https://www.esa.int/ESA_Multimedia/Videos/2024/08/Juice_s_lu...
(for those that are more visual)
(everyone is more visual, though we have less aggregated data on how blind people use their visual cortex)
- 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...
"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.
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.
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.
From the Earth’s frame of reference there is no change in delta-v other than a change in direction. It’s only from the Sun’s frame of reference that there is velocity added in the speed component (v_infinity, commonly). If you can find a single measurement to the contrary, that’s novel enough to be worth publishing.
That’s why you can’t gravity assist around the Sun to get around the Solar System faster.
Wait! Wouldn't Earth's gravity take away when departing just as much as given when arriving? However, the probe's direction could change based on how close it passes Earth.
As the probe passes Earth, a mass proportionate amount of Earth's velocity would be shared to the probe. I have a distant grade-school memory of an analogy of two people on a roller-skate rink. The passing and passed persons link hands and some of the passed person's velocity is emparted to the passing person's velocity.
Prepositions are fascinating. Why is it that NASA and ESA don't get a "the" but the Sun, Earth, Moon and USA do? Why does it always feel wrong when Apple doesn't use "the" before iPod, iPhone, etc?
0. https://academicguides.waldenu.edu/writingcenter/grammar/pre...
