"Minmus is easier than Mun." So is it, or am I just a backwards person?

[jros83]

In Career I frequently have more of an issue getting an intercept and capture with Minmus than I do Mun, however for a long time now the community has been pretty solid with the "Minmus is easier" party line.

Without a concrete example right now (sorry for that), are there any fundamental issues that would cause someone to have difficulty with Minmus juxtaposed against little difficulty with Mun?

I have a suspicion that for me it's an issue with Minmus' inclination...

 

When I was last playing regularly I didn't have quite an issue getting an intercept for Minmus, however we are talking 1.0, 1.05.

Edited April 3, 2017 by jros83

[Nicias]

Getting an intercept with minmus is harder, because of the smaller SOI and inclination. Once you have an intercept, getting in orbit, landing, getting back to orbit and getting home are easier. All of those things require less dV, lower TWR, and are more tolerant of human error.

[Toastie_Buns]

Minmus intercept is easier than you think.

Mess around with the camera a bit until you find the point of which Minmus's orbit intersects the Mun orbit. At this point, you can intercept for a perfect polar orbit. Line up a node so you're boosting in that general direction and you'll be fine.

Obviously there's two points like this, so use your judgement for which one Minmus will be at first.

[The Aziz]

Let's put it into comparison. 

Mun: you need equatorial orbit around Kerbin

Minmus: you need inclined orbit (6.2°?) -more d-v

Mun: is much closer

Minmus: is further - more d-v (by, like, 60m/s iirc)

Mun: is bigger, thus has higher gravity - more d-v for circularising, landing, takeoff, return burn

Minmus: much smaller, d-v needs are also smaller.

Mun: re-entry velocity lower if done in one shot

Minmus: re-entry velocity higher.

[Eckee]

Just as @Nicias said. You can minimize inclination change dV by launching at the target AN/DN with correct inclination to LKO as possible, you can make little correction after the launch. Then all you need is to create a manuever node with ~920/950 dV (930 according to dV Map) depending on the desired flyby/orbit around the Minmus. It takes a little more dV to be captured by Minmus' SOI, but it takes significantly lower to adjust your orbit, land/take off and return. Because of its low gravity, it's much easier to mess around it, feels even kinda cheaty 

[Warzouz]

The simplest way to get to Minmus

• Align with Minums si you're 60° behind
• Burn prograde until your AP reach the orbit of Minmus. In most case, you should get an encounter.
• Add a node at AN/DN and change plane to get a better encounter.

For Mun, it's easier because you always get a perfect encounter, (except if your messed your ascent and you're not in Kerbin equatorial plane which can be easily spotted before attempting to go to the Mun)

[Snark]

1 hour ago, jros83 said:

In Career I frequently have more of an issue getting an intercept and capture with Minmus than I do Mun, however for a long time now the community has been pretty solid with the "Minmus is easier" party line.

Without a concrete example right now (sorry for that), are there any fundamental issues that would cause someone to have difficulty with Minmus juxtaposed against little difficulty with Mun?

Which one's "easier" depends on what you have trouble with.  To sum up:

• Mun is easier to navigate.
• Minmus is easier to design a rocket.

Probably the reason why the community as a whole tends to come down on the "Minmus is easier" side, is that for most new players, "design a rocket with a big enough dV" is a harder problem than "navigate".  (Part of that may be because you only have to "solve" navigation once, for all ships you'll ever build; whereas you have to "solve" the design problem new and differently for each different ship, which requires learning a more complex set of rules.)

But "most" != "all".  It's going to be different for each player.  It can also be different for each individual player over time, depending on where they are in their KSP skills development, and also where they are in the tech level of a particular career.

For example, I've been playing KSP long enough now that I can slap together a rocket that will go to the Mun (or Minmus) and back in just a couple of minutes, practically in my sleep.  And I can navigate to Minmus (or the Mun) just as easily.  I'm not bragging, here-- this is what happens to everyone when you play KSP long enough, since you'll be going to both places so many times.  You'll be there too, soon enough.    On the whole, I tend to side strongly with the "Minmus easier than Mun" folks.

However, whenever I start a new career, I almost always go for the Mun first!  Why?  Because I like to go to Mun-or-Minmus as early as possible in career.  At the low end of the tech tree, even a single mission to one of Kerbin's moons can make a huge contribution to a fledgling space program.  But when I'm that early in the career, I don't have patched conics or maneuver nodes yet.  And personally, I find navigating to Minmus without patched conics to be a pain in the neck.  It's just not worth the hassle to me.  Whereas the Mun is so easy that patched conics are practically an afterthought-- I use 'em when I have 'em, to optimize dV usage, but I can make a Mun trip pretty easily without them.

 

[dangerhamster]

Perhaps this should be changed to "Minmus is more forgiving"

 

 

Unless you're driving a fast rover.....

[Jarin]

29 minutes ago, Snark said:

And personally, I find navigating to Minmus without patched conics to be a pain in the neck

Yeah, that is one major note. A newbie can get to the mun without even creating a maneuver node. "Burn prograde at Munrise" is basically foolproof. It's just the major landing/takeoff dV requirement that makes Mun difficult. I have lost count of the number of kerbals I've stranded on Mun now.

Edited April 3, 2017 by Jarin

[tater]

When you launch into a typical, equatorial orbit in KSP, select Minmus as your target. You will see the ascending and descending nodes (AN/DN markers). The line between them is the "line of nodes" and is a dotted line in KSP.

That line is where the two orbital planes cross. If you burn at either one of these nodes prograde, you will raise your orbit roughly along that line (exactly if you are circular). If you raise the apoapsis along the line of nodes to Minmus orbit then you are certain to get an encounter at some point in the future. Pick the side such that Minmus is heading towards your new, higher apoapsis, and it will happen when you reach apoapsis or thereabouts. Note that you can fiddle with the node, raising your orbit a little past Minmus means you'll hang out at apoapsis longer, giving Minmus time to reach you (you'll hit the SoI heading back down to periapsis).

Edited April 3, 2017 by tater

[Snark]

29 minutes ago, dangerhamster said:

Unless you're driving a fast rover.....

Never really understood that one, myself-- I've heard plenty of comments along the lines of "driving a rover is hard on Minmus", but I find roving Minmus to be as easy as roving anywhere else.  Easier, in some ways-- less stress on the wheels means less likely to pop one, and the low gravity means plenty of time to sort things out before impact when I happen to go "airborne".

[cantab]

Minmus is harder to get to but easier to land on.

[bewing]

A couple of points that haven't been hit yet. I'm mostly with snark, but ...

Minmus is always my first target after I go suborbital on Kerbin. Why? Because in the early game, Minmus and the Mun are lined up perfectly to hit both their SOIs in one trip.

As snark said, that first trip is done without patched conics (because I *need* to upgrade the Ast Complex and Mission Control and R&D and Launchpad and VAB first! Tracking is a luxury). But I launch that first trip straight up, all the way to Minmus. No orbits, no patched conics, no problem.  You just have to lead your target by 30 to 45 degrees.

 

[Spricigo]

5 hours ago, dangerhamster said:

Unless you're driving a fast rover.....

Well, no one drive a rover because its convenient.

 

5 hours ago, Snark said:

... and the low gravity means plenty of time to sort things out before impact when go "airborne"...

IF one is paying minimal attention (what usually is the difficult part).

 

[Aegolius13]

One other thing: the flats on Minmus are very... er... flat.  Which makes it very easy to land,  especially with the low gravity. 

[Capt. Hunt]

My understanding is that Delta-V wise, they are roughly equal.  It takes more to reach minmus then the moon, but that is balanced by it taking less delta-v to capture and land on the surface.

[WanderingKid]

2 hours ago, Capt. Hunt said:

My understanding is that Delta-V wise, they are roughly equal.  It takes more to reach minmus then the moon, but that is balanced by it taking less delta-v to capture and land on the surface.

Not really.  In practice, from LKO:

• Intercept: 850 dV to Mun, 950 dV to Minmus + 200 dV for a badly missed takeoff vector for alignment.
• Capture: 350 dV Mun, 175 dV Minmus
• Landing: 550 dV Mun, 165 dV Minmus  (+ Landing dV, ~100-200 dV)
• Takeoff: 550 dV Mun, 160 dV Minmus
• Return + Kerbin Landing: 280 dV Mun, 280 dV Minmus (Assuming AeroBrake)

Mun: 2,750 dV or so

Minmus: 2,100 dV or so.

The only part of Minmus that makes it more difficult is what was mentioned above: Getting the intercept on a tiny SOI that's off angle.

EDIT: Those are rough numbers from memory.  If I'm off a bit somewhere, forgive me, it's just to get the concept across, not create a dV map.

Edited April 4, 2017 by WanderingKid
Adjusting a few numbers.

[CSE]

On 04/04/2017 at 8:37 PM, WanderingKid said:

Intercept: 850 dV to Mun, 950 dV to Minmus + 200 dV for a badly missed takeoff vector for alignment.

If you've mis-aligned your launch plane against Minmus' orbit, the best place to make the correction is when you're about half-way from Kerbin to Minmus (by distance). A plane change here to make the encounter should typically require less than 50m/s and often less than 20m/s.

Sometimes if Minmus' orbit isn't passing over KSC when I've got a convenient window in my schedule, I just launch to an equatorial parking orbit, make the transfer burn in the equatorial plane and correct it on the way. It's less hassle than rescheduling other activities to make room, and less costly than trying to align and mucking it up.