Large Asteroid Control Techniques

[ScottyDoesKnow]

So I just captured a class E and am slowly working on lowering the apoapsis, I'm just winging it so I wondered how others are handling it. My technique is to push it with the grabber in free pivot mode, and "herd" the center of mass to keep it on the maneuver node. It works but it's just really painstaking. I first tried a puller with massive arms but they weren't massive enough, though maybe they could be if I put them on the far end from the grabber and angled them outwards.

So what techniques are you guys using?

[Taki117]

While I have not been able to put theory to practice (The next 'roid is 12 days away) I have the idea to use the KAS winches and attach points to pull the asteroid wherever I need it to go.

[Th1rt3en]

I used a similar technique of free motion and locking it square on the center of mass. Additionally, I built a ship that has 4 RCS grabbers just off the top (Claw, 2 medium RCS tanks, remote control core and 4 RCS ports. I come up on an asteroid, impale it with a couple of the RCS pods and then attach the main tug and align. Even with it a little off, the RCS will keep it aligned during burns and makes turning the thing much easier. Once attached, it sees the whole thing as one big ship and will use the RCS pods as needed as you can see from a couple pictures I took the other day. Only used this on class C so far, works like a charm.

Edit: bah, I'm a newb when it comes to Images. Thank you Padishar

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Edited April 4, 2014 by Th1rt3en
getting pictures to work

[Padishar]

For an imgur album you just use:

[ imgur]pBzRP[ /imgur]

(without the spaces after the opening square brackets)

[mellojoe]

Additionally, I built a ship that has 4 RCS grabbers just off the top (Claw, 2 medium RCS tanks, remote control core and 4 RCS ports. I come up on an asteroid, impale it with a couple of the RCS pods and then attach the main tug and align. Even with it a little off, the RCS will keep it aligned during burns and makes turning the thing much easier. Once attached, it sees the whole thing as one big ship and will use the RCS pods as needed

For larger asteroids, it seems having multiple grabbers seems like a good solution. My current craft has 3 grabbers:

1) The main grabber attached to the big engine pod

2) Two small units that consist of a grabber, RCS, and reaction wheels.

Once the main craft grabs, the two small grabber side units detach from the craft and fly to each side of the asteroid. These help stabilize the whole mission.

I'm experimenting with a craft that splits into two, one main engine cluster at the front, and one main engine cluster at the back, with two side grabbers with reactionwheels and rcs. It becomes a much bigger task, but a lot more fun.

[LiveHereNow]

I never imagined you could use multiple claws to attach RCS probe/pods around the asteroid! This is genius! Thanks for sharing. Please post pics as this develops. I think you're really on to something for the larger asteroids.

[TheScareCake!]

I have an idea, why shouldnt you use 3 or 4 arms instead of one?

[ScottyDoesKnow]

I have an idea, why shouldnt you use 3 or 4 arms instead of one?

You need to be able to pivot around the grabber so you can aim the asteroid, so having multiple screws that up.

So I finally managed to get my asteroid into a stable orbit with some aerobraking and a painful 6 minute circularization burn. Still need to adjust a lot of inclination but it's close enough (about 250km) that I'll just find a less efficient, easier way (6 giant ASAS stacks anyone?) to fix that.

That little ship you see in the screenshot is 700t when fueled.

[Th1rt3en]

That little ship you see in the screenshot is 700t when fueled.

http://i.imgur.com/Ulub2Gx.jpg

Nice Catch. Pokemon Syndrome anyone? "Gotta catch em all."

[Vanamonde]

To change my direction of thrust on a 2100 ton asteroid, I plotted the maneuver, un-clawed my ship and turned toward the maneuver marker, and then RCSed around to re-claw through the COM.

[Claw]

-snip-

TWR of 0.04. Nice!

And nice shot over the crater.

[RocketPilot573]

Um, how are you guys doing this "free Pivot" thing? When I turn it on, the ship STILL can't turn anywhere near enough to actually keep the thing under control (trying to turn also trys to turn the asteriod, so nothing hapens). Help?

Edited April 4, 2014 by RocketPilot573

[ScottyDoesKnow]

Um, how are you guys doing this "free Pivot" thing? When I turn it on, the ship STILL can't turn anywhere near enough to actually keep the thing under control (trying to turn also trys to turn the asteriod, so nothing hapens). Help?

You right click the grabber and there's a "free pivot" option. For larger asteroids, what I've done is free pivot, go into IVA view and zoom in on the navball. Then you "herd" the target of center of mass marker by burning very slightly to one side of it so it moves in the direction you want.

But I've just learned that all you need is about 1 orange tank separation between an engine and the asteroid for you to be able to thrust right into the asteroid and have it still work, so pulling is probably much easier for large ones.