Struggling with Satellite Contract

[BentRim]

I have come across a few of these Satellite contracts that I can't figure out how to complete.  In this case I am to position a Satellite in a specific orbit of Duna which happens to cross paths with Ike.  I've tried nearly everything I can think of the manuever this into proper position but it always ends up having an interaction with Ike.  

Currently I have the sattelite in a Polar orbit of Duna with a good save point to try different things.

I had the same problem with a Kerbin contract that had the Satelite crossing the Mun path,  I finally gave up.   

I feel like I'm missing something pretty significant.

Can anyone offer any suggestions?

[Snark]

5 minutes ago, BentRim said:

Can anyone offer any suggestions?

Ike is big, and inconvenient, and frequently in the way, yes.

But it can only be in one place at once.  So just put your satellite in the orbit when Ike's on the other side of Duna (or at least not in the immediate vicinity).

Note that your satellite doesn't have to be in a permanently stable orbit.  As long as it's in the designated orbit, and stays there for ten seconds until the contract completes, then it doesn't matter if it blunders into Ike a few orbits later.

The easy way to avoid colliding with Ike's SoI isn't super convenient now, in a polar orbit, but here's what you could do next time a situation like this happens:

1. Put the satellite into a circular orbit of Duna that is coplanar with the target orbit, but much bigger (so it's safely outside anywhere Ike can touch it).
2. Place a maneuver node somewhere on your orbit and drag the retrograde handle until your Pe drops down to where it just touches (and is tangent to) the target orbit.
3. Do you see a projected collision with Ike's SoI along the way?
4. If you don't, then you're good!  Do the maneuver, then when you get down to your Pe, do another burn to adjust the orbit to match the target.  Bam, contract completed.
5. On the other hand, if in step 3 you do see a projected collision with Ike's SoI, just grab the center of the maneuver node and drag it forward or backward along your current orbit until you get to a spot where you don't have a projected collision with Ike's SoI.  Then follow the advice above.

Simple, easy, works like a charm.

Also note that the other option is to have an initial orbit that's smaller (i.e. inside) the orbit, instead of outside.  Works the same way, just change "retrograde" to "prograde" and "Pe" to "Ap". 

 

[Spricigo]

 

If the orbits are in same direction its just a matter of timing your satellite's orbit to meet Ike.

For a retrograde orbit, I consider this a possible case where the random parameters resulted in a contract much more difficult than supposed to be (maybe even impossible?). If that was a contract I got, probably would consider not worth the trouble and cancel/let it expire and consider it a lesson.  Other people would instead just match the required orbit as close as possible than complete the contract in the debug menu.

[bewing]

Doing it from a smaller orbit is more fun, because you get to choose the timing much more easily and quickly. I also find that the whole "maneuver node" thing is a waste of time. You get a better orbit doing it by eye, I think.

 

[DD_bwest]

ive had satelite contracts that are impossible to finish, when i come across these ill put it in an orbit as close to what it wants and f12 it to completion.

the first time it happened, it wanted me to put a satelite in what was essentially the muns orbit, but retrograde.  so no matter what i could possibly do, it would have to hit the mun within 1 orbit so it would always habe an encounyer and never be able to meet its requirements.  i opted to place it slightly higher in orbit lol

[bewing]

It's possible (in fact, even easy) to complete a satellite contract in much less than a quarter of an orbit (once you get to the proper altitude). -- If you've figured out the trick of it. So yes, a retrograde orbit in the same orbit as a moon should definitely be a 3-star contract. But it's not impossible.

[BentRim]

In this case, I cannot figure out how to complete it.  The orbit of the contract is the opposite direction of Ike and crosses paths twice.  I am now coplanar and orbiting Duna outside the contract and not withing Ike's SOI.  When I lower one apsis to touch the contract orbit I then enter Ike's SOI before I can get to the periapsis to lower the other side.  

I'm considering calling this one quits as I have wasted an entire earth day trying to figure it out.  

Hate doing that though...  I guess I just assume there must be something significant that I am missing again.  Does KSP really generate contracts that are truly impossible?

[Snark]

27 minutes ago, BentRim said:

In this case, I cannot figure out how to complete it.  The orbit of the contract is the opposite direction of Ike and crosses paths twice.  I am now coplanar and orbiting Duna outside the contract and not withing Ike's SOI.  When I lower one apsis to touch the contract orbit I then enter Ike's SOI before I can get to the periapsis to lower the other side.

It's okay if you traverse Ike's SoI en route.  That's where the maneuver node can come in handy, because it gives you the projected path even after crossing.  Have you tried sliding the maneuver node back and forth to minimize the Ike problem, then adjusting the node so that you end up with an apsis on the target orbit?

27 minutes ago, BentRim said:

Does KSP really generate contracts that are truly impossible?

It sometimes generates some humdingers, yes.  But what you've described isn't impossible, merely difficult.

For example, you're already in a polar orbit, yes?  So just drop a maneuver node over Duna's north (or south) pole that will adjust your orbit so that it crosses the target orbit right at the AN/DN.

Does that involve an Ike encounter?  If so, just click the + button on the node as many times as necessary to get Ike on the other side of Duna when you're crossing the danger zone.  Do the burn, then when you hit the AN/DN, do a second burn to match orbits.  There, done.

[bewing]

This one is doable, I promise you. I think it would be smarter to do it from inside Ike's orbit (and the satellite's Pe), because you would be moving faster. Moving faster means that it takes less time to set the whole thing up. Dangling out there in front of Ike while moving slowly is extremely likely to get you an encounter.

And so far, I've seen three or four examples over the last year of contracts that people have posted that looked impossible to me -- and then the community found ways to complete every one of them. So I'm not going to claim anything is impossible right now -- I've been proven wrong far too often already.

 

[bewing]

Step 2: wait until Ike is just about to go by your Ap.

3: Raise Ap to satellite Pe altitude.

4: Travel to new Ap.

5: Ike should be on other side of Duna by that time.

6: Burn to get the Ap correct on the other side of the satellite orbit.

7: Done! Now save the satellite from getting ejected from system by next close pass to Ike.

 

Edited March 9, 2017 by bewing

[Blaarkies]

5 hours ago, DD_bwest said:

ive had satelite contracts that are impossible to finish, when i come across these ill put it in an orbit as close to what it wants and f12 it to completion.

the first time it happened, it wanted me to put a satelite in what was essentially the muns orbit, but retrograde.  so no matter what i could possibly do, it would have to hit the mun within 1 orbit so it would always habe an encounyer and never be able to meet its requirements.  i opted to place it slightly higher in orbit lol

That not impossible . You have at least 1/3 of a Kerbin month to do that maneuver. Heres how you do it:
- Launch west(270')
- Setup a maneuver of that will give you an AP as high as the contract's orbit, move and adjust this maneuver forwards/backwards in time so that it will be just an hour too late to catch the Mun
- After the burn, wait until you are halfway to Ap, then fix you inclination. You want to burn "north"/"south"(Normal/Anti-normal) until you AN/DN(yellow marker) matches up with the intersection point of your orbit, and that of the contract's orbit. You must touch the contract's orbit as close as you can.
- Create a maneuver node on that intersection point. Use all directions on the node to define a burn that will match lines with that of the contract.
- Wait 10 seconds. Profit. Wait a few days and BOOM! 

This works because when you change your orbit, you will always pass through the same point in space again no matter how much you burn in which ever random direction*. So you need at least two burns, each in two different points in time, to actually get away completely from your original orbital trajectory in space...in this contract, you want to do the opposite.

* not including escape velocities, suborbital trajectories, gravity assists or Jeb staging.

Edited March 9, 2017 by Blaarkies

[Kryxal]

If you're set up outside (how FAR outside?) it shouldn't be a problem as long as you're not having a huge arc of the transfer orbit in danger from Ike.

If there IS a huge arc in danger, either raise your AP and do a bi-elliptic transfer (mostly for the eccentricity you want) or use radial in to get you on the transfer, and radial out to match orbits (along with pro/retrograde).

[BentRim]

As always I appreciate everyone's attempts to help.  This one has me stumped.  I've done my best to try to understand what each of you have suggested.  I can't seem to figure out how to get the orbit matched to the target without an interaction with Ike.  

To make matters worse in my frustration and not thinking I reached up and hit F5 rather than F9 and overwrote my decent save,  so I now have much less dV available and am in a coplanar orbit with the target rather than a polar orbit of Duna.  My bad for not creating a proper named savepoint.  Live and learn....

All is not totally lost if I can't complete it,  the ship has a scanner on it and I can maneuver it into a proper polar orbit of Duna to get some science..

This game is always a mental challenge for me.   

 

UPDATE:  WooHoo... I finally got it.  Starting from the image below which was coplanar,  I set a node on the AN an rotated the orbit to 90°.  My thoughts were that position would minimize the possible interactions with Ike.  Since the prior orbit had the proper shape I then lowered the Ap and Pe to the proper distance once that was done I waited until Ike was on the opposite side and rotated the orbit back to coplanar.  What I was missing and not thinking about properly was that the Ike encounter was always going to be there and that it simply needed to occur after the target orbit was achieved ...    

The Ike encounter also throws the craft into a nice polar orbit of Duna so with a little adjustment it will be in a good orbit to activate the scanner and get some science as well.  

I had worked on this for days and got tunnel vision and wasn't thinking clearly.  A good nights rest and a thread review helped tons.  

 

Edited March 9, 2017 by BentRim
Success!!!

[Spricigo]

I also learned something, was under the assumption that a future encounter would prevent the completion. Looks like the game just check if the current trajectory is consistent with the required orbit.