The 165-foot-tall Ariane 5, equipped with two strap-on solid-fuel boosters and two hydrogen-fueled core stages, blasted off from the Guiana Space Center near Kourou, French Guiana, at 6 p.m. EDT, knifing through a cloud deck as it arced away to the east over the Atlantic Ocean.

A half hour later, the rocket’s payload of two communications satellites — Germany’s Heinrich-Hertz-Satellit testbed and the French military’s SYRACUSE 4B — were released one at a time to fly on their own in an initially elliptical orbit.

Both will use on-board propulsion to reach a circular “geosynchronous” altitude 22,300 miles above the Earth where satellites take 24 hours to complete one orbit and thus appear stationary in the sky, allowing the use of fixed antennas on the ground.

“This is the last time we’re doing this, and we would be lying if we said we’re not tearing up a bit, this is the last live tweet of an Ariane 5 launch!” tweeted the rocket’s builder, ArianeGroup.

https://twitter.com/ArianeGroup/status/1676701830112215041?s=20

Including Wednesday’s flight, the Ariane 5’s final tally was 112 fully successful missions in 117 flights, putting 239 satellites and science probes into space, including NASA’s $10 billion James Webb Space Telescope.

“After 27 years, the mighty Ariane 5 is hanging up her boots and retiring to hand over to her younger sister, Ariane 6,” said Arianespace webstream host Katy Haswell. “Very exciting times ahead.”

But the rocket’s retirement marks a major shift in the international launch marketplace, leaving Europe without a heavy-lift rocket until the lower-cost Ariane 6 becomes available, likely in 2024.

ESA and the French joint venture ArianeGroup originally hoped to have the Ariane 6 flying in the 2020 timeframe, providing a cheaper, more competitive alternative to SpaceX’s partially reusable Falcon 9 rocket and the huge Super Heavy-Starship currently in development.

But the Ariane 6 program has been repeatedly delayed, often without explanation. In the meantime, with Russian Soyuz rockets off limits because of Ukraine invasion sanctions, American rockets, primarily SpaceX’s, offer the only near-term solution for heavy European payloads.

Last Saturday, SpaceX successfully launched ESA’s $1.5 billion Euclid space telescope from Cape Canaveral. It was originally intended to launch atop a Soyuz only to lose its ride after Russia’s invasion of Ukraine. ESA also now plans to launch its Hera asteroid probe on a Falcon 9 in 2024.

“SpaceX has undeniably changed the launcher market paradigm as we know it,” ESA Director General Josef Aschbacher wrote in May. “With the dependable reliability of Falcon 9 and the captivating prospects of Starship, SpaceX continues to totally redefine the world’s access to space.”

Europe, he wrote, “finds itself today in an acute launcher crisis with [an albeit temporary] gap in its own access to space and no real launcher vision beyond 2030.”

If there is a silver lining to this “true crisis,” Aschbacher said, it has forced Europe “to candidly reflect on the causes and decisions that brought us here, draw the subsequent and necessary painful lessons, and come out stronger than before. More resilient, more clever, more visionary.”

He said the near-term priority is to “ensure the successful inaugural flight of Ariane 6. … Once operational, I am convinced that Ariane 6 will be an excellent launcher for many years to come, continuing the performance of Ariane 5 at significantly lower cost to satisfy European and commercial needs. ”

The Ariane 6 will provide similar performance as its predecessor, able to lift two communications satellites at a time, weighing a combined 21,000 pounds, to geosynchronous orbit.

The new rocket also will fill a variety of other roles, helping launch Amazon’s Kuiper internet relay satellites, Europe’s Galileo satellite navigation constellation and other payload combinations.

Depending on the configuration, the Ariane 6 is expected to cost between $70 million and $125 million per flight. While more competitive with the Falcon 9, it will not be even partially reusable. Projections show it will not fly often enough to make booster recovery, refurbishment and re-launch cost effective.

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Europe’s iconic Ariane 5 rocket, with its liquid hydrogen-fueled core stage and solid rocket boosters, has guaranteed Europe’s access to space, providing a unique capacity for launching satellites and spacecraft into precise orbits over almost three decades.

Its long run comes to an end when the final Ariane 5 rocket lifts off from Kourou, French Guiana, no earlier than July 5, carrying a French military communications satellite and a German communications satellite to geostationary transfer orbit. The 65-minute launch window window runs 7 p.m. to 8:05 p.m. local time (6:00-7:05 p.m. EDT / 2200-2305 UTC). Bad weather delayed the launch from July 4.

Ariane 5’s much heralded debut launch in June 1996 ended in failure and its second launch a year later was only partially successful. But after these initial setbacks the rocket achieved a 96-percent success rate across 116 total launches.

The rocket has proved to be a true workhorse, launching dozens of commercial satellites into geostationary orbit and national security payloads for the nations of Europe.

The rocket has also launched a series of important space science missions, including In addition to launching dozens of commercial satellites, the Ariane 5 played a crucial role lofting many of the European Space Agency’s most important scientific missions including XMM-Newton, Envisat, Rosetta, Herschel, Planck, BepiColombo and the Jupiter Icy Moons mission JUICE. It also carried cargo to the International Space Station on five Ariane Transfer Vehicle missions. One of its most celebrated launches came in December 2021 when it was entrusted to loft the NASA’s James Webb Space Telescope (JWST) into a precise orbit which doubled JWST’s estimated mission lifetime to 20 years.

Ariane 5’s final launch, which has been delayed for two weeks because of faulty pyrotechnical transmission lines, will be its 117th. In that time the rocket, operated by Arianespace for the European Space Agency (ESA), has endured only a total of two failures and three partial failures, giving it a success rate of 96 percent.

The rocket followed Ariane 4 and proved a major evolution for the Ariane family with significantly more power than its predecessor and benefiting from more advanced technologies.

A combination of liquid and solid propulsion systems provided the rocket with a powerful and reliable launch capability. Its two-stage design comprise a cryogenic main stage powered by Vulcain engines and solid rocket boosters (SRBs) providing the initial thrust during liftoff.

Three successive generic versions – Ariane 5G, Ariane 5G+ and Ariane 5GS, along with the Ariane 5 ES, which was used for various missions including ESA’s Automated Transfer Vehicle (ATV) to the International Space Station (ISS) – were all previously retired from service leaving one operational configuration, the Ariane 5 ECA (Evolved Cryogenic, model A).

With the ability to carry heavy payloads of up to 10 tons to geostationary transfer orbit (GTO), the European workhorse rocket has been instrumental in launching large communication satellites, scientific payloads and even interplanetary missions, a high capacity which made it a reliable choice for both commercial customers and space agencies worldwide.

This Ariane 5 ECA variant featured an upgraded core stage and increased payload capacity, enabling it to carry one, two or three very large satellites. A dual launch configuration was the most commonly used.

Ariane 5’s final interplanetary launch was in April 2023 when it sent Europe’s €1.6 bn ($2 bn) Juice spacecraft on an eight-year voyage to Jupiter and its icy moons to investigate for signs of life in the liquid oceans beneath their frozen surfaces.

Speaking to Spaceflight Now, ESA’s Director of Space Transportation, Toni Tolker-Nielsen, said: “Ariane 5 leaves behind an incredible legacy, having contributed to some major ‘firsts’ for Europe with the launches of the first ESA missions to a comet (Rosetta) to Mercury (BepiColombo) and to Jupiter (Juice).

“The reliability and technical prowess of this launcher, as well as its international character, explain why it was chosen for the very high-profile launch of the James Webb telescope, and the launch was so precise that it saved fuel allowing to significantly extend the expected lifetime of the space telescope.”

Ariane 5’s final launch, designated VA261, carrying the French Syracuse 4B and German Heinrich Hertz satellites, marks the end of an era, especially for the many people at the launch site in Kourou, French Guiana , and across Europe who have been involved with the programme for a large part of their working lives.

Among them is Ariane 5 veteran Stephan Osmann who first went to Kourou from Germany 23 years ago and is responsible for the integration of the launcher’s upper stage. Already part of the team when Ariane 5 took off on for the first time in 1996, he said: “It’s hard to imagine that soon Ariane 5 won’t be part of the landscape here in Kourou. You can feel that something big is coming to an end.”

Another long-standing team member is Helene Requiston from France who works as Launcher System Industrial Manager and is in charge of managing activities, from the preparation of the launcher in Europe and French Guiana to the delivery of the launcher for lift-off on the launchpad.

“Every launch is a unique moment, but this one is particularly special,” she says. “I’m very proud to be part of it, and perhaps a little bit nostalgic. But we know that Ariane 6 is coming.”

Europe’s follow-on heavy lift launcher incarnation, Ariane 6, has been in development for a decade and after several programme delays isn’t quite ready to take over the launch baton just yet. Industry analysts currently expect its first flight to be sometime in 2024.

The last Ariane 5 rocket was hauled to the launch pad on Monday at the Guiana Space Centre, Europe’s South American spaceport. Ariane 5, which for years was the world’s leading commercial satellite launcher, is scheduled to make its final lift off on Tuesday, carrying a French military satellite and a communications technology testbed spacecraft for Germany.

Propelled by a 540-horsepower, diesel-powered tug, the 180-foot-tall (54.8-meter) Ariane 5 rocket rolled out of its final assembly building at jungle launch site and travelled along rails to the ELA-3 launch zone. The 1.7-miles (2.7-kilometer) journey took about two hours. With the rocket in place at the pad, technicians will work to connect the mobile launch table to the ground propellants lines that will feed liquid hydrogen and liquid oxygen into the rocket during the countdown.

Liftoff of this final mission, designated VA261, is scheduled at the opening of a 95-minute launch window that opens at 6:30 p.m. Kourou time (5:30 p.m. EDT / 2130 UTC) on Tuesday. The Ariane 5 will carry the Heinrich-Hertz and Syracuse 4B satellites into a geostationary transfer orbit from the Guiana Space Center on the northeastern coast of South America.

Syracuse 4B, built by Airbus, will relay secure communications between French military aircraft, ground vehicles, and naval vessels, including submarines. It was built by an industrial consortium formed by Thales Alenia Space and Airbus Defence and Space. The Heinrich Hertz satellite, built by OHB, will test new communications technologies on a mission funded by the German space agency, DLR. The spacecraft features onboard processors that can be reprogrammed to employ new communication protocols as they are developed.

This last mission will be the 117th for the Ariane 5 since it was introduced in 1996. The European rocket, marketed by Arianespace, was once dominant in the commercial launch business, but lower-cost launch services from Elon Musk’s SpaceX have eroded its position.

The retirement of the Ariane 5 will for now leave Europe without its own independent access to space. The new Ariane 6 vehicle is not expected to make its inaugural launch until 2024, years later than planned, and the Vega C small satellite launcher has been grounded since a failure in December 2022. In addition, the Russian invasion of Ukraine ended a cooperative venture that launched Soyuz rockets from Europe’s French Guiana spaceport.

Europe’s last Ariane 5 rocket is now scheduled to lift off July 4 after being grounded for more than two weeks due to a problem with the pyrotechnic systems required to jettison the launcher’s strap-on solid rocket boosters. Europe’s workhorse rocket is being retired after 27 years of service.

The Ariane 5 was originally scheduled to fly on June 16, but officials from Arianespace, the rocket’s commercial operator, announced on the eve of launch that they were delaying the mission to replace pyrotechnic transmission lines on the vehicle.

The suspect systems identified fire explosive charges that jettison one of the two solid rocket boosters two minutes into flight, then to activate the “distancing” system, which uses small thrusters on the boosters to ensure the spent casings safely fly clear of the Ariane 5’s core stage as it continues its climb to orbit.

Engineers at Arianespace and ArianeGroup, the Ariane 5’s builder and prime contractor, were informed of a problem discovered during inspections of a pyro line on another project. After X-ray inspections of the pyrotechnic lines on the Ariane 5 rocket being prepared for launch, officials found three pyro lines were “doubtful,” said Pierre-Yves Tissier, chief technical officer at Arianespace at a press briefing on June 15.

“These tests were not all successful and therefore we are not able give confidence on the reliability of the redundancies, it was decided not to go for flight and to replace these doubtful lines,” Tissier said.

On its final mission, designated VA261, the Ariane 5 will carry the Heinrich-Hertz and Syracuse 4B satellites into a geostationary transfer orbit from the Guiana Space Center on the northeastern coast of South America. The launch window on July 4 runs 6:30 p.m. to 8:05 p.m. local time (2130-2305 UTC).

Syracuse 4B, built by Airbus, will relay secure communications between French military aircraft, ground vehicles, and naval vessels, including submarines. The Heinrich Hertz satellite, built by OHB, will test new communications technologies on a mission funded by the German government.

This last mission will be the 117th for the Ariane 5 since it was introduced in 1996. The retirement will leave Europe without its own independent access to space. The new Ariane 6 vehicle is not expected to make its inaugural launch until 2024, years later than planned, and the Vega C small satellite launcher has been grounded since a failure in December 2022. In addition, the Russian invasion of Ukraine ended a cooperative venture that launched Soyuz rockets from Europe’s French Guiana spaceport.

An Ariane 5 rocket took off from French Guiana Friday with the heaviest interplanetary science probe ever launched, kicking off a $1.7 billion European Space Agency mission on a decade-long quest to Jupiter’s icy moons in search of environments that could be habitable for life.

The Jupiter Icy Moons Explorer mission took off at 8:14:36 a.m. EDT (1214:36 UTC; 9:14:36 a.m. French Guiana time) to begin an eight-year cruise to the solar system’s largest planet. The mission, known as JUICE, will enter orbit around Jupiter for a series of flybys of three of the planet’s largest moons, then will make history by becoming the first-ever spacecraft to orbit one of Jupiter’s moons in the mid-2030s.

JUICE carries a high-resolution camera and ground-penetrating radar to map the frozen landscapes of Ganymede, Callisto, and Europa, along with a suite of spectrometers to measure the composition of their icy crusts. After launch, the JUICE spacecraft will deploy an insect-like array of antennas and booms with sensors to study particles and dynamic plasma fields around Jupiter and its moons.

The 13,141-pound (5,961-kilogram) JUICE spacecraft rode into space aboard the Ariane 5 rocket for nearly 28 minutes, getting enough of a velocity boost to escape Earth’s gravity and head off into the solar system. After separating from the Ariane 5’s upper stage, JUICE contacted a ground station and unfurled its two power-generating solar array wings, each arranged in a distinctive cross-like formation.

We have a mission! We are flying to Jupiter,” said Andrea Accomazzo, operations director at the ESA control center in Darmstadt, Germany. “We go there fully loaded with questions.”

The solar panels are the largest ever built for an interplanetary spacecraft, stretching nearly 89 feet (27.1 meters) tip to tip with an area of 915 square feet (85 square meters). Their large size will allow JUICE to produce enough power for the spacecraft and its science instruments at Jupiter, around five times farther from the sun than Earth. The spacecraft’s 23,560 solar cells will generate 850 watts of power.

According to ESA, JUICE’s solar arrays could power an entire road of houses when collecting solar energy near Earth. At Jupiter’s distance from the sun, the solar panels could only power a single microwave.

Liftoff of the Ariane 5 rocket from French Guiana with Europe’s Jupiter Icy Moons Explorer, or JUICE, mission.

JUICE is kicking off an eight-year interplanetary journey to explorer Jupiter and three of its largest moons.https://t.co/FZ6eqEewD2 pic.twitter.com/vzYzNhpEJc

— Spaceflight Now (@SpaceflightNow) April 14, 2023

“We’ll explore Jupiter and its icy moons, which are Europa, Ganymede and Callisto, with a particular focus on Ganymede, which is a unique object in the solar system, the only moon with a magnetic field and the biggest moon of the solar system,” said Olivier Witasse, project scientist for the JUICE mission at the European Space Agency. “The main goal is to understand whether there are habitable environments among those icy moons around a giant planet like Jupiter.”

Scientists believe Europa, Ganymede, and Callisto harbor oceans of liquid water beneath their icy crusts.

“We will characterize, in particular, the liquid water oceans which are inside the icy moons,” Witasse said. “So the question is, where are those oceans located, at which distance underneath the surface of the moons, what is the depth of this ocean? How much water do we have? What is the composition of this water?”

Built by Airbus, JUICE has 10 science instruments developed by research teams across Europe, the United States, and Japan. According to ESA, the mission is outfitted with “the most powerful remote sensing, geophysical, and in situ payload complement ever flown to the outer solar system.”

An Italian-led radar sounder will probe the icy crust covering Jupiter’s moons, revealing structures as deep as 6 miles (9 kilometers) under the surface. JUICE’s main camera will take pictures of Jupiter’s cloud patterns, rings, and the chaotic and cratered terrain of Europa, Callisto, and Ganymede.

“To understand this question of habitability, we need to explore the Jupiter system globally,” Witasse said. “So to study Jupiter, its atmosphere, its weather, its strong rotating magnetic field, the volcanic moon Io, the other moons in the system, and how all these bodies are connected to to each other.”

The launch of the JUICE mission Friday occurred a day later than planned. Officials called off a launch attempt Thursday due to the risk of lightning at the launch base in French Guiana.

But weather conditions were acceptable Friday morning, and the Ariane 5 lit its hydrogen-fueled main engine and two solid rocket boosters to power off the launch pad with 2.9 million pounds of thrust. An upper stage did the final work of propelling the JUICE spacecraft on a trajectory to take it into the solar system.

“This is something that I think Europe can be extremely proud of,” said Josef Aschbacher, director general of ESA. “Extremely proud because because this is a mission that is answering questions of science that are burning to all of us.

“Of course, one of these questions is is there life out there? JUICE will not find life, I have to be very clear, but JUICE will be identifying the habitability of these icy moons of Jupiter. This is a very important mission for all of us, for all mankind, is life possible and what would be the habitat where life could exist?”

The spacecraft’s first 17 days after launch will include a series of instrument, antenna, and boom deployments.

“JUICE is a spacecraft has taken the better part of the past decade to be designed and developed, and is now ready for launch on top of the Ariane 5 launcher,” said Alessandro Atzei, ESA’s payload system engineer for the JUICE mission. “So we’re talking about rather large spacecraft with many key features that really are striking. The very large high gain antenna, the huge solar arrays, 85 square meters, and many, many deployable booms. So just after launch, it will be a lot of work to make sure that everything gets deployed properly so we can start our mission.”

ESA selected the JUICE mission for development in 2012, beating out proposals for an X-ray astrophysics observatory and a gravitational wave detector mission in a competition for funding in the agency’s Cosmic Vision space science program.

Despite a big boost from the Ariane 5 rocket, the JUICE spacecraft will not take a direct route to Jupiter. It will circle the sun one time before returning for a flyby of the Earth and the moon in August 2024, a maneuver to use gravity to begin reshaping the probe’s orbit. The flyby will be the first time a spacecraft performs a gravity assist maneuver with both the Earth and the moon.

A similar gravity assist flyby with Venus is scheduled in August 2025, followed by two more Earth flybys in 2026 and 2029. In a make-or-break moment for the mission, JUICE will fire its main engine to be captured into orbit by Jupiter’s gravity in July 2031. That milestone will begin a series of 35 flybys of Ganymede, Callisto, and Europa, making precise measurements of the thickness of Europa’s global ice sheet and searching for organic molecules.

“Jupiter, it’s really a miniaturized solar system,” Witasse said.

Then, in 2034, JUICE will maneuver into orbit around Ganymede itself for a detailed survey.

The spacecraft will attempt to confirm the existence of a deep subsurface ocean on Ganymede. A laser altimeter instrument primarily funded by Germany will measure tidal deformation to help scientists learn more about Ganymede’s hypothesized internal ocean, and gather data for a global topographic map of the solar system’s largest moon.

JUICE’s instruments will create a high-resolution map of its icy surface, and investigate Ganymede’s magnetic field. When JUICE runs low on fuel, ground controllers will guide the spacecraft on a collision course with Ganymede to ensure it doesn’t contaminate any other moons in the Jupiter system, which could hinder future missions searching for life.

Many of JUICE’s goals follow up on discoveries made by NASA’s Galileo mission, which toured the Jupiter system from 1995 to 2003.

The JUICE mission won’t be alone at Jupiter. NASA plans to launch its own multibillion-dollar Jupiter-bound spacecraft, Europa Clipper, from Kennedy Space Center in Florida in October 2024.

Europa Clipper will launch on a more powerful rocket, SpaceX’s Falcon Heavy, and arrive in orbit around Jupiter in April 2030, a year ahead of JUICE. The two missions are complementary, with JUICE focused on Ganymede and Europa Clipper primed to study Europa, one of the best candidates for a habitable world elsewhere in the solar system.

“Jupiter, it’s really a miniaturized solar system,” Witasse said.

Scientists in the United States and Europe are investigating opportunities for coordinated observations between the Europa Clipper and the JUICE spacecraft.

“We have studied the two trajectories in the system, and we can see that we can do great science at Europa, when the two spacecraft can observe this moon together,” Witasse said. “One example would be a flyby of Clipper, followed by the flyby of JUICE just four hours later.”

Another robotic mission currently orbiting Jupiter is NASA’s Juno spacecraft, which arrived at the gas giant in 2016 and has now completed 50 orbits around the planet. Juno’s scientific payload is designed to study the atmosphere and internal structure of Jupiter, but scientists have recently expanded the scope of the mission to image Jupiter’s largest moons.

Europa Clipper and JUICE will become the third and fourth spacecraft to orbit Jupiter, following a series of one-shot flybys that began with NASA’s Pioneer 10 and 11 probes in 1973 and 1974.

The JUICE spacecraft’s sensitive avionics are contained within a lead-lined vault to shield them from the harsh radiation around Jupiter.

“Mass, power, everything is really optimized for these sorts of missions,” said Justin Byrne, head of science programs at spacecraft builder Airbus Defense and Space. “The radiation is a killer for the electronics, and unless you protect it, the electronics will start failing. We would have memory corruptions and then catastrophic failure of the computers eventually.”

JUICE will head deeper into the cosmos than any European spacecraft has ever gone on its own. ESA’s Huygens probe, which landed on Saturn’s moon Titan, hitched a ride to Saturn with NASA’s Cassini spacecraft.

The JUICE spacecraft was designed with redundancy, with two computers and backups for most major systems, according to Byrne.

“In addition, because Jupiter is a long way away, we can’t directly control it,” Byrne said.

It takes about an hour-and-a-half for radio signals to make the round-trip journey between Earth and Jupiter. That required engineers to design the JUICE spacecraft with autonomous software to detect problems and put itself into a safe configuration long enough to await commands from controllers back on Earth.

JUICE’s 8.2-foot-wide (2.5-meter) high-gain antenna will beam imagery and science data back to Earth. Scientists at research institutions around the world will analyze the measurements.

“We are not going to detect life with with JUICE,” Witasse said. “But nevertheless we are going to study interesting aspects related to life and habitability.”

An ion mass spectrometer on JUICE will measure water vapor and other molecules in the tenuous atmospheres of the icy moons. Another instrument will measure vertical profiles of the moons’ atmospheres.

“Really, the most interesting aspect of of the mission to know where is this water?” Witasse said. “What is the composition in terms of salt? How does that relate to the habitability of those moons?”

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The liftoff of Europe’s first mission to Jupiter aboard an Ariane 5 rocket was scrubbed Thursday in French Guiana due to a high risk of lightning at the launch site, delaying until Friday the start of the JUICE spacecraft’s voyage of exploration.

Arianespace, the Ariane 5 rocket’s commercial operator, called off the countdown around 10 minutes before the scheduled launch time at 8:15 a.m. EDT (1215 UTC) Thursday. A final pre-flight weather briefing indicated a high risk of lightning over the spaceport in Kourou, French Guiana.

The Ariane 5 rocket was expected to be drained of its cryogenic liquid hydrogen and liquid oxygen propellants later Thursday as teams reset for another countdown to begin late Thursday night. Arianespace and the European Space Agency will try again to launch the Ariane 5 rocket with JUICE at 8:14:29 a.m. EDT (1214:29 UTC) Friday, or 9:14 a.m. local time in French Guiana.

The mission has until April 25 to depart Earth and begin its eight-year interplanetary journey, a narrow window of a few weeks constrained by the positions of the planets in the solar system.

The $1.7 billion mission is Europe’s first spacecraft to travel to the outer planets, carrying a suite of 10 science instruments to survey Jupiter and three of its icy moons — Europa, Callisto, and Ganymede. It will take eight years for the JUICE spacecraft, built by Airbus, to reach Jupiter, using a series of planetary flybys with the moon, Earth, and Venus to help give it a boost toward the outer solar system.

The Ariane 5 rocket will initially send JUICE on a trajectory to escape Earth’s gravity and enter a loop around the sun, called a heliocentric orbit. The spacecraft will return to Earth for a flyby in August 2024, using gravity to begin reshaping the probe’s orbit around the sun. The flyby will be the first time a spacecraft performs a gravity assist maneuver with both the Earth and the moon.

A similar gravity assist flyby with Venus is scheduled in August 2025, followed by two more Earth flybys in 2026 and 2029. In a make-or-break moment for the mission, JUICE will fire its main engine to be captured into orbit by Jupiter’s gravity in July 2031. That milestone will begin a series of 35 flybys of Ganymede, Callisto, and Europa, making precise measurements of the thickness of Europa’s global ice sheet and searching for organic molecules.

In 2034, JUICE will steer into an orbit around Ganymede itself for a detailed global survey. Ganymede is the largest moon in the solar system, and the only moon known to have its own magnetic field. Scientists have discovered evidence Ganymede harbors a deep underground ocean of liquid water under an icy crust.

JUICE will be the first-ever spacecraft to orbit one of Jupiter’s moons. It will operate in tandem around Jupiter with NASA’s Europa Clipper spacecraft, which is scheduled for launch from Kennedy Space Center in Florida in October 2024. Europa Clipper will perform a series of close flybys with Europa, one of the solar system’s best candidates for finding signs of life, but will not enter orbit around the icy moon.

The launch of JUICE will mark the penultimate flight of an Ariane 5 rocket, and the 116th Ariane 5 mission since the European launcher debuted in 1996. It will also mark Arianespace’s first flight of 2023, and the company’s 345th mission since 1979.

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Arianespace’s live video webcast will begin approximately one hour before launch and will be available on this page.

These photos and a time lapse video from the European Space Agency chronicle the final preparations for launch of the Jupiter Icy Moons Explorer, or JUICE, spacecraft from the Guiana Space Center on the second-to-last Ariane 5 rocket.

Built by Airbus, the 13,142-pound (5,961-kilogram) JUICE spacecraft was installed on top of the Ariane 5 rocket inside the final assembly building in Kourou, French Guiana, on April 1. The mating of the spacecraft with the Ariane 5 rocket completed nearly two months of launch campaign preparations on the payload, which arrived in French Guiana on Feb. 9 with a trans-Atlantic flight on an Antonov cargo plane from Europe.

During the launch campaign, technicians loaded more than 3.5 metric tons of hydrazine and nitrogen tetroxide propellants into the JUICE spacecraft. The toxic fuel and oxidizer will feed thrusters and JUICE’s main engine for critical burns to guide it on its journey to Jupiter, including the make-or-break maneuver to enter orbit around the gas giant in 2031, then to enter orbit around the moon Ganymede four years later.

On April 4, the rocket’s Swiss-made payload shroud was lowered over the spacecraft. The fairing will protect the JUICE spacecraft during final launch preparations and during the first three minutes of the flight through the dense lower layers of the atmosphere.

The time lapse video below, produced by ESA, shows the major milestones of the launch campaign.

From integration to rollout to the launch pad, here’s what @ariane5 #VA260 and #ESAJuice have been up to during the past two days.#DestinationJupiter #ExploreFarther pic.twitter.com/9ncreBfwHq

— ESA’s Juice mission (@ESA_JUICE) April 13, 2023

On April 11, two days before the scheduled launch, the 180-foot-tall (54.8-meter) Ariane 5 rocket was tugged the 1.7-mile (2.7-kilometer) distance from the final assembly building to the ELA-3 launch zone at the Guiana Space Center. A 540-horsepower Titan truck towed the rocket and its mobile launch table along rail tracks to reach the launch pad.

Once the rocket arrived at the pad, technicians connected the launch table to the ground power supply and propellant lines that will feed fuel into the two-stage Ariane 5 during Wednesday’s countdown.

Liftoff with the JUICE spacecraft to begin an eight-year flight to Jupiter is set for 9:14 a.m. local time (8:14 a.m. EDT; 1214 UTC GMT) Friday, April 14. A launch attempt Thursday, April 13, was scrubbed due to the risk of lightning. The mission has an instantaneous launch window each day through April 25.

The launch will be the penultimate flight of an Ariane 5 rocket, and the 116th Ariane 5 mission since the European launcher debuted in 1996. It will also mark Arianespace’s first flight of 2023, and 344th mission since 1979.

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Follow Stephen Clark on Twitter: @StephenClark1.

The European Space Agency’s $1.7 billion robotic Jupiter Icy Moons Explorer mission is ready for liftoff Thursday from French Guiana, beginning an eight-year cruise to the solar system’s largest planet before becoming the first-ever spacecraft to orbit one of Jupiter’s moons in the 2030s.

The mission, known by the acronym JUICE, carries a high-resolution camera and ground-penetrating radar to map the frozen landscapes of three of Jupiter’s largest moons — Ganymede, Callisto, and Europa — and a suite of spectrometers to measure the composition of their icy crusts. After launch, the JUICE spacecraft will deploy an insect-like array of antennas and booms with sensors to study particles and dynamic plasma fields around Jupiter and its moons.

“We’ll explore Jupiter and its icy moons, which are Europa, Ganymede and Callisto, with a particular focus on Ganymede, which is a unique object in the solar system, the only moon with a magnetic field and the biggest moon of the solar system,” said Olivier Witasse, project scientist for the JUICE mission at the European Space Agency. “The main goal is to understand whether there are habitable environments among those icy moons around a giant planet like Jupiter.”

Scientists believe Europa, Ganymede, and Callisto harbor oceans of liquid water beneath their icy crusts.

“We will characterize, in particular, the liquid water oceans which are inside the icy moons,” Witasse said. “So the question is, where are those oceans located, at which distance underneath the surface of the moons, what is the depth of this ocean? How much water do we have? What is the composition of this water?”

JUICE has 10 science instruments developed by research teams across Europe, the United States, and Japan. According to ESA, the mission is outfitted with “the most powerful remote sensing, geophysical, and in situ payload complement ever flown to the outer solar system.”

An Italian-led radar sounder will probe he icy crust covering Jupiter’s moons, revealing structures as deep as 6 miles (9 kilometers) under the surface. JUICE’s main camera will take pictures of Jupiter’s cloud patterns, rings, and the chaotic and cratered terrain of Europa, Callisto, and Ganymede.

“To understand this question of habitability, we need to explore the Jupiter system globally,” Witasse said. “So to study Jupiter, its atmosphere, its weather, its strong rotating magnetic field, the volcanic moon Io, the other moons in the system, and how all these bodies are connected to to each other.”

Built by Airbus, the JUICE spacecraft is enclosed within the nose cone of an Arianespace Ariane 5 launcher for liftoff at 8:15:01 a.m. EDT (1215:01 UTC) from the Guiana Space Center, the European-run spaceport in Kourou, French Guiana. The Ariane 5 will vault off the launch pad with 2.9 million pounds of thrust from its hydrogen-fueled main engine and two side-mounted solid rocket boosters.

The European rocket is making its penultimate flight with the JUICE spacecraft. A final Ariane 5 launch with two communications satellite is scheduled for June, then the workhorse rocket will be retired in favor of Europe’s new-generation Ariane 6 rocket, which is still in development.

The Ariane 5 is one of the most powerful operational rockets in the world, with 115 missions to its credit, including the historic launch of the James Webb Space Telescope on Christmas Day 2021.

The 13,141-pound (5,961-kilogram) JUICE spacecraft will ride the Ariane 5 rocket for nearly 28 minutes, getting enough of a velocity boost to escape Earth’s gravity and head off into the solar system. After separating from the Ariane 5’s upper stage, JUICE will contact a ground station and unfurl its two power-generating solar array wings, each arranged in a distinctive cross-like formation.

The solar panels are the largest ever built for an interplanetary spacecraft, stretching nearly 89 feet (27.1 meters) tip to tip with an area of 915 square feet (85 square meters). Their large size will allow JUICE to generate enough power for the spacecraft and its science instruments at Jupiter, around five times farther from the sun than Earth. The spacecraft’s 23,560 solar cells will generate 850 watts of power.

“At Earth, such a (solar array) surface area could power an entire road of houses, but at Jupiter, it can power a single microwave just once,” ESA officials wrote in the JUICE press kit.

Ground controllers at ESA’s spacecraft operations center in Darmstadt, Germany, will oversee JUICE’s cruise to Jupiter. The first 17 days after launch will include a series of instrument, antenna, and boom deployments.

“JUICE is a spacecraft has taken the better part of the past decade to be designed and developed, and is now ready for launch on top of the Ariane 5 launcher,” said Alessandro Atzei, ESA’s payload system engineer for the JUICE mission. “So we’re talking about rather large spacecraft with many key features that really are striking. The very large high gain antenna, the huge solar arrays, 85 square meters, and many, many deployable booms. So just after launch, it will be a lot of work to make sure that everything gets deployed properly so we can start our mission.”

ESA selected the JUICE mission for development in 2012, beating out proposals for an X-ray astrophysics observatory and a gravitational wave detector mission in a competition for funding in the agency’s Cosmic Vision space science program.

Despite a big boost from the Ariane 5 rocket, the JUICE spacecraft will not take a direct route to Jupiter. It will circle the sun one time before returning for a flyby of the Earth and the moon in August 2024, a maneuver to use gravity to begin reshaping the probe’s orbit. The flyby will be the first time a spacecraft performs a gravity assist maneuver with both the Earth and the moon.

A similar gravity assist flyby with Venus is scheduled in August 2025, followed by two more Earth flybys in 2026 and 2029. In a make-or-break moment for the mission, JUICE will fire its main engine to be captured into orbit by Jupiter’s gravity in July 2031. That milestone will begin a series of 35 flybys of Ganymede, Callisto, and Europa, making precise measurements of the thickness of Europa’s global ice sheet and searching for organic molecules.

“Jupiter, it’s really a miniaturized solar system,” Witasse said.

Then, in 2034, JUICE will maneuver into orbit around Ganymede itself for a detailed survey.

The spacecraft will attempt to confirm the existence of a deep subsurface ocean on Ganymede. A laser altimeter instrument primarily funded by Germany will measure tidal deformation to help scientists learn more about Ganymede’s hypothesized internal ocean, and gather data for a global topographic map of the solar system’s largest moon.

JUICE’s instruments will create a high-resolution map of its icy surface, and investigate Ganymede’s magnetic field. When JUICE runs low on fuel, ground controllers will guide the spacecraft on a collision course with Ganymede to ensure it doesn’t contaminate any other moons in the Jupiter system, which could hinder future missions searching for life.

Many of JUICE’s goals follow up on discoveries made by NASA’s Galileo mission, which toured the Jupiter system from 1995 to 2003.

The JUICE mission won’t be alone at Jupiter. NASA plans to launch its own multibillion-dollar Jupiter-bound spacecraft, Europa Clipper, from Kennedy Space Center in Florida in October 2024.

Europa Clipper will launch on a more powerful rocket, SpaceX’s Falcon Heavy, and arrive in orbit around Jupiter in April 2030, a year ahead of JUICE. The two missions are complementary, with JUICE focused on Ganymede and Europa Clipper primed to study Europa, one of the best candidates for a habitable world elsewhere in the solar system.

“Jupiter, it’s really a miniaturized solar system,” Witasse said.

Scientists in the United States and Europe are investigating opportunities for coordinated observations between the Europa Clipper and the JUICE spacecraft.

“We have studied the two trajectories in the system, and we can see that we can do great science at Europa, when the two spacecraft can observe this moon together,” Witasse said. “One example would be a flyby of Clipper, followed by the flyby of JUICE just four hours later.”

Another robotic mission currently orbiting Jupiter is NASA’s Juno spacecraft, which arrived at the gas giant in 2016 and has now completed 50 orbits around the planet. Juno’s scientific payload is designed to study the atmosphere and internal structure of Jupiter, but scientists have recently expanded the scope of the mission to image Jupiter’s largest moons.

Europa Clipper and JUICE will become the third and fourth spacecraft to orbit Jupiter, following a series of one-shot flybys that began with NASA’s Pioneer 10 and 11 probes in 1973 and 1974.

The JUICE spacecraft’s sensitive avionics are contained within a lead-lined vault to shield them from the harsh radiation around Jupiter.

“Mass, power, everything is really optimized for these sorts of missions,” said Justin Byrne, head of science programs at spacecraft builder Airbus Defense and Space. “The radiation is a killer for the electronics, and unless you protect it, the electronics will start failing. We would have memory corruptions and then catastrophic failure of the computers eventually.”

JUICE will head deeper into the cosmos than any European spacecraft has ever gone on its own. ESA’s Huygens probe, which landed on Saturn’s moon Titan, hitched a ride to Saturn with NASA’s Cassini spacecraft.

The JUICE spacecraft was designed with redundancy, with two computers and backups for most major systems, according to Byrne.

“In addition, because Jupiter is a long way away, we can’t directly control it,” Byrne said.

It takes about an hour-and-a-half for radio signals to make the round-trip journey between Earth and Jupiter. That required engineers to design the JUICE spacecraft with autonomous software to detect problems and put itself into a safe configuration long enough to await commands from controllers back on Earth.

JUICE’s 8.2-foot-wide (2.5-meter) high-gain antenna will beam imagery and science data back to Earth. Scientists at research institutions around the world will analyze the measurements.

“We are not going to detect life with with JUICE,” Witasse said. “But nevertheless we are going to study interesting aspects related to life and habitability.”

An ion mass spectrometer on JUICE will measure water vapor and other molecules in the tenuous atmospheres of the icy moons. Another instrument will measure vertical profiles of the moons’ atmospheres.

“Really, the most interesting aspect of of the mission to know where is this water?” Witasse said. “What is the composition in terms of salt? How does that relate to the habitability of those moons?”

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