Juice probe scores epic fuel save after snapping selfies with Earth and Moon
- Reference: 1724243410
- News link: https://www.theregister.co.uk/2024/08/21/esa_juice_gravity_assist/
- Source link:
The ultimate destination of the spacecraft is Jupiter, but to save fuel, the probe is using the gravity of the Earth, Moon, and Venus to send it on its way. The European Space Agency (ESA) reckons the slingshots will save the mission up to 150 kg of fuel, even if it likely cost controllers some chewed fingernails as the probe made its lunar-Earth flyby.
The closest approach to the Moon, which increased Juice's speed relative to the Sun by 0.9 km/s, occurred at 2115 UTC on August 19, and the nearest approach to the Earth, which decreased the probe's speed by 4.8 km/s, occurred at 2156 UTC on August 20, ESA said.
[1]
"The gravity assist flyby was flawless, everything went without a hitch, and we were thrilled to see Juice coming back so close to Earth," said Ignacio Tanco, the mission's Spacecraft Operations Manager.
[2]
[3]
It did indeed come close to Earth, passing 6,840 km above Southeast Asia and the Pacific Ocean, to be precise. Eight of the probe's instruments collected data during the Earth flyby. Ten were running during the Moon flyby. One was the spacecraft's scientific camera, JANUS – an abbreviation of the Latin phrase "Jovis, Amorum ac Natorum Undique Scrutator" (Comprehensive exploration of Jupiter, and his loves and descendants) – collected data which will be downloaded in the coming weeks.
[4]ESA's Juice probe dances with Earth and Moon before shooting off to Jupiter
[5]ESA's Jupiter-bound Juice spacecraft has a sticky problem with its radar
[6]ESA's Juice blasts off to squeeze secrets from Jupiter's moons
[7]Launching soon: ESA's Juice to probe Jupiter's moons for signs of possible life
Stars of the show, however, were Juice's cameras designed to monitor the deployment of the probe's appendages. These were pressed into service to capture images from the flyby and, after some light processing, produced some impressive results. [8]In one set , the spacecraft is clearly visible, with the Moon in the background. [9]Another shows the Earth.
The Moon, as seen by Juice (Credit: ESA/Juice/JMC Acknowledgements: Simeon Schmauß & Mark McCaughrean)
So precise was the flyby that controllers only required a small fraction of the propellant reserved for course corrections. Coupled with a flawless Ariane 5 launch in April 2023, Juice has a little extra, er, juice in the tank for when it reaches its final destination.
"This will add to the margins we keep for a rainy day, or to extend the science mission once we get to Jupiter," Tanco said.
While using gravity to adjust trajectories and save fuel is not new, hats must be doffed to the ESA Flight Dynamics team for the calculations behind an inherently risky maneuver. Hopefully, there will be time for some celebrations and perhaps some beverages at ESA's Darmstadt control center before the next rendezvous with Venus in August 2025. ®
Get our [10]Tech Resources
[1] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2ZsYPKOd2hNwme6BLhQQlnQAAAMU&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[2] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZsYPKOd2hNwme6BLhQQlnQAAAMU&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ZsYPKOd2hNwme6BLhQQlnQAAAMU&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[4] https://www.theregister.com/2024/08/19/esa_juice_gravity_assist/
[5] https://www.theregister.com/2023/04/29/esa_juice_jupiter_problem/
[6] https://www.theregister.com/2023/04/14/esa_jupiter_juice/
[7] https://www.theregister.com/2023/04/13/esas_juice_spacecraft_jupiter/
[8] https://www.esa.int/ESA_Multimedia/Images/2024/08/Juice_snaps_Moon_en_route_to_Earth
[9] https://www.esa.int/Science_Exploration/Space_Science/Juice/Juice_rerouted_to_Venus_in_world_s_first_lunar-Earth_flyby
[10] https://whitepapers.theregister.com/
Re: Excellent
The payload isn't going to change, the satellite is already in space. What this really means is that there is 150kg more fuel for future adjustments, so better lifetime returns, or longer lifespan.
Re: Excellent
The thing that concerns me is that the indirect route they're taking means that the satellite is going to take six years to get to Jupiter, which means it has much longer for components to die as it flies in circle after circle around the sun before hitting its final destination.
I'm not a rocket surgeon, and this has almost certainly been taken into account - but it feels a bit excessive to have 6 flybys to get to the fourth closest planet, spread across six-odd years.
Gravity?
See the animation on [1]https://www.esa.int/Science_Exploration/Space_Science/Juice/Where_is_Juice_now .
The acceleration is not due to the gravitation of the Moon, Earth and Venus, but due to their orbital velocity.
[1] https://www.esa.int/Science_Exploration/Space_Science/Juice/Where_is_Juice_now
Re: Gravity?
Gravity assists like this are made possible by the Oberth effect, increasing V (from mv^2) at a higher base velocity causes a much stronger increase in Kinetic Energy.
The increased V comes from converting Gravitational Potential Energy to Kinetic Energy by being deeper in a celestial body's gravity well.
I might be missing something here, I read your comment as "due to [the celestial body's] orbital velocity" rather than "due to [the probe's] orbital velocity".
Re: Gravity?
Gravity is still the force that causes the spacecraft to accelerate...(!)
Re: Gravity?
So, how is the acceleration applied then?
Nail biting?
If I were the controller I don't think I would be doing that about the trajectory. Science data take perhaps. The trajectory was set after the first course correction. I would have checked the orbit several times after that though to make damn sure it didn't need another burn. Now I would be doing the checking several times again to see if it needed another course correction before getting to the right point in space next to Venus. If they don't need another burn before that I will be very impressed.
If we had the power
If we had the power, we would just fly straight there. These intricate manoeuvres show just how feeble we are in planetary terms.
Re: If we had the power
I want a Doc Smith inertialess drive for xmas, please.
Excellent
While, given the scope of the mission, the 150 kg savings might be considered fairly small, it does mean the mission payload can larger and heavier. But I reckon the real win is the ability to do this, and possibly even more intricate gravity assists in future missions to get to places both faster and with less fuel than had previously been considered essential.