redirecting class E asteroid

[Cannon]

i have to redirect class e and dock it on my orbital station (which is at 120km height).

it's nearly impossible to control the giant asteroid but my station is huge too, what should i do?

please help, what's the best and easiest way to do this?

[AlanP]

Easy does not come into it! I did an ejection from the solar system on a class D.

Use a lot of SAS but turn it off for burns. Use a Rhino engine, unless you like really long burns(they'll still be long but better).

setup a drilling and refinery operation on the asteroid to fuel it. You need to watch it though, as your drills will deplete the ore of the asteroid even when the tanks are filled(I made this mistake)

make sure you claw and ship are aligned with the center of mass. make orientation changes far in advance of your burn( they take time to do. You could use vernor engine for changes too(more powerful rcs). I haven't done this, but you could try undocking the clap and re positioning the ship for direction changes and redock from that direction.

My other question is why are 120k? I would be easier to circularize the asteroid at what ever height it is at and bring the station to it or build the station on it.

Hope any of this helped. Good Luck.

[Sharpy]

First bring the asteroid into a roughly similar orbit. For class E you either need a lot of patience or the right craft. Even then it's a plenty of careful work.

Then the docking. The station may be big, but is still several orders smaller than the asteroid, and it has the RCS (if it doesn''t, add it!). It's best to assemble the station from pieces on the surface of the asteroid, but if you can't, you're still better off driving the station carefully.

For AlanP: Sure it would be easier to bring the station to a higher orbit but if it's to be a fuel station, it should be just a short hop from LKO so that you wouldn't need to launch extra fuel to reach the station.

[AmpsterMan]

I'm having a similar issue, but with a more modest payload. Class C. Do you guys recommend trying to get it to aerobrake? I cheated (infinite fuel) my first time just to get the feel, and my probe and the rock exploded.

Cheers

[Sharpy]

Aerobraking the asteroids nowadays is a terrible chore. They are quite aerodynamic and quite heavy and they overheat. The one Class E I tried to aerobrake through 42km periapsis (IIRC), lost a whooping 1.3m/s in its braking pass (out of some 3200).

Although with class C airbrakes could be much more efficient than with class E (they improved the above result by a whole 0.7m/s!).

[Cannon]

alright this is how it looks right now:

and this is my rocket:

what do i do?

[Mister Dilsby]

what do i do?

Frankly, I would get a new rocket It is MUCh easier to pull than push. Here's mine:

That's the Kranefly, adjusting the orbit of a Class-E for future use as an LKO station mount. Key design elements are:

--nuclear motors for high dV

--lots of liquid fuel storage. Over 14,000 units LF on this ship, and still the max dV towing a class E is about 300 m/s.

--radiators to get rid of the heat from said motors

--motors placed far, far away from the asteroid so that thrust does not impinge

--sufficient RCS to maneuver around the asteroid

--lots of solar for drilling and refining

When I want to pull the rock somewhere, I orient the ship for the maneuver node, fly it around the asteroid until it's targeting asteroid COM and aimed at the node, back up and capture, then set the Klaw to "Free Pivot" and thrust.

Doing this is NOT easy. Good luck!

[Hotblack Desiato]

how about adding a drill (or several drills) and a highly skilled engineer?

this way you can suck ore out of the asteroid, making it lighter AND giving you extra fuel.

I'm just not sure how much fuel a class E asteroid gives.

[Mister Dilsby]

I'm just not sure how much fuel a class E asteroid gives.

They're pretty much made of fuel; typically ~90% of the mass is convertable to ore, and that ore can be converted to LFO on a 1:1 basis. So yeah, you can mine it and throw the fuel away and drag a much smaller rock where you want it--or try to preserve as much as possible for practical use later.

[pellinor]

My most fuel-efficient solution is to

* aerocapture into an orbit that crosses the mun's

* gravity-assist my way into the desired inclination (may take multiple encounters)

* aerobrake to the desired height

I once pulled this off using around 100-150m/s of deltaV, most of which was needed to lift the periapsis out of the atmosphere at the end. Saves lots of fuel but you pay in playing time instead, tinkering with manouver nodes.

[Cannon]

how about adding a drill (or several drills) and a highly skilled engineer?

this way you can suck ore out of the asteroid, making it lighter AND giving you extra fuel.

I'm just not sure how much fuel a class E asteroid gives.

the thing is, i need it full, docked on my station so i can drill it from my station

[AlanP]

Your best bet is to encounter the asteroid as much before Pe as possible, to give yourself as much time as possible to burn. you may want to capture a smaller asteroid to fuel the mission. Keep trying.

I agree sharpy. At the time I didn't explicitly know his intent.

[Sharpy]

the thing is, i need it full, docked on my station so i can drill it from my station

if you burn half the ore contained to get it into LKO, you'll still have a plenty for refuelling other crafts. Just think: 1000m/s of delta-V applied to 2000t asteroid, being half the ore - converts to how much dV applied to 100t craft?

[Axelord FTW]

I've done ONE such mission once and it was a real pain in the ass.

Thankfully, I already had an E class on an impact trajectory with kerbin (rather glancey too) so the amount of dv required to have the damn thing just pass through the upper atmosphere for aerocapture and aerobraking some more on two more passes (had to raise the AP a bit at the PE each time, minimal dv consumption).

Though getting it to reach a specific station might be problematic. In my case, the orbit came in at a high angle. I would have transferred the station to the right plane (even at PE, the dv for plane change would have been prohibitive).

It was pretty neat to see the exact procedure I went through to get that mission done applied in the book to get Greg's Skeleton to meet with Izzy.

[Sharpy]

If you capture the asteroid, leaving apoapsis quite high (beyond Minmus), the delta-V to change the plane is quite reasonable. And if it's to serve as fuel station before transfers, it needs to be in equatorial LKO or close to it.