The Big Jool Mission Coming Up! Need some advice.

[DSM92]

So My first Jool transfer window is coming up. The major goals of this mission includes:

With a single probe-

Getting high orbit science (and hopefully low orbit science) from all bodies of the Jool system

Land on Laythe and collect surface science.

And thats it!

The Mission abstract looks like this:

1 PE kick from LKO- Aim for 1 full orbit before final ejection burn node

Course Corrections

Upon Jool SOI- Adjust orbit to encounter Pol (Jool Aerobraking)

Pol ->Bop

Bop->Tylo

Tylo->Vall

Vall-> Laythe-Chuted Landing

(Transfer order contingent on being efficient- Mix&matching expected)

So are there of you out there who have accomplished anything similiar? Obviously the Jool 5 Challengers out there, but I thought this would be a little different since I don't want to spend the DV to actually orbit any moons (Except Laythe).

I'm not looking for exact numbers, just some general advice.

Thanks!

dsm

Edited February 10, 2014 by DSM92

[Taki117]

Not entirely sure what your looking for. If your only goal is high/low science you can use an ion powered probe (which will have tons of dV) and then put your ship into a parking orbit around lay the to drop your lander to the surface and back. Don't forget you can use parachutes and aerobraking on Laythe. The issue is getting back to Kerb in again, in which case dump all the weight you can (like that lander) and use gravity assists off of lay the and tylo to help you get out of Jool's gravity well.

[Geschosskopf]

So My first Jool transfer window is coming up. The major goals of this mission includes:

With a single probe-

Getting high orbit science (and hopefully low orbit science) from all bodies of the Jool system

Land on Laythe and collect surface science.

And thats it!

That's a huge job in terms of delta-V. Taking off from Laythe requires about 3500m/s all by itself. And unless you've got the patience to play Gravity Ping-Pong between all the various moons and Jool, so you can get fly-bys for little delta-V, expect to spend anywhere from 1000-1500 per trip between moons, more for Pol and even more for Bop due to their inclinations. But note that Gravity Ping-Pong is all luck of the draw, depending on where the moons are when you get there, and it's only really good for Laythe, Vall, and Tylo. Pol's a bit too far out and is inclined enough that you probably won't hit it. You almost certainly won't hit highly inclined Bop this way. And note that hitting either one will probably screw you up for all the others due to putting you in an inclined orbit yourself. So either way, expect to spend a lot on travels between moons.

Because of all this, it's pretty difficult to do all the above with a single vehicle. Going between all the moons, Ping-Pong or not, is probably best down with an ion ship as mentioned above, due to all the delta-V you need in space. But this ion probe won't do for landing on Laythe, and a Laythe lander will be too heavy for ions to push. So what I'd do instead is make a dedicated Laythe lander, then either 1 ion probe for everything else or separate probes for each moon. And throw in another for a Jool lander

[Claw]

Although realize the OP never said anything about returning to Kerbin. Just that the probe was going to land at Laythe last (presumably because it isn't going to be taking off).

Sounds like he/she's planning on several fly-bys. Perhaps the delta-v chart will help a little. Although it will overestimate since I doubt you will want to return to Jool after every fly-by.

[Geschosskopf]

Although realize the OP never said anything about returning to Kerbin. Just that the probe was going to land at Laythe last (presumably because it isn't going to be taking off).

Ah, OK. So deduct 3500m/s for the Laythe take-off. But even the parachutes for a 1-way Laythe probe will make it too heavy for ions, and doing all the moons in 1 trip requires so much delta-V that you almost have to use ions. Otherwise you'll need this hulking monster of a ship. So landing on Laythe almost forces you to have 2 probes. Now, you can land with ions on Bop, maybe even Pol. So it might be better to get the surface data there instead of Laythe.

[Lucy1nTheSky]

If you aren't against mods, try Kethane, and send a refueling station along for the ride and have infinite dv to potentially even land on all the moons

[technion]

I'd highly recommend reordering to hit Laythe first. Whatever you plan on landing there will by far be the heaviest part of your mission, and since you can aerobrake directly at Laythe, your largest capture burn is avoided. The rest can then be done without that extra weight.

[SSSPutnik]

Use jets to take off on Laythe. Saves a lot of weight.

[Mobjack]

Just do it.

Try to hit every moon, but if you can't, hit as many as you can before landing on Laythe. You are sending a probe to explore the unknown and part of the fun is figuring the stuff out on your own.

[Claw]

I'd highly recommend reordering to hit Laythe first. Whatever you plan on landing there will by far be the heaviest part of your mission, and since you can aerobrake directly at Laythe, your largest capture burn is avoided. The rest can then be done without that extra weight.

Use jets to take off on Laythe. Saves a lot of weight.

Arg. The OP is landing on Laythe last because he/she isn't planning on returning to Kerbin. Which probably also means he/she isn't going to bother taking off from Laythe.

Here's a better version of the dV chart.

http://i.imgur.com/jGxK1zG.png

Also, nobody has mentioned some things like:

-Don't forget that if you're sending an unmanned probe, that you'll only get one use out of some of the science instruments. So make sure you bring enough. If you're going to put all of them on one probe, then make sure you plan a large enough core probe to handle all that.

-Sure, you can also do this by sending a mother ship and dispersing a cloud of probes. But if that's not what you want to do, you could make it so you can jettison the used science containers after you transmit the data.

-Don't forget to bring enough batteries. It can take up a lot of juice to send off all those packets at once. (and solar panels or NUK!)

-Quicksave is your friend...

Like Mobjack said, Just do it!

If you have something like Engineer or MechJeb installed, that can help out your dV planning during the flight. Again, like Mobjack said, if you find yourself running out of dV, you can change the priorities of your mission to get those things you want. At least you will have learned something.

[SSSPutnik]

Oh yeah, getting carried away sorry.

Well just chutes for Laythe, a jet can be useful for extra deceleration or avoiding water.

[Rusty6899]

That was pretty much what I did on my first trip to Jool (or planned to). My first mistake was to get myself into a retrograde orbit, which pretty much eliminated my chance of landing on Laythe (I wasn't particularly good at accurately setting up intercepts at that point. I also struggled with encountering Bop.

Firstly, a prograde orbit is pretty important. It lengthens the duration of encounters, and makes a Laythe landing much easier.

I doubt the Delta-V requirements will be anything remotely like 1000 between moons if you only plan to encounter, rather than orbit... more like 1000 for the combined manoeuvres if you make them at a low Jool Periapsis.

Look at a delta-V map, the Delta-V requirements between moons are equal to the difference in delta-V required to intercept from a low Jool orbit, so between Pol and Bop it is 2500-2430 = 70m/s. This assumes you have a Jool periapsis at ~150km and apoapsis at Pol's orbit at the start of the manoeuvre. As long as you can get to an eccentric, prograde Jool orbit with about 4 tons of fuel, a nuclear engine and a total mass < 10 tonnes (plenty of spare mass for a light landing set up for Laythe) you'll be fine.

The best order, by far, to do this in is the way you have outlined, outermost > innermost, in order. You would be wasting 100's of m/s of delta-V to do it any other way.

The only other thing I would consider is how close you get to Tylo, you don't want to end up getting a massive gravity assist and ending up leaving Jool's SOI. I can't say I am too sure about how gravity assists work, though so I'm not sure how to approach it to ensure a close encounter without it affecting your orbit too badly.