tater

NASA Human Landing System

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Edited by tater

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Reusable moon lander is a pretty simple problem, honestly -- simple enough that you can boil it down to 3 or 4 basic configurations.

 

Anyone listen in?

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5 minutes ago, sevenperforce said:

Reusable moon lander is a pretty simple problem, honestly -- simple enough that you can boil it down to 3 or 4 basic configurations.

Reusable probably must have an airlock chamber with a suit cleaning pump or so. Otherwise it will be dusted before the reuse.
So, resources, chambers, etc.

Also depends on the docking ability. 

Edited by kerbiloid

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With LOP-G in a NRHO rather than a frozen orbit, the dV cost between the station and the surface is 2.6 km/s. That's pretty high, too high for a single-stage reusable lander (which must bring 5.2 km/s by comparison) running on anything but cryos.

I would love to see NASA put up money for some actual missionable architectures, like "Give us a space truck that will deliver X tonnes from LOP-G to the surface" and then let the market compete over reuse. If you want a manned lander then you can have the manned lander delivered as a payload to the surface by the space truck.

I like the idea of an autonomous space truck that will deliver a significant payload to a low suborbital trajectory...like, to the point that you only need 300 m/s or so to safely land. Then the payload can perform its own landing rather than being tied into some specific touchdown configuration determined by the space truck. The space truck would drop the payload, move away, and then boost itself back to LOP-G to refuel. Could also work with a manned lander; the space truck would drop it off just short of landing, and then it would land on its own and return to LOP-G later as a single stage.

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I listened to the event while driving. It wasn't very useful. More CLPS than this crew thing talked about.

Bridenstine said that they imagine the Gateway to have a tug (to drag a lander to and from LLO), then landers, and ascent vehicles (might be the same, might not be the same, I guess. Maybe systems that leave descent prop drop tanks on the surface?

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The challenge I see in cislunar reuse is the delivery mode. Sure, fine, you design a reusable architecture...but how do you deliver propellant? Presumably you're going to have to launch it from Earth with a docking-capable delivery vehicle with its own engines. What do you do with that vehicle? Expending one rocket to deliver fuel for another seems like a colossal waste of time.

Unless your fuel delivery vehicle (and its engine) is planned for return to Earth for refurbishment and relaunch, then it just makes more sense to make your delivery vehicle an expendable tug and have it deliver fuel for a smaller reusable stage. 

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Yeah, Gateway is idiotic.

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If the lander/ascender has a docking capability, probably LLO-station is an emergency vault. And maybe a coast guard station to lift a crew if the ascender is broken.

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2 hours ago, sevenperforce said:

The challenge I see in cislunar reuse is the delivery mode. Sure, fine, you design a reusable architecture...but how do you deliver propellant? Presumably you're going to have to launch it from Earth with a docking-capable delivery vehicle with its own engines. What do you do with that vehicle? Expending one rocket to deliver fuel for another seems like a colossal waste of time.

Unless your fuel delivery vehicle (and its engine) is planned for return to Earth for refurbishment and relaunch, then it just makes more sense to make your delivery vehicle an expendable tug and have it deliver fuel for a smaller reusable stage. 

Starship comes in with more guns blazing.

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10 hours ago, sevenperforce said:

Could also work with a manned lander; the space truck would drop it off just short of landing, and then it would land on its own and return to LOP-G later as a single stage.

Now where have we seen that...

10d_separation.JPG

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8 hours ago, tater said:

Yeah, Gateway is idiotic.

Gateway makes sense if you are strapped to low-dV Orion+SLS, which makes sense if you are determined to continue the SLS pork project. Otherwise not.

If your lunar aspirations are not constrained to the lunacy (see what I did there?) of Orion, then a frozen orbit at 86° will do just fine, as long as you don't mind periodic occultation. That's what relays are for.

14 hours ago, tater said:

Bridenstine said that they imagine the Gateway to have a tug (to drag a lander to and from LLO), then landers, and ascent vehicles (might be the same, might not be the same, I guess. Maybe systems that leave descent prop drop tanks on the surface?

Lunar reuse is just messy. It takes an engine to deliver fuel...so unless you have a "fuel ferry" that carried props from LEO to your cislunar station, then returns, aerobrakes down to LEO, and is refueled...what's the point? You might as well just expend.

But if we have the gateway...

Prop transfer for pressure-fed hypergols with nitrogen press is a solved problem (ISS). I could envision a reusable hypergol-fueled manned lander carrying about 3 km/s when full, docked to the Gateway. Orion would arrive at the Gateway with crew and consumables, then a cryo space tug (based around ACES or a BE-3 architecture) would arrive from LEO carrying hypergols as payload. It would transfer hypergols to the lander and mate to it, then drop it off suborbitally on the moon as a crasher stage. The lander performs touchdown, ascent, and return to the Gateway under its own power. The same space tug design could be used to drop stuff off at the Gateway and deliver payloads to the lunar surface, perhaps with multiple planned uses (if boiloff management could be solved) per mission.

The other immediate architecture would be a beefier lander with about 2 km/s in its internal tanks and another 2 km/s in drop tanks. The same sort of space tug would carry hypergols and replacement (full) drop tanks, attach them to the lander, and then tug the lander to an 86° frozen orbit. The lander would descend, drop its tanks, and land, then perform the ascent on internal tanks to rendezvous with the tug for the tow back to the Gateway. Of course then you end up with a derelict tug.

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KSP obviously doesn't have near-rectilinear halo orbits. But if you want to simulate a lunar gateway in stock, you can do so by using the debug menu's "Set Orbit" function as follows:

  • Semi-major axis to 12 million
  • Eccentricity to 0.1
  • Inclination to 5
  • Vary your MNA (iteration necessary) so that you lead the Mun by as small an angle as possible without crossing its orbit.

This orbit has the same period as the Mun, but the slight eccentricity and inclination means that the gateway will appear to orbit in a perpendicular corkscrew around the Mun's own orbital path, so it will always be nearby but never in exactly the same place. The dV required to get in and out, relative to Kerbin and the Mun, approximates the proportions between real-life and the Kerbin system.

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3 hours ago, sevenperforce said:

Of course then you end up with a derelict tug.

A substitute seismic charge.

3 hours ago, sevenperforce said:

so unless you have a "fuel ferry" that carried props from LEO to your cislunar station, then returns, aerobrakes down to LEO, and is refueled...what's the point?

The Russian Ryvok crew ferry has been spotted crawling out of the grave last week. Compounded with Roscosmos’s intent to provide a cislunar cargo vehicle, there might just be a chance.

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For base building, how about a two-stage lander? Reusable crew ascent stage, mated to an oversized landing stage designed to work as a wet lab, using a benign fuel such as LH2 or methane. Leftover landing propellants can be drained and stored for future use, and then the tanks can be outfitted from the cargo pods, or simply open hatches leading to the equipment bays. 

I know, I know, wet labs always sound great in theory, but devil is in the details. 

Edited by StrandedonEarth

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26 minutes ago, StrandedonEarth said:

For base building, how about a two-stage lander? Reusable crew ascent stage, mated to an oversized landing stage designed to work as a wet lab, using a benign fuel such as LH2 or methane. Leftover landing propellants can be drained and stored for future use, and then the tanks can be outfitted from the cargo pods, or simply open hatches leading to the equipment bays. 

I know, I know, wet labs always sound great in theory, but devil is in the details. 

Heyyyyyyyyyyyyyyy............

What about using a descent stage tank as the airlock?!

Base building or no base building, you want an airlock if you're going to be able to spend any extended amount of time on the surface. But airlocks are basically just a big room. So have your reusable crew capsule establish a lower berth connection with a propellant tank. The tank would have a door cut into the side of it. Once on the surface, the tank is purged of its contents by valve and then you can lower a ladder into it. Open the door and walk out, and vice versa. 

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43 minutes ago, sevenperforce said:

Heyyyyyyyyyyyyyyy............

What about using a descent stage tank as the airlock?!

Mocked up quickly in KSP:

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More images below.

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The reusable crew hab, with its tanks, would dock base-first to the Gateway using RCS. For each lunar sortie, a new descent-and-airlock module would be delivered under its own power to the gateway and dock port-to-port. The descent module would deliver the hab to the surface and then vent, and so forth.

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Note that with the dual-engine configuration, the vehicle can also be used as a skycrane to lower cargo, supplies, or even an external hab to the lunar surface. The BE-3 (540 kN) might be overkill but a smaller engine like the Rutherford (26 kN) could be a solution, and an electric turbopump is perfect for cislunar activity.

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Hmm, not a bad plan, use the fuel tank as the airlock and the dregs in the LOX tanks could be used for repressurization. Equipment/cargo pods could also be hung outside. Ideally there would be a way to connect them together

So I see a request for landers, but I ya rant heard anything about base modules. What I think is really needed is a lunar bulldozer so that base modules could be buried for radiation and  MMOD protection. 

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Just now, StrandedonEarth said:

Hmm, not a bad plan, use the fuel tank as the airlock and the dregs in the LOX tanks could be used for repressurization. Equipment/cargo pods could also be hung outside. Ideally there would be a way to connect them together

Yeah, you could have a single central LH2 tank and carry nitrogen bottles for purging outside. Once purged, vent LOX from other tanks into the purged fuel tank to bring it up to breathable levels.

Plenty of space underneath or along one side for a rover, etc. 

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15 hours ago, sevenperforce said:

so unless you have a "fuel ferry

+1
A long-lasting interorbital nuka-ferry, otherwise you'll be mostly fueling the fuel ferry.

Wait... Then why fuel? Just call it "tug" and taxi the capsule along the Earth-Moon-Earth route.

...But they why dock/undock the capsule. Make the capsule a part of the tug and taxi on the ISS-LOPG-ISS route.
So, just let it be an interorbital bus carrying the passengers delivered to ISS by a reusable Dragon/Dreamchaser/whatever.
Let it have it's Orion capsule as an escape pod (but don't land it every time) to abandon the tug if something went wrong.
And let it carry fuel just for a reusable lunar lander. Also the lunar fuel is additional rad protection for the crew, so no need in additional tug.

Imho, until long-lasting nukes, any lunar program will be just a hull test with poor lunar landing abilities. Particularly, LOP-G. 
Imho the only purpose of LOP-G is exactly a hull&equip testing of a future long-term (Martian?) ship, with limited lunar applicability.

Quote

NASA is emphasizing speed in its plans to return to the Moon

Sounds like "They are speaking about the rear-side Chinese rover, let's remind that we are still here, too."

10 hours ago, StrandedonEarth said:

For base building, how about a two-stage lander? Reusable crew ascent stage, mated to an oversized landing stage

Or a fully-reusable lander with replaceable fuel tanks for landing, and inner one for ascending.
They can vent and detach the tanks and use for their lunar needs.

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21 hours ago, sevenperforce said:

Lunar reuse is just messy.

Well, when you want permanent presence near (or on) the Moon then you'll need it. Heck, even CNSA is gaining in that field.

Edited by YNM

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21 minutes ago, YNM said:

Well, when you want permanent presence near (or on) the Moon then you'll need it. Heck, even CNSA is gaining in that field.

I cant imagine NASA working with Romocos and CNSA and God-knows-what to build a Moon base.

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