Sadly, the tech savy of the news seems to be going the other direction IMHO. It might also be that "redirected" sounds like something went wrong and will get more clicks.
I'm not a fan of this inexact and incorrect language.
"Rerouted" means that the route was changed, not that the trajectory was changed. The route was planned before launch, and that hasn't changed. The headline makes it seem like there was an unplanned change.
“using the gravity of Earth to send it Venus-bound”
While technically correct, this sentence is misleading. The ESA can do better.
Passing by a body can deflect a spacecraft. So technically, the Earth’s gravity sends the craft “Venus bound.” But “the gravity of Earth” imparts no net delta-v and wouldn’t on its own allow the craft to reach Venus.
A “gravity assist around a planet changes a spacecraft's velocity (relative to the Sun) by entering and leaving the gravitational sphere of influence of a planet” [1]. The Earth’s revolution around the Sun gets the craft to Venus, not the Earth’s gravity.
The gravity of the Earth absolutely changes the speed of the probe.
In terms of the basic momentum transfers, non-propulsive gravity assists are essentially the same as elastic collisions with balls of non-equal mass. In particular, energy can be transferred, and that is mediated by the interaction forces: if a very heavy ball is rolling along at speed v and I place a tiny ball at rest in front of it, the tiny ball will bounce off at about 2v. We could certainly say “the atomic forces between the heavy ball and the tiny ball during the collision propel the tiny ball to its new destination”. This is true even though the tiny ball’s speed is constant in the center-of-mass frame.
ninju|1 year ago
https://www.esa.int/ESA_Multimedia/Videos/2024/08/Juice_s_lu...
(for those that are more visual)
istultus|1 year ago
(everyone is more visual, though we have less aggregated data on how blind people use their visual cortex)
istultus|1 year ago
munchler|1 year ago
gmiller123456|1 year ago
smcin|1 year ago
- 2nd and 3rd Earth flybys 9/2026 and 1/2029
- 7/2031 arrives Jupiter; Jupiter orbit insertion and apocentre reduction with multiple Ganymede gravity assists
- 1/2032 .. 11/2034 Reduction of velocity with Ganymede–Callisto assists. Increase inclination with 10–12 Callisto gravity assists.
- 12/2034 enter Ganymede orbit for its close-up science mission
- 12/2035 will impact on Ganymede when runs out of propellant
summarizing https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Explorer#Sum...
johnklos|1 year ago
"Rerouted" means that the route was changed, not that the trajectory was changed. The route was planned before launch, and that hasn't changed. The headline makes it seem like there was an unplanned change.
JumpCrisscross|1 year ago
While technically correct, this sentence is misleading. The ESA can do better.
Passing by a body can deflect a spacecraft. So technically, the Earth’s gravity sends the craft “Venus bound.” But “the gravity of Earth” imparts no net delta-v and wouldn’t on its own allow the craft to reach Venus.
A “gravity assist around a planet changes a spacecraft's velocity (relative to the Sun) by entering and leaving the gravitational sphere of influence of a planet” [1]. The Earth’s revolution around the Sun gets the craft to Venus, not the Earth’s gravity.
[1] https://en.m.wikipedia.org/wiki/Gravity_assist
jessriedel|1 year ago
In terms of the basic momentum transfers, non-propulsive gravity assists are essentially the same as elastic collisions with balls of non-equal mass. In particular, energy can be transferred, and that is mediated by the interaction forces: if a very heavy ball is rolling along at speed v and I place a tiny ball at rest in front of it, the tiny ball will bounce off at about 2v. We could certainly say “the atomic forces between the heavy ball and the tiny ball during the collision propel the tiny ball to its new destination”. This is true even though the tiny ball’s speed is constant in the center-of-mass frame.
verzali|1 year ago
anigbrowl|1 year ago
unknown|1 year ago
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xeonmc|1 year ago
snapcaster|1 year ago