Juice burns laborious towards first-ever Earth–moon flyby

On 17 November 2023, ESA’s Juice spacecraft carried out one of many largest and most essential maneuvers in its eight-year journey to Jupiter.

Utilizing its fundamental engine, Juice modified its orbit across the solar to place itself on the proper trajectory for subsequent summer season’s Earth–moon double gravity help—the primary of its sort.

The maneuver lasted 43 minutes and burned virtually 10% of the spacecraft’s total gas reserve. It is the primary a part of a two-part maneuver that might mark the ultimate time that Juice’s fundamental engine is used till its arrival within the Jupiter system in 2031.

Mission to Jupiter picks up velocity

ESA’s Jupiter Icy Moons Explorer (Juice) launched from Europe’s spaceport in French Guiana on 14 April 2023.

It is on a mission to make detailed observations of the enormous fuel planet and its three massive, ocean-bearing moons—Ganymede, Callisto and Europa.

However Juice will not start its investigations into the character and doable habitability of the Jupiter system till its arrival in 2031.

Why does it take so lengthy to get to Jupiter? Properly, the brief reply is that it has much less to do with the space between Earth and Jupiter and extra to do with combating the solar’s huge gravitational pull as you enterprise outwards by means of the photo voltaic system.

Missions to the enormous fuel planets, corresponding to Juice, Europa Clipper, Galileo or Juno, could be little greater than large gas tanks in the event that they needed to retailer all of the vitality wanted to beat the solar’s gravity by themselves.

As an alternative, they make use of “gravity-assist” or “flyby” maneuvers to achieve vitality by swinging by means of the sturdy gravitational fields of varied planets on the way in which.

Capturing for the moon

Juice’s first enhance will come from its dwelling planet, when it returns to Earth in August 2024, a couple of yr after launch.

In truth, in a first-of-its-kind flyby, Juice will first move by the moon to provide it an additional kick and make the flyby of Earth that takes place 1.5 days later much more efficient.

However even with this additional enhance, to get essentially the most out of the gravity help, Juice has to reach on the Earth–moon system at exactly the proper time, on the right velocity and touring within the right route.

That is the place immediately’s maneuver is available in.

On 17 November, at 16:10 (CET), Juice’s fundamental engine carried out a burn that lasted roughly 43 minutes.

“This maneuver used up roughly 363 kg of gas—or virtually precisely 10% of the 3650kg of gas that Juice launched with,” says Julia Schwartz, Flight Dynamics Engineer at ESA’s ESOC mission management heart in Germany.

That is Juice’s largest maneuver thus far. Till immediately, Juice had solely used roughly 10 kg of gas—largely as a part of a collection of brief burns used to assist free its caught RIME antenna.

“It was the primary a part of a two-part maneuver to place Juice on the proper trajectory for subsequent summer season’s encounter with Earth and the moon. This primary burn did 95% of the work, altering Juice’s velocity by virtually 200 m/s,” provides Julia.

“Juice is without doubt one of the heaviest interplanetary spacecraft ever launched, with a complete mass of round 6,000 kg, so it took loads of drive and loads of gas to realize this.”

“In just a few weeks, as soon as we have analyzed Juice’s new orbit, we’ll perform the second, a lot smaller second a part of the maneuver. Splitting the maneuver into two components permits us to make use of the second firing of the engine to iron out any inaccuracies of the primary.”

A further, a lot smaller maneuver utilizing Juice’s smaller thrusters could also be carried out in Might 2024 for the ultimate fine-tuning in the course of the strategy to Earth.

Final use of the principle engine till 2031

For a mission on an eight-year journey, burning 10% of your gas reserve in simply 43 minutes could seem loopy. However investing all that gas now will repay for years to return.

“If all goes properly with each components of this maneuver, we doubtless will not want to make use of the principle engine once more till we enter orbit round Jupiter in 2031,” says Ignacio Tanco, Juice Spacecraft Operations Supervisor. “For small trajectory corrections between at times, we’ll use Juice’s smaller thrusters.”

However that does not imply nothing attention-grabbing will occur between now and Juice’s arrival at Jupiter. Fairly the other, the journey is attention-grabbing as a result of it permits Juice to get all the way in which to Jupiter with out firing its fundamental engine once more, lowering the quantity of gas the spacecraft wants and permitting it to be packed stuffed with scientific devices.

After the Earth–moon double flyby of 2024 (often called a Lunar–Earth Gravity Help; LEGA), Juice will first make one flyby of Venus in 2025 and two additional flybys of Earth in 2026 and 2029 (each with out the extra enhance from the moon).

“At the moment’s maneuver will guarantee Juice arrives on the Earth–moon system on the proper time subsequent yr for the double flyby,” provides Ignacio.

“And, due to the intelligent trajectory designed by our Mission Evaluation staff, that flyby will line it up virtually completely for the entire others, with out us having to fireside the principle engine once more.”

With every flyby, the spacecraft will achieve extra vitality than could possibly be achieved by burning an inexpensive quantity of gas—vitality that may assist it climb in direction of Jupiter towards the pull of the solar’s gravity.

“It was crucial that we stock out this maneuver immediately. In any other case, the associated fee—how a lot gas we would wish to burn to succeed in the brand new orbit we’d like—would start to shoot up dramatically,” says Ignacio.

At the moment’s burn additionally gave the groups the chance to ensure Juice’s fundamental engine is working accurately. It was first examined shortly after launch, but it surely till immediately, it hadn’t been used for such a giant maneuver out in deep house.

“There have been some issues that we could not check prior to now. For instance, we solely had an estimate for the way the liquid within the gas tanks will transfer round because the spacecraft accelerates. This is essential to know exactly, as a result of if the gas behaves totally different to how we anticipate, it may trigger the spacecraft to float off beam in the course of the burn. So, we’re monitoring intently.”

Subsequent cease: Jupiter

The subsequent time that Juice will completely have to fireside its fundamental engine is throughout its Jupiter orbit insertion in 2031. That is the one most essential maneuver that the groups at ESOC will oversee.

Simply 13 hours after swinging by Ganymede and getting into the Jupiter system, the spacecraft might want to decelerate by about 1 km/s—5 occasions the change in velocity achieved immediately.

“That makes immediately’s maneuver additionally an essential check for Jupiter insertion—the earlier we all know if we have now any points with the principle engine, the higher,” says Ignacio.

As soon as in orbit across the fuel large, Juice can start its exploration of the Jupiter system. Groups at ESOC will steer Juice by means of a collection of 35 flybys of the ocean moons. The place as soon as flybys have been a yearly prevalence, at Jupiter they are going to be carried out as typically as as soon as each two weeks.

These close-ups of the icy moons will permit the spacecraft and scientists on Earth to assemble the information wanted to raised perceive these mysterious alien worlds.