The best way to get to Ike?

[Shneb]

So I am planning a trip to Ike. I've built a ship in orbit. Now all I need to do is get there. I don't want to go to Duna at all. I just want to land on Ike. What is the best way to get to Ike specifically when coming into the Duna system?

[Taki117]

It's more fuel efficient to aerobrake at Duna to get an Ike encounter.

[robopilot99]

Its hard not to hit Ike. Ike's SOI is so big compared to Duna's that getting an inercept is extremely easy. I think the best way to do it would be to aerrobrake then just transfer up to Ike's orbit just as you do Mun or Minimus. Alternatively you could also try a using a gravity assist to enter Ike's orbit.

[NASAHireMe]

I don't know your experience level, so the exact answer may vary.

But in my opinion, it's a LOT easier to travel to Duna first and use its atmosphere to aerocapture and aerobrake into an Ike-crossing orbit. You can theoretically transfer from Kerbin to Ike's SOI 'directly' without first establishing an orbit around Duna, but you will be carrying a lot of speed at Duna-and-Ike SOI entry that you will have to negate by burning retrograde. Since Ike has such a small mass, this burn will be pretty lengthy. By using Duna to aerobrake to the correct apoapsis, you won't have to burn retrograde as much to capture around Ike.

Conveniently, Ike is pretty much on the same plane as Duna, so you don't have to worry about a large inclination change like with Gilly or Bop. Anyways, try either strategy (or both!) and tell us how it goes.

[Srpadget]

In my experience, the best way to get an Ike intercept is to send out a mission to Duna with a fuel load and mission profile that assumes a direct-inject to a Duna aerobrake. Ike will be RIGHT THERE in your approach path, every time. :-D

[Shneb]

Its hard not to hit Ike. Ike's SOI is so big compared to Duna's that getting an inercept is extremely easy. I think the best way to do it would be to aerrobrake then just transfer up to Ike's orbit just as you do Mun or Minimus. Alternatively you could also try a using a gravity assist to enter Ike's orbit.

How would the gravity assist work?

[Srpadget]

But more seriously--what Taki said. Aerobrake at Duna first.

[Cerberus738]

If you come into Duna orbit so you're going the opposite direction as Ike you're pretty likely to hit it

[Taki117]

How would the gravity assist work?

From what I understand if you get an Ike encounter prior to reaching Duna proper you want to pass in front of Ike so that it's gravity slows you down relative to Duna, then aerobrake at Duna as normal.

If you'll notice, everyone is telling you to aerobrake and for good reason. It will save you tons of fuel that you would otherwise be burning to get an Ike capture. That's tons of fuel you don't have to get to LKO, or transfer with you, or anything like that.

[astropapi1]

You don't get to Ike, Ike gets to you.

Seriously, the damn thing always gets on the way of my missions to Duna. No, I'm not visiting you, you boring grey piece of rock!

What I would do is aerobrake into a highly elliptical orbit that intercepts Ike's path. Since Ike is a female dog pretty big moon relative to Duna, it should be too hard for you to do. It'll also use less fuel than going for a low Duna orbit and then doing the transfer with your rockets.

I guess you could also get creative and use Ike's gravity to slow you down into orbit without using Duna's atmosphere, but it'll take some knowledge of how gravity assists work for you to do the maneuver with the least ammount of fuel possible.

Or, if you just want to get to Ike without much hassle, you could always do it the traditional way. Use brute force instead of intelligence, you know? Just pack enough fuel to do a propulsive capture at Duna, and then do a normal Hohmann transfer to Ike like you would do when going to the Mun.

[cantab]

The simple and efficient way is to aerocapture into an orbit with apoapsis level with Ike's orbit. Alterbaron's calculator or the Trajectories mod will help.

If you don't want to aerocapture, you can do a propulsive capture into a similar orbit (simplest), a direct Ike encounter and capture (a tad more complicated but a bit more fuel-efficient), or an Ike gravity assist into Duna orbit (even more fuel-efficient but tricky to set up). 350 m/s should suffice for the powered captures, so it's not that bad.

Whatever you opt for the key to getting, avoiding, or adjusting an Ike encounter is to make a mid-course correction on your way from Kerbin to Duna, and use a mixture of pro/retrograde and radial burning. This allows you to change your arrival time at Duna while keeping the same Duna periapsis, and thus you can get there when Ike is where you want it - either on your course or safely out of your way.

Edited December 8, 2014 by cantab