I’ve been playing around with the NASA Break the Ice Challenge for a bit. In my two previous posts Help Wanted and Want to Play I pretty much just threw them open. For today I’d like to present a general scenario as a point to work around. But chime in on anything.
To start off the NASA area of operations is actually one of the sites under consideration for the Artemis landing. As such I’m going to expand NASA’s direct challenge parameters and attempt to fit this scenario into the broader and longer term mission. That mission is the Lunar Base. As I cannot imagine NASA actually proceeding with a human landing without at least one test of the landing system on the moon. I’m going to slot this mission after Viper but just before Orion/Artemis 3. As a bonus as i think the National Team’s design is BS, I’ll center around the Dynetics lander, with the full understanding that SpaceX would do even better.
We are going to the South Pole of the Moon for more then just that it somewhere we haven’t been before, it is the expected access to volatiles that can be used to support further missions. Water is of course one of the keys. Just getting rocket fuel out of a 1/6 gee gravity field drives the price per mission down tremendously. Even with the re-usability of the Dynetics lander it will take two additional earth based launches to refuel. The need for in-situ resource utilization (ISRN) is one of the major thrusts of NASA research right now. The Moon is attractive as a starting point for many reasons. Even having a bit of gravity can help.
Because I’m thinking longer term in the context of this challenge, I started out with the broader concept of bootstrapping. Just looking at a crater immediately brings to mind an open pit mine. From there the thought of how would I work it alone with limited resources at the start. Just one step past that when looking at the actual ore, it is clear that it resembles more of a sand and gravel pit. Those are things you see all over and more than one farm is using a tractor to work them as needed. That is the basis of this scenario: Tractors, farm road, and gravel pits.
Looking at the operational area you can see that the eventual base site is towards 5 o'clock from the delivery site or (tank farm, landing area). An actual road from landing to base is almost straight forward. Dropping 80 meters over 2 kilometers gives a very acceptable grade even in 1/6th gee. The challenge for any road building is the 450 meter drop in only 3 kilometers to the excavation site. Getting down is a whole lot easier then getting back up with meaningful cargo. This is actually a traction concern, going down empty, coming up full. Even with a good plotted path, long term some better transport route will be needed. With other objectives like landing site improvement or base construction, I’m going to focus on road building as that activity can be translated into those other tasks.
Looking at the NASA provided assets and the excavation site map, it is pretty clear that they would prefer we use their water extraction plant. A quick glance at the map and where they want us to place the plant indicates this will become a more general processing area. More realistically that extraction plant is probably a more generalized for volatile extraction. LCROSS found a lot of interesting volatiles including methane that would be valuable. So as I intend to use the extraction plant at the site designated, getting its 700 kg there will be the first task. Its mass will also be used for a limiting factor. I said earlier that it would be easier going down the crater than it would be coming back up. I mentioned that it was a traction consideration. That is because weight and mass are actually different. That fact is something I’m going to incorporate.
Scenario Intro
To start I’m going to talk about Rovers. Six rovers will make up the cohort. These rovers will mainly be just generic mobility platforms. Much like tractors they will just add attachments as the job requires. I’ll use the Moon Buggy specs from Apollo of about 200 kg of mass with about 500 kg of payload mass (a bit lighter and stronger then actual but close). NASA is planning to have its initial set of rovers human controlled, either earth based or on site. The communications loop is short enough for that to be possible. One other thing in regards to Rovers and other equipment, we are not solely dependent on batteries. NASA is providing 10 kW electrical power at 120 VDC, that means we can plug in for high power operations. Many of those attachments will be designed to operate off the rovers. Cranes and winches in particular should be designed with static applications in mind. As such the will need independent thermal, power, dust mitigation, and stability.
Task 1 Equipment to Processing Site.
Task 1: Intro
This part is really all about dust control. The Apollo Moon Buggies were able to cover a lot of ground during each EVA. It is certainly possible to devise a route to the processing site that requires no improvement. Perhaps with some uphill and downhill support. But it will be really dusty at points and so will the return trips. Lunar dust is nasty. It is abrasive and sticks to everything gumming every moving part up. It is a basic design consideration for lunar exploration. Just clearing and gears or other bearing surfaces will need to be considered even here. Anything we can do to limit this across the entire mission is important.
Any excavation in this task is more of a training tool for the actual mining operations. This is important as we will be moving a lot of dirt. 300,000 Kilograms at a minimum.
By the time any mission lands we will have much better mapping data to plot the best path. Moon Trek or QuickMap shows you what we have right now. (The elevation profile is from Moon Trek). It drops 400 meters over 3.5 kilometers. That seems overall a workable grade. I’m willing to spend a significant part of the mission time doing this first task. Building even a lunar dirt road starting at the top of the hill is easier then starting at the bottom. Pushing rocks and dirt downhill allows gravitational acceleration on the pushed mass. As we move to the extraction site, we are selecting the actual path and improving it as we go. Not really building a finished roadway. Just something to get the job done. Later we may improve it, but for now we are just doing enough to make the job easier.
Once we get to mining we will be moving a lot of dirt anyway, so that equipment is available. I plan on quite a few winches and cables for mining operations so they are available here. Looking at the profile of first 300 meters, you can see the challenges and opportunities. We start out knocking down the up slope at the start and moving the overburden down slope as fill.
We will target 100 meters a day for progress. That is pretty aggressive, but not unreasonable. Prior to the mission as the area will be surveyed closer and in more detail, we should be able to select a very efficient path. Or more likely a range of possible paths.
Task 1 Days 1-4
As soon as the dust settles after landing the first two rovers are deployed. These rovers have been pre-launch configured as surveyors with extra batteries. As a pair they will be sent out to processing site along the primary path. While where we landed is fixed, the eventual processing site is much less so. Getting rovers to the selected processing site as early as possible to pin it down (or select an alternative) is important. We are sending them out as a pair so they can both cover a slightly larger area and if required assist one another (Astronauts has to lift their rover to get it deployed and rovers can get stuck). The first couple of hours for the surveyor configured rovers will be a close in mapping of the landing site out 100 meters in the general direction of travel. That will allow for better mission planing for the immediate future and give controllers some real lunar experience. They should begin the processing site survey no later then the end of day one. Up to the three days would then be spent exploring and mapping the return paths more extensively and completely.
The other four rovers would be tasked with path preparation for the first targeted pathway one or two days construction. Since it appears that we will be starting out on an up slope it will allow us to test the harder aspects. Soon in the process we should test using a pair of rovers to lift as massive a rock as the design specs envision and move it to the down slope. We will want to see how much we can utilize rocks as part of the low spot fill or what size we need to avoid. Minimizing dust will be a major concern all along moving slow at the start is important as we work out operational strategies.
To begin the slope preparation we will start just on the down slope side of the high point. Where exactly we start will be determined when we get there, but the general principal will be to use gravity to assist. We are just filling low spots for now. We will probably start near the top and use barrel drum diggers. We are just knocking the peak top down so we want to use the slope and gravity to minimize dust at the landing so this a slowly advancing undercut. As the barrel fills we back up a bit and spin it in reverse to unload allowing gravity to do its work. The only real difference here then the designs you may see, is that I propose a pair of rovers with the drums mounted between them on the side to minimize their dust contact. NASA has done a lot of work on drum excavation, they even had a design challenge that ended just last April.
My primary dust mitigation strategy is based on a paper by Lawrence A Taylor and Thomas T Meek in Journal of Aerospace Engineering. Microwave Sintering of Lunar Soil: Properties, Theory, and Practice discussed in general microwaves and regolith interactions. Taylor was one of the few who actually got his hands on an Apollo returned sample and did work on it. Almost all of the other work done relies on simulants. This paper gelled with some of my own work with sintering in regards to powder metal. Without getting too technical right now, both the composition and the shape of the lunar regolith particles should lead to very good processing. The important part here is the Taylor found that the half power penetration depth was 62cm (two feet) and as temperature rose that decreased. This means that we can get at least densification at depth with increasing levels of sintering as we more of the energy is used closer and closer to the surface. My own work indicates that Time at Temperature is the biggest factor in sintering.
So this needs to be tested soon in the process. We are not looking to get a glassy paved road. More like a cinder paved surface. We want the surface sintered enough so that the dust is controlled. How fast we can accomplish that goal will determine the speed of the path improvement. Several different tests will be run. First of course is different speeds of the rover. My target is 5 meters a hour, that allows for a hundred meters a day with slack. I also intend to run these tests with a thermally reflective blanket in front of and trailing the emitters.
Task 1 Days 5,6
These two days will be a mostly in the nature of a technical and dress rehearsal. The initial plan is to improve the path for five hours or 25 meters. Move the processing unit and all other spare parts and other equipment 25 meters along the road for a hour. Then repeat.
Since we have spent much of the first four days doing preparation by testing we will start out with 50 meters of just microwave dust control sintering and then start the cycle. While that is going on the remaining rovers will finish unloading the lander. I envision two rovers to lift the processing unit from the front and back. Going uphill two rovers in advance and two at the side to assist if needed up the slope. The reverse going down.
In normal operations I see five rovers dedicated to path preparation. One doing the sintering and the other four doing the rest. The sixth rover will be tasked with dust mitigation and load shifting along the road behind. Periodically each of the advance rovers will return and get looked at and cleaned. It will be the sixth rover tasked with that.
Task 1 Day 7
Will be a full up evaluation and planning review. The Artemis III mission is scheduled for 6.5 days on the surface it seems right for a review at this point.
Task 1 Days 8-arrival
Based on the review we will transfer to normal operations. At this point we can include some other things. First we really haven’t spoken about what NASA may require. NASA is giving us a power source and a distribution network, but haven’t told us much more about them. For planning I’m just using the processing unit as the power distribution node and essentially just dragging a long extension cord behind it. This is why I move it along as we go. However I expect to see transmission lines along the route just like every rural highway. So we should identify 30 or 40 way points along the path for that future development.
Part 1 Conclusion
This is just a partial narrative to promote discussion. I’m focusing on just one aspect as a point to depart from. Please chime in on any aspect of the total challenge.
Part of a NASA challenge is to break out of group think. They are just now starting to think in industrial terms. While this is just a demonstration project at the conceptual level. Just a bit more effort and cost would be required to not only get 10,000 kg of water, but 290,000 kg of bricks for the ore processed. I’ll get more into that in one of the next parts. But jump ahead if you want.
I started doing this as a diversion and possibly getting others here to join in enough to think about and actual submission. Thoughts about that are welcome also.
