In: Physics
In physics, environment phenomenology is how a particular environment arises. For example, if you were to design an underwater base, you might consider the pressure on the system and how that environment arises, which is through the weight of the column of water above the base. Give a brief explanation of an environment phenomenology for each system below:
1. Reactor used to extract oxygen from the lunar soil
2. Thermal mining on the moon to obtain water
3. Home base habitat on the moon
1. Environment phenomenology for the reactor used to extract oxygen from the lunar soil
* The lunar environment presents several unique challenges to the system design. At the lunar poles, where ice may exist in the soil, the ambient temperature can be -230ºC. The lunar ambient pressure is ~1x10-8 Pa, and the gravity level is 1/6th of normal earth gravity.
* These environmental factors may heavily influence both instrument behavior and design. The system must also cope with the abrasiveness of the lunar soil which affects hardware durability as well as ability to seal. The approach is to deal with these challenges in a stepwise fashion.
2. Environment phenomenology for the thermal mining on the moon to obtain water
* The water on the moon would need to be mined, then refined.
* The process of extracting the water is similar to cooking it out of the soil. Scientists have been able to extract two grams of water in the form of ice per minute using a one-kilowatt microwave.
* At that rate, astronauts would be able to extract about a ton of water per year [source: NASA].
* It would take an estimated one ton of lunar dirt to extract one quart or liter of water. While that would make water a scarce commodity,
* In 2009, NASA crashed a rocket into a large crater near the South Pole and directly detected the presence of water ice. Data from this mission and other orbiters have confirmed that the Moon has reservoirs of water ice, potentially amounting to millions of tons. ( Volatiles Investigating Polar Exploration Rover, or VIPER, )
* we need to understand the location and nature of the water and other potentially accessible resources to aid in planning how to extract and collect it.
3. Environment phenomenology for the home base habitat on the moon
The diurnal cycle on the Moon is 29.53 Earth days, almost evenly split between daylight and nighttime. The lack of atmosphere has many implications for potential lunar dwellers, such as a lack of shielding against radiation and micrometeoroids, but also that daylight is in extreme contrast, which has implications for outposts at the poles.
* The temperature transition from daylight to nighttime is rapid (about 5 °C/ h). At the Apollo landing sites, the temperature ranged from 111 °C to −171 °C, resulting in major thermal expansion/contraction and thermal cycling challenges to surface structures.
* . If a structure is to be directly exposed to these extreme temperatures it must be made of highly elastic materials, and materials with different coefficients of thermal expansion must be used carefully.
* Material fatigue due to thermal cycling is generally a problem that needs to be ameliorated.
* Even those structures that are shielded are susceptible to material fatigue and brittle fracture and since everything will be exposed during construction (because the shielding is not yet in place), designs must be careful of this phase.
* Partial gravity
At the lunar surface, gravitational acceleration is about 1/6 g, where g = 9.8 m/s2 on Earth. This means that the same structure will have six times the weight-bearing capacity on the Moon as it would on the Earth.
Conversely, to support a certain loading condition, one-sixth the load bearing strength is required on the Moon as on the Earth. Therefore, the concepts of dead loads and live loads within the lunar gravitational environment have to be reconsidered. Mass-based rather than weightbased criteria will need to be developed for lunar structural design codes, because mass is invariant whereas weight depends on the gravitational acceleration.
* Radiation
The lack of atmosphere and negligible magnetic field of the Moon raises challenges for the design of structures with shielding against various forms of radiation from the Sun and deep space.
There are highenergy galactic cosmic rays (GCR) composed of heavy nuclei, protons and alpha particles, and there are the products of solar flares, or solar particle events (SPE), which are a flow of high-energy protons that result from solar eruptions. Such radiation has serious implications for human and plant survivability, as well as possible effects on materials and electronics . Various categories of Various categories of radiation require shielding. Solar particle events originate in the Sun and are correlated to solar activity.
These pose few hazards except during solar storms, at which time living beings on the Moon would require extra protection. Galactic cosmic radiation originates from the stars and the short-term effects are not hazardous, but long-term exposure can increase the risks of cancer.
A third type of radiation are the X-rays that result from high-energy electron collisions with metal conductors or passive radiation shields. In this case, the shielding can cause more biological damage than the original particles being shielded. Galactic cosmic radiation is very difficult to shield against.
A 1 GeV proton has a range of about 2 m in regolith, with secondary particles – released due to the primary particle collisions – penetrating deeper. The high-energy particles, from these collisions within spacecraft materials and lunar regolith, produce secondary radiation that is more dangerous than the primary radiation.