First-ever slingshot around Earth and the Moon results in fantastic new photos

Daniel Sims

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The big picture: The European Space Agency's ongoing mission to study Jupiter and its moons involves a complex series of gravitational maneuvers within the inner solar system, including the first-ever slingshot around both Earth and the Moon. During an early stage of one of these flybys, the mission provided an opportunity to capture detailed photos of the lunar surface.

The ESA recently released new photos of the Moon's surface, captured during humanity's first attempt at a gravitational slingshot around both Earth and its natural satellite. The spacecraft responsible for the images is scheduled to reach Jupiter in 2031.

The snapshots reveal various lunar landmarks and color variations, including the Humboldt crater (near the bottom right) and Mare Fecunditatis (at the top center). Earth is faintly visible in one of the photos, appearing as a glowing ring near the top center.

Interestingly, the cameras that captured these images weren't originally designed for space observation. Although the spacecraft is equipped with a scientific camera, the lunar flyby positioned the equipment-monitoring cameras perfectly to take the new photos.

The flyby is part of a groundbreaking gravitational assist that is a crucial step in the ESA's Juice mission to study Jupiter and its moons. The spacecraft was launched last April aboard an Ariane 5 rocket from the ESA spaceport in French Guiana.

While previous space missions have reached Jupiter in about a year, Juice will take a more extended journey, not arriving at Jupiter until the next decade. This slower pace is intentional, as the spacecraft is aiming for a stable orbit and carries the largest payload of scientific instruments ever sent to the Jupiter moon system, weighing over 6,000 kg.

Normally, propelling such a massive spacecraft on the roughly 800-million-kilometer journey to Jupiter would require an enormous amount of fuel. Moreover, slowing the spacecraft down to counteract the accumulated inertia and achieve a stable orbit at its destination would demand even more fuel than was needed for the journey.

Instead, Juice will use gravity assists from the Moon, Earth, and Venus to gain and transfer momentum, allowing it to approach Jupiter at the correct speed. The ESA has just completed the first maneuver – a first-ever Moon-Earth slingshot. The next flyby, involving Venus, is scheduled for August next year. Two additional gravity assists from Earth are planned for 2026 and 2029. If Juice reaches Jupiter in 2031, its mission to study 35 of the gas giant's moons is expected to last until 2035.

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It amazes me that spacecraft can navigate to, frankly, anything outside the Earth/Moon SOI. The distances and speeds involved MUST be precisely accurate or its a loss of mission. And the distances in the vastness of only our solar system (much less outside Sol, one day) are hard to wrap your head around. AND this thing from the illustration looks to be doing 5 orbits around the sun to accomplish its multiple gravity assist maneuvers before starts its final travel to the Jovian system.

I'm a firmware engineer and would LOOOVVEE to peak under the hood at the navigation control/monitoring code, 100% Yum heh
 
It amazes me that spacecraft can navigate to, frankly, anything outside the Earth/Moon SOI. The distances and speeds involved MUST be precisely accurate or its a loss of mission. And the distances in the vastness of only our solar system (much less outside Sol, one day) are hard to wrap your head around. AND this thing from the illustration looks to be doing 5 orbits around the sun to accomplish its multiple gravity assist maneuvers before starts its final travel to the Jovian system.

I'm a firmware engineer and would LOOOVVEE to peak under the hood at the navigation control/monitoring code, 100% Yum heh
That's because space is almost entirely a controlled environment. There have been a lot of other slingshot maneuvers used by previous spacecraft, many of which are detailed here: https://en.wikipedia.org/wiki/Gravity_assist#Notable_examples_of_use
 
That's because space is almost entirely a controlled environment.
N-body perturbations keep it from being anywhere nearly precise enough to perform these maneuvers in a fully ballistic manner. This JUICE mission, for instance, performs up to four separate burns (course corrections) each time it passes a celestial body.
 
I understand why gravity assists work but, as a programmer, I haven't a clue how I'd go about calculating the flightpath. Do they just simulate a 1000 different directions and then score the best ones (didn't crash, left Earth's gravity, amount of fuel left, anywhere near Jupiter etc). Then perhaps take the top 100 routes and refine those paths (adjusting the direction and thrust). Then repeat that process endlessly until they get a match. Maybe they could do it from both directions to see if any routes match in the middle? I can't see how else they'd do it. Does anyone actually know?
 
I understand why gravity assists work but, as a programmer, I haven't a clue how I'd go about calculating the flightpath. Do they just simulate a 1000 different directions...
As someone with a physics degree, the analytic approach is quite simple, though it goes by the intimidating name of 'patched conics' -- just convert the problem into a series of simpler 2-body problems, which require nothing but high school math to calculate.

That's an approximation that can be very rough to extraordinarily accurate for certain mission types. But all modern missions use a numerical method that breaks the trajectory into very tiny time-steps, the iterates over each step the change in position and velocity. I haven't seen their code, but pretty much wherever you are in the solar system, you don't need to take into account more than the gravity of the sun, Jupiter, and the body you're nearest to. When you're extremely close to a body (say, for a slingshot around the moon), you can't treat it as a point object, but rather must take into account the oblateness of its spherical shape, and perhaps even local mass anomalies (the earth and moon have a few). Still, the math is not complex: if you're a programmer, you could write such a sim using Euler's method easier than I could.
 
At certain points eg Lagrange points where a rockets flight plan can be changed quite a lot for very little energy..
Any 2 body system as 5 such points, but the solar system has as alluded to above N is much greater

A 2 second burn on a flight path may or may not have same result as 2 second burn 2 hours later in flight .

There are quite a few ways/variations to get extra boost over and above a straight forward gravitational slingshots

Probably a fascinating science. My guess is take theoretical tools, or approximation tools , and then use applied to optimise them.
I know they now have some tools to that have allowed scientists to calculate even more stable 3 body systems , think its well up in hundreds now , soon to go to thousands ( again from memory )

Plus if you have very close fly bys of the outer planets , some of the data may not be accurate enough. Gravity is not equal on earth at every point on a greater imagined sphere with it's centre the same as earths. Want to lose weight, weigh yourself at the north pole
Still finding moons, Jupiter has about 95 I think, plus maybe could hit some dust particles .
So will always need minor course adjustments, but slingshotting the Voyagers were incredible accurate, given moving small targets in the vastness of space
 
the analytic approach is quite simple, though it goes by the intimidating name of 'patched conics' -- just convert the problem into a series of simpler 2-body problems, which require nothing but high school math to calculate.
I can picture that working if I know the simple start and end points (the Earth and Jupiter) but when you have a very chaotic route involving multiple gravity assists, how would you come up with that original chaotic route? Would an guy (or girl) say to themselves that they wanted to go 5 times round the moon, then twice round the sun then off to Jupiter and then start breaking it down into cones? Maybe they do, it just seems an odd way to go about things.

Gravity is not equal on earth at every point on a greater imagined sphere with it's centre the same as earths. Want to lose weight, weigh yourself at the north pole
I think it actually might be the other way round and you weigh less at the equator. I think it's something to do with centripetal force, distance to the centre of gravity and what you had for breakfast ;)
 
I can picture that working if I know the simple start and end points (the Earth and Jupiter) but when you have a very chaotic route involving multiple gravity assists, how would you come up with that original chaotic route?
Your instincts are correct -- there's no way (we know of yet) to 'solve' for the best route. It was proven long ago that, if you're limited to two burns (impulses), then a Hohmann Transfer is the best trajectory. But I can remember being giddily excited when a minimizing three-impulse "bi-parabolic" transfer was first discovered ... and for 4+ impulses, it's still a topic of ongoing research in optimization dynamics.

I think it actually might be the other way round and you weigh less at the equator. I think it's something to do with centripetal force, distance to the centre of gravity and what you had for breakfast ;)
You're both right. Gravitational force is less at the poles, but your "scale weight" will be less at the equator. In a rotating frame of reference, the two are not equivalent.

There are quite a few ways/variations to get extra boost over and above a straight forward gravitational slingshots.
Very true. The below is one of the best known; there are actually cases where the loss from accelerating in the exact wrong direction is less than what you gain from the effect:

 
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