Minmus -> Moho?

[LN400]

I have a SCANSAT map/biome satellite which eventually will take a polar orbit around Minmus after Kerbin and Mun. Seeing I overbuilt it in terms of dv I am pondering sending it off to some other planet when it's done around Kerbin. If I refuel it before leaving Minmus, the total dv budget is 5620 m/s. This leads to some questions:

Does it take the same dv to leave Kerbin to a given planet as leaving the less massive Minmus, considering that Minmus is orbiting at a speed one perhaps could use to one's advantage?

How does 5620 sound for a polar orbit around Moho? Unfortunately, it is a 2 stage rocket with a fuel capacity for 1700 m/s in the first stage so wherever it goes, it will be a one way trip.

How about radiators? I have KIS/KAS installed so I could fit some in orbit if needed. Currently the sat has 4 1x6 solar panels but again, more can be fitted if I go further out.

Any other ideas of where to send the satellite mucho welcome.

 

[Kerbal101]

You can get some answers yourself in a fun and interesting way.

"Does it take the same dv to leave Kerbin to a given planet as leaving the less massive Minmus, considering that Minmus is orbiting at a speed one perhaps could use to one's advantage? "
Make a lightweight probe, from OCTO, TR-18A stack decoupler (deactivated), four small fuel tanks with legs, one tiny engine below and antenna.
See that it has around 1000dV, you can get this through KER - current and total stage dV are displayable, then just bring one copy to Minmus surface - and leave one copy on Minmus.
Do typical maneuver nodes for both, writing down changes in deltaV before and after each maneuver and you'll get exact answers yourself. =) 

Spoiler

Leaving from Minmus orbit is like leaving from "high Kerbin orbit", since Minmus gravity is nearly absent. So, its much much more fuel-efficient to leave from Minmus than from Kerbin 70/70, not only in TWR, but also in dV required. You get like ~150-200 dV to leave SOI, where from Kerbin its ~1000.

However, that means that applies if you have (or mean to have) two identical, equally fueled vehicles on these spots.
If you mean going to orbit around Minmus from Kerbin low orbit first - and then leaving Kerbin SOI, as compared to just leaving Kerbin low orbit, then leaving from Kerbin low orbit directly will be more efficient due to Oberth effect. Especially, if you manage to ninja a slingshot through Mun, but it requires a lot of patience and practice.

"How does 5620 sound for a polar orbit around Moho?"
The stronger the gravity force, the lesser efficiency (TWR) engines can provide. Thats why changing inclination is best done in distance, I call it "injection correction".
Burn normal/antinormal to change inclination and radial-in/out to change approach distance to surface, usually it takes a handful dV (~100-50) if done in distance.

"How about radiators?"
Depends.. Moho is hot, but not too hot. The critical distance to Kerbol is around 600,000,000 m, the "low orbit" is around 1,000,000,000 m.
These are values which I got with own lightweight probe, it really makes large part of fun it.

[LN400]

Thanks tons for the detailed post. I am definitely not going directly with this satellite as its original mission was and still is to map all 3 bodies before it needs to find another job. It was my gross miscalculation on the plus side that made me think of putting the fuel to good use.

[Zhetaan]

If you fly it correctly, you can get to Moho from Minmus for 5620 m/s.  I know you said you decided against it, but when you're done mapping the Kerbin system, you'll still be able to top up the fuel then and do it, if you like.  After all, if you already have the probe, why pay for another?

Don't transfer to Moho; that's hideously expensive.  The trick is to transfer to Moho's apoapsis and make the inclination change at the same time (Moho's orbital nodes and apsides coincide); then burn retrograde for an encounter when you reach the apsis.  Once you get an encounter, tweak it to get a gravity assist (and perhaps repeat this step two or six times) and you'll make Moho orbit with enough fuel left to manoeuvre once or twice.  It will take some time, but you can spend the wait by doing other missions.

[Spricigo]

22 hours ago, LN400 said:

Thanks tons for the detailed post. I am definitely not going directly with this satellite as its original mission was and still is to map all 3 bodies before it needs to find another job. It was my gross miscalculation on the plus side that made me think of putting the fuel to good use.

Probable the most obvious "good use" is to keep that fuel and wait for contracts asking to reposition the satellite.  Its easy, quick and you get some funds.

In regards to your question: according to alexmoon it takes ~5400m/s to tranfer to Moho from minmus orbit and ~5000m/s from LKO. You can save a bit more starting at minmus and lowering you  periapsis to barely above  Kerbin's atmosphere.  The issue is timing/ejection angle. 

Apart from the tricks Zhetaan mentuoned you can also use a gravity assist at Eve in your way to Moho,  reasonable easy to set and offer quite a bit of DeltaV. 

 

[LN400]

Having sent 2 satellites, KSOI and Kerbol 1 out of Kerbin's SOI have already answered a few questions I had about heat. Oddly enough, it turns out the most efficient orientation of the medium radiators is to have the end pointing directly at the sun. I was expecting that having a cooler in the shadow of the space craft would offer better cooling but the tests show otherwise. Kerbol 1 is heading for a periapsis around the sun at about 1.6 million km. The sat is stuffed with panels and radiators size small and medium and will tell me a lot about heat that close to the sun, as well as how to use and not to use radiators and panels. KSOI's mission is to give me a hint on dv requirements and time enroute for a quick pop out and return to Kerbin for a manned flight. Should also prove useful for asteroid hunting later on.