by Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on exciting discoveries, scientific advances and more.
The European Space Agency’s Juice mission is about to take two historic steps on its long journey to study the possible habitability of Jupiter’s icy moon.
The Juice, or Jupiter Icy Moons Explorer, spacecraft – launched in April 2023 – will make the first back-to-back flybys of the moon and Earth and the first double gravity assist maneuver on Monday and Tuesday. This process will act as a slingshot, allowing Earth’s gravity to put the brakes on Juice’s current trajectory and redirect it for a Venus flyby in August 2025.
Then, Juice can take a shortcut through the solar system and be on track to reach Jupiter and its moons in July 2031.
Juice will first fly by Earth’s moon on August 19 at 5:16 pm ET, then zip by Earth nearly 25 hours later at 5:57 pm ET on August 20. The space agency will provide animated tracking of the spacecraft on available, and some people with binoculars or telescopes in Southeast Asia may be able to see a sap as it flies directly overhead.
Throughout the journey, Juice’s two cameras will take photos during the flight and send them back to Earth, where they will appear on the agency’s blog.
But the cutting-edge maneuvers are also extremely daring and challenging, and one small mistake could throw Juice off course and end the mission.
“It’s like going through a very narrow lane, very fast, very fast: pushing the accelerator to the maximum when the margin on the side of the road is only a millimeter,” said Ignacio Tanco, Operations Manager Spacecraft Juice, in a statement.
High risk, high reward
On average, Jupiter is located 497 million miles (800 million kilometers) from Earth, so reaching it without a very powerful rocket or thousands of pounds of propellant on board requires careful strategizing by mission planners. And the plan for Juice’s journey has been in the works for 20 years.
By using the gravity of planets like Earth and Venus it can make the right adjustments to Jupiter’s trajectory to put it in the right direction and at the best speed to reach Jupiter and enter orbit without orbiting the planet.
Gravity assists can speed up or slow down spacecraft, depending on how they are used, and they conserve fuel and allow spacecraft to be equipped with many scientific instruments.
The double flyby of the Earth and the moon will slow down Juice just enough so that it can be flown by Venus for an energy boost next year before looping around our planet twice for more boosts, according to the agency.
Fine adjustments to Juice’s flight pattern put the spacecraft on track to reach the moon and Earth at the right time and speed while coming incredibly close to both. Juice will first pass 434 miles (700 kilometers) from the surface of the Moon and then fly 4,229 miles (6,807 kilometers) from the surface of Earth.
The moon’s gravity will bend the juice path slightly so that it receives much more gravitational help from Earth. But every detail of the dual flight has to go perfectly.
“For conventional gravity assistance, spacecraft operations must be very precise,” said Angela Dietz, Juice Spacecraft Operations Engineer, in a statement. “For a double flyby, they must be pinpointed.”
Operators using ground stations around the world will closely track Juice’s data before, during and after the flight to make any necessary adjustments at a moment’s notice.
The flight control team has trained and practiced for the flyby in case of any anomalies so that they can quickly get Juice back on track.
“A moon-to-Earth flight had never been attempted before,” Dietz said. “There are risks, but all of the systems on board Juice have been rigorously tested, and we are well prepared.”
Although Juice was designed to explore the cold, faint regions of the solar system near Jupiter, it will be closer to the sun during the flyby and will have to tilt its solar arrays to prevent overheating. The spacecraft will also aim its high-gain antenna at the sun to act as a heat shield, while its low-gain antenna will remain pointed at Earth to communicate during the flight.
Chance opportunity
Telescopes and observatories are tracking Juice’s close approach throughout the summer.
On July 6, the object triggered NASA and ESA’s automated warning systems that monitor potentially hazardous asteroids. The object was estimated to be 164 feet (50 meters) in diameter and on track to pass very close to Earth and the moon.
But it was just juice, and since it has large solar reflective arrays, the spacecraft appeared much larger and brighter, like an asteroid. And the agencies have confirmed that juice poses no risk to the Earth or the moon during its flight.
Juice will also activate all 10 scientific instruments during the double flyby to calibrate them before Jupiter approaches. In addition to testing the instruments, the mission team could make a number of discoveries about Earth and the moon while the instruments are operating.
The RIME team, which is in charge of the Icy Moon Exploration Radar instrument, is eager to collect data on electronic noise inside the spacecraft that appears to be interfering with the instrument. This could be one of several chances to measure any impact on the instrument before it reaches Jupiter.
During the flight, RIME will take eight minutes to make observations while the other instruments stop or go into silent mode, and that data could help the mission team solve the noise problem.
For more CNN news and newsletters create an account at CNN.com
