Got a contract to put a class E asteroid into Bop orbit...

[tsotha]

Show of hands - how many people have done this (or something like it)? Is it even possible outside sandbox?

[Superfluous J]

Anything possible in sandbox is possible outside of it.

I suggest you look into gravity assists, especially at Jool. If you come in right and pass Laythe's orbit at the right time, you don't need to burn OR aerobrake and can get your apoapsis out to Bop. Then it's just a hefty burn to get into Bop orbit. I think you can do the same with Tylo but never have, and it'll save you some dV on the final Bop burn as your orbit's Periapsis will be higher.

I'm not saying it's not going to take a crazy long time and a crazy large amount of fuel, but I wholeheartedly think it's possible.

[tsotha]

The reason I say "outside of sandbox" is I have a limited amount of money. Clearly I can build a giant ship, refuel it, send it to Jool, refuel it, and put it into Bop orbit. I'm not sure I can do that with the 7.4MM I have, though. But even beyond that I was wondering if anyone had actually tried this, or if that's a contract people just turn down. I just did a class D system eject, and that was pretty brutal.

Edited December 2, 2014 by tsotha

[Superfluous J]

I'd surely try it, but don't see any reason not to test in Sandbox first to see how much fuel you'd need. The big burn (Kerbin-Jool transfer) should be done with nukes. Thanks to the massive size of the asteroid, you can bring a dozen or more and not worry too much about their added mass, and needing that many means you could build a big cage-like apparatus so you could pull the asteroid instead of pushing it, making COM concerns much less.

Also, if you bring all those nukes back and land them near the KSC, it will "only" cost you the fuel it took to get there and back.

Now I want to do this, even without a contract.

[cicatrix]

If you have money - make several tugs (6 ideally). You can get by with only one, I suppose, but it will be painful.

Stick each one to prograde, retrograde, normal +/- and radial +/- of the asteroid. When it start rotating (and it will) after you start applying thrust to it, you will be able to compensate by switching between different tugs and correct its course.

P.S. Bring A LOT OF fuel - you'll need it.

[Oafman]

How much is the reward for completion?

[tsotha]

How much is the reward for completion?

2,316,737 money/3154 science/4320 rep on the default "hard" settings.

If I do it that will be the end of the science tree for this game

[tsotha]

I'd surely try it, but don't see any reason not to test in Sandbox first to see how much fuel you'd need. The big burn (Kerbin-Jool transfer) should be done with nukes. Thanks to the massive size of the asteroid, you can bring a dozen or more and not worry too much about their added mass, and needing that many means you could build a big cage-like apparatus so you could pull the asteroid instead of pushing it, making COM concerns much less.

Also, if you bring all those nukes back and land them near the KSC, it will "only" cost you the fuel it took to get there and back.

Now I want to do this, even without a contract.

Well, if you're gonna do it you should land it at KSC first and then launch it again

[Oafman]

2,316,737 money/3154 science/4320 rep on the default "hard" settings.

If I do it that will be the end of the science tree for this game

Well that is pretty good, considering hard settings. I think you have to go for it!

If you have mods like KSPI it will be much easier than if you're using stock.

[worir4]

The easiest thing to do is instead of taking the asteroid to Bop, take Bop to the asteroid!.

[tsotha]

Bahahaha. So I captured an asteroid, all 2000 tons worth. My dV went from 6000 m/s to 350 m/s as soon as I attached to it. On a ship about as big as I normally build them.

Oy.

Does anyone know the mass range of class E rocks? Do they get much smaller than this?

[Darkday560]

Show of hands - how many people have done this (or something like it)? Is it even possible outside sandbox?

I did it on career. I had played that save for a long time b/fore it was corrupted, and one of the things I did was move an asteroid from the Mun's orbit, and used a giant 3-layer structural plate satellite that took 8 pieces to put together. I eventually pushed the asteroid enough of out orbit to where it was safe to add more things on the ship. I detached the giant sattelite from the ship, and came back with another ship that had a ton more engines. I moved that asteroid w/ the 3 layer satellite thing from the Mun all the way to Jool. The satellite structure held up nicely, though it did break in a few places, and I'm sure if we pushed that asteroid any further in Jool's gravity pull, it would rip off my ship. It was a pretty low orbit because I came into jool a bit fast. It was a type D Asteroid.

[cantab]

I've heard of E classes as light as 800 tons. The heaviest seem to be around 3000.

The task is possible, of course. I doubt though that it will be profitable.

You can save delta-V by gravity assists, but achieving the required precision will be tough with such a vast craft. I would try and meet the asteroid in solar orbit, then ping-pong it off Kerbin and Eve to push the apoapsis out to Jool. Then Tylo can help match Bop's inclination and raise the Jool periapsis, which will reduce the needed capture burn at Bop. I strongly recommend PreciseNode and plenty of patience.

The "trick" to the gravity assists, incidentally, is that you want to be crossing the assisting body's orbit. Just touching it like you would for a Hohmann transfer doesn't work very well. So your first Kerbin flyby should put your periapsis nicely inside Eve's orbit.

Edited December 8, 2014 by cantab

[m4rt14n]

This is so awesome! Pics please..

[Laie]

Search this forum for "how to steer and asteroid". The Vessel cost me about one million over two launches (sans fuel), and by the time I met the rock I had 8700m/s left, immediately before docking. My screenshots show no delta-v from immediately after docking, but vessel mass went from 950t to 3150t. Should be possible to calculate delta-v from these figures.

I recommend to skip this mission, it will give you no end of trouble. Mostly because the claw isn't quite up to the task of transmitting the necessary forces -- it will bend, a lot. I could only apply a fraction of my thrust or everything would veer off in a random direction; 300mm/s² was breakneck speed, and I had to babysit the entire burn. In solar SOI it was still bearable, I could get burns down to the nearest 1m/s, but in high Kerbin orbit even 5m/s was high-precision. Forget about aerobraking, or well-executed gravity assists. When I thought I had it right, I immediately had to leave the vessel lest phantom forces would ruin everything, then restart KSP because I snatched the "frozen orbit" bug each and every time I did anything with that vessel.

[tsotha]

I've heard of E classes as light as 800 tons.

800 I can do. The contract lasts for 34 years, so I guess I'll keep searching for the right rock.

[tsotha]

I recommend to skip this mission, it will give you no end of trouble. Mostly because the claw isn't quite up to the task of transmitting the necessary forces -- it will bend, a lot. I could only apply a fraction of my thrust or everything would veer off in a random direction; 300mm/s² was breakneck speed, and I had to babysit the entire burn. In solar SOI it was still bearable, I could get burns down to the nearest 1m/s, but in high Kerbin orbit even 5m/s was high-precision. Forget about aerobraking, or well-executed gravity assists. When I thought I had it right, I immediately had to leave the vessel lest phantom forces would ruin everything, then restart KSP because I snatched the "frozen orbit" bug each and every time I did anything with that vessel.

I couldn't find your post. Did you push or pull? The recommendations I've seen have all been to pull to avoid the problems you're describing.

[Laie]

http://forum.kerbalspaceprogram.com/threads/100591-how-to-steer-an-asteroid

Pulling may help, but it certainly won't avoid the most severe problems: the claw can't keep a 2000t rock in check, the thing will sway a lot. This is pretty much guaranteed to trigger the claw bugs. Pulling also won't help you with the phantom forces when in high orbit around Jool, or any orbit around Bop. Or miniscule oscillations shaking the projected orbit by +-10m/s (which is a lot if you want a gravity assist, or aerobraking).

This may all go away if you can securely attach your vessel to the rock using (e.g.) KAS struts. That's also discussed in the thread. But if the only connection you have is the claw, this project will give you grey hair.