Question about flying up to a satalite in geosynchronous orbit

[xendelaar]

So I had this shower thought…

if you have a satellite in geosynchronous orbit… and you’re standing straight under its position on the ground…

What would happen if you fly straight up in a rocket towards the position of the satellite (so pitch @ 90 degrees)?  Would you encounter the vessel? The relative velocities wouldn’t match, right? Since there is a difference in horizontal velocity…  does anybody know? 

[fulgur]

Not sure, but considering that you are moving Westwards and so are they, at the same velocity, if you did a horribly inefficient ascent profile, you might just be able to do it...
(and by horribly inefficient I mean literally impossible in real life, and you'd probably have to use Far Future tech in KSP to match orbits in the very short time limit...)

[xendelaar]

18 minutes ago, fulgur said:

Not sure, but considering that you are moving Westwards and so are they, at the same velocity, if you did a horribly inefficient ascent profile, you might just be able to do it...
(and by horribly inefficient I mean literally impossible in real life, and you'd probably have to use Far Future tech in KSP to match orbits in the very short time limit...)

the thing i just can't wrap my head around is that if i go straight up I should somehow see the satalite coming closer and closer, right? because, when I go down again, I land back at the same place I started, am I right? so during this whole flight, I would be able to "see" the  satelite in front of me? but when I get really close to the ship, what will happen then? my peripasis is way different so there must be a huge velocity difference somehow... 

argh... i want to test this!!!

[Rhomphaia]

26 minutes ago, xendelaar said:

the thing i just can't wrap my head around is that if i go straight up I should somehow see the satalite coming closer and closer, right? because, when I go down again, I land back at the same place I started, am I right? so during this whole flight, I would be able to "see" the  satelite in front of me? but when I get really close to the ship, what will happen then? my peripasis is way different so there must be a huge velocity difference somehow... 

argh... i want to test this!!!

Then test it, but i left a hint in the quote.

[xendelaar]

haha

3 minutes ago, Rhomphaia said:

Then test it, but i left a hint in the quote.

ah, so that assumption is where i "fornicated up" XD... 

 

[Mikenike]

With enough boosters, and planning, moar boosters are needed. So pack moar boosters than you need, and try it!!!

[Rhomphaia]

Pretty much.  the requirements are not as harsh as suggested earlier, nothing like far future tech is required. the difficulty is in the precision, but something capable of landing on the Mun should meet the deltaV requirements, if the rough tests i have tried are any indication.

Could make a fun challenge, fastest time to geostationary orbit directly over KSC.

[Gargamel]

Moved to S&S, as is this not purely about the game. 

[cubinator]

The satellite in GEO has a lot more angular momentum than you because it's rotating around a really big radius. That means that if you go straight up towards it, you'll start drifting west because you only have the angular momentum you got from the ground, which is a lot less than you need to orbit the Earth high above it. In order to match the velocity of the satellite you'd have to pitch eastward at altitude and accelerate, but by then the sat that was originally right above your head would be much farther along. The most efficient way to get to the satellite would be to get into low orbit as usual, then do a Hohmann transfer.

[Shpaget]

While the ground and GEO sats have the same angular speed, they have vastly different tangential velocity. You need to match tangential velocity to rendezvous with a sat.

[RoninFrog]

Ever notice how you land in the grasslands to the west when launching straight up from the KSC?  Same reason you can't rande-how's-it-spelled with a geosynchronous satellite by going straight up.  In one day, both Kerbin and the satellite go around 360°, but the satellite covers a lot more distance than Kerbin's surface.

[Superfluous J]

9 minutes ago, RoninFrog said:

rande-how's-it-spelled

Just pronounce it wrong while typing it.

Ren-dez-vous.

Rendezvous.

Easy

[KerballingSmasher]

23 minutes ago, Superfluous J said:

Ren-dez-vous

Technically, it's

 

Ron-Day-Voo (as in Deja Vu) but that's just me being a picky French student  

Edited April 22, 2020 by Kerballing (Got Dunked On)

[magnemoe]

37 minutes ago, RoninFrog said:

Ever notice how you land in the grasslands to the west when launching straight up from the KSC?  Same reason you can't rande-how's-it-spelled with a geosynchronous satellite by going straight up.  In one day, both Kerbin and the satellite go around 360°, but the satellite covers a lot more distance than Kerbin's surface.

That one is pretty obvious, the planet rotate below you.
And yes if you are at equator straight below an satellite in geosynchronous orbit and pointed an laser at it you would hit it, however your rocket uses time to reach the satellite and it moves on, 
Now if you go pretty slow and use 24 hours to geo you will reach it

[sevenperforce]

To get into circular orbit with the ground-tangential speed of Earth's rotation, you'd need to be much higher than geostationary orbit. Earth's surface rotates at 460 m/s; even the moon orbits at more than twice that. Not even sure you could do it inside Earth's Hill sphere.

Imagine a carnival carousel. You're on a bike, freewheeling and holding onto the edge as it carries you around. A rope attached above you extends out 30 feet to another biker, also freewheeling as the carousel carries him around.

You want to join the other biker, so you pull out a section of rope, tie one end to the edge of the carousel, and then slowly begin to release it. Unfortunately, you will NOT drift out slowly and radially to join the other biker; rather, you will fall behind because he has much more angular momentum than you do. You'll have to pedal to increase your speed as you move away from the carousel even though your angular speed remains constant.

[Superfluous J]

5 hours ago, Kerballing (Got Dunked On) said:

Technically, it's

 

Ron-Day-Voo (as in Deja Vu)

I know that, silly. That's why I said:

6 hours ago, Superfluous J said:

pronounce it wrong

 

[KerballingSmasher]

23 minutes ago, Superfluous J said:

I know that, silly. That's why I said:

 

Oh.

[mikegarrison]

Let's say you had infinite fuel and enough thrust to do this. You could launch straight up at the satellite and follow a path that goes straight up. However, as you followed that path you would find yourself thrusting both up and forward in order to stay on the path, because in order to stay on that straight path you would need to provide an ever-increasing horizontal velocity.

The reason for this is because the path itself is actually sweeping forward with the rotation of the planet's surface.

Edited April 23, 2020 by mikegarrison

[RCgothic]

It's the same issue as coriolis. It may look like everything is going the same speed, but that's only an illusion - a coincidence of angular velocity.

In long-range rifle shooting if you fire a bullet North/South the path noticeably deflects because the earth's crust at different latitudes has different tangential velocity due to a differing distance from the axis of rotation. You think you're firing at a stationary target, but actually it has a different tangential velocity to you and by the time the bullet arrives the target has either fallen behind or overshot you. Rather - the bullet has differing sideways velocity to the target because it isn't in direct contact with the earth and keeps the velocity of the latitude it started at.

This situation is the same. It looks like satellite and earth are rotating together, but actually that's just a coincidence of angular velocity. The satellite is actually going much faster than you!

If you tried to ascend by thrusting directly up from the equator your tangential velocity remains unchanged. As you ascend your angular velocity reduces because tangentially you aren't going any faster, but you have a bigger diameter to complete in one rotation.

The earth appears to start rotating faster than you - the equator has the same speed but the surface is moving along a much smaller diameter. The higher latitudes are going slower than you, but have even smaller radius circles to complete.

The satellite also appears to start rotating faster than you - it's on a larger diameter but it is going very much faster than you.

Edited April 23, 2020 by RCgothic

[xendelaar]

Thanks eveybody. it makes sense now! i also tested it, just for chips and giggles and  found the wrong assumption i made. thanks for contributing.