well and finally head toward Jupiter.
