Asteroid Interceptor

[phantom000]

I was not sure where to put this and this seemed to most relevant place. If i'm wrong i do apologize.

In 40 days an asteroid is going to impact Kerbin. I want to catch it and put it in a stable orbit to use as a mining station for re-fueling. So I need a ship that can grab it, divert it from an impact then maneuver it into a stable orbit around Kerbin. I am probably going to have to assemble it in orbit, one section at a time with docking ports but aside from that i just don't know what to do.

Any suggestions?

[Heckspress]

What I'd recommend would be an SSTO with a klaw on the front, or with a bunch of tiny klaw drones. It's really not much to maneuver them

Plus they don't do any damage upon landing, unless you're unfortunate enough to have it land directly onto your craft

[KerrMü]

Hi Phantom000

There are lots of ways to capture asteroids. Personally I found that drills and an ISRU unit are very useful on asteroid tugs. With that you only need enough fuel for the rendevouz maneuver at launch. And since engineers greatly improve the performance of mining equipment my tugs are usually manned.

For engines: LV-Ns are nice because of their high ISP. If you want to use the asteroid later on for refueling other ships, it would be nice if there was a reasonable amount of ore left in it after stabilizing its orbit.  For numbers of engines, you can get away with one, but if you are hauling big rocks, then you want a little more thrust. I once intercepted a huge e-class with an unmanned tug with only one LV-N and the course corrections took AGES.

Here is a picture of my standard asteroid tug in my current career save:

4 LV-Ns, 3 big drills, 2 ISRU units (hidden in the fuel pods with some ore tanks) and quite a few reaction wheels. I´ve got two of these ships in orbit right now and they hauled 6 E-classes into Kerbin orbit (7 very soon), 1 to Duna, and a D-class to Eve, Mun and Minmus. So they are fine for the job. I could have assembled them in orbit, but got a bit lazy and launched them in one piece.

Tip: If you are fine with a minor cheat, autostrut your ship to the asteroid. Otherwise the claw has a very wobbly connetion and every maneuver is a balancing act. Autostruts make this a lot more comfortable.

My strategy is unsually to rendevous the target asteroid in orbit arund the sun pretty early and get me an intercept with the Mun which I use to change the inclination to get as equatorial as possible, and then brake it down to the desired orbit hight around Kerbin.

This flyby got a bit too close for comfort. Yes that´s my shadow

Now rescue the planet, be a hero and have fun  

[Rune]

17 hours ago, KerrMü said:

I once intercepted a huge e-class with an unmanned tug with only one LV-N and the course corrections took AGES.

Basically what he said, but with a special emphasis here. See, this also happened to me:

And not only does it take ages, sometimes in high orbits the acceleration is low enough that KSP just doesn't count it (especially when you are running the nuke at 1/3rd to keep it fed form ISRU, and it's giving you ~20kN). So this (and the fact that ISRU units now work much slower without engineers so you can no longer feed a nuke as you drill) is the reason that the for next one, I launched a chemical manned tug with enough internal tankage for a long-ish burn:

As you can see, it's not that big either, but that's the efficient engineer in me that sees the potatoroid as a big fuel tank to stick an engine to. I figure the slightly lower Isp is a worthy price to pay for not dying of boredom (220kN, 10 times the thrust), and half of thousands of tons of fuel is still a lot of fuel. I'll just have to be efficient on my navigating and have kerbin's atmosphere and the Mun do most of my propulsion for me. Besides, mostly I want these things to build on them cool stuff!

Oh, and a final note: to plan fancy (and efficient!) solar orbit rendezvouses, just plan to leave kerbin's SOI on exactly the same trajectory the asteroid is coming in, but reversed, and you will nail a pretty decent intercept every time, with plenty of time so tiny corrections have a huge impact on you kerbin encounter (i:e: steer into an aerobrake to drop your obit or a Munar flyby to fix your inclination, or ideally both at the same time).

 

Rune. KIS/KAS is a must if you are going to mess with 'roids, IMO.

Edited January 3, 2017 by Rune

[phantom000]

I never thought about mining the asteroid while i capture it. Trouble is i have never mined for fuel before...is there a tutorial online somewhere that shows how t use one?

[KerrMü]

35 minutes ago, phantom000 said:

I never thought about mining the asteroid while i capture it. Trouble is i have never mined for fuel before...is there a tutorial online somewhere that shows how t use one?

This guide is a little bit out of date. The changes to the mechanic I can remember are: Drills don´t deplete the asteroids ore anymore if your ore tanks are full, so you can keep them running, but they automatically shut down once power is out, and ISRU units (like Rune said) work a lot slower without an engineer now.

For mining an asteroid you need essentially just a big drill, a big ISRU Converter, an ore tank (the smallest one is enough, but personally I use the big ones, because ore is pretty dense, so it is a fantastic way to store propellant and you can turn it into fuel and monoprop if you need it.) and ideally a good engineer. A three star engineer is adequate, but the better he/she is, the faster he mines and convertes. And of course you need energy to power the whole process. A few Gigantor XL solar arrays and batterys will do the trick.

Edit: I forgot. Drills and ISRU units produce heat. Like the LV-Ns. So don´t forget radiators

 

Edited January 3, 2017 by KerrMü

[Foxster]

Last time I tried this there wasn't much fuel to be had from an asteroid to make this worthwhile, especially if you convert the ore to fuel to power the re-orbit. That changed?

[Rune]

2 hours ago, KerrMü said:

 A few Gigantor XL solar arrays and batterys will do the trick.

Edit: I forgot. Drills and ISRU units produce heat. Like the LV-Ns. So don´t forget radiators

 

...and then the potato bill block the sun in the orientation you have to do your burn in (because Murphy), and you'll swear in Hebrew.   Myself, I always pack two or three big fuel cells on all my ISRU equipment, to power it through the shade. The tiny fraction of ore spent powering the whole thing is tiny. Don't mention conservation of energy .

Also, the radiator bit is important: use the folding ones or learn how the fixed ones work, because they can't always pull heat from the parts you want them to (only parent and grandparent parts for the fixed radiators). Otherwise everything will run x100 slower because of the overheating.

 

Rune. Wonky game thermodynamics FTW.

Edited January 3, 2017 by Rune

[phantom000]

What makes me nervous about this mission is I only have one chance to get it right. I have to assemble the ship in space which takes a couple days of game time then I have to intercept it while it is on the edge of the Kerbin system, I won't be able to revert back to launch.

So, how deep do the drills have to be to extract ore? and for radiators, do i have to mount them on the drill and converter unit?

[Heckspress]

put the drills as close to the bottom of the craft as possible, and yes

 

[Rune]

6 hours ago, phantom000 said:

What makes me nervous about this mission is I only have one chance to get it right. I have to assemble the ship in space which takes a couple days of game time then I have to intercept it while it is on the edge of the Kerbin system, I won't be able to revert back to launch.

So, how deep do the drills have to be to extract ore? and for radiators, do i have to mount them on the drill and converter unit?

It is a hair-rising mission when you contemplate it, but not so much when you actually perform it. Remember that, in high orbits, you have all the time in the work to make corrections, one hour past apoapsis is essentially the same as apoapsis at Mun's height. And of course, drop a named quicksave every now and then! Now onto the actual questions.

Drills only have to be touching the collision box to work. So basically, even the small drills can be made to work if they are close to the Klaw, as long as they go farther than it when extended, you are golden.

Radiators, it depends. I they are the fixed kind, they will only cool the part they are attached to, and the parts attached to that one. So you would have to mount them in the same part that you mount the drills and converter (since the converter has no surface for you to attach stuff to). If they are the kind that unfolds like solar panels, though, it doesn't matter where they are placed, can be as far as you please, so much easier.

 

Rune. Good luck and favorable windows!

[phantom000]

This is my DnC (short for Docking and Control) module. It will serve as the control and latch onto the asteroid. When the asteroid is safely in orbit the DnC will remain attached to the asteroid and serve as a connector between it an a space station so it can be used for orbital refueling.

The engines and fuel tank are already in orbit so I just have to launch and dock this section. I might have messed up because they seem to be orbiting in the opposite direction the asteroid is coming.

By the way, do i need two engineers? or can i get buy with just one?

[KerrMü]

One engineer is enough. And the opposite direction of the orbits must not be a big problem. Are you going to intercept the asteroid in Kerbins or the Suns Influence?

And I´m curious to see the complete craft in orbit.

[Rune]

10 hours ago, phantom000 said:

This is my DnC (short for Docking and Control) module. It will serve as the control and latch onto the asteroid. When the asteroid is safely in orbit the DnC will remain attached to the asteroid and serve as a connector between it an a space station so it can be used for orbital refueling.

 

The engines and fuel tank are already in orbit so I just have to launch and dock this section. I might have messed up because they seem to be orbiting in the opposite direction the asteroid is coming.

By the way, do i need two engineers? or can i get buy with just one?

That is a very sensible ship, can't fault it at all. Might be a bit short on radiators, but OTOH it might very well not, depending on how fast you get the ore in (a refinery needs about 200kW of rejection at full use, and I only see 150kW that can act on it on the three deployable radiators). But that is only going to slow you a bit in the worst case. I'd make it a bit shorter, for looks, but the extra length could also make a tractor design work (you tow the asteroid behind you instead of pushing it). That is more stable structurally if you are suffering from a wet noodle syndrome, but then again, I should just recommend you the wonderful autostrut function, which can be activated mid-flight between, say, the docking port and the heaviest part (AKA the asteroid), to make everything solid as a rock.

Oh, and make sure you have a decent amount of tankage in the stage you dock to it to do the pushing: you can refuel it between burns, but you need enough storage space to do a decent burn. This puppy is capable of about 50m/s pushing that 1,000mT rock, in about four minutes. This asteroiding thing is becoming downright easy for me, the trickiest thing is navigating the asteroid with such tiny burns spaced days apart, takes a lot of maneuver node wrestling and head scratching. Which, BTW, is the part I enjoy the most, I feel like the guys at JPL when I manage a good tricky maneuver like a gravity assist.

For the next one (I catch all class E's that come nearby in my slow-moving save, so I have three missions going on right now in different stages), I have ditched the purpose-built ships and am trying to work out a modular architecture that uses pieces I already use for other things. More or less from left to right: a Klaw Pod, a Cuppola tug (I want to leave a local control point behind on the asteroid, and I need one to move the pieces around without losing kerbnet), a KIS container to start building on the way back that actually carries the drills, and a refinery module of the kind I put in space stations (the thing in the bay), all carried by a Magdalena-class transport (Mk2) to provide the muscle, powered with four drive pods (although I could put more). I think the whole thing looks much more stylish than the other one, too.

10 hours ago, phantom000 said:

 I might have messed up because they seem to be orbiting in the opposite direction the asteroid is coming.

I almost missed that. That is exactly what you want, so you can leave kerbin's SOI along the path the astroid is coming from. It will mean a pretty hefty burn to match velocities (~0.5-1km/s), but you can refuel just afterwards, and that will give you lots of time to change you approach to kerbin form very far back, which means you need a  very tiny amount of dV to steer the asteroid anywhere. If, however, you plan to catch the asteroid in Kerbin's SOI, then it will just make the rendezvous trickier, but still doable, but then you also have to brute-force the asteroid into remaining in Kerbin's SOI, with lots of dV.

 

Rune. I'm getting literal tons of experience doing this.

Edited January 10, 2017 by Rune

[phantom000]

Here it is! Asteroid Interceptor 1 is online!

[Thor Wotansen]

Here's one I made

It weighs about 80t fully fueled and has about 5500m/s DeltaV sans asteroid.

[Rune]

I'm noticing something very weird on unmanned ships, the drills not cooling at all, no matter the radiators installed, unless a kerbal steps in and then everything is fine (and working many times faster). I have a feeling it shouldn't be so (the temperature thing, not the increased efficiency). Is that the same for you guys? It's making me do weird things, improvising with what I have on hand. Now that's going to be a series of looooong burns.

 

Rune. That must be one of the weirdest uses of an Orca in the history of ever. There are reasons.

Edited January 12, 2017 by Rune

[phantom000]

It looks like asteroid interceptor 1 is a flop. Making the rendezvous is simple enough but once latched on it wobbles violently like giant metal tube man. I'll have to redesign with, probably throwing out the mining equipment so i can have fewer contact points.

[phantom000]

I got it to work! Asteroid Interceptor 2 actually works and Kerbin now has 3 moons!

 

[Freshmeat]

On 12/1/2017 at 7:52 PM, Rune said:

I'm noticing something very weird on unmanned ships, the drills not cooling at all, no matter the radiators installed, unless a kerbal steps in and then everything is fine (and working many times faster). I have a feeling it shouldn't be so (the temperature thing, not the increased efficiency). Is that the same for you guys? It's making me do weird things, improvising with what I have on hand. Now that's going to be a series of looooong burns.

 

Rune. That must be one of the weirdest uses of an Orca in the history of ever. There are reasons.

 

I just saw this post and no one had reacted on it. It is on the bugtracker, for now you need personnel to avoid overheating. Which makes heavy asteroid capture with life support saves a bit more tricky.