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Thank you everyone for entering this challenge. Below you will see the current Finalists that the judges have picked for this challenge. As the Judges are deliberating please keep the comment section free from hateful misconduct. Any form will result in a ban from GrabCAD and the removal of your entry if you are apart of this challenge.
This applicant did an amazing job of understanding the technical details and implications of the challenge and went to great lengths to design a viable solution. The solution is absolutely implementable and appears to be one of the most viable and defensible concepts presented.
This is a well-developed heavy lift for unprepared lunar terrain; the hand-off design is clever and would allow for a large working area with just 2 cranes. It also seems a promising concept for offloading cargo & modules from landers (since the crane can be moved over to the landing site and set up) and would be good to lower the common hab into place. Idealized operation may lead to adding a hoist to the crane.
This applicant designed a system for crane-to-crane transfer, which not only is needed for the surface transportation, but is also needed to receive the Common Habitat from the Starship's offloader. The outrigger legs and swing arms maintain stability regardless of terrain slope, but the outrigger legs may require modification for stable ground interface on rocky terrain.
The connecting arm concept is interesting and proposed to reduce the number of cycles from 455 down to 205. But this is not always viable. It requires the two crane bases to be in line with each other with no obstructions between them. This is not always possible, so the transit time is somewhere between that and 455 cycles.
Ultimately, this is a promising concept despite the emotional discomfort in the "bucket brigade" concept of handing the common hab back and forth 250 times over a 2- week period to get it to the site. (The crane itself looks very good but using it to traverse terrain “feels” like there will be a failure at some point.) There is also some concern that the system may be labor intensive to maintain.
This concept has everything needed to transport the Common Habitat from landing zone to habitation zone. It is directly linked to existing technologies and remaining work is engineering optimization. With some refinement, this is also a very good crane concept for offloading the Common Habitat from Starship or doing other heavy lift operations at multiple sites. The documentation of this design was one of the most appealing aspects of this submit. The Level of detail affords us the opportunity to see areas of improvement more easily and possibly lead to viable use.
This is a very interesting approach to the use of inflatables and is worth having in the trade space for this reason. It is not clear whether the technology development associated with (1) inflatables or (2) use of hydrogen or helium as an inflation gas justifies the use of inflatables as an alternative to more traditional methods. However, it is hoped to keep this in the trade space as an alternative in the event that a fatal flaw is found with the use of more traditional systems in the harsh extremes of the Moon and Mars.
This solution is an integrated moveable gantry crane solution, though it may require close control between driving and articulation of legs. The advantage of this solution is being able to carry any module around, and even potentially offloading moving other stuff around at the base camp site. Note that the sizing of batteries as if the entire traverse is up a 20-degree slope was a good move. This was not specified (and is not known), but it is possible that the landing zone could be downhill from the habitation zone.
The use of Hydrogen as the inflatable gas gives us pause, as it is difficult to store, and any hydrogen will be at a premium for water and rocket fuel uses. The author described using hydrogen as an inflation gas in the paper, but the MEL indicates that helium is the inflation gas. It is not clear which one was intended, but both do have unresolved problems with gas leakage. The noted concern about other gases becoming liquid in super-cold lunar environments is an important note that could impact traverses if other gases were used.
The nature of this system is such that it can maintain a near-level orientation itself and use hoists to compensate for any disturbances, keeping the Common Habitat level at all times. This surface transporter will move smoothly over level terrain, but the rover-leg interface was not well-developed in this proposal. While individual leg lengths can be shortened through the internal inflation chambers to keep the entire system level over uneven terrain, it is not clear that the legs have an "ankle" that can keep the system vertical when the individual rovers are forced into pitch or roll angles due to terrain. The rover-leg interface concern is exacerbated on rocky terrain, because an individual rock or boulder may cause an individual rover to reach an angle well in excess of 20 degrees. A significant redesign in leg inflation chambers may be needed to improve articulation over terrain.
A key area of concern is that when receiving the Common Habitat from its delivery lander, this configuration cannot negotiate the lift cables from the Cargo Starship that will be suspending the Common Habitat. However, at the other end of the transit, when it is ready to unload the habitat in the Habitation Zone, this concept can easily position itself such that the Common Habitat is directly over the trench and lower it into place.
This concept gave close attention to impacts of Mars gravity and lunar temperatures on material selection. They do not seem to have adequately considered hydrogen leakage, however.
In general, this proposal's highest value is it is eye catching. Inflatable crane system concepts are relatively rare. It does appear to have all the performance needed to complete the intended mission, except it is a problem that its current configuration cannot perform the handover to accept the Common Habitat from a cargo Starship.
That being said, an inflatable crane system may offer tremendous value to the Common Habitat Architecture for a different application - the deployment system that unloads the Common Habitat from its lander. For the Starship cargo lander that delivers the Common Habitat, its internal cargo volume is extremely limited, and it may well be that an inflatable crane system such as this might be the best option for packaging within the limited shroud volume remaining after accounting for the Common Habitat's volume. IF this concept works it a good idea, and several of the judges would be more convinced after seeing a prototype articulating inflatable structure as a proof of concept.
The gantry approach is a very good approach, and this concept should work. On first inspection, this appeared to be an extremely strong candidate, and it does have very high potential, but as details were examined it became apparent that multiple changes would be required to utilize this concept. It clearly looks feasible with some modifications.
Structural sizing of the gantry structure was not performed and that is a significant miss. It clearly should be lightweight as compared with other concepts, but the proposal would have been stronger had structural analysis been performed and a reliable mass been provided. The entire feasibility rests with the gantry being a sufficiently low mass. The cradle will need to be redesigned – it currently blocks hatches and science airlocks on the Common Habitat.
The concept seems intuitively simple but is also very close to a perpetual motion machine and some complex machinations are required to address this in the form of the turntable and the base adjustment of the telescopic gantry. At the current level of detail these are magic devices. They can be made to work, but they are significantly undeveloped.
It is not clear how the turntable rotates the Common Habitat, which is critical to the system being able to change direction. It is further unclear how turntable stabilizes itself on a slope or how it rests on rocky terrain, or if it can elevate the Common Habitat above rocks that might block a successful rotation, or even prevent it from being offloaded from the gantry. There would likely need to be restraints strong enough to protect the Common Habitat from falling out of its cradle.
Initial deployment was not discussed, and it looks like it might have to be assembled by the ATHLETE robots. This may have to occur at the time of the Common Habitat offloading because the gantry structure looks like it would interfere with the lift cables from the Common Habitat’s lander’s offloading system. The ATHLETES might need to assemble the gantry around those lift cables, which is possible, but is a very complex operation.
Given funding, this concept could be prototyped on Earth relatively easily, and the gantry crane is a very common terrestrial option for moving a large item.
The SHLT is based on commercial/industrial equipment with modifications, which should significantly lower the design lead time. This concept has each mobility bogey with a wide stance that ought to keep it stable. However, it has been shown that tracked mobility may have additional problems that need solving. Overall, this concept is a good combination of gantry type (even though it is not really a gantry) and mobility platform -- good concept and very workable. That being said, the SHLT is better suited to traverses on level surfaces than the unknown, off-road terrain the Common Habitat must be prepared to traverse between landing site and habitation zone.
The SHLT can readily traverse smooth, level terrain, and the mobility chassis can traverse rocky terrain, but unfortunately it cannot handle a sharp convex transition without the habitat contacting the ground. The system needs to provide greater clearance. SHLT also does not maintain a horizontal, level orientation for the Common Habitat.
The paper mentioned consideration of environmental extremes but did not provide details. This and other unknowns in the concept as presented carry mass growth impacts and the SHLT is already at the maximum limits of its mass allocation.
This is a very cool-looking concept. However, while the Spider rover offers visual appeal, it is possible that the Spider rover might not be needed at all (and there are some severe technical concerns concerning Spider). If the Starship can rotate the Common Habitat to horizontal during the offload, it can set the habitat down on the Bison. However, the problem remains of releasing the Common Habitat at the Habitation Zone. Solving this problem might require Bison to be able to split in two halves, and gently lower the Common Habitat between the two halves as they separate from each other. (Spider, as presented, would not have been able to perform the transfer of the Common Habitat to/from the Bison. Its arm placed the Common Habitat in an unsupportable position and the system would have fallen over. This will be immediately evident in any c.g. analysis.)
Bison would be able to traverse fine regolith on level terrain if the wheels were sufficiently sized. Wheel width dimensions were not given and using two different wheel sizes complicates the analysis, but it does appear that the 28" wheels in the model are too small. At a 28-inch diameter, these wheels might need to be as wide as their diameter, or possibly wider.
The images in the presentation do suggest that the Bison cannot maintain a horizontal, level orientation for the Common Habitat. Some degree of leveling is possible, but it would have problems with leveling on rocky slopes.
Bison’s delivery lander can offload it with a crane, and once on the surface it can self-deploy into an operating condition and drive away. The Bison crawler does not have the vertical clearance to lift itself or the Common Habitat 5 meters above the surface. Consequently, Bison may have some challenges with high centering, but in general Bison can traverse well with or without a payload.
The author has attempted to consider the environment with mixed success. Presumably, the purpose of the weather antenna is to detect dust storms on Mars. The sonar sensors mentioned in the paper were probably intended to be sodar antennas. This will offer potential value on Mars, but of course it will do nothing on the Moon. It is not clear whether the author has made any attempt to address hydrogen leakage due to ambient temperatures. And there is a glaring lack of thermal control other than an air-cooling fan in the engine that will not offer any benefit on the Moon or Mars.
Despite these limitations, the concept offers promise as a surface crawler transporter and has the potential to be modified into a system that can carry the Common Habitat and other large cargo on the surfaces of the Moon and Mars.
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