Subscribe to CNN's Wonder Theory science newsletter. Explore the universe with news about exciting discoveries, scientific advances, and more..
The European Space Agency's Juice mission is set to make two historic discoveries during its long voyage to explore Potential Habitability of Jupiter's Icy Moons.
The Juice spacecraft, or Jupiter Icy Moons Explorer, launched in April 2023, will conduct the first back-to-back flybys of the Moon and Earth and the first double gravity assist maneuver on Monday and Tuesday. The process will act as a slingshot, allowing Earth's gravity to slow Juice's current trajectory and redirect it for a Venus flyby in August 2025.
Juice could then take a shortcut through the solar system and be on its way to Jupiter and its moons in July 2031.
Juice will first fly by the moon on Aug. 19 at 5:16 p.m. ET, then zoom past Earth nearly 25 hours later at 5:57 p.m. ET on Aug. 20. The space agency will provide animated spacecraft trackingand some people with binoculars or telescopes in Southeast Asia may see Juice flying directly overhead.
During this time, two cameras on Juice will take photographs during the flyby and send them back to Earth, where they will be appear on the agency blog.
However, the innovative maneuvers are incredibly daring and complex, and one small mistake could throw Juice off course and end the mission.
“It's like driving through a very narrow corridor, very, very fast: pushing the gas pedal to the max when the distance to the curb is only a few millimeters,” Ignacio Tanco, Juice's spacecraft operations manager, said in a statement.
High risk, high reward
On average, Jupiter is 497 million miles (800 million kilometers) from Earth, so reaching it without an extremely powerful rocket or thousands of pounds of onboard fuel requires careful strategy by mission planners. And Juice's journey has been in the works for 20 years.
Using the gravity of planets like Earth and Venus, it is possible to make the necessary adjustments to Juice's trajectory to point it in the right direction and at the optimal speed to reach Jupiter and enter orbit without flying too close to the planet.
Gravity assist maneuvers can speed up or slow down spacecraft depending on how they are used, and also save fuel and allow spacecraft to be equipped with a variety of scientific instruments.
The double flyby of Earth and the Moon will slow Juice down just enough for it to fly past Venus for a recharge next year, before circling our planet twice for an even bigger boost. according to the agency.
Minor adjustments to Juice's flight plan allowed the spacecraft to reach the Moon and Earth at the right time and speed, coming very close to both planets. Juice will first pass within 434 miles (700 kilometers) of the Moon's surface, and then fly by within 4,229 miles (6,807 kilometers) of Earth's surface.
The Moon's gravity will bend Juice's trajectory slightly, so it will receive a much larger gravitational assist from Earth. But every detail of the double flyby must go perfectly.
“For a typical gravity assist maneuver, the spacecraft operations have to be very precise,” Angela Dietz, Juice spacecraft operations engineer, said in a statement. “For a double flyby, they have to be precise.”
Operators using ground stations around the world will closely monitor Juice data before, during and after the flyby to make any necessary adjustments at any time.
The mission control team conducted training and rehearsed the flyby in case any anomalies occurred so they could quickly get Juice back on course.
“A flyby of the Moon and Earth has never been attempted before,” Dietz said. “There are risks, but all of Juice's onboard systems have been thoroughly tested and we are well prepared.”
While Juice was designed to explore the cold, dim corners of the solar system near Jupiter, it will be closer to the sun during the flyby and will need to tilt its solar panels to prevent overheating. The spacecraft will also point its high-gain antenna at the sun to act as a heat shield, while its low-gain antenna will remain pointed toward Earth to relay communications during the flyby.
Chance, opportunity
Telescopes and observatories tracked Juice's approach throughout the summer.
On July 6, the object activated NASA and ESA automated warning systems that monitor potentially hazardous asteroids. The object was estimated to be 164 feet (50 meters) in diameter and was on track to pass very close to Earth and the Moon.
But it was just Juice, and given that it had large reflective solar panels, the spaceship seemed much bigger and brighterlike an asteroid. And agencies have confirmed that Juice poses no danger to the Earth or the Moon during its flyby.
Juice will also activate all 10 of its science instruments during the double flyby to calibrate them before arriving at Jupiter. In addition to testing the instruments, the mission team may also make some discoveries about Earth and the Moon while the instruments are running.
The RIME team, responsible for the Radar for Icy Moon Exploration instrument, is aiming to collect data on the electronic noise inside the spacecraft that appears to be interfering with the instrument. This could be one of the few chances to measure any impacts on the instrument before it arrives at Jupiter.
During the flyby, RIME will take eight minutes to make observations while other instruments are turned off or in silent mode. This data could help the mission team address the noise issue.
For more CNN news and newsletters, create an account at CNN.com