6 ms·

If KSP is to be believed, this is shockingly difficult to do

by FredPret 2y ago

lizzas 2y ago
The same gravity that wants to pull you in keeps you in orbit. And any object we launch starts off in the suns orbit.
- FredPret 2y ago
  It's only the v0 you start off with from being in orbit already that makes it hard. Earth (and Kerbin) orbit at a very high speed.
- feoren 2y ago
  > The same gravity that wants to pull you in keeps you in orbit I would say it's your velocity that keeps you in orbit. Without the velocity, you fall into the star. Without the star's gravity, you keep going away in a straight line. Any object we launch starts off with Earth's velocity.
  - Terr_ 2y ago
    It's like a joke I recall from Hitchhiker's Guide to the Galaxy: You are indeed falling towards the ground... but the trick is to miss. Your lateral velocity is what keeps you missing, whether you want to or not.
beAbU 2y ago
In order to 'land' on the sun, or any celestial body, you need to get rid of your orbital speed. Higher orbital speed means higher orbit altitude. Landing on earth is comparatively easy, because you can use the atmospheric drag to slow down. It is so difficult to land on Mars because of it's thin atmosphere. Alternatively you need a shitload of fuel to burn to kill that velocity. Earth's orbital velcity is ~30km/s. So by extension, anything that comes from Earth will at least have that speed. So the probe needs to find 30km/s delta v in order to actually get close to the sun.
- FredPret 2y ago
  I wonder if you can use atmospheric drag to pull you into the Sun / a different star / Kerbol. Long ago, playing Elite if I remember correctly, you could fly close to a star and scoop up a load of hydrogen for later resale. I'd be interested to see a graph of gas density vs tendency to melt spacecraft compared to distance from the core for a typical star.
  - JumpCrisscross 2y ago
    > wonder if you can use atmospheric drag to pull you into the Sun You can, and I believe this probe will. The Sun’s atmosphere is just much nastier than our own, which means your aerobraking destroys your spacecraft quicker.
  - anigbrowl 2y ago
    It was Elite. Once you had a fuel scoop there was no requirement to dock and refuel any more so it was much easier to be a pirate or privateer. There was a bug (or was it?) in the very PC version where by if you had fuel scoops installed, set your view to looking out the rear of the ship, flew toward a star, and ignored all the warnings on your dashboard, you could fly right through the star. If you were being chased at the time you had the additional satisfaction of watching your pursuers' ships explode as they tried to follow you in.
- nostromo 2y ago
  You could use a solar sail to project a satellite towards the sun.
  - Jeff_Brown 2y ago
    How do you sail into the solar wind?
    - tedunangst 2y ago
      Just need a triangular sail and some zigzagging.
aziaziazi 2y ago
In SpaceFlight Simulator it’s quite easy IIRC (it’s been a while): 1. Orbit yourself around low earth 2. When entering the transfer window (opposite side of the sun-facing earth, i.e. above midnight longitude) booooost 3. For orbit, aim for tangent with your target. For sun discovery, aim for sun center. Choose but don’t change. The game is in 2D and you got nice auto-calculated transfert windows and trajectories. Is it one of those game simplification that makes it easy or there’s more difficulties?
- LorenPechtel 2y ago
  The math is simple enough, it's just the delta-v requirements are brutal. Or you take the slingshot approach at which point the math requirements are brutal. And I'm not aware of any KSP mod that helps you plan slingshots. And even if there was a slingshot maneuver requires a lot of precision because your ejection angle is highly sensitive to exactly how close you came. The Parker probe was sent outward to Jupiter and used it to slingshot away much of it's energy. (We normally think of using a planetary encounter to gain energy but it works both ways. Ejection velocity from a slingshot at Jupiter can be anywhere from hitting the sun to solar escape. It's just most probes are heading out, not in.)
  - lmm 2y ago
    > I'm not aware of any KSP mod that helps you plan slingshots. As someone who played before they added patched conics, I'd consider patched conics such a thing.
  - aw1621107 2y ago
    > And I'm not aware of any KSP mod that helps you plan slingshots If you're willing to go for the full n-body package, Principia [0] has a pretty nice flight planner that is quite usable for planning more complicated missions. KSP Trajectory Optimization Tool [1] is a non-mod alternative with some additional capabilities beyond flight planning as well. I think this one is designed for stock gravity so it should be usable in an otherwise vanilla install. [0]: https://github.com/mockingbirdnest/Principia https://github.com/mockingbirdnest/Principia [1]: https://github.com/Arrowstar/ksptot https://github.com/Arrowstar/ksptot
kccqzy 2y ago
There's a difference between flying directly into the sun as if landing there, and orbiting the sun but so close that the spacecraft is inside the solar atmosphere. This is doing the latter.
ostacke 2y ago
It requires seven Venus flybys, and 24 orbits around the sun[1]. Wikipedia has a nice animation of the trajectory[1], and NASA has another one here[2]. [1]https://en.wikipedia.org/wiki/Parker_Solar_Probe?wprov=sfti1#Trajectory https://en.wikipedia.org/wiki/Parker_Solar_Probe?wprov=sfti1... [2]https://svs.gsfc.nasa.gov/3966/ https://svs.gsfc.nasa.gov/3966/
- DiggyJohnson 2y ago
  Second link is beautiful and really shows the whiplash of the last set of solar encounters. Recommend clicking through to anyone with a passing interest.
zamadatix 2y ago
It's actually not too brutal so long as you don't try to do it directly. Launch a craft out past Jool then when you start falling back burn retrograde. It's like the opposite of what you do to efficiently burn when leaving Kerbin. In real life they used a set of Venus gravity assists instead. This has allowed them to slowly get closer while observing over time instead of a long wait and then one big bang close up before being shot ridiculously far back out.

If KSP is to be believed, this is shockingly difficult to do

lizzas 2y ago

The same gravity that wants to pull you in keeps you in orbit. And any object we launch starts off in the suns orbit.

FredPret 2y ago
It's only the v0 you start off with from being in orbit already that makes it hard. Earth (and Kerbin) orbit at a very high speed.
feoren 2y ago
> The same gravity that wants to pull you in keeps you in orbit I would say it's your velocity that keeps you in orbit. Without the velocity, you fall into the star. Without the star's gravity, you keep going away in a straight line. Any object we launch starts off with Earth's velocity.
- Terr_ 2y ago
  It's like a joke I recall from Hitchhiker's Guide to the Galaxy: You are indeed falling towards the ground... but the trick is to miss. Your lateral velocity is what keeps you missing, whether you want to or not.

beAbU 2y ago

In order to 'land' on the sun, or any celestial body, you need to get rid of your orbital speed. Higher orbital speed means higher orbit altitude. Landing on earth is comparatively easy, because you can use the atmospheric drag to slow down. It is so difficult to land on Mars because of it's thin atmosphere. Alternatively you need a shitload of fuel to burn to kill that velocity. Earth's orbital velcity is ~30km/s. So by extension, anything that comes from Earth will at least have that speed. So the probe needs to find 30km/s delta v in order to actually get close to the sun.

FredPret 2y ago
I wonder if you can use atmospheric drag to pull you into the Sun / a different star / Kerbol. Long ago, playing Elite if I remember correctly, you could fly close to a star and scoop up a load of hydrogen for later resale. I'd be interested to see a graph of gas density vs tendency to melt spacecraft compared to distance from the core for a typical star.
- JumpCrisscross 2y ago
  > wonder if you can use atmospheric drag to pull you into the Sun You can, and I believe this probe will. The Sun’s atmosphere is just much nastier than our own, which means your aerobraking destroys your spacecraft quicker.
- anigbrowl 2y ago
  It was Elite. Once you had a fuel scoop there was no requirement to dock and refuel any more so it was much easier to be a pirate or privateer. There was a bug (or was it?) in the very PC version where by if you had fuel scoops installed, set your view to looking out the rear of the ship, flew toward a star, and ignored all the warnings on your dashboard, you could fly right through the star. If you were being chased at the time you had the additional satisfaction of watching your pursuers' ships explode as they tried to follow you in.
nostromo 2y ago
You could use a solar sail to project a satellite towards the sun.
- Jeff_Brown 2y ago
  How do you sail into the solar wind?
  - tedunangst 2y ago
    Just need a triangular sail and some zigzagging.

aziaziazi 2y ago

In SpaceFlight Simulator it’s quite easy IIRC (it’s been a while): 1. Orbit yourself around low earth 2. When entering the transfer window (opposite side of the sun-facing earth, i.e. above midnight longitude) booooost 3. For orbit, aim for tangent with your target. For sun discovery, aim for sun center. Choose but don’t change. The game is in 2D and you got nice auto-calculated transfert windows and trajectories. Is it one of those game simplification that makes it easy or there’s more difficulties?

LorenPechtel 2y ago
The math is simple enough, it's just the delta-v requirements are brutal. Or you take the slingshot approach at which point the math requirements are brutal. And I'm not aware of any KSP mod that helps you plan slingshots. And even if there was a slingshot maneuver requires a lot of precision because your ejection angle is highly sensitive to exactly how close you came. The Parker probe was sent outward to Jupiter and used it to slingshot away much of it's energy. (We normally think of using a planetary encounter to gain energy but it works both ways. Ejection velocity from a slingshot at Jupiter can be anywhere from hitting the sun to solar escape. It's just most probes are heading out, not in.)
- lmm 2y ago
  > I'm not aware of any KSP mod that helps you plan slingshots. As someone who played before they added patched conics, I'd consider patched conics such a thing.
- aw1621107 2y ago
  > And I'm not aware of any KSP mod that helps you plan slingshots If you're willing to go for the full n-body package, Principia [0] has a pretty nice flight planner that is quite usable for planning more complicated missions. KSP Trajectory Optimization Tool [1] is a non-mod alternative with some additional capabilities beyond flight planning as well. I think this one is designed for stock gravity so it should be usable in an otherwise vanilla install. [0]: https://github.com/mockingbirdnest/Principia https://github.com/mockingbirdnest/Principia [1]: https://github.com/Arrowstar/ksptot https://github.com/Arrowstar/ksptot

kccqzy 2y ago

There's a difference between flying directly into the sun as if landing there, and orbiting the sun but so close that the spacecraft is inside the solar atmosphere. This is doing the latter.

ostacke 2y ago

It requires seven Venus flybys, and 24 orbits around the sun[1]. Wikipedia has a nice animation of the trajectory[1], and NASA has another one here[2]. [1]https://en.wikipedia.org/wiki/Parker_Solar_Probe?wprov=sfti1#Trajectory https://en.wikipedia.org/wiki/Parker_Solar_Probe?wprov=sfti1... [2]https://svs.gsfc.nasa.gov/3966/ https://svs.gsfc.nasa.gov/3966/

DiggyJohnson 2y ago
Second link is beautiful and really shows the whiplash of the last set of solar encounters. Recommend clicking through to anyone with a passing interest.

zamadatix 2y ago

It's actually not too brutal so long as you don't try to do it directly. Launch a craft out past Jool then when you start falling back burn retrograde. It's like the opposite of what you do to efficiently burn when leaving Kerbin. In real life they used a set of Venus gravity assists instead. This has allowed them to slowly get closer while observing over time instead of a long wait and then one big bang close up before being shot ridiculously far back out.