Deltav to redirect this asteroid around Kerbin (Class B)

[Andiron]

Hi !

I'd like to try to redirect an asteroid passing near Kerbin at only 700km from it. My goal is to build around it a space station. I tried once few months ago with a C-class asteroid and I didn't have enough fuel to orbit it. Do you know what should be the minimum deltav needed, or any tips to do it, at least for this one ? :

Thanks !

Edited September 29, 2016 by Andiron

[Superfluous J]

Sadly, I can't tell you because the amount of dV you arrive at the asteroid with, and the amount you'll have when you clamp on, will be different numbers and will be quite dependent on what kind of ship you take out there.

Just looking at that orbit though, if you're able to latch onto the asteroid before it passes Pe it shouldn't be that bad. Just burn retrograde right at Pe until it's JUST captured, and then you can bring up more fuel later. Or alternatively, try to meet it way out as it just enters Kerbin's SOI and burn radially inward to aerocapture it.

NOTE: I've never tried aerocapture of an asteroid since 0.90 (See pic in signature ) and do not know how well you'll fare plowing through the atmosphere at about 4000m/s.

[Andiron]

3 hours ago, 5thHorseman said:

will be quite dependent on what kind of ship you take out there.

I call it "Bender's arm", should be very stable when pushing the asteroid

[Andiron]

Mission successful ! Asteroid in high Kerbin orbit (600 km) with a 9500m/s deltav craft.

[Vanamonde]

If you meet an asteroid out between Kerbin and Duna, you can make big changes in its trajectory with relatively small burns. You can also save a lot by having it aerobrake on arrival. 

Oh, and the tutorials section is for supplying guidance rather than asking for it, and so the thread has been moved to Gameplay Questions. 

[Blaarkies]

10 hours ago, Andiron said:

Mission successful ! Asteroid in high Kerbin orbit (600 km) with a 9500m/s deltav craft.

DV is very dependent on your craft's dry mass. That is why a tiny 3x stage probe can have 9000m/s, but we know it will never budge an asteroid. This is because when you clamp onto the asteroid, suddenly your dry mass increases by 20t(class B ?).

To find the DV required, you need to add dry mass to your craft in the VAB and check what the numbers show.
1. Complete the design of the ship(only the stage/piece that reaches the asteroid). Remove fuel until you have the same amount that you would have had upon reaching the asteroid
2. Now add "9.5~42.5 tons" of locked fuel tanks(ore tanks also work nicely). That is the mass of class B asteroids
3. Read the new total DV. Thats the number you are looking for.

For step 1. i would remove 1500m/s dv worth of fuel since i launch the roid vehicle from low orbit. Thats about 1000m/s to escape Kerbin SOI and then 500m/s safety margin to do the deep space burns.

* You can bring with a tiny empty ore tank + a tiny ore drill to hollow out the asteroid. Just "jettison" the mined ore from your tank until the roid is empty...the roid should become at least 80% lighter -> more dv for you

[HalcyonSon]

On 9/29/2016 at 10:09 PM, Blaarkies said:

* You can bring with a tiny empty ore tank + a tiny ore drill to hollow out the asteroid. Just "jettison" the mined ore from your tank until the roid is empty...the roid should become at least 80% lighter -> more dv for you

Good advice in your post, but this bit bugs me.  Was it meant as a joke?  If you're going to bring along ISRU equipment, you may as well turn ore into fuel for further dv.

[Blaarkies]

On 10/12/2016 at 8:25 PM, HalcyonSon said:

Good advice in your post, but this bit bugs me.  Was it meant as a joke?  If you're going to bring along ISRU equipment, you may as well turn ore into fuel for further dv.

Oh no sorry about that. It was like, an alternative option 
The sane thing to do is obviosly to make fuel, but for that you need the extra parts like solar panels, radiators, ISRU, fuel tanks big enough to provide +- 200m/s dv in one sitting, an engine to do that in less than 10min(alternator engines could help here), and of course reaction wheels to handle the loaded mass of the roid.

Launching all that into orbit is a bit more difficult than a simple Nuke tug(with the drill and ore drum)...that is, if you ONLY want to complete the roid contract. But free fuel already in orbit is well worth the effort in hard mode careers

[Tyko]

where is the listing that shows asteroid tonnage by Class?