Something tells me i'm not circuralizing around Moho right...

[Norpo]

Well, here's the gist of it. I'll be going towards Moho at 2500 m/s, no biggie.

I start my circuralization burn as I would, say, for Dres or the Mun. (no aerobraking, obviously, it's Moho)

The maneuver node says I need 2400 m/s or so, and I have 5000 m/s in my tank according to kerbal engineer, so i'm good.

...Except when I finish the burn, I have just 500 m/s in my tank. What gives? That's 1600 m/s gone into thin air. This is annoying, considering I need more delta-v to land, and I have no idea where it's going.

Am I doing it wrong? Is there some trick? I use the maneuver node and execute it normally, if it was t -1 minute i'd start at t- 30 seconds and end at t+ 30 seconds. Do I need to do it differently for Moho? I'd like to know before I try to get my scansat into orbit (which has a tighter delta-v margin)

I may consider lithobraking using my skycrane to try to land the rover...

Help?

EDIT: Picture of the rover, with KER readouts, in case they might be relevant (I don't think the exhaust is hitting anything, i've tested it before)

Edited January 17, 2015 by Norpo
forgot to put [Answered] D:

[breakthrough]

If the node was at periapsis and some of the burn took place far away from periapsis (likely in a Moho encounter), then Oberth effect is working against you and it will take more delta-v than the node indicates since the node assumes an instantaneous burn.

[Norpo]

If the node was at periapsis and some of the burn took place far away from periapsis (likely in a Moho encounter), then Oberth effect is working against you and it will take more delta-v than the node indicates since the node assumes an instantaneous burn.

Hm, that's what I thought. I guess I just need more TWR, or lower my relative speed to Moho beforehand, perhaps?

Thanks! I guess lithobraking (see: crashing) might be the best option at this point

Hopefully my scansat probe will fare better (I might actually run a few tests..)

[cantab]

I've seen this before. KER is incorrectly assuming you will decouple your rover before expending your fuel, throwing the calculations *seriously* off. You can see this in the stage-by-stage breakdown - reports 0 m/s in stage 1, the current stage, and all the delta-V in stage 0.