Moving a BigS Rock

[XtraChrisP]

Hey guys,

Long time lurker, first time poster...

So here's my question:  I have recently come into possession of a 3,000 ton asteroid in solar orbit and I want to capture it in LKO.  I have no problem getting it back to Kerbin; if I hadn't sent up the mission it would have smacked into the planet, but it's coming in from a high inclination and I want to move it into an equatorial orbit.  I have all the dV I need for this as I sent up a ISRU and I have about 3,000 kN of thrust available at max power.  The only problem is that this thrust is applied through a single Klaw, so when I did a practice burn, you can imagine how unstable it was.  

These are the ideas I've come up with thus far:  throttle down and use some ridiculously long burns (may be problematic when I'm retro-burning to keep it in Kerbin's SoI), dive deep into the atmosphere to aerobrake, or try to fix the inclination and set up a couple of gravity brakes from the mun.  

I'm writing to see if any of the resident experts have any tips and tricks they like to use when it comes to moving Class E asteroids around.  The long slow burn seems like a likely candidate, but again, I will need to shed a lot of dV when I get close to Kerbin.  I like the aerobrake idea, but I'm worried about the rock tumbling around and exposing my ship's unshielded backside to too much heat, and I'm worried that the Mun assists will take many in-game months to be effective.   

So that's where I'm at.  Looking forward to reading what you guys come up with.  Thanks. 

[Geonovast]

Much better to pull instead of push. 

@Rocket In My Pocket

[Cpt Kerbalkrunch]

Not just your ship, but the asteroid itself will overheat and explode in the atmosphere. I definitely would not try to aerobrake. For control, as @Geonovast said, it's better to tow it than push it. I prefer to build the top section upside-down to make this easier later. You need a long base and multiple engines set out wide for stability. I strut the crap out of everything because the ship will twist and bend.

However, it sounds like you have your ship, so that won't help. I would speed up gently (hold down shift to accelerate instead of pressing "z") and as soon as it starts shaking out of control, hit "x" tap timewarp quickly to stabilize, then begin again. This can be tedious, though, but it usually does the trick.

[Rocket In My Pocket]

2 hours ago, Geonovast said:

Much better to pull instead of push. 

@Rocket In My Pocket

I'm here! (How I feel when people mention me in a topic under spoiler)

Spoiler

Although...I'm not sure what for exactly lol.

Yes it is easier to pull than to push, the wobble of the joint's will be much less pronounced and the mass will tend to want to "follow" you along. Also make sure you click on the Asteroid and select "target COM" so you can try to Klaw it as close as possible to that. If you have KER you can set the Klaw to rotate freely and watch the "torque" readout as you very carefully move the ship, try to get it as low as possible before re-locking it.

Edited January 12, 2018 by Rocket In My Pocket

[Cpt Kerbalkrunch]

And @XtraChrisP, hope I don't come off too self promoting with this video, but I only recently opened an imgur account, and I don't have too many screenshots on there yet. On my phone, so I'm kinda limited. It's only a 4 minute video if you wanna check it out. Especially the ship in the video. It's my largest asteroid catcher (dubbed the Atari 2600), and by far my favorite. I use it to bring Class E's to Jool and Eeloo for contracts. You'll see how the engines are set out wide and the top section is upside-down like I said earlier. In the video, I use it to bring a Class D through the Mun arch at orbital velocity. This was only possible because the ship is extremely stable and easy to maneuver. Which is why it's my favorite asteroid catcher. All my others are based on it. Anyway, take a look if you want.

 

 

[XtraChrisP]

Thanks for the help guys, appreciate all the input.  I knew I came to the right place 

I'm at work so I'll have to check out the video later, but my main reason for pushing instead of pulling was that I was worried that I wouldn't be able to get my exhaust clear of the rock I was moving.  

Good advice on the aerobrake.  I'll cross that off my list of possible solutions.

Thanks again for the replies, guys.

R/

Chris

[Cpt Kerbalkrunch]

15 minutes ago, XtraChrisP said:

Thanks for the help guys, appreciate all the input.  I knew I came to the right place 

I'm at work so I'll have to check out the video later, but my main reason for pushing instead of pulling was that I was worried that I wouldn't be able to get my exhaust clear of the rock I was moving.

Yeah, you'll see in the video the ship has a long fuselage for exactly that reason. It'll kinda look like I'm pushing, but I'm actually facing retrograde to make the adjustments to get through the arch. You'll see what I mean. Hope all goes well. 

[peteletroll]

You can push easily if you autostrut the ship engines to heaviest part, that is the asteroid itself.