Need help capturing Class-E asteroids.

[TaintedLion]

Does anyone have any idea how to get a class E asteroid into orbit around Kerbin? Any ship designs would be appreciated.

[Crusher48]

I think your best bet would be to assemble a massive tug in orbit, attach it to the asteroid, and hope you can put enough delta v on the asteroid to stabilize its orbit.

[LethalDose]

Intercept it as far away from Kerbin as possible, preferably in interplanetary space. Out there, alter it's kerbin intercept's PE to be as low as possible, potentially even atmospheric. Burn like h*** when you get near your periapsis

After the rock is captured, you have time to do whatever you need to do with it.

[cantab]

Meet it it solar orbit, nice and far from Kerbin. This takes more delta-V, but that's delta-V when you're not pushing the asteroid so it's cheap fuel-wise. There's a tutorial on how to meet asteroids in solar orbit but the key idea is to leave Kerbin's SOI in the direction the asteroid is set to come into it.

Once you've met it, course correct for an initial aerocapture. Give yourself a margin of safety, for example aim for a periapsis of a few thousand km. Alternatively, correct for a gravity assist from the Mun into a closed Kerbin orbit. Either way this should not require much delta-V.

Make final corrections in Kerbin's SOI. Again, not much delta-V needed unless you have an awkward desired orbit.

I captured a 500-ton class D using this tug with nuclear engines and half an orange tank of fuel. Extrapolating from that, three orange tanks should be good for a class E. Double that if you're using chemical engines.

As for how to handle the asteroid, I used detachable control sections dotted round the asteroid. They turn the rock and the rock turns the tug. Another way is to not try and turn the rock round at all, but instead fly the tug and claw facing the desired way to push/pull it.

[mckamx]

In my experience, the issues with moving large asteroids around are:

1. the larger the asteroid, the more fuel required to generate the necessary delta-V.

2. with large asteroids, maintaining your heading is difficult because any offset from the asteroid CoM will cause large torques. The effect of this is that, even with massive reaction wheels, you have to keep your thrust down when pushing an asteroid. The design implications of this are that TWR is not your friend - add more reaction wheels, and leave off the extra engines. Get used to VERY long (1-2 hour) low-thrust burns to achieve orbit changes.

I can send you a craft file if you want, but it is not stock - I use SnackPartsByWhyren, SmartParts, MechJeb, and others on most of my ships.

[Mister Dilsby]

I've found that the only way to go is to PULL the asteroid. Here's my class-E hauler, the KSS Archimedes (we call it 'Arxie' for short):

Arxie carries four clusters of 4xLV-N engines, loads of fuel, RCS, and SAS stabilizers. The long tail is necessary to put enough space between engine exhaust and the rock (otherwise it impinges and you get no thrust)

If I recall correctly, with a full tank Arxie can put about 150 m/s on a 3000t rock. I made a lot of mistakes in my run, correcting orbit too close to Kerbin and had to send a tanker, but it all worked out in the end. Good luck!

[Kryxal]

I could see being able to increase your total thrust by limiting your individual engines ... the last pusher is pitching hard left and down, so reducing thrust on the lower-left engine should help.

[Streetwind]

Doing long, low-thrust burns with high dV requirements - there's a case to be made for ion engines here.

Or it would be, if stock KSP wouldn't cause you to kill your part count with excessive numbers of tiny xenon fuel tanks and engines and solar panels and batteries. Still, people have actually done asteroid captures with ion tugs, and they do work just as advertised.

If you were to install an addon... perhaps one involving technologies from the near future of mankind... *winkwink*nudgenudge* ...then you might find yourself with larger xenon tanks, engines and power production equipment that will let you do an electric asteroid redirector (as NASA is actually planning it) without killing your framerate!

[thadisjones]

For class E asteroid, you want nuclear engine, no other stock engine give you enough dV fast enough. Also want to make asteroid in tow, not push, or ship fold in half and explode like tanker truck with bad brakes on icy road. But that is problem- what if engine thrust hit asteroid and not make thrust, or is asymmetric? Need to build long tug, so engines far away, or wide tug, so thrust goes around asteroid. I prefer wide, though is harder to bring into orbit. Is less likely to snap in half when torqueing asteroid!

So you have grabbed asteroid with tug. Is good! But only first step. Class E is heavy as great many potato, or even more. If RCS and reaction wheel is powerful enough to get Class E rotating, will break locking pivot on claw and tumble out of control. If ship survive, will be useless for stable orbital insertion burn. How you do, is bring along remotes tug. Just claw, cheap flight computer, reaction wheel, much RCS, power systems. Place one on opposite side of asteroid of main tug. Is ok, but even better place two to four more same kind, spaced evenly at 90 degrees to axis of towing. Then have much RCS to rotate Class E around itself, is very stable, will not stress pivot if done carefully. If spacing is not perfect, is OK as long as is close since when docked to asteroid, all count as one ship and RCS system is smart enough to coordinate. Better spacing means can burn nuclear engines at higher power without tumbling, make good orbital insertion burn.

I hopes this is helpful. Have used technique above to capture all kind of asteroid on many planet, have very few bug or explosion.

[Vorg]

When you latch ships, and RCS modules to a roid, Is it all treated as 1 large ship so that all the attached ships work together? Could in that case attach more then one ship with engines same as docking to a station. Also, What about using struts and parts from KAS mod to better secure ship/s and control modules after the claw latches on?

[Frostea]

With Tweakscale you can scale up parts to meet the delta-v requirements without the use of nuclear or ion thrusters. I had to do this as I was playing with the ADIOS tech tree and haven't unlocked the nukes or ion thrusters. The Kerbodyne part pictured below is scaled to 7.5m on the bottom stage. Marked on the right is a rockomax science craft. It is not efficient but it gets the job done.

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Just for the record I had calculated that with that big 7.5m rocket I can only get about 300-500 delta-v after I hooked on to the rocket, so capturing the asteroid in Sun orbit might be a better idea if you aren't playing with life support or Remotetech.

When you latch ships, and RCS modules to a roid, Is it all treated as 1 large ship so that all the attached ships work together? Could in that case attach more then one ship with engines same as docking to a station. Also, What about using struts and parts from KAS mod to better secure ship/s and control modules after the claw latches on?

Yes you can do all of that but it is not needed. In fact, if you put more engines on the asteroid you absolutely have to make sure you have the center of mass and center of thrust lined up or you will be put in an uncontrollable spin when trying to move the asteroid. As you can imagine, it is hard to do that outside of the VAB.

Edited March 17, 2015 by Frostea

[cantab]

On the other hand if you do have multiple engines - even all on the one tug - you can tweak the thrust limiters on them to compensate for any misalignment. If you have KER it will even tell you the thrust torque, just play with the limiters until that's near zero.

[kakxow]

I just did that quest - taking E-class asteroid to Kerbin's orbit.

That's pretty straight. Using procedural parts and tweakscale (for reaction wheels) I've created one of the biggest craft I've ever done - 700t tug, using only huge 3.75 reaction wheels and a bunch of vernor engines for rotation. Met The Rock in solar orbit, precisely docked (many quickloads, really) and took it to Kerbin, using MechJeb. Approximatly 10 years, btw...

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This monster also could be done only using stock parts - tug's tanks diameter is 3.75.

Edited March 17, 2015 by kakxow

[Jsouders]

What I find to work the best is to use as light a ship as possible, adding only a fuel tank, engine, and mining/refining facilities. Works like a champ. This guy got me a class E in kerbin orbit today. Good luck!

[Laie]

Does anyone have any idea how to get a class E asteroid into orbit around Kerbin? Any ship designs would be appreciated.

Have a look at this thread: How to Steer an Asteroid, especially the last post.

When you latch ships, and RCS modules to a roid, Is it all treated as 1 large ship so that all the attached ships work together? Could in that case attach more then one ship with engines same as docking to a station. Also, What about using struts and parts from KAS mod to better secure ship/s and control modules after the claw latches on?

Yes, if you attach several pieces to one asteroid it becomes a single vessel. It's no different from docking several craft to make a large ship.

The main problem with moving large rocks is that the claw makes a comparatively weak connection. It doesn't take very much force to make it flex and bend. Bending the claw is Kraken-bait (bugtracker). Building you vessel short and stubby like Jsouders did, above, is highly recommended. Even then, you should keep the forces low: he has two large reaction wheels on his vessel and the mod engine he uses has 450kN of thrust (equalling 8 stock nukes or 2/3rds of a Skipper), and I'm not sure if it's truly possible to run them at full throttle.

The burn times aren't even the worst. Usually you don't need more than a few gentle nudges; I haven't recovered that many asteroids, but so far, it never took more than ~300m/s over several maneuvers. Jsouder's vessel if perfectly up to that task: if I get the numbers right, one tank will apply 50m/s even to the heaviest asteroid and refueling it's tanks will take about twenty minutes. Seeing as there is a single engine, it may even be possible to run the converter during the burn.

What's truly annoying is how long it takes to bring the vessel around. You may want to look into torque pods: basically nothing more than a claw and a few reaction wheels stuck to the asteroid. The last time I did that (in 0.25 IIRC), five large reaction wheels were already more than a single claw could handle well, and even with 25 large wheels spread over the rock, it still took 5+ minutes to turn.

So, be patient, and bring MJ to assist you with turning and maneuevring. You may also consider Kerbal Join Reinforcement for a more resilient claw (then one claw can handle ten wheels or more), or KAS to allow you to strut the vessel to the rock.

I have no experience with pulling asteroids. It may allow you to apply much more thrust, but I guess you're even more limited in the torque department.

[tutike2000]

Drill + ISRU + nukes spaced as far out as possible, so that you can tweak their thrust to reduce your torque.

I've only moved class Cs, but it shoudl work for Es as well.

MJ or Engineer to show you your current torque.

KAS/KIS to add struts to the roid, if that's even possible. RCS thrusters as well.

[Xentax]

I am still working on my design, but I've been able to capture a ~1600t Class E with it. It needs more torque mainly (multiple SAS near the claw, or some small RCS/SAS pods as suggested above - I'll probably try that). Also, I'm going to upgrade to the larger refinery, the small one is too slow and inefficient.

http://imgur.com/a/t9Tku

Also, I right click the asteroid when I'm close and "target center of mass" and grab that (as close as possible). I never rotate the claw. I've had SOME offset from that, but rarely a lot vs. just how painful it is to change rotation in general.

Edited January 5, 2017 by Xentax

[Draalo]

On 16.3.2015 at 3:10 AM, cantab said:

I captured a 500-ton class D using this tug with nuclear engines and half an orange tank of fuel. Extrapolating from that, three orange tanks should be good for a class E. Double that if you're using chemical engines.

As for how to handle the asteroid, I used detachable control sections dotted round the asteroid. They turn the rock and the rock turns the tug. Another way is to not try and turn the rock round at all, but instead fly the tug and claw facing the desired way to push/pull it.

Oh, thx for that advice. So all vessels docked/clawed to the asteroid count as one Vessel? And the separate Probes fire their RCS too?

 

Awesome, never considered that.

[Sharpy]

Look at my answer here:

Using nukes for Class E is such a chore that... no. Just no. It took me a week (real time) to capture a Class E using stock LV-N. It takes me maybe 2 hours to get one into LKO through Rhinos.

Large ISRU only. The small one is way wasteful. No need to overdo it; asteroids are so good at fuel production,e specially if you have a decent engineer on board, that you really don't need any overkill on the number of ISRUs or drills.

Make sure your cooling and power source are good though. Especially depending on solar may be tricky. Asteroids cast really big shadow