Thrust to Leave Moho Orbit

[Zosma Procyon]

I'm designing a large rocket station to go to Moho, rescue some stranded kerbals in orbit, rendezvous with a lander lifting one kerbal off the surface, and bring a tiny capsule back. It won't land, but will go relatively close to the surface. At the moment, it is propelled by 8 of those tiny side mounted "thug" motors, with a maximum acceleration in its departure configuration is about 3 m/s/s. It that enough acceleration to break away from Moho's SOI?

Edited January 2, 2016 by Zosma Procyon

[Tex_NL]

The maximum acceleration is irrelevant. 100m/s² or 0.01m/s² the end result will be the same. What does matter however is how long you can maintain that acceleration. The dV.
Even a tiny Ant engine can move an E class asteroid with enough fuel. It just takes an eternity.

Edited January 2, 2016 by Tex_NL

[Sovek]

What @Tex_NL said. I've broken orbit of Kerbin with a single Ion Thruster before, with like .1 Kn of thrust. Granted it was still a small probe, but still could be done.

[juanml82]

I think you're using the wrong engines. Ideally, you want nukes, but if your ship is too big, the TWR may be too low for a comfortable RV (or even capturing at Moho).

But with dV requirements for Moho high as they are, I'd try to go either with nukes or some high isp chemical engine like the Rhino

[Guest]

" to break away from Moho's SOI? " is fairly easy, about 870 m/s. The difficulty is in what you plan to do once you leave Moho SOI. And I think you are overlooking the most difficult thing of all, how do you plan on getting into Moho SOI in the first place.

[moogoob]

Also consider your capture burn. What you have are several things conspiring to make very-low-thrust approaches to Moho difficult:

1. Moho is very close to the sun, so it's SOI is small (low gravity world deep in the massive Kerbolar gravity well)

2. You're going very very fast when you get to Moho, so your burn will be long

These two things mean that:

3. If your thrust is too low, you won't have enough time to do a proper capture burn before either getting flung out of Moho's space again OR hitting Moho because you started burning too early.

Things to consider. You CAN do something like burning to slow down before you hit the soi, but that starts getting really complicated. Like, MESSENGER probe levels of complicated.

 

[ExtremeSquared]

On 1/2/2016 at 2:39 AM, Tex_NL said:

The maximum acceleration is irrelevant. 100m/s² or 0.01m/s² the end result will be the same. What does matter however is how long you can maintain that acceleration. The dV.
Even a tiny Ant engine can move an E class asteroid with enough fuel. It just takes an eternity.

Well... temper this advice with the fact that floating point inaccuracies in the game engine can bring a twr down to a round 0.00. Don't bother trying to move an E class asteroid with an ion thruster, no matter how good it sounds on paper. It will not budge regardless how many tanks of xenon you dump in there.

Edited January 3, 2016 by ExtremeSquared