Under pressure mission (I need help)

[Dyson Sphere]

I have tried to complete this mission repeatedly but just can’t slow down enough to orbit Mercury. I have about 57% fuel before entering the gravity field of Mercury. Here’s what I did to get to Mercury and where I ended up. I used two gravity assists from Venus. What can I do to save fuel and other suggestions?

 

[Pink]

Ever since elliptical orbits you need to watch out which way you enter.
When you use Venus to lower your periapsis, make sure the resulting periapsis is on the right side of Mercury's orbit, where it is closest to the sun. That way your encounter velocity will be much less.

 

[Altaïr]

Hello Dyson Sphere,

In addition to the advice given by Mooncrasher, you should be careful to your trajectory when you intersects Mercury's trajectory, this really change things.

When you exit Venus after your gravity assist, your trajectory should ideally look like that:

See how my transfer trajectory is practically tangent to Mercury's orbit?

Then when you manage to get an encounter, make sure you adjust your periapsis as close as possible to Mercury. Now, this is my situation when I enter Mercury's SOI:

See my speed? It's only slightly above 1100 m/s. In comparison with yours that is above 5800, that changes everything.

Then when you want to slow down, wait for your ship to be close to the periapsis: the maneuver is cheaper when it's done close to the planet (this is the Oberth effect):


In the end, I can land quite easily:

If I can call this a landing...

If your encounter trajectory is like this:

Then it's not optimal, you can see that now my speed is 3000 m/s. Now it's a guaranteed fail.

 

[Dyson Sphere]

Thank you Mooncrasher and Altaïr for the tips and advice. I hope this will help me.