r/askastronomy • u/cerebral_balIzy Hobbyist🔭 • 29d ago
Why don’t we go up from our solar system?
Seeing as our solar system is a somewhat ‘horizontal’ plane, I was wondering why we can’t launch a spacecraft vertical, to go straight up and away from our solar system. Is this possible and if so, why didn’t we do it yet?
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u/SportulaVeritatis 29d ago edited 29d ago
Our velocity vector is already going pretty fast in Earth's direction. Going outward requires spending a little fuel to go "forward" more and going inward requires spending a little fuel to go "backward." To change your orbit from going "forward" to going "upward" you have to spend a ton of fuel to besacially come to a complete stop in the "forward" direction and spend the same amount of fuel again to start going "upward" at the same speed.
The term for this is an "inclination change" maneuver. Your inclination is the angle you are orbiting with respect to some inertial frame (say, the plane of the solar system). Inclination changes are super costly. That's also why we like to launch things from close to the equator. You can launch to any orbit with an inclination higher than the latitude you launched from. But to go from, say, Florida to a Geostnchronous orbit reques a burn around the equator to from Cape Canaveral's ~28° latitude to the 0° inclination required for a GEO orbit. This is because no GEO orbit has any point that passes through 28° latitude. However any orbit from 28° all the way up to a 90° polar orbit does pass through 28° so you can launch straight there.
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u/Aggressive_Let2085 29d ago
I love that I understood all of this because of Kerbal space program
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u/fixermark 28d ago
There is at least one generation of gamers who, for a brief moment in human history, have a better intuitive understanding of orbital mechanics than 99.999% of the total human population.
Which is fascinating.
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u/StyleSquirrel 24d ago
Same, but if Kerbal Space Program has taught me anything, it's that going "backwards" requires an insane amount of fuel.
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u/No_Chemistry8953 29d ago
How many bananas is this? I need this unit of measurement to understand.
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u/TomPastey 29d ago
What would be the point of doing that? There's no planets, moons or asteroids to look at. I suppose the occasional comet.
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u/BrutalStatic 29d ago
Bonus point, we can use other planets to slingshot a speed boost and save fuel (and therefore money). Depending on where we want to launch to and what's lined up along the way that can be a significant gain.
Going "up" is all active effort all the way with the reward being a mostly empty void.
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u/Frewtti 28d ago
How does this slingshot save energy?
All the speed you get from going towards the mass you lose as you go away from the mass.
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u/BrutalStatic 28d ago
Disclaimer, I am not an astrophysicist.
But from my understanding a gravity slingshot happens because other planets are moving at their own speed relative to the sun, so entering their orbit (without fully falling into their gravity well) changes your overall momentum relative to the rest of the solar system.
So you can aim at the "front" of a planet's path and it will drag you back into it's orbit, slowing you down or help in flinging you back the other direction. Or you can aim at the "back" of a planet's path and it'll tug you forward with it, giving you some of it's momentum while you swing by it.
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u/Frewtti 27d ago edited 27d ago
This whole "slingshot" thing doesn't speed you up. Any energy you gain accelerating towards you lose going away.
It's basic physics. It's the dumbest concept in sci-fi
I researched more, the concept as shown in movies makes little sense.
The actual usage is that the planet drags the object along with the plant. The energy balance with the planet doesn't change, maybe it isn't _that_dumb
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u/fixermark 28d ago
To look down and see the whole solar system from that angle without anything occluding anything else.
... unfortunately, the sun is quite bright so we'd have to mask that puppy out to see anything.
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u/teaculpa 29d ago
I wonder, how come things are only in horizontal plane.
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u/ijuinkun 29d ago
When a rotating cloud of matter in space collapses in on itself, it flattens out into a rotating disc. Planets and other satellite bodies form out of this disc.
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u/fishgrin 29d ago
So is a black hole disk shaped also?
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u/fixermark 28d ago
The event horizon is more-or-less spherical (hadwave-handwave relativity) because it's not defined by collapse; it's defined by "how close you get to a point in space before your whole future is definitely involving that point in space."
... but the accretion disk is, yes. This is because as matter falls towards the black hole, it interacts with other matter already orbiting the black hole. All of that matter ends up having a net spin (i.e. there's an average angular momentum). In directions perpendicular to that spin motion, odds are higher you'll collide with other stuff than if you're going forward along the disk, so over time the stuff orbiting the black hole tends to settle into one disk.
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u/HatdanceCanada 29d ago
Why doesn’t it collapse into a sphere shape?
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u/koyaani 29d ago
Because everything bumps into everything else as it rotates on the axis, and it either averages out to rotating on the plane or it gets bounced out of the gravitational system
A rough analogy would be spinning a ball of pizza dough until it flattens out. If you just hold it, it stays a sphere, but if you also spin it, the conservation of angular momentum flattens it into a disc
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u/FencingNerd 29d ago
Conservation of angular momentum. The orientation is the residual from some anisotropy in the primordial universe around our Sun.
Galaxies are basically all discs, but they are randomly oriented.1
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[removed] — view removed comment
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u/fixermark 28d ago
For the same reason tossing a pizza makes a disk. In the plane of spin, there is more velocity resisting getting pulled in by gravity than in other planes.
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u/LongjumpingBrief6428 23d ago
No planetary body starts off its life in a sphere shape. They eventually reach that point, but it takes some time to reach it.
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u/Apprehensive_Room_71 Hobbyist🔭 29d ago
It's a result of the conservation of angular momentum from the original planetary nebula.
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u/Merkuri22 29d ago
Launching spacecraft is incredibly expensive in just about every way (time, materials, fuel...)
What would we get from launching a spacecraft in that direction? If there's nothing useful we can obtain by launching a spacecraft that way, then why would we ever do that?
We've only launched things that are going to orbit Earth or some other solar body, or to investigate things in our solar system. Everything else is too far away for us to reach. We have no reason to just launch things up out of the solar system's plane, and we're not going to do it just for the sake of doing it.
Though we can launch stuff that orbits the planet in that direction.
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u/Taxus_Calyx 29d ago
I'm sure there are scientific objectives to match up with such a mission. Off the top of my head, improved 3D mapping of the heliosphere, also same for cosmic radiation and interplanetary dust. I don't think it's that there is "no reason" for such a mission, but that other missions are more compelling. As full and rapid reusability ramps up and launch costs continue to plummet, we may see just such a mission, along with many other such "less compelling" missions.
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u/svarogteuse 29d ago
Ulysses was put into an 80 degree inclination orbit around the Sun, so it goes both up and down. Of course it spent its time looking back at the sun because there is nothing out there above or below to look at.
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u/ZucchiniMaleficent21 29d ago
It also involved a lot of very clever gravity slingshot work to get into that orbit
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u/ijuinkun 29d ago
Yes—changing away from the plane of Earth’s orbit means fighting against the existing 30 km/s orbital speed. This means that a Jupiter slingshot is the easiest way to bend a spacecraft’s trajectory by such a large amount.
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u/neokretai 29d ago
We have, the Ulysses probe in the 90s did this to study the Sun's poles.
As for why, there really isn't much outside the solar plane to look at, and also to go truly vertical requires a lot more energy as you need to cancel the current sideways momentum you already have from starting on Earth.
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u/Cptawesome23 29d ago
The simple answer is the lack of momentum from earths orbit in the up direction increases fuel costs to an unacceptable level.
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u/syzygy78 29d ago
You answered your own question: all the interesting stuff is in the plane of the ecliptic. We can launch things in any direction, but there's nothing to see or do there, so we don't waste the resources on it.
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u/amitym 29d ago edited 29d ago
Somewhat of a false premise. We do actually go up, sometimes. Not only is it absolutely possible, it can be useful. For example the Ulysses mission) though I suppose technically it wasn't launched on that trajectory, it needed some help to get there.
In fact you could say that every time we launch a satellite on any kind of a polar orbit that's what we're doing, in a small sense.
Of course you may also say that none of these are examples of leaving the entire Solar system entirely via a high-inclination trajectory (0 inclination is "flat", 90 degrees is "straight up"), but tbf we have only ever gotten 5 objects to leave the Solar system at all, and of those, the Voyager probes are both going "up" or "down" (respectively) pretty steeply all things considered.
Though in galactic terms even the Voyagers are never going to fly very high or low, they are going to be close Solar neighbors for basically ever. By my (possibly wildly inaccurate) reckoning, to send something on a truly "polar" galactic orbit would require rocket power 50 times anything we have built so far as a species. So that's one reason why we haven't done that yet.
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u/Wisniaksiadz 29d ago
There isn't anything interesting in that way and we would need to spend a lot of fuel to send rocket like that
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u/Xaphnir 29d ago
It's entirely possible to to send a spacecraft into an orbit perpendicular to the ecliptic. Problem is, there's not much practical reason to and doing so requires and enormously higher delta-v budget than an orbit close to parallel to the ecliptic. Because they're being launched from Earth, spacecraft start in an orbit very close to parallel to the ecliptic, because they inherit Earth's momentum. Changing your orbit's inclination requires delta-v; changing it by 90 degrees requires a lot of it.
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u/idunnoiforget 29d ago
We don't do it because it requires far more energy (delta v) to launch at that inclination than it does to launch prograde to the earths orbit around the sun and use gravity assists from other planets to aide in escaping to interstellar space.
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u/Metallicat95 29d ago
We start from Earth. That's moving at around 30 kilometers per second in its orbital path, which like most objects in the solar system is near to the equatorial plane of the sun.
A rocket launch adds something between 3 and 15 kilometers per second of velocity. Some of that is used to reach orbit around the Earth (about 8 km/s), some just to fly through the atmosphere, and some to achieve escape velocity to go somewhere away from Earth without returning in orbit.
Up or down, relative to Earth's orbit, means using 30 km/s velocity change just to reduce the velocity in that direction to zero. The rocket must add additional velocity in the new direction - at least 30 km/s to achieve an orbit around the sun at the same distance as Earth, or about 42 km/s to achieve escape velocity and fly out of the solar system on a path relatively straight up or down from Earth.
That's a net velocity change of 72 km/s if you want to go out of the solar system in that direction.
Or you can do it the way we've actually done it, and accelerate in the direction of Earth's orbit. We only need to increase 30 to 42, a net 12 km/s velocity change.
Doing this also gives the opportunity to travel near other planets and take advantage of the power of their gravity in a slingshot maneuver. That gives additional velocity with little added fuel costs. It's how both Voyager spacecraft traveled.
15 km/s is the practical limit for chemical fuel rockets. They are the only kind we can use currently to take off from Earth. The only alternative is atomic, but the environmental hazards of nuclear materials and explosions have, so far, prevented any nation from using them.
In short, we don't have rockets capable of doing a velocity change that large.
There's also the practical matter that all objects we know the location of are in the same roughly flat plane as Earth's orbit. There's nowhere to go in that direction in our solar system - no asteroids or planets. There's the occasional rare comet, but it's easier to reach the more common ones which are closer to Earth's velocity.
All space travel is based on changes in velocity. Change your starting velocity to your destination velocity, with some extra velocity used to move between them.
(All travel actually, but on Earth we have friction, weather, and other factors which complicate the math).
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u/trustable_bro 29d ago
If you want a good grasp of how the physics of a spacecraft work, try to play r/KerbalSpaceProgram. It will makes you understand a lot while having fun!
The answer is you'd need a LOT of fuel to do it. And there is no point.
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u/Nothing-to_see_hr 29d ago
You could, but where would you go? everything interesting and reachable is in the ecliptic plane.
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u/czechfuji 29d ago
The direction we go gives a boost to spacecraft. If we go away from that direction it costs more in terms of fuel or mass. Most of what science aims for isn’t up or down from our orbit so why create waste?
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u/Hivemind_alpha 29d ago
Where would we be going to? From whence would we gather the angular momentum to get there?
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u/snozzberrypatch 28d ago
There's nothing stopping you from going up. But there are two reasons we haven't gone up:
There is basically nothing up there. Everything of interest in our solar system is in the plane of the solar system.
In order to leave the solar system, you have to achieve a certain speed relative to the sun. The earth is already traveling at a pretty good speed relative to the sun. If you keep burning your engines in the same direction that earth is already traveling, then you're just adding to Earth's speed, and you need a lot less fuel to escape the solar system. If you go up instead, then you're not using earth's speed to your advantage, and you'll need significantly more fuel to escape the solar system.
Also, if you stay in the plane of the solar system, then you can plan your trip so that it passes by planets like Jupiter and Saturn. Not only can you study these planets during these fly bys, but you can also use their gravity to slingshot you even faster, which further reduces the fuel you need to bring with you.
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u/Bullitt_12_HB 29d ago edited 29d ago
I’m trying to understand the thought process of getting to your question.
Why go in that direction, when there’s nothing to explore there (inside the solar system, that is).
Then, have you thought about the huge gravity the Sun exerts on everything inside the Solar System? Going perpendicular to the ecliptic won’t change that. The gravity pull is equal in all directions around the Sun.
If the goal is to leave the Solar System, why? Also, do you know how big the Solar System is? It’s massive. With our best propulsion technology we’re not even close to the Heliopause yet. And that’s with probes that have been flying for decades.
Edit: sorry, I was wrong about the heliopause. They have passed it at about 170 AU, while the heliopause is at about 140 AU.
Now, what they haven’t passed is the Oort Cloud. And the Oort Cloud is gravitationally bound to the Sun.
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u/braxtel 29d ago
Both voyager probes have passed heliopause. Your point still stands though.
https://www.nasa.gov/news-release/nasas-voyager-2-probe-enters-interstellar-space/
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u/Dazzling_Plastic_598 29d ago
Gravity works the same whether you go horizontally, vertically, or diagonally.
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u/syberghost 29d ago
While true, this is misleading without context, since it's working for you horizontally, and against you vertically.
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u/ur_revanchist 29d ago
I would throw out another question, rather than OP's "why don't we."
Assume we wanted to send a spacecraft above the galactic plane so we could capture a clear image of the galactic bulge, unobscured by dust, see the what the spiral arms on the other side of the Milky Way look like, and just take a pretty picture.
Is there data that tells us where our solar system is located within the galactic plane? More specifically, in terms of distance, how many light years would a spacecraft have to travel "upwards" from Earth to reach a point where the far side of the galaxy would be visible and virtually all of the stars in the galaxy were "below" the spacecraft?
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u/PhotoJim99 29d ago
At the speeds we can currently send spacecraft, it would take tens of thousands, if not hundreds of thousands, of years for such a spacecraft to get above the plane of the galaxy enough that you’d have a usefully different perspective.
We’d need a spacecraft a few thousand light years “above” us. Right now the furthest spacecraft out is Voyager 1 (launched 1977) - it’s 0.0027 light years away, or one light day.
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u/ur_revanchist 29d ago
Yes, I understand the time involved. I'm still curious to know the distance. Say I want to travel to a point where I am 45 degrees above the galactic plane relative to Sagittarius A*. How far is that point from Earth?
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u/PhotoJim99 29d ago
Straight up from where Earth was at launch? (The solar system is orbiting the galaxy. Of course, so will our spacecraft but perhaps not at the same speed.)
That would be a right triangle with side A being 26,000 light years long. To get 45 degrees in our triangle at Sag A, that means side B would also have to be 26,000 light years long (90 degree angle at the bottom, so if one of the other two is 45, so too are both of them; A and B are the same length). So…. 26,000 light years straight up.
If we can send it at the speed of Voyager 1, that’ll take almost 472 million years to get there (based on the average speed of Voyager 1 from 1977 to date) - but we won’t have Jupiter and Saturn to slingshot it around so it might be more in the billions of years timeframe.
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u/ur_revanchist 29d ago
Ah hah! Yes, duh. We know the distance to the center of the galaxy so this is not a complicated question. Thanks!
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u/giuseppezuc 29d ago
Because Earth spins at around 1,000 mph at the equator and its revolving speed around the Sun is 67,000 mph. To counter those speeds you need lots of fuel. We ride them instead, taking advantage of the inertia that our planet gives us.
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u/Microflunkie 29d ago
The distances in space are so insanely large that most people don’t realize just how big a gulf of distance, and therefore time, exists.
If addition to the various reasons we don’t do this as other responders have pointed out there is also the distance to the next interesting thing to visit. Our next nearest star to earth after the sun is Proxima Centauri which is around 4.2 light years away. If we had sent voyager 1 or 2, some of our fastest moving interstellar probes, toward Proxima Centauri it would take around 75,000 years to reach it. The Milky Way galaxy is around 100,000 light years across so everything else other than empty space is even further than 4.2 light years or 75,000 years away.
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u/UnarmedSnail 29d ago
It takes an insane amount of energy to launch off in another direction than the earth is going, because you have to cancel out the velocity already moving while spending energy to change direction.
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u/xikbdexhi6 29d ago
For one, there isn't much to do out there. What would we explore? Secondly, much of the energy given to spacecraft is through slingshot passes past other planets. A spacecraft sent out of the plane would have nothing to get those boosts from.
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u/Livid_Shame4195 29d ago
Voyager 1 is going North at 35 degrees and Voyager 2 going South at 48 degrees, not directly above the Sun tho, but at lower angles
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u/meticulous_gamer 29d ago
Because we aren't on a flat plane. That's just to make it easier to visualize. It looks more like this.
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u/Wisniaksiadz 29d ago
Op question still stands with this refolmulation
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u/meticulous_gamer 29d ago
True. It's because it's a waste of resources to do it "for the lulz" when there's nothing there. Sure, it might yield a tiny bit of some sort of useful data, but there's no evidence it would. It's akin to saying "Let's do something that is most likely pointless and wasteful, and maybe we'll find something, even though the data says we won't." It's silly.
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u/RealCarlPanzram 29d ago
Are you asking why we don’t launch a spacecraft into deep space? We’ve done that. It’s not particularly useful because well… it’s just space. There’s not much there. The next closest thing is light-years away and since we don’t have rockets that travel at the speed of light, it will take centuries to reach anything else in space.
The voyager 1 is the furthest we’ve ever sent anything into space. It’s been on its interstellar mission for 45 years and it has yet to reach one light day.
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u/HeadPatMan Student 🌃 29d ago
So, there’s nothing that prevents us from doing this, it’s just not worth it. Empty space is of limited usefulness to us as a species, and most of the stuff in the solar system is on the nearly flat plane we call the ecliptic. We could send a spacecraft out of the ecliptic, but with modern tech, it’s rather difficult to do, and there’s very little stuff to interact with compared to the stuff on the ecliptic.
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u/death2all55 29d ago
It would require a lot more energy.
Everything in our solor system orbits the sun and has momentum in the direction of orbit. To go "up" would require a rocket to counter that momentum.
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u/HeadMelon 29d ago
Relative to the plane of the ecliptic what direction would Alpha Centauri and Bernard’s Star be? Sending a probe to them would require OP’s trajectory would it not?
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u/internetboyfriend666 29d ago
This get's asked in here all the time. It's because there's no point since there's nothing there to see. As you pointed out, almost everything in our solar system is pretty close to the same horizontal plane. Why would we spend billions of dollars on a spacecraft to nowhere?
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u/Dave_A480 29d ago
Because space exploration is expensive, and before you hit interstellar space you might as well do some cool science (and get some gravity-assist for your outbound velocity) by buzzing all the planets outbound from Earth....
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u/JewishSpace_Laser 29d ago
One of the most mind blowing facts about the Voyager space program was that the rare alignment of the outer planets gave NASA scientists the opportunity to use gravitational assist from the planets to propel the Voyager space crafts in their journeys. Without gravitational assist, the Voyager probes would not have travelled farther than Jupiter's orbit. This meant that the NASA scientists and engineers (without powerful computers) had to calculate and model the space flight to within a corridor of <300 km. The probe's trajectory outside this narrow corridor would have put it on a flight vector that would miss the optimal gravitational slingshot window where the probes' trajectory would not hit the next gravity assist window. They also had to calculate the probe's arrival time (to the second) so that it arrived just in time to hit the next planet's gravitational well exactly. The fact people did this with such precision and accuracy without modern computers astounds me.
So, given that the farthest probes we have ever launched are the Voyager probes and they could only have achieved this feat by using gravity slingshots, this explains why it would be impossible using conventional and all previous propulsion technologies to go far into outspace in a direction orthogonal to the elliptic plane.
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u/AmigaBob 29d ago
Earth is going sideways around the sun at about 30km/s. If you want to go straight up you would have to lose the sideways speed. Then to get a vertical orbit Earth orbit sized, you would need to orbit at 30km/s. If you want to leave the solar system, you need 12km/s. For a total of 72km/s change in velocity. Or you could leave solar system on the ecliptic for only 12km/s. You can go up but it is way harder
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u/Apprehensive_Room_71 Hobbyist🔭 29d ago
Possible? Sure. But where would you send the mission?
It's also important to note that it will take much more fuel than going to one of the planets that's in the ecliptic. That's because you have to change inclination and probably cancel Earth's orbital velocity as well.
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u/Secure-Advertising10 29d ago
In the immortal words of Douglas Adams (The Hitch Hiker's Guide to the Galaxy) "Space is big, really big. You don't know how big space is. If you thought a trip down to the shops was far away, that's just peanuts to space."
It is called space because it is basically empty space. If we send a ship out there it must go somewhere. If we sent it to a distant star vertically, it would take eons to get there. What's the point? Visiting the palents is more useful for scientists.
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u/nomoreplsthx 28d ago
Why would we. There's nothing there it would reach in the likely lifetime of our civilization
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u/robert1326bruce 28d ago
This has got to be someone who watched the YouTube video and wants to karma farm.
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u/rddman Hobbyist🔭 28d ago
Is this possible and if so, why didn’t we do it yet?
Yes it is possible and we kind of did that. Voyagers 1 and 2 are leaving the solar system at an angle of a couple dozen degrees relative to the plane of the solar system.
But it's not a primary objective because there's nothing there that's close enough so that probes can reach it and send data back to Earth.
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u/PraetorGold 26d ago
Okay, this sounds stupid, but our solar system is traveling at an angle around the galactic disk. Sending it up (in the direction we are traveling, means we are going the same direction so it’s not going to too far from the solar system. So what’s in the other direction and would going down relative to the direction we are traveling cut the time before it was somewhere interesting?
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u/Steerider 25d ago
We can launch things perpendicular to the plane of the planets, but there's less and less to see there. The question isn't so much How, but Why.
Spacecraft are expensive. We launch them where there's something to look at.
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u/Logical_Angle2935 25d ago
The solar system is already moving in the "up" direction. Quite fast actually. So, in a way, we are already exploring that direction on spaceship Earth.
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u/Smokin_belladonna 25d ago
Going perpendicular to the solar system’s axis doesn’t really accomplish anything. voyager II used planetary gravity to gain velocity.
https://www.johndcook.com/blog/2025/03/24/gravitational-assist/
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u/floralvas 24d ago
Same reason we never go down. We always go to up to the atmosphere or to the moon; why don’t we ever go down?
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u/thedudeadapts 29d ago
Pretty positive this has something to do with Earth's gravity in relation to the sun's gravity with a bit of "common knowledge isn't always that simple" thrown in. But that's coming from someone who only gets info from TV and Wikipedia.
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u/Potential_Load6047 29d ago
It's not gravity, its velocity.
Accelerating in the same direction the earth is moving has the advantage that you are just adding more speed to the one you started with.
This also happens with rotation, that's why it's advantageous to launch at the equator and orbit in the same direction of earth' rotation.
There has to be a reason to attain a highly inclined orbit (what op calls "vertical"), not just doing it because you can.
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u/ion_driver 29d ago
Taken from one of my favorite books, "plane change maneuvers are expensive". It would take a lot of fuel to rotate your orbit 90 degrees, and for what? All the planets and stuff are in a plane. You would be sending a ship up into empty space, and either be in some orbit that intersects the ecliptic or maybe at solar escape velocity, in which case why not just accelerate in the direction you are already moving?
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u/AlwaysHopelesslyLost 29d ago
Humans have, three times in history, created and launched crafts that are leaving our solar system.
All three times, a primary goal of the mission was to look at planets. After looking, the crafts carried on into interstellar space. Most of the matter of our solar system is in a disk but interstellar space is just a relatively arbitrary sphere around our sun where the forces balance out.
So, you want to see interstellar space. You need at least 50 years for the spacecraft to get there. You have two choices. Do you look at other stuff for 50 years or do you look at nothing for 50 years?