My brain just suggested something lunatic - Colonizing and hauling an E-Class Asteroid to Duna

[Commissioner Tadpole]

Yes, you read that right. (And this includes the part about my brain having a life of its own. Don't ask.)

Recently, I've been contemplating how to fulfill this idea: Finding and redirecting an E-Class asteroid into Medium Kerbin Orbit, and then slowly setting up a space station around it... then haul it to Duna to work as a space station there. Why I want my Duna Space Station to be based around an asteroid rather than taking the easy path and making them be artificially-built I don't know, but heck if I like the idea.

Thing is: I'm mediocre at rendezvous - and I've never redirected an asteroid, let alone an E-Class one. I'd like to see some tips on how to redirect these monstrous beasts into MKO, the best way to construct a station around them(I intend them to have basic space for ~16 astronauts, a Science! laborotory, a fuel depot, and five Duna landers), and finally how to transport that behemoth into an orbit around Duna. All while knowing that I've never redirected an asteroid in my life, and am not an expert in a rendezvous.

Yeah, I'm crazy, no need to tell me that.

Edited April 5, 2015 by Commissioner Tadpole

[Specialist290]

For the general topic of asteroid rendezvous, you may find this guide by my fellow moderator Claw to be quite useful. I'll leave the specifics of how to build and fly a craft capable of putting an E-class asteroid in Kerbin's orbit to those with a little more experience in doing so, as sadly I haven't quite managed it myself.

[nightingale]

In my Tourism contract pack there's a contract for setting up a station with multiple asteroids for tourists to visit. One thing I learned while testing is to be careful and fear the Kraken. Basically, save often, and keep multiple saves, because I found myself getting into situations where one of the multiple vessels I was working with (station, tug, asteroid) would suddenly go into crazy mode (basically seemed to decide it had zero velocity, and started crashing away towards Kerbin).

[Commissioner Tadpole]

For the general topic of asteroid rendezvous, you may find this guide by my fellow moderator Claw to be quite useful. I'll leave the specifics of how to build and fly a craft capable of putting an E-class asteroid in Kerbin's orbit to those with a little more experience in doing so, as sadly I haven't quite managed it myself.

It is interesting, but I don't think a rendezvous in Solar orbit would do since I want to set up the base before the next Kerbin-Duna transfer window. I already have three Kerbals sitting on a Duna base there and I don't want them to stay bored and lonely for that long.

Ah well, I'll try it anyway. (Hopefully there is an E-Class potatoroid around for me to redirect.)

In my Tourism contract pack there's a contract for setting up a station with multiple asteroids for tourists to visit. One thing I learned while testing is to be careful and fear the Kraken. Basically, save often, and keep multiple saves, because I found myself getting into situations where one of the multiple vessels I was working with (station, tug, asteroid) would suddenly go into crazy mode (basically seemed to decide it had zero velocity, and started crashing away towards Kerbin).

Uh oh. The last thing I want is to have an entire space station with Kerbals in it compromised.

Ah well, no risk no reward I guess.

[Mister Dilsby]

Hey, partially in response to this question I posted my hauler, the Kranefly Mk.E http://forum.kerbalspaceprogram.com/threads/114595-Asteroid-Hauler-Kranefly-Mk-E. It worked for me to get class E rocks into Kerbin and Minmus orbit. No reason it can't haul to Duna as well, if I were doing that I would just build a bunch of tankers with their own klaws and link those to the rock somewhere in Kerbin orbit (then dump them when empty).

Hopefully this gives you some design ideas. The key learnings I applied to this ship were (1) it's a lot easier to pull (with klaw set for Free Pivot!) than push (2) if you're going to pull you need a long boom so the exhaust doesn't hit the asteroid and cancel thrust.

[Commissioner Tadpole]

Claw's tutorial is very confusing; I still haven't managed to do an encounter yet. Thankfully I quicksaved.

[Mister Dilsby]

Well you know you won't get an "encounter" like the ones you get for a planet or moon, right? You can only get an "intercept" since the asteroid is a Part that has no gravity. That said--how far along are you getting before giving up? When I do it, I typically start looking for an intercept once reaching solar SOI, on a parallel course with the target rock.

[cantab]

From a fuel usage perspective you are much better off not stopping in Kerbin orbit. Meet the asteroid in solar orbit and arrange a gravity assist, possibly powered, to boost you on to Duna. I strongly recommend the PreciseNode mod for any gravity assist work. Then either build the station once the rock is at Duna, or send the station parts up to meet the rock during its flyby of Kerbin. The latter approach is what I took when I sent a C class to Ike.

If you must stop in Kerbin orbit, consider an aerocpature into an elliptical one, something like 100x10,000 km. Make sure it's safe from Mun encounters.

As for construction, be aware that while multiple station modules clawed to the asteroid looks cool it also attracts game bugs. If you're happy with a single block of station bits then attach with a single claw.

[Mister Dilsby]

If you must stop in Kerbin orbit, consider an aerocpature into an elliptical one, something like 100x10,000 km. Make sure it's safe from Mun encounters.

This one is I think a very good idea. A high elliptical orbit would keep the asteroid and hauler within range for easy refueling (if needed), but minimize fuel cost on the transfer to Duna.

[Commissioner Tadpole]

Good news: I managed to rendezvous with the asteroid, using Kuzzter's craft.

Bad news: IT. WON'T. STEER. And if you try, it makes the orbit dance like crazy. I also burned through most of the craft's fuel in the process, so it'll have to wait in Kerbin orbit before bouncing to Duna.

EDIT: Would the glitches with the Claw dissipate if I used KerbalInventorySystem to attach Docking Ports into the asteroid, and attach vessels to said docking ports?

Edited April 3, 2015 by Commissioner Tadpole

[helaeon]

EDIT: Would the glitches with the Claw dissipate if I used KerbalInventorySystem to attach Docking Ports into the asteroid, and attach vessels to said docking ports?

You know... it might... That's a really good idea actually. You should try it and let us know how it goes!

Make sure you quicksave and re-load the save though. There are some KAS/KIS weirdness when you add parts like that.

For example sometimes you can remove a fuel pipe and the ship you fly away lists in the direction of the pipe like it were still attached. Reload the quicksave and it flies like it should.

[Mister Dilsby]

Bad news: IT. WON'T. STEER. And if you try, it makes the orbit dance like crazy. I also burned through most of the craft's fuel in the process, so it'll have to wait in Kerbin orbit before bouncing to Duna.

You mean you're trying to steer a 3000t asteroid using RCS and reaction wheels? Um, maybe someone else's ship can do that, but mine certainly cannot. Best practice here is to set your maneuver node, undock, then fly the ship to redock with the asteroid such that you are aimed in the correct direction to pull the asteroid on course. Then be certain to set the klaw for 'free pivot' and thrust away.

[Commissioner Tadpole]

You mean you're trying to steer a 3000t asteroid using RCS and reaction wheels? Um, maybe someone else's ship can do that, but mine certainly cannot. Best practice here is to set your maneuver node, undock, then fly the ship to redock with the asteroid such that you are aimed in the correct direction to pull the asteroid on course. Then be certain to set the klaw for 'free pivot' and thrust away.

...you should've told me that beforehand. Its reaction wheels are also still pretty weak and lacks enough RCS thrusters. Bugger.

Well, with an orbit that not only dances insanely, but is massively elliptical(it extends past Minmus' orbit) AND inclined, I don't think I can do a rendezvous. I'll still try, though. Is there a way to improve the ship's reaction wheels(such as attaching multiple vessels with ASAS units to the boulder), or I'll have to ditch it and come up with a better one?

[Beowolf]

No, Kuzzter's right. I'm too lazy to calc it, but the delta-v required to rotate, and then stop, a 3000t asteroid in reasonable time is going to be absurd. It isn't a job for RCS or reaction wheels; more like a full stage of main engine fuel. And you can't afford that, so you'll have to grab/dock with your engines pointing roughly where they need to be.

Since his design has the engines pulling the asteroid, once anchored you can "free pivot" the klaw, then use reaction wheels to aim your engines, and have limited steering that way.

[Claw]

I'm sorry if my tutorial is confusing. If you let me know what part doesn't make sense, I can update it or try to clarify for you.

Beyond that, my tutorial is mostly aimed at capturing the asteroid around Kerbin. If you are serious about capturing a Class E as the base for a station around Duna, I would highly recommend meeting up with it well outside of Kerbin's SOI. Then, you can adjust it's inbound Kerbin trajectory such that it crosses around the equator (for correct inclination) and set it up for aero braking. That will save loads of dV on the capture and takes a lot less dV to adjust it's inbound Kerbin trajectory. If you get lucky enough, you might be able to find an asteroid that is set up such that you can use the Kerbin flyby to slingshot it toward Duna, and bypass setting it up in LKO all together.

When capturing it around Kerbin, you can leave it in an elliptical orbit to save fuel when sending it along to Duna. However, if you're going to to that, you need to make sure the Apoapsis is pointed the right way for a trans-duna injection. Otherwise it won't help out at all and may, in fact, make it much more difficult.

As for asteroid control, you can attach multiple RCS and torque control units via small helper claw ships all around the asteroid. Monopro and electricity are shared all over the ship (including through an asteroid), so that makes it a little easier to keep the part count down with all the extra helper ships (they don't all need solar panels or RTGs). Distributing RCS makes it easier to control, and adding torque units to them helps distribute the torque load and prevent all bending from going through a single claw.

Keep in mind, as has been noted, that the claw is quite buggy. Using multiple claws can make things worse. So save often and keep backups. If you run into a problem, don't be afraid to exit KSP completely, then transfer over a quicksave as your persistent before reloading. Once you hit a claw bug, quickloading generally doesn't make it go away.

Be patient. Moving 3,000t takes a lot of patience and time. And yeah, disconnecting and reconnecting the puller is sometimes more efficient for major orbit maneuvers.

[Commissioner Tadpole]

Thanks for the help, everyone(especially you, Kuzzter), but after some time thinking, I guess I came to the conclusion that hauling the E-Class to Duna just isn't worth it.

I mean, what's the point? Besides looking cool, it just makes work harder due to having to tow 3k tons around just for something a normal space station can do with much more ease. And, as some have mentioned, the Klaw is quite buggy, and the last thing I want to suffer after killing myself to bring an asteroid to Duna orbit with a space station attached to it is for said station to break thanks to the Klaw. That, and I don't have the patience to do it(rendezvous and docking are already hard for me) - and due to my... anger issues, I was already getting a headache from trying to manuever the vessel around the asteroid.

Ah well, thanks again for all the help. Maybe I'll try to haul a D or C-class instead of an E later on, but for now I'm beat.

[cantab]

When capturing it around Kerbin, you can leave it in an elliptical orbit to save fuel when sending it along to Duna. However, if you're going to to that, you need to make sure the Apoapsis is pointed the right way for a trans-duna injection. Otherwise it won't help out at all and may, in fact, make it much more difficult.

Can this not be worked around by waiting for a Duna departure window that puts the asteroid's elliptical orbit at the right angle?

[Mister Dilsby]

Thanks for the help, everyone(especially you, Kuzzter), but after some time thinking, I guess I came to the conclusion that hauling the E-Class to Duna just isn't worth it.

You're welcome. I'd encourage you to see what you can do with the asteroid you have, and yes to try and improve on the Kranefly. I daresay you'll learn a lot that way.

If you really do want to get an asteroid to Duna, think hard about the dV involved... you now have some idea of how much dV you can put on a large rock with a reasonably sized towship. You also know something about the challenges of steering a large rock. If you can manage your goal, that will be a very rep-worthy mission report.

Come to think of it, I might try and drag a class-E to Duna myself with the Kranefly, just to show it can be done

[Claw]

Can this not be worked around by waiting for a Duna departure window that puts the asteroid's elliptical orbit at the right angle?

Sure, although I've never bothered to look at how harmonic the windows are. But really, my comment was based on...

It is interesting, but I don't think a rendezvous in Solar orbit would do since I want to set up the base before the next Kerbin-Duna transfer window. I already have three Kerbals sitting on a Duna base there and I don't want them to stay bored and lonely for that long.

In which case, if the areocapture around Kerbin is with the AP pointed the wrong way, it won't do him much good because he doesn't want to wait for another transfer window.

Cheers,

~Claw

[Mister Dilsby]

In which case, if the areocapture around Kerbin is with the AP pointed the wrong way, it won't do him much good because he doesn't want to wait for another transfer window.

Indeed. I was thinking about this some more, and the easiest way by far must be to intercept in solar SOI and nudge toward Duna aerocapture. Remember, it costs over 1000dV to go from Kerbin SOI to Duna, and a ship the size of the Kranefly can only give a Class E about 150m/s before needing a refuel. If you pick the right asteroid it should be possible to hit Duna on one tank...IF you pick the right asteroid. The trouble is that you can't play around with patched conics and maneuver nodes to get an intercept solution until you have an active ship in similar orbit or attached to the asteroid.

If I were to do this (and I am in the middle of tanking up for an Eve attempt, so no probably not until after 1.0) I might send a bunch of fast drones to scout some asteroids between Kerbin and Duna; drag maneuver nodes until I find a promising candidate, then dispatch a Kranefly to finish the job.

- - - Updated - - -

Since his design has the engines pulling the asteroid, once anchored you can "free pivot" the klaw, then use reaction wheels to aim your engines, and have limited steering that way.

Yes, this works, but the asteroid's momentum WILL swing it around considerably... in my experience the oscillations will damp out in a reasonable time, provided you are not trying to correct by more than a few degrees at a time.

[Claw]

Not that I've sent an asteroid to Duna myself, but I agree that I would probably lean toward redirecting the Class E toward Duna, vice trying to capture it around Kerbin first. I imagine it would be far less expensive (fuel and ship wise) to push the station infrastructure to Duna and meet the asteroid there, vice capturing around Kerbin, building, then pushing that huge mass out to Duna. I might also consider trying to do the slingshot off of Kerbin, but probably wouldn't try to speed up station parts to meet it, since it's likely going faster than I care to push the station parts. But that may all highly depend on the asteroid and it's path.

If you pick the right asteroid it should be possible to hit Duna on one tank...IF you pick the right asteroid. The trouble is that you can't play around with patched conics and maneuver nodes to get an intercept solution until you have an active ship in similar orbit or attached to the asteroid. ... I might send a bunch of fast drones to scout some asteroids between Kerbin and Duna; drag maneuver nodes until I find a promising candidate, then dispatch a Kranefly to finish the job.

Yes. This is precisely why I posted my tutorial about intercepting well outside of Kerbin's SOI. With a small probe, you can really pour on the dV when leaving Kerbin for the intercept. Even without trying to go excessively fast, you can intercept asteroids in 1/3 to 1/4 of the time compared to waiting until they get into Kerbin's SOI. That still leaves plenty of time to dispatch a proper mission craft for the job, and know what kind of rock you'll find when you get there.

Cheers,

~Claw

Edited April 5, 2015 by Claw