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The reason for a detour to Jupiter is that it's actually fairly hard to get closer to the Sun. Somewhat surprisingly (if you haven't seen it before), it takes q
by thatcherc 7y ago
The reason for a detour to Jupiter is that it's actually fairly hard to get closer to the Sun. Somewhat surprisingly (if you haven't seen it before), it takes quite a bit of energy to drop from Earth's orbit around the Sun to ie Mercury's. In this case, it looks like it would take less energy to fly out to Jupiter and get the gravity assist (which is very substantial because of the planet's mass), and fall back toward the Sun than it would be to drop straight into a low solar orbit from Earth. This type of trajectory was actually considered for the Parker Solar Probe [0], but was eventually rejected because it would take too long.* If you're going on an interstellar voyage, the time to get out to Jupiter might not impact the timeline as much.
[0] - https://wikipedia.org/wiki/Parker_Solar_Probe https://wikipedia.org/wiki/Parker_Solar_Probe
* notably, the new trajectory still includes gravity assists off Earth and Venus, underscoring the amount of delta-V needed to lower a solar orbit
- xt00 7y agoYea interesting! Parker solar probe will hit a whopping 0.064% of the speed of light.. and the orbit is quite interesting as you said — needs to slow down to cancel out the speed of earths orbital velocity. So ya know, for a reference point, the 1% of the speed of light that the Trisolaran fleet is flying at is just a mere 6.7 billion miles per hour.. so 0.5 million ain’t too bad...
- pdonis 7y ago> it takes quite a bit of energy to drop from Earth's orbit around the Sun to ie Mercury's More precisely, you have to lose a significant amount of energy relative to the Sun, and it takes significant delta-v for a spaceship starting at Earth (to cancel out at least part of Earth's orbital speed about the Sun) to do that. Yes, that's a valid point.