Difference between revisions of "Show Stoppers"
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Materials designed for the worst Earth industrial environments are becoming available for lunar work. | Materials designed for the worst Earth industrial environments are becoming available for lunar work. | ||
| − | *Besides boots, there are some mitigation ideas for dust discussed in the [[Long Endurance Rovers]] article dust section. Also the [[Robots in Space Suits]] refers to something like boots to cover joints in machinery. It uses the words, "bellows that has flanges pressed to points above and below the joint by a threaded ring" and is | + | *Besides boots, there are some mitigation ideas for dust discussed in the [[Long Endurance Rovers]] article dust section. Also the [[Robots in Space Suits]] refers to something like boots to cover joints in machinery. It uses the words, "bellows that has flanges pressed to points above and below the joint by a threaded ring" and is referring to a gas tight covering for a bearing. This could work for hydraulic pistons too with some limitations on structural shapes and the range of rotation of the bearings at each end of the piston. There would need to be slides on those exposed polished steel cylinders attached to the inside corners of the bellows to hold the bellows in place. It is certainly possible to design such slides so that they will nest together without taking up to much space when the piston is contracted and still not bind when sliding back and forth. The bellows will of course protect against dust as long as it remains gas tight. Replacing the bellows is also discussed in the robots article. |
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Latest revision as of 18:19, 4 June 2013
This article is a topic of debate. |
Show Stoppers
Major problems that can stop our whole effort
Show Stoppers are problems for which we currently have no solutions, yet we cannot accomplish some major part of our mission until these very problems are solved.
Often there will be a long list of pros and cons around a technical idea, yet one small, insignificant problem will block all progress. All the other problems then become nothing but smoke or red herrings. Spotting and solving Show Stoppers is one of the great skills for a technical person that approaches being a Zen master.
The following Show Stoppers are blocking our way to returning the Moon. Can you come up with viable solutions?
Great Problems
The Interest of the American Public is Missing
The American people are not showing any interest in returning to the Moon.
What is at risk:
The entire Return to the Moon program is at risk of being dropped, again. Funding could dry up completely.
Technical Details of the Problem:
The idea of returning to the Moon was put forward by President George W. Bush, but did not catch on. It was subsequently driven from the public stage by the War in Iraq and Global Climate Change. Funding for NASA has been cut.
We will need to keep the return to the Moon idea alive even while moving substantial amounts of our space resources are moved back to Earth science to develop the data needed to understand and address the Global Climate Change problem.
Available Actions:
On Lunarpedia the Purposes List provides a wide selection of ideas on possible action to strengthen the Return to the Moon mission. Some of these articles look at what needs to be done and some look at how to do it.
The most important idea is to assist the American public to build a powerful vision of success around returning to the Moon. Once that vision is in place, actions will follow.
Change in philosophy of US government
Every two years we get a new congress, potentially a new president every 4 years. The president as head of the executive branch may set a new direction for NASA.
What is at risk:
The NASA-sponsored Return to the Moon could be terminated, scaled back, or otherwise changed in a way that would make it simply a colossal waste of money.
Technical Details of the Problem:
The 2007 change in congress and a potential 2009 change in presidential party are expected to bring new philosophies to bear in US governance. Such changes can be detrimental to long-term activities such as large-scale space operations, and in particular the "New Vision" for space. Consider the many design changes the ISS when through in the 1990’s and problems and expense this incurred in this program.
Available Actions:
NASA received a new bi-partisan authorization bill in 2006 that endorsed the "New Vision"; congressional legislation to rescind that seems unlikely. Communication to congressional delegates about the science and economic benefits of the new program should help continue bipartisan support. There is even potential for increased funding to support both science and the lunar mission, given the differing priorities of the parties on budgeting and taxation.
Global Climate Change
The climate of the Earth is changing due to human activity - the science on this issue has been extensively reviewed by the Intergovernmental Panel on Climate Change which recently released their most conclusive assessment that shows warming already happening, and pins the blame on humans.
What is at risk:
The entire Return to the Moon mission could simply be forgotten – again--.
Technical Details of the Problem:
Greenhouse gases building up in the atmosphere from human activity are causing the global average temperature to rise and already producing unprecedented weather patterns. The primary human activity responsible is the burning of fossil fuels for energy; if alternative energy sources are not found, the problem will only accelerate, with serious consequences for many human populations, and many species of plants and animals are threatened.
The challenge represents a problem, but also an opportunity, for those interested in pursuing the development of space. Space satellites provide the ideal platform for studying the Earth; even the Moon has been suggested as a location to monitor Earth's global average temperature through measuring the warmth provided by Earthlight during the lunar night. Space resources may also provide solutions to the problem, whether through proposals such as the solar shield at the Earth-Sun L1 point to block a portion of solar input, or by replacing fossil fuels with Solar Power Satellites, Lunar Solar Power or Lunar Helium3, or through other lunar In Situ Resource Utilization.
But the total amount of money available for space related activities is limited. If space funding is focused on monitoring and measurement systems, funds for developing space and particularly the present NASA plans to Return to the Moon will be jeopardized.
On the other hand, if space resources are recognized as potentially a direct part of the solution to the global warming problem, human activities on the surface of the Moon may even be accelerated, with a focus in that direction.
Available Actions:
We have had at least two practice runs on addressing similar environmental problems: Acid Rain, and the Ozone hole. In both cases the problems were substantially solved through international regulation: a market-based "cap and trade" system for acid rain pollutants, and a ban on production of certain chemicals, made possible thanks to technical innovations that introduced new coolant chemicals, in the ozone case. The Climate Change Problem is in many ways similar, but much bigger.
A large number of technological innovations will be needed and many are under development. Traditional renewable or non-fossil technologies (wind, solar, nuclear, etc.) have received most of the attention, and likely all need government backing to make a dent in the problem. Ideally we can have potential space resources, particularly the potential for using the Moon, included in the funded solution mix.
Robotic science instruments for climate monitoring will clearly be funded if this becomes a priority - there is no shortage of good ideas for science missions in this area.
Massive societal change during this century is certain. Change beyond historic levels is currently being driven by technological innovation, the rising population, and depletion of resources. Big social changes to address the Climate Change Problem will be just part of the mix.
If lunar resources are not considered useful for solving the climate problem and that does become modern society's top priority, the return may have to wait until people at least feel that we are moving to a solution and that technology is leading the way. If we can get the Climate Change Problem to the level of solution we now have for acid rain and the ozone hole, then we should be able to move forward to the Moon.
Technical Problems
Afternoon Temperatures at the Equator
The afternoon surface temperatures at the Lunar Equator are so high that special efforts are needed to maintain human life support and maintain exploratory devices and industrial machinery within operating temperatures.
What is at risk:
No lunar site near the Equator can be visited for more than a few days until this problem is addressed. A permanent settlement in any of these promising locations requires protection from temperature extremes. This problem is in some ways easier to deal with at the poles.
Technical Details of the Problem:
Maintaining living temperatures for the crew is one of the most important parts of a life support system. Also designing equipment, such as your return vehicle, to withstand high temperatures for long periods of time is difficult and expensive. High surface temperatures create a significant risk to both crew and mission.
In space the only way to dump waste heat is to radiate it to deep space. Specialized thermal radiator panels are used and must have a wide view of space. If these panels also see an expanse of hot lunar surface, they will work very poorly.
The temperature of lunar surface in the afternoon at the Equator can be above 100 C for more than 100 hours. Some key temperatures include:
| On the Earth: | Celsius | Kelvin | Fahrenheit |
|---|---|---|---|
| Human Body | 37 C | 310 K | 98.6 F |
| Room Temperature | 22 C | 295 K | 72 F |
| Hot living limit on Earth | 50 C | 322 K | 120 F |
| Boil an egg | 100 C | 373 K | 212 F |
| Afternoon on the Moon at the Equator: | |||
| Mean | 107 C | 380 K | 225 F |
| Maximum | 127 C | 400 K | 260 F |
| Daytime on the Moon at the Poles: | |||
| Mean | 0 C | 272 K | 32 F |
Very little equipment can stand being soaked at these high temperatures for long. Normal space suits would keep you alive only a limited time. Your return spacecraft could become unusable even after it cools after sunset. At present this is seen as a problem that must be dealt with.
Available Actions:
This is the primary reason that sites for NASA's first lunar station are only being considered at the poles.
Life support could be maintained with a complex double cycle refrigeration system. These systems are complex and require significant mass shipped from Earth. The reliability of these systems is under question.
Some form of umbrella or tent is possible for outside equipment, such as your return spacecraft. The protection is adequate with a reasonably designed system. Failure of a sunshade or shade from ambient infrared would be a critical safety issue. An awning in the form of an arch that blocks out a 1.5 degree wide strip of the sky from the point of sunrise to the point of sunset will shade an area from sunlight all day every day of the year on the moon. Walls north and south of the protected area high enough to block infrared radiation from the surroundings would remove problems from the hot neighboring landscape. There is a vacuum on the moon so no temperature will be carried by wind from the surroundings. Anything in shade is automatically cold. Radiators will be needed for both industrial processes and living spaces in a colony. They could be in a cold shaded area. The shade for a colony's radiators would best be removed by a considerable distance from rocket landing sites. We can count on engineers designing the colony to think of that. The problem of high temperatures at the equator is one of the least difficult problems to solve for a colony.
In the medium run a number of actions are possible:
- Sheltered bases could provide a relatively easy to reach safe heavens.
- Living space can be covered with Lunar Regolith as described in Architecture as Mole Hills. This both stabilizes the temperature and provides radiation protection.
- Partially buried hangers for outside equipment and robots are also possible.
In the long run, Lava Tubes and artificial caverns may be used to provide protection from this and other perils.
Temperature extremes on Luna require attention but are not in any a way show stopper.
Lunar Dust
The damage to suits, equipment, and seals done by the dust portion of the lunar Regolith could be so high that long term settlement and commercialization of the Moon will be uneconomical.
What is at risk:
All long-term lunar settlement and industrial operations are at risk.
Technical Details of the Problem:
Maintaining equipment on the Moon is a big problem. Ware from grit is a major source of equipment wearing out and breaking down. Failure of seals from grit abrasion is a major risk for spacesuits and habitat entrances.
The spacesuits used on the Apollo missions were worn out in only three days. Problems included both the retention of dust by the outer Bata cloth layer and damage to seals, particularly at the wrists.
Another example of a piece of standard industrial equipment that is causing concern is the hydraulic piston. These are used extensively on Earth for construction and industrial activity as they can provide great force through a linear distance. It is quite common to see their exposed polished steel cylinders in construction site equipment. These pistons must be sealed against high pressure hydraulic fluid to work.
The seals for these cylinders have several stages. The outer most stage wipes off dust and dirt, while the inter stages apply a film of oil to keep the cylinder rust free.
The lunar environment is radically different from the one the pistons see on Earth. The oil film is broken down by ultraviolet light from the Sun to make a sticky brown film. The omnipresent grit coats everything and can even move around on its own by electrostatic forces. Currently we are denied one of the real work-horse devices of industry.
Available Actions:
A great deal of work is being done on seals, particularly for the new spacesuits. All the surfaces of these suits are also being designed to be smooth and shed dust.
We need more work on hydraulic oil and lubricants for space use. Currently very high priced space versions of these materials (for example $700.00 a pound for grease) are available.
We need more work on elastic boots to cover moving parts on the Moon. One Earth example many people are familiar with is the neoprene boots on the CVC joints in the front end of a car. If boots fail, then CVC joint soon follows. A lunar rated flexible boot would be a real step forward.
Materials designed for the worst Earth industrial environments are becoming available for lunar work.
- Besides boots, there are some mitigation ideas for dust discussed in the Long Endurance Rovers article dust section. Also the Robots in Space Suits refers to something like boots to cover joints in machinery. It uses the words, "bellows that has flanges pressed to points above and below the joint by a threaded ring" and is referring to a gas tight covering for a bearing. This could work for hydraulic pistons too with some limitations on structural shapes and the range of rotation of the bearings at each end of the piston. There would need to be slides on those exposed polished steel cylinders attached to the inside corners of the bellows to hold the bellows in place. It is certainly possible to design such slides so that they will nest together without taking up to much space when the piston is contracted and still not bind when sliding back and forth. The bellows will of course protect against dust as long as it remains gas tight. Replacing the bellows is also discussed in the robots article.
Cosmic Rays and Solar Flares
What is at risk:
Tissue damage, cancer, and a serious reduction in life expectancy. Self-sustaining populations will not be a possibility if this is not addressed.
Technical Details of the Problem:
For technical details see Radiation Problem and Architecture as Mole Hills.
Available Actions:
The most reliable solution for daytime heating is perhaps the only solution for this problem: Go underground.
- Bury your surface habitation modules under plenty of regolith and import heavy mining equipment.
- Find a sufficiently stable lava tube and excavate an entrance to set up there.
- Dig tunnels to move into
- Use a nearby partially collapsed lava tube for shelter. These have the benefit of being presently identifiable.
