Eject a Class D asteroid out of the solar system - Lessons learnt.

[Mat2ch]

Hi,

I'm pretty sure this is one of the hardest things to do in Career Mode. I clicked it by accident, the numbers looked great and I didn't realize what I was up to. So I sent in my first little ship, just to realize this asteroid was huge and I didn't bring enough power or fuel or anything to handle it. I didn't have any problems capturing it. It's fiddling with the manouver nodes, which is tricky, because there are a few bugs (I can't click more than 5 times on the "do on the next orbit" button until it resets. So time warping and trying).

What did I learn? When handling big stuff, bring heavy tools. The mission got me around 3 million credits and I spent 2 million for the ship. It uses 28 LV-Ns, weighs 718 tons and has over 12000 dV, which was a bit too much 10000 would've done. With it's launcher the start weight was 5000t. I bet there are more efficent ways to get this beast up, but I haven't found them yet.

Most important things:

• Pull, don't push. I made several tries with pushing, until I saw a post here where somebody pulled. Works much better.
  
• Bring enough RCS with you, put many RCS thrusters at the end (or at the top, depends on where you're pointing ) to stabilize, because if you don't hit the center of gravity very very precise it will wobble. And I never made a very precise grab. In fact I tried several times and I always slipped away. Unlocking the grabber so it can tilt didn't do the trick. Luckily I had plenty of RCS with me and let SAS do the rest.
  
• It took me around an hour after grabbing the asteroid to get it out of the system. Bring time!
  

Just for the fun of it I made a safe game and then "landed" the asteroid on Kerbin. Very satisfying after weeks of fiddeling around to get the ship right and then get it up into orbit... (Did you know? These things leave no crater and roll around like boulders... )

So, whatever you do, if you see this contract, try to complete it. I've learned a lot. Also thanks to the rest of the forum, without some hints from different threads I wouldn't be able to write this.

[Rus-Evo]

Would this be a task suitable for a gravity assist? My understanding was that although you would leave Jools SOI at the same speed you entered you would pick up some of Jools orbital momentum along the way. Of course this wouldnt work for me personally as I tend to be an inefficient navigator.

[Der Anfang]

Yeah, I have been wondering myself about how to do these kinds of missions. I found only one contract so far and it wanted me to eject a class E.... not sure how big they are, but the amount of creds it offered meant it wasn't going to be easy... at all. I declined it out of intimidation. I wonder, how long of a wait do you have in order for another one of these contracts to pop up?

[helaeon]

I think if I were to attempt one of these plan would be to assist off of Eve out to Jool, then off of Jool out. Maybe Eve, Eve (and/or Kerbin), Jool if the alignment and correction burns could be made to work similar to how Cassini got out to Saturn.

[Mat2ch]

As far as I know you are able to do gravity assist. But I found it hard to do scheduled burns. Even though I brought much RCS and had many thrusters at the back it was hard to get it accelerating in one direction. I had to stop often to realign with the node. So doing a precise burn takes time.

Oh, and Class E means very very big. Have a look: http://wiki.kerbalspaceprogram.com/wiki/Asteroid

It says 854 ~ 3,828 tons. Moving this will take even a bigger rocket (or more fuel, speed is not the problem, but time is, at least for me).

[r4pt0r]

I have never had any luck time warping with an active claw. My ship always spontaneously explodes.

But awesome job man!

[monophonic]

As far as I know you are able to do gravity assist. But I found it hard to do scheduled burns. Even though I brought much RCS and had many thrusters at the back it was hard to get it accelerating in one direction. I had to stop often to realign with the node. So doing a precise burn takes time.

Oh, and Class E means very very big. Have a look: http://wiki.kerbalspaceprogram.com/wiki/Asteroid

It says 854 ~ 3,828 tons. Moving this will take even a bigger rocket (or more fuel, speed is not the problem, but time is, at least for me).

I have yet to tackle even a puny A class myself. Everything I have read though suggests that the trick with the big ones is to pull, not push. That of course means you have to somehow keep the engine exhausts from hitting the asteroid. I have seen three solutions, either mount the engines wide enough to thrust aside the rock, tilt them outside so the exhaust clears the stone or have a tow "bar" so long that the exhaust does not reach the boulder.

[cantab]

My pusher handled a 500-ton D OK. I think key is to use an engine cluster and tweak the thrust limiters to fine-tune the balance. Also consider "control sections", little probes with a claw, reaction wheels, and maybe RCS that you dot about the asteroid. Finally be patient when slewing the asteroid around - turn SAS off, build a little speed, and wait for it to drift onto its target heading.

If I were trying to eject a rock from the solar system I'd opt for gravity assists. In an ideal world you can ping-pong off Eve and Kerbin until you get your apoapsis out to Jool which will easily fling you into interstellar space. However with a large and heavy asteroid tug getting the precision for gravity assists may be hard. A single powered flyby of Kerbin will take around 1000 m/s of delta-V to get a Jool encounter, vs 1800 m/s for a direct boot out of the system, and may be more manageable.

[Levelord]

Most important things:

• It took me around an hour after grabbing the asteroid to get it out of the system. Bring time!
  

Okey dokey

[cantab]

Is that a real smartwatch app? WANT.

[Mat2ch]

I have yet to tackle even a puny A class myself. Everything I have read though suggests that the trick with the big ones is to pull, not push. That of course means you have to somehow keep the engine exhausts from hitting the asteroid. I have seen three solutions, either mount the engines wide enough to thrust aside the rock, tilt them outside so the exhaust clears the stone or have a tow "bar" so long that the exhaust does not reach the boulder.

Class A are tiny rocks in space. They're easy to move around and I suggest a pusher here. No need for something big.

But I wanted to upload a picture of my Class D mover. Here it is on start ramp:

And in orbit:

[dimi64]

Hello I also have this contract and built a drilling prob with enines and I realized the asteroid was ejecting himself.

[Salvator]

Would a little workaround do? Mining reduces size of the asteroids, right? So why not mine a class D asteroid for ore, maybe even process some of it to fuel if needed, dump the rest of the ore and eject the asteroid out of the system when it is small enough to handle it with a cheaper ship? Ofc i'm not sure if this could work as the classification of the asteroid would change i suppose...

[Mat2ch]

Hello Salvator,

the report was written back for 0.90, where we had no resource mining.

Today I'd build a smaller tug, with just enough fuel to catch up on the asteroid, mine it and use the converted fuel to accelerate it. No, the class does not change with mining, but it's weight. It's even possible now to mine a Class E dry and land it on Kerbin, because it's light as a feather.

[Salvator]

Hello Salvator,

the report was written back for 0.90, where we had no resource mining.

Today I'd build a smaller tug, with just enough fuel to catch up on the asteroid, mine it and use the converted fuel to accelerate it. No, the class does not change with mining, but it's weight. It's even possible now to mine a Class E dry and land it on Kerbin, because it's light as a feather.

Hi, that's exactly what i had in mind i just wasn't sure about the class change. Thank's for reassuring, I'll start working on it right away