How cheap can I get a science lander on the Mun?

[ZDPro]

Hi guys, I picked this game up on the last Steam 75% sale and it's really addicting. I'm having a blast. I started a career, and landed on the Mun for the first time yesterday, which was so cool. My first lander had all the science I had unlocked with it, and the full price to get it there was around 43k. This feels so expensive since my Mun orbiter for tourists is only 25k. 

How cheap can I get a science lander to the Mun to hit the biomes? Any thoughts on my design that I can improve?

Thanks!

Here are some images.

https://imgur.com/a/uv6Ent0

I can get to orbit with boosters, and empty the lower stage tank to get Lower orbit, then burn for Mun intercept. If a poor launch, I might be a couple hundred Dv short. If I land without mistakes, I have 300-400dv of fuel left in lander, but if I have troubles, I can easily burn through that.

 

[Geonovast]

Moved to Gameplay Questions.

First thing I would do is rebuild your lander so it's only using one of those engines.  Should save you a good amount of cost and weight.  You can also cut down on the number of landing legs, and, since you'll be cutting weight, you'll need to bring less fuel.

[CBase]

You can afford it, so why make it cheaper ? If you want to launch it multiple times to get all science: Don't, instead try to build restartable biome hopper in order to visit multiple biomes with 1 Kerbin launch and transfer. Yes it will be more expansive once, but should be cheaper than x times this one.

If you want save money in general: Do not stage first stage before orbit and try to return vom LKO towards KSC for maximum return.

[VoidSquid]

One of my earlier landers (stock) for one Kerbal, it does the job  

https://imgur.com/a/bJ2H99v

But if you want to go really cost efficient, follow @CBase suggestion:

1 hour ago, CBase said:

try to build restartable biome hopper in order to visit multiple biomes with 1 Kerbin launch and transfer.

Such craft will probably need an ISRU unit plus required utilities (harvester, cooling, power).

Edited November 3, 2019 by VoidSquid

[Streetwind]

The thing about science missions is that the science parts themselves are very expensive. When you have all the instruments unlocked, a complete package for the Mun (two goo for balance, one materials bay, one of each of the four sensors) already costs 20k funds. The seismometer and gavioli detector in particularly hit the bottomline hard, and you want to make sure to return them. The Breaking Ground surface experiments and support equipment will cost you another 15k

Next, you probably want at least two Kerbals (a pilot and a scientist), though I usually carry three in order to get them XP in a timely manner. A three-man pod costs 3.8k (or just 3k with Making History). Landing legs cost you another 1k-2k depending on your setup. So you're already at 40k total, and you don't even have fuel, decouplers, or engines yet.

Here's what my latest midgame Mun lander looked like. It has all the equipment mentioned above, so 40k invested towards a three-Kerbal lander with all experiments onboard; and then, another 30k is used for all the rest of said lander, and the stages below it. It's actually quite healthily overprovisioned; the second stage still has fuel when I start the deorbit burn at the Mun, and the lander has more than 2025m/s too, because the four nosecones decouple during Kerbin ascent when they're no longer needed. Only the materials bay is ditched, the rest of the science experiments are returned to Kerbin. Well, the surface experiments obviously stay up there too... The variant without surface experiments (you only need them once, after all) has even more excess dV, and I've done small hops to neighboring biomes with it. Gotta keep the hops really small though, and flown the rest of the mission well, or it'll run out of fuel on the way back to Kerbin. Hops are more expensive than you think.

There are solar panels you can't see here, there's an OKTO-2 probe core in case there's no pilot in need of XP, and batteries and an antenna stashed in the service bay. Four Spark engines on the lander. I'd only need two as far as thrust is concerned, but I like symmetry. The stages below are driven by a Cheetah and a Mastodon respectively.

I could probably make it a bit cheaper if I really tried, but as said before, the only savings that can be made are in the 30k that makes up the rocket, not in the 40k that make up the science and the pod. So the potential to scrooge is somewhat limited. Probably downsizing the first stage a little would be the approach I'd take. Might save 2-3k.

[Armisael]

@Streetwind I'm honestly not sure how to read a post saying 'this rocket is just about as tight as it'll go, but it also has gobs of excess dv'. If your goal is to deliver kerbals and science gear to Mun's surface then get the kerbals back, you could easily cut 15k off the cost of that ship - more if you decide to simply always use the probe core.

Edited November 3, 2019 by Armisael

[Streetwind]

1 hour ago, Armisael said:

I'm honestly not sure how to read a post saying 'this rocket is just about as tight as it'll go, but it also has gobs of excess dv'

Ah, apologies. It was not meant to come across like that. It is indeed not intentionally cost optimized - hence the last part, where I said that thef first stage probably has the most potential or savings, even if they won't be that large. See, I aimed to give a practical example of how the majority of the spacecraft's cost is tied up in the science experiments themselves, which defines a bottom floor below which the cost may never fall, no matter how frugal you build. And even if you could shave off money of this, the difference wouldn't be that large. OP seemed to have trouble flying consistent profiles by their own admission, so being overprovisioned is something they need.

How would you save 15k, though? Best I could do was half that (almost exactly 7500) by replacing the first stage with a Pollux SRB and steerable winglets (at the cost of being very unpleasant to fly), and the four Sparks by a single Terrier (at the cost of making the lander look a bit awkward). The resulting vessel had about 200m/s excess instead of the other one's ~600m/s, and that's a number I wouldn't go below in case something doesn't go according to plan. Besides, that fuel can be put to use in ensuring a landing close the KSC for good recovery values.

I'm curious to how you'd do it. Remember, it must carry three Kerbals (not optional, I am bringing them along to get XP), all six non-atmospheric science instruments, and a full set of Breaking Ground non-atmospheric surface experiments and the power to run them (that'll be two power stations, since these are low-level Kerbals).

 

Edited November 3, 2019 by Streetwind

[Signo]

Maverick supersonic, I'll be there in thirthy seconds.

[Armisael]

@Streetwind This still had 577 m/s of dv after my Munar ejection burn so there's still more cutting to do, but here's a quick first cut at it. I wasn't sure if you included the antenna as part of the ground experiments, but assumed not since the numbers lined up without it (and you'd want relays for continual coverage of the site anyways).

You're absolutely right about reusing your science gear many times for actual cost-efficiency, of course.

 

[Fierce Wolf]

Make it cheaper by reducing the amount of trips you need to do to Mun. If one trip nets you, say, science in 3 biomes, you already reduced your total mission cost.

[Streetwind]

17 hours ago, Armisael said:

@Streetwind This still had 577 m/s of dv after my Munar ejection burn so there's still more cutting to do, but here's a quick first cut at it. I wasn't sure if you included the antenna as part of the ground experiments, but assumed not since the numbers lined up without it (and you'd want relays for continual coverage of the site anyways).

You're absolutely right about reusing your science gear many times for actual cost-efficiency, of course.

 

Yeah, on the Mun you don't need a surface antenna. The KSC tracking station, even at just level 2, is close enough even to Minmus to let the control station phone home just fine. Or relays work too.

Interesting approach, but I must ask - is that actually safe to return? Last time I tried to reenter a lander can without a heatshield, it promptly burned up, even on a relatively benign trajectory. Admittedly, that was a few versions ago, before they reworked the Mk2. I've always just assumed that it wasn't meant to be, since even the descriptions state them to be unsuitable for reentry, IIRC.

Also, which part decouples after landing? The entire structure above the probe core? That would be... counterproductive, IMHO. Because the science is so expensive, the return value is a significant factor in total mission cost. I don't always get the full ~35k value of my return vehicle, but I probably get at least 25k if I use my excess fuel to control my EDL timing and vector. That would put the total mission cost of my original 70k vehicle at around 45k funds at most, which is likely less than what you'd pay for a 54k vehicle that only returns two lander cans and assorted greebling.

I recommend paying the (very small) price in weight and cost to put a 1.25m service bay on top of the Mk1 lander can. You have the dV to spare, and you can fit the probe and all the expensive sensors in there, safe for reentry and recovery. You can still ditch the surface part carrier and the materials bay, they have very little recovery value.

[IncongruousGoat]

If we're talking absolute cheapest route, I had good success with this design a while back when trying to get science back from every biome on the Mun:

It doesn't have a crew capsule, but that's because I needed to fit it into the T1 VAB and launchpad (you'll notice it has 30 parts and weighs less than 18 tons). For me at the time, this wasn't a problem since I couldn't do EVAs or take surface samples, but I have no idea how far you've upgraded your space center. If anyone does try and replicate it, note that the design is a bit hard to copy from a screenshot due to high levels of part clipping in the lander.

[Armisael]

6 hours ago, Streetwind said:

Interesting approach, but I must ask - is that actually safe to return? Last time I tried to reenter a lander can without a heatshield, it promptly burned up, even on a relatively benign trajectory. Admittedly, that was a few versions ago, before they reworked the Mk2. I've always just assumed that it wasn't meant to be, since even the descriptions state them to be unsuitable for reentry, IIRC.

Also, which part decouples after landing? The entire structure above the probe core? That would be... counterproductive, IMHO. Because the science is so expensive, the return value is a significant factor in total mission cost. I don't always get the full ~35k value of my return vehicle, but I probably get at least 25k if I use my excess fuel to control my EDL timing and vector. That would put the total mission cost of my original 70k vehicle at around 45k funds at most, which is likely less than what you'd pay for a 54k vehicle that only returns two lander cans and assorted greebling.

I recommend paying the (very small) price in weight and cost to put a 1.25m service bay on top of the Mk1 lander can. You have the dV to spare, and you can fit the probe and all the expensive sensors in there, safe for reentry and recovery. You can still ditch the surface part carrier and the materials bay, they have very little recovery value.

It’s entirely safe for reentry from Mun. Heating is a joke in stock KSP. Mk1 Lander Can has always been safe for that (I don’t know about the old heavy Mk2 can - I never used it) . That’s why I didn’t use a cargo bay: it doesn’t add anything but weight.

You’re right about saving the science experiments. You can keep everything but the science he with negligible changes in performance, which makes up about 18k of the 20k returnable science (can’t bring back the ground experiments).

[ZDPro]

Thank you for the replies, guys. I guess I was thinking too conventionally with the leg struts and not having an idea how to have the science jr survive reentry, so I left it behind. Landing on the engines itself seems interesting.

Edited November 10, 2019 by ZDPro