MOHO lander suggestions

[Siska]

Hello, 

 

MOHO is last planet i haven't been to. I landed on Eve, and all other bodies.

 

Do you have any lander and mothership suggestions for MOHO?

 

Problem is that you need a lot of delta V just to brake at MOHO which is relatively small planet, to get into orbit. It just takes too much fuel.

 

Any suggestions?

[Speeding Mullet]

I can certainly tell you how not to do it:

 

Seriously though, a few tips:

• Unless you want to end up with the above, the shave weight at every opportunity in order to build in fuel margin. If it isn't mission critical - Strip it out.  Pack extra delta-V though.  You will use it...
• Plan your launch window and transfer very carefully.  Moho above all requires precision, otherwise your transfer or capture costs go through the roof.  There are a few different ways of getting to Moho, but I believe the best option is to deal with your inclination at the ejection burn, which puts you in good shape for arrival from the start.  You should be able to achieve the transfer for around 4-4.5K delta-V from memory if you are snappy.
• Have a High TWR for your capture burn if it is possible.  You will be melting past Moho with gusto if you fly anything like me.
• Unless anything has changed, plan for about 1.5km/s to get to the surface in your lander, and build in maybe 3km/s overall.  Getting down and back up from Moho isn't much harder than Mun, so a similar lander would suit to be honest.  You don't need ladders from memory, and I doubt you need mono with inboard SCS so leave it behind.  1 tiny solar panel will pump the power out so don't use more unless mining.

Here is a great post thanks to @Geschosskopf which explains your options in some more detail with respect to the transfer:

Moho is hard.  We are hear for you 

SM

[Siska]

44 minutes ago, Speeding Mullet said:

I can certainly tell you how not to do it:

 

Seriously though, a few tips:

• Unless you want to end up with the above, the shave weight at every opportunity in order to build in fuel margin. If it isn't mission critical - Strip it out.  Pack extra delta-V though.  You will use it...
• Plan your launch window and transfer very carefully.  Moho above all requires precision, otherwise your transfer or capture costs go through the roof.  There are a few different ways of getting to Moho, but I believe the best option is to deal with your inclination at the ejection burn, which puts you in good shape for arrival from the start.  You should be able to achieve the transfer for around 4-4.5K delta-V from memory if you are snappy.
• Have a High TWR for your capture burn if it is possible.  You will be melting past Moho with gusto if you fly anything like me.
• Unless anything has changed, plan for about 1.5km/s to get to the surface in your lander, and build in maybe 3km/s overall.  Getting down and back up from Moho isn't much harder than Mun, so a similar lander would suit to be honest.  You don't need ladders from memory, and I doubt you need mono with inboard SCS so leave it behind.  1 tiny solar panel will pump the power out so don't use more unless mining.

Here is a great post thanks to @Geschosskopf which explains your options in some more detail with respect to the transfer:



Moho is hard.  We are hear for you 

SM

Well, getting to MOHO isn't that hard, you just have to be precise, i managed to get to moho (without braking to get into orbit) with arround 1500m/s delta v cost.

 

braking there is hard, and it is quite hard to make efficient rocket with number of parts that doesen't make the game laggy.

 

btw, your flying scycraper, how much parts does it have? I have i7, 1060 gtx 6gb, 16gb of ram and flying this would be like watching the slideshow.

looks heavy!

[Zhetaan]

2 hours ago, Siska said:

Do you have any lander and mothership suggestions for MOHO?

Moho is an airless body with a surface gravity of .275 g (this is not quite double the Mun's gravity; I believe it is closest to Vall if you've been there).  Since it is airless, you have a free hand to design the shape of your lander; simply ensure it has the fuel and thrust to make it down and back to orbit intact.

One particular issue is to be mindful of the day.  Solar panels work extremely well that close to the sun, but Moho's solar day is over 123 days long.  If you are landed on Moho at night, then it can be a long, long time before you get solar power again.  Be certain to prepare.

3 hours ago, Siska said:

Problem is that you need a lot of delta V just to brake at MOHO which is relatively small planet, to get into orbit. It just takes too much fuel.

 

1 hour ago, Siska said:

Well, getting to MOHO isn't that hard, you just have to be precise, i managed to get to moho (without braking to get into orbit) with arround 1500m/s delta v cost.

There is an alternative way to get there that can reduce the braking cost by essentially doing the braking while still in orbit of the Sun.  The key is to launch for a Moho orbit transfer (but not an encounter) at Moho's ascending or descending node.  Once you reach Moho's node, you burn to lower your apoapsis to get something called a 'phasing orbit', which means that you burn to encounter Moho at its node after one orbit (one of your orbits, that is:  Moho will make between one and two orbits in this time).  The shorter you can make that orbit, the better, because it will reduce your relative velocity once you do get the encounter.  It will still be expensive to capture but doing it this way spares you the need to make an inclination change and can actually be cheaper than a standard interplanetary transfer.

[Speeding Mullet]

12 hours ago, Siska said:

Well, getting to MOHO isn't that hard, you just have to be precise, i managed to get to moho (without braking to get into orbit) with arround 1500m/s delta v cost.

 

braking there is hard, and it is quite hard to make efficient rocket with number of parts that doesen't make the game laggy.

 

btw, your flying scycraper, how much parts does it have? I have i7, 1060 gtx 6gb, 16gb of ram and flying this would be like watching the slideshow.

looks heavy!

Getting to / doing Moho is considered the hardest location in KSP as far as I am aware, but given you have been to all other planets I am sure you will be fine

the flying skyscraper was on the large side and included a lander with room for 2, orbital outpost with room for 24, and return vehicle with habitat supporting a crew of 3 on an extended return mission.  Full details in the mission report I linked in my post above, but in essence it was a very silly thing to do.

1. Tall - 50.2 meters to be precise.  Not the tallest out there but nearly the height of the VAB and certainly long enough to experience massive noodling
2. Wide - Almost exactly 25 meters each way.  It's both long and very chubby
3. Heavy - Four thousand five hundred tonnes, and seven hundred kilos (snacks). the trans Moho injection vehicle and payload alone are over 800 tonnes
4. Computer crushing - 608 parts on the launch pad.  Could be worse but it's not friendly.  Luckily Gerty 3000 was up to the job
5. Expensive - 1,659,692 things.

I was running an i5 4690K, GTX 970 Strix, and 16 Gig of pretty decent Ram, SSD etc.  Seemed to work fine on full everything, but this was March 2016 and I'm sure the game has changed quite a lot since.  I'm literally only just booting up KSP and visiting the forum for the first time in over a year myself.

good luck with the mission - Link the report if you get a chance!

SM

[Geschosskopf]

On 7/1/2019 at 9:51 AM, Zhetaan said:

One particular issue is to be mindful of the day.  Solar panels work extremely well that close to the sun, but Moho's solar day is over 123 days long.  If you are landed on Moho at night, then it can be a long, long time before you get solar power again.  Be certain to prepare.

It's also a good idea to have the active, sun-tracking radiators.  Moho is so hot that EVA Kerbals will show heat bars.

On 7/1/2019 at 9:51 AM, Zhetaan said:

There is an alternative way to get there that can reduce the braking cost by essentially doing the braking while still in orbit of the Sun.  The key is to launch for a Moho orbit transfer (but not an encounter) at Moho's ascending or descending node.  Once you reach Moho's node, you burn to lower your apoapsis to get something called a 'phasing orbit', which means that you burn to encounter Moho at its node after one orbit (one of your orbits, that is:  Moho will make between one and two orbits in this time).  The shorter you can make that orbit, the better, because it will reduce your relative velocity once you do get the encounter.  It will still be expensive to capture but doing it this way spares you the need to make an inclination change and can actually be cheaper than a standard interplanetary transfer.

This is my preferred method.  

An alternative that's not quite as cheap is to leave Kerbin on an Eve window and use Eve to gravity-brake your solar Pe down towards Moho's level.  Also, this means you won't get to Moho on its AN/DN with Kerbin, you need to use Eve to make your inclination as close to Moho's as you can get, too.  Then you'll have to do a burn to finalize your inclination as well as to adjust your orbit into the phasing type described above to minimize the capture burn.

[Zhetaan]

3 hours ago, Geschosskopf said:

It's also a good idea to have the active, sun-tracking radiators.  Moho is so hot that EVA Kerbals will show heat bars.

@Siska:

Definitely pay attention to this.  A good heat emitter, such as a radiator, is also a good heat absorber.  Do not bring the static radiator panels to Moho or else you risk heating your vessel to failure.  The sun-tracking panels (all of them are called some variation of Thermal Control System in the VAB) are actually sun-avoiding panels; they turn to present their edges to the sun for the minimum possible solar heating.

3 hours ago, Geschosskopf said:

An alternative that's not quite as cheap is to leave Kerbin on an Eve window and use Eve to gravity-brake your solar Pe down towards Moho's level.  Also, this means you won't get to Moho on its AN/DN with Kerbin, you need to use Eve to make your inclination as close to Moho's as you can get, too.  Then you'll have to do a burn to finalize your inclination as well as to adjust your orbit into the phasing type described above to minimize the capture burn.

There's a trick to make the Eve assist cheaper:  assist at Eve twice.  The idea is to get Eve to lower your apoapsis to get an orbit with slightly less than a 262-day period.  That's one Eve year.  Then you use the second encounter to lower your periapsis to get close to the Moho encounter (two assists from Eve won't get you all the way there; you are welcome to try for a third, but you're really only reiterating that Moho is difficult to reach at that point).  However, aside from the technical skill on display, there is not a lot of delta-V to save from doing it that way.

Edited July 2, 2019 by Zhetaan

[Geschosskopf]

2 hours ago, Zhetaan said:

There's a trick to make the Eve assist cheaper:  assist at Eve twice.  

Yup, that will keep the fuel usage down, but it takes the longest.  That's the typical trade-off in KSP, spending time instead of fuel.

The Eve-assist adds another level to this trade, though, because it doesn't take Moho's inclination into account unless you set it up that way, so that Eve will be in one of the right places relative to Moho's inclination when you get there.  If you leave on an arbitrary Eve window, you'll likely have to make a major burn to match Moho's inclination.  This will eat up some of the dV savings you get from the gravity assist(s).  Best case is that Eve is on Moho's AN/DN line with Kerbin when you get to Eve, so that no plane change is required at all, just as with the bi-elliptic transfer from Kerbin.  Next best case is 90^ off that line and using the gravity assist  leaving Eve to give you as much inclination as possible.  That way, your own AN/DN line will be approximately parallel with Moho's and you just have to adjust some up or down.  Worst case is Eve being somewhere in between so your inclination will be skewed relative to Moho's (largely different LAN), so you not only have to finish matching Moho's inclination but also move your LAN around the sun.  The worst case is still cheaper than going direct to Moho from Kerbin, but not as cheap as a bi-elliptic transfer without a single gravity assist.

So, back to trading time for fuel.  Eve windows are almost 1 year apart.  It will likely be at least several years before you get an Eve window in the right place relative to Moho's orbit.  Thus, while waiting for such a window, you're trading pre-flight time for fuel.

 

Edited July 2, 2019 by Geschosskopf

[GRS]

My method...

1.Directly get to Moho.

2.Apoapsis Inclination Correction.

3.Set Maneuver.

4.Set 2nd Maneuver until there's a Small Separation, then Tweak First Maneuver and Execute it.

5.Use 2nd Maneuver for final Correction, put Periapsis between 10 and 20 Km.

6.Execute a Bare Capture.

And Congrats...you have been captured on Moho !!!

[Siska]

Actually, i waited a bit to get better science, to get S3 KS-25 "Vector" Liquid Fuel Engine

(i restarted career mode and went from beginning)

Now i am able to build smaller rockets with engine plates.

But the problem still persists, to get back from MOHO to Kerbin.

Does anyone know how much delta V you averagely need to get to MOHO (without braking) and to return from MOHO.

 

I landed on MOHO once, but had  to little fuel to get back and Jebediah stayed stuck in Sol orbit.

 

[Superfluous J]

Here's a video of a ship I used to go to Moho and back. It was low-thrills, nothing but a science run. It was also in science mode, so no money though the ship wasn't in the least bit crazy for career mode.

Spoiler

 

 

[Siska]

2 hours ago, 5thHorseman said:

Here's a video of a ship I used to go to Moho and back. It was low-thrills, nothing but a science run. It was also in science mode, so no money though the ship wasn't in the least bit crazy for career mode.

  Hide contents

 

 

What i learned is that i overbuild ships. Especially landers, i'm always affraid of running out of fuel, but at the same time i spend it more for overengineering.

[Empiro]

It's been a while since I've been to Moho, but I agree with a lot of the advice. The first time I went, I spent tons of delta-V at the capture burn, and I learned that just getting an encounter is not enough. You need to make sure that the encounter lets you capture efficiently too.

One thing that can save you a lot of delta-V is to deal with the inclination while burning at Kerbin. Remember that inclination changes are easiest when you are far out, and burns are most efficient when you're near a large body like Kerbin.

Basically burn such that you eject from Kerbin going both retrograde and normal relative to Kerbin, putting you in Moho's plane. You'll want to do this when Kerbin is at the Ascending node (I think -- it might be at the other node). Note that the AN/DN are NOT symmetrical, because Moho has an Argument of the Periapsis of 15 degrees (the angle from the AN to the PE), so one of the nodes is much closer to the PE than the other. You want to burn at the farther node, so you arrive at Moho near its PE. This saves a lot of delta-V in the capture burn because you'll be moving much faster than Moho when you arrive, so you want it to be moving fast too (there's a 6km difference in Moho's orbital velocity, so this can make a big difference).

You can save even more delta-V if at Kerbin, you launch directly into the right inclination so that you only have to burn prograde to eject from Kerbin in the right direction. This can be somewhat difficult to pull off.

As others have said, you're basically in a phasing orbit after you leave Kerbin, so you should be able to get an encounter if you burn at your PE the right amount. It's somewhat less efficient than just waiting (until you eventually get an encounter), but the difference isn't that huge, because Moho isn't a very big planet, so efficiency gains from burning in its gravity well aren't as big compared to Kerbin.

Another option is to use Eve to correct both your inclination and also reduce your PE down to Moho. It might require several assists to do this, and you'd spend a lot of time waiting around, so I haven't really every tried it this way.

Edited July 25, 2019 by Empiro

[Superfluous J]

4 hours ago, Empiro said:

You can save even more delta-V if at Kerbin, you launch directly into the right inclination so that you only have to burn prograde to eject from Kerbin in the right direction. This can be somewhat difficult to pull off.

I've found it very useful for things like this (launching to the correct angle in particular, but any ejection really) to have a ship/station in orbit. It doesn't need fuel or engines but does need to be able to make maneuver nodes. Make a maneuver node that will do what you want with that station (in this case, eject from Kerbin in the correct direction and speed at the correct time to eject to Moho), and then when you're on the launch pad target that ship, and launch in such a way that your orbit has 0 (or at least close to 0) tilt relative to the maneuver node's direction.

[GRS]

@Siska

Here's a "Slightly Overbuilt" Moho Science Run

 in a Short Explanation, was so Thrilling because of Lower Kerbol Space below the Million Kilometer Threshold (Which I'm going to revisit), mission took 5 Kerbals in total (Also you seems to be an Indonesian).

This mission took like 5500 Science Points in Normal Mode.

And if you follow my Method, you'll get like 1700 m/s of Capture Burn, total of like 4800 m/s from LKO to LMO, without much Stress.

In the Meantime, here's a Direct Ascent, Nukeless ones...

Your PC is Stronger than my own, so those rockets i show you shouldn't really Bother you.

Edited July 27, 2019 by GRS