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Solis

How to do Rescue and Satellite contracts?

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Solis    5
Posted (edited)

All of my contracts are either rescue someone from orbit or to launch a satellite in some incredibly specific orbit.

The satellite part seems impossible at my current tech level so im left with rescue contracts but im not sure where to even start.

Edited by Solis

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mabdi36    136

You actually need crew cabins to do any rescue mission. Then you target the object, rendevous, then Eva the person into the crew cabin. (The crew cabin doesn't have any hatches, so he/she has to go through the Mk1 command pod.)

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Solis    5
1 minute ago, mabdi36 said:

You actually need crew cabins to do any rescue mission. ...

Thanks, I completely forgot about crew cabins lol :P

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...you don't? You could use an empty Mk I pod with a probe core.

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Waxing_Kibbous    494

You can also use a Mk-1 plus a lander can or two if you have the cans unlocked. Having a one star pilot can be handy for rescues.

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Spricigo    440

I strongly recommend to give satellite contracts a try (and if you have difficulty ask for help) .  It's a good way to practice orbital maneuvers and ship/mission design.  As long the required orbits ate within communication coverage, no extra technology is necessary (but Propulsion Systems is certainly a good one for satellite contracts)  

For rescue missions you can just put a probecore and remove the crew of you regular crewed vessels. Don't forget to maintain a hatch accessible for your rescuees. Also,  remember to remove the unnecessary crew before launch. 

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bewing    1277

EVAing the stranding victim into the rescue ship actually involves a trick, too. You have to rendezvous within 2.2km. When you are within that range, the [ or ] keys will suddenly become functional. Those are the only keys you can use to gain access to the stranded ship. Then as said above, EVA the stranding victim, use R to turn on their RCS jetpack, and fly them over to the rescue ship. Flying an EVA RCS jetpack is a little bit tricky -- it takes a few minutes to learn. So you may want to create a few savegames during that process.

 

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Wanderfound    1198

Specific orbits, for either satellite or rescue contracts, don't require tech: they just need a bit of skill. Once you know how to launch and manoeuvre into a particular orbit, the satellite contracts are actually easier, as the payloads are typically very lightweight and there's no rendezvous involved.

For a rescue mission, you need to intercept and rendezvous with the target in a vessel with a spare seat, then bring it back down. Either a two-seater or one + probe core will do.

What tech do you have, and what sort of orbits are required? Have you ever done an orbital rendezvous before?

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Solis    5
8 hours ago, Wanderfound said:

Specific orbits, for either satellite or rescue contracts, don't require tech: they just need a bit of skill. Once you know how to launch and manoeuvre into a particular orbit, the satellite contracts are actually easier, as the payloads are typically very lightweight and there's no rendezvous involved.

For a rescue mission, you need to intercept and rendezvous with the target in a vessel with a spare seat, then bring it back down. Either a two-seater or one + probe core will do.

What tech do you have, and what sort of orbits are required? Have you ever done an orbital rendezvous before?

The orbit for the rescue mission I have is about 80/80 so that parts easy but I don't know exactly how to rendezvous. I can get into the exact orbit that hes in but I don't know what to do from there.

As for my tech I have all of tier 3 (not counting "start") , fuel systems, electrics, and I have maneuver nodes unlocked.

Also, you may want to know that I have a rocket that can orbit the Mun and return to Kerbin. Maybe I could put a service bay with a drone core inside for launching satellites? Or would that be overkill? I could post a picture of it if you would like.

My satellite orbits are about 12k km and kind of offset like the thing you get when you burn normal. What I don't understand, though, is the other specifics such as Inclination 11.8°, longitude of ascending node 205°, and argument of periapsis 120.8°.

 

 

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Kryxal    142

For orbital parameters, you don't have to worry much about anything besides inclination.  They describe the orbit mathematically, but you're also shown the orbit if you're in map view, and that's enough to go with.  Generally, if you can make a maneuver node so the orbits look the same, it's enough ... possible exception on the really eccentric orbits, the periapsis can take some fine-tuning because the number's so small to start with.

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17 minutes ago, Kryxal said:

For orbital parameters, you don't have to worry much about anything besides inclination.  They describe the orbit mathematically, but you're also shown the orbit if you're in map view, and that's enough to go with.  Generally, if you can make a maneuver node so the orbits look the same, it's enough ... possible exception on the really eccentric orbits, the periapsis can take some fine-tuning because the number's so small to start with.

^ Pretty much that. Might sound stupid, but you need to pay attention to the direction of the orbit, too. With the right knowledge and a bit of mucking around, it's quite easy to match the orbits, but it's also easy to do it the wrong way. So watch the shade of the line and its movement, because reversing an orbit is much, much more difficult.

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Spricigo    440

The orbital parameters parameters are just a way to describe the orbit.  Fortunately the game also draw it for us. Because,  IMHO, is hard to explain without a picture. 

300px-Orbit1.svg.png

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bewing    1277

Doing a rendezvous is quite tricky to learn. Do a search for "rendezvous tutorial". It's not trivial, but it's one of the most important things the game is trying to teach you. I am certain there are also tutorials around about matching satellite orbits. There are lots of ways of doing that. The most important thing to do is go into map mode and look at the required orbit. The most important thing to see is the An and Dn values, and their positions on the orbit. The most important thing to know is that those An and Dn values are with respect to the ship that currently has focus. You can do everything else with just your eyes. So, you can burn Normal just before you get to a Dn, until the Dn value goes to 0.0 -- and then you are on the same plane. Then burn prograde wherever you need to until your orbit matches the requested orbit.

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On 05/06/2017 at 0:18 PM, Solis said:

The orbit for the rescue mission I have is about 80/80 so that parts easy but I don't know exactly how to rendezvous. I can get into the exact orbit that hes in but I don't know what to do from there.

Working from a matching orbit is really easy:

Set the target vessel as, well, the target so that you will get closest approach markers.

Burn either prograde or retrograde until you either get a very close approach, (for an 80X80 orbit, you ideally want less than 1km), or you are close to having it shift by an integer fraction, (½, ⅓, ¼, etc.), of the current difference.

If you did the latter, wait until the last orbit before they will match and burn either prograde or retrograde to line it up as close to exactly as you can.

When you are making that close approach, switch your navball to target mode and you can now burn retrograde to target to match velocities.  You can also use the pink "direction towards/away from target" markers to make a final approach, (as a rule of thumb, burning will push away the retrograde marker and pull in the prograde marker as compared to the direction you are accelerating).

 

If you want practice, start a sandbox game and set up a pair of vessels already in orbit using the cheat menu.

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Wanderfound    1198
Posted (edited)
On 6 June 2017 at 2:18 AM, Solis said:

The orbit for the rescue mission I have is about 80/80 so that parts easy but I don't know exactly how to rendezvous. I can get into the exact orbit that hes in but I don't know what to do from there.

As for my tech I have all of tier 3 (not counting "start") , fuel systems, electrics, and I have maneuver nodes unlocked.

Also, you may want to know that I have a rocket that can orbit the Mun and return to Kerbin. Maybe I could put a service bay with a drone core inside for launching satellites? Or would that be overkill? I could post a picture of it if you would like.

My satellite orbits are about 12k km and kind of offset like the thing you get when you burn normal. What I don't understand, though, is the other specifics such as Inclination 11.8°, longitude of ascending node 205°, and argument of periapsis 120.8°.

You have more than enough tech to handle this sort of thing.

For the satellite missions, just put the satellite (usually just a probe core, radio, solar and batteries plus maybe a little science gear) on top of an FL-T400 and a Terrier. Stick a pair of FL-T800s under that with a Swivel on the bottom, plus enough SRBs on radial decouplers to give it a launch TWR of about 1.5. That should give you plenty of range.

For an inclined orbit, timing your launch is important; look at the map screen, and wait until the target orbit passes directly over KSC. Then launch towards it; if it's inclined "up", launch towards the northeast, if it's inclined "down" launch to the southeast, if it's a retrograde orbit launch west instead of east. You should be able to see little moving dots on the target orbit indicating direction

At launch, do your normal gravity turn and then keep burning prograde until your apoapsis is close to the altitude of the target apoapsis or periapsis, whichever is nearest in time. Don't worry if you don't get the inclination exactly right; big orbits are easy to fine tune once they're established.

Wait until you get to your apoapsis and try to correct any errors in the orbit as you raise your periapsis to match the target orbit. If your inclination is correct, burn prograde. If you need to raise it a bit, burn a bit off prograde, towards normal. If you need to lower the inclination, burn a bit towards anti-normal. Again, don't worry if it isn't perfect.

Once you've got a stable orbit established that is roughly the right shape, you just need to tweak it until it's close enough to fulfil the contract (you usually need SAS turned off for a few seconds as well to make it complete). Set a maneuver node on the place where your orbit crosses the target orbit, at whichever of the two places is at higher altitude. A normal or anti-normal burn there (your ascending or descending node relative to the target orbit) is the cheapest place to alter the inclination.

If you need to do radial/anti-radial burns to tweak the location of the apoapsis or periapsis, those are best done at periapsis/apoapsis respectively. You shouldn't often need to do that, however.

If you're not sure what to do, just go to the map screen, set a maneuver node, then experiment with the node while watching what happens to the orbit. Or lock the ship into normal or radial or whatever, apply a small amount of throttle and watch what happens to the orbit. You should be able to figure out how to make them match once you see it happening. Just remember to do your burns at the nodes etc.

Edited by Wanderfound

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Spricigo    440
On 05/06/2017 at 1:18 PM, Solis said:

The orbit for the rescue mission I have is about 80/80 so that parts easy but I don't know exactly how to rendezvous. I can get into the exact orbit that hes in but I don't know what to do from there.

https://m.imgur.com/a/DmGTv

If you are behind/ahead your target you just need to stay in a orbit of different heigh. Lower orbits will be faster. 

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Kryxal    142
7 hours ago, Spricigo said:

https://m.imgur.com/a/DmGTv

If you are behind/ahead your target you just need to stay in a orbit of different heigh. Lower orbits will be faster. 

If it makes things easier, consider going into an eccentric orbit and working from there.  It will take longer, but it's easy to set up the intercept since orbits cross already.

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Spricigo    440
9 minutes ago, Kryxal said:

If it makes things easier, consider going into an eccentric orbit and working from there.  It will take longer, but it's easy to set up the intercept since orbits cross already.

? I dont see it to make much difference, since you ultimately want both orbits to be equal. If the interceptor's orbit not reaching the target's orbit you want to burn prograde somewhere, if its crossing you want to burn retrograde somewhere.

Ok, you may just use one of the points where the orbit crosses as your intercept point, but that just mean you burn retrograde, to match orbit, will also be the final approach maneuver.

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Kryxal    142

It was probably more useful when maneuver nodes were trickier to change, but it was handy being in a crossing orbit then just going to next orbit till you could burn to fine-tune the close approach.  At times it can be a pain to drag a node that's multiple orbits forward.

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Spricigo    440
2 minutes ago, Kryxal said:

It was probably more useful when maneuver nodes were trickier to change, but it was handy being in a crossing orbit then just going to next orbit till you could burn to fine-tune the close approach.  At times it can be a pain to drag a node that's multiple orbits forward.

well, maybe that is way I don't noticed the difference. I rely on KAC's prediction of closest approach to know If I need to burn prograde or retrograde to fine tune my intercept (several orbits ahead), doing that burn where the orbits are already tangent is what I found to be most reliable and convenient.

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