Astronovice ;- Questions.

[skinbath]

I have some questions and I`m sure I`m not the only Astronovice here.

For those who know:Perhaps you`ll be kind enough and patient enough to answer some of them.(some may seem quite basic).

For others;Perhaps you have some questions too?

Thanks, Yours in wonderment,
Skinbath.


Pierre;

In your assertion that NASA did not go to Mars;Are you also saying that all/some of the pictures from all/some of the other missions/probes are also fakes?

For others;

What would be the purpose of faking a visit to Mars?

Long term periods aboard Mir.;Are there any medical effects upon the body or mind?

How is enough oxygen supplied/carried/generated?

What is worn whilst in space?i.e. some type of second skin body suit? What is it made of?

Are there any photographs/pictures/film available from any Russian missions?

Do the Russians still have a space program?

What is Time Dilation?

[JayUtah]

What would be the purpose of faking a visit to Mars?

I can't really speak authoritatively about others' motives. Hollywood studios fake visits to Mars in order to tell stories that take place on or near Mars. Conspiracists seem to believe that NASA fakes visits to Mars in order to conceal either their inability to make such visits or the true nature of Mars.

It is generally dangerous logic to say, "He had a motive for doing this, therefore he must have done it." That's especially dangerous when the thing proposed is difficult to do. It is better to show objective evidence that the thing was or was not done.

Long term periods aboard Mir.;Are there any medical effects upon the body or mind?

Many. Physiologically you loose muscle mass and strength and your bones decalcify. Your vascular system adapts to the lack of gravity and changes the distribution of blood pressure.

Psychologically the effects of long-term space habitation are fundamentally similar to those of any long-term close confinement. It is theorized that these effects may increase on a trip to Mars where the sky would be essentially devoid of significant features.

How is enough oxygen supplied/carried/generated?

There are many strategies for supplying breathable oxygen in space. For short missions it can simply be carried in compressed or cryogenic form. If your ship designs are non-linear, you can set it up so that oxygen is a by-product of some other reaction. For long-term purposes, and where a reliable source of electrical power is available, you can "crack" exhaled carbon dioxide and recover the oxygen from it.

What is worn whilst in space?i.e. some type of second skin body suit? What is it made of?

Inside the spacecraft it depends on whether the ship has been engineered for a shirtsleeve environment. It is generally more practical to provide that than to require the astronauts to wear environmental clothing inside. For the foreseeable future, spacecraft will be engineered to provide heat, light, and air comparable to Earth's surface.

In space the astronaut requires thermal protection, mechanical protection, a suitable means of retaining internal pressure, and something to breathe. For lengthier suit use, eating and drinking and toiletry have to be considered.

Not all those problems have to be solved simultaneously by one single piece of engineering. Thermal control is achieved typically by completely insulating the astronaut thermally from his environment. This prohibits heat from conducting either direction through the suit. The outer layer of the suit has optical properties that reject incoming thermal energy in the form of light. Then some means must be provided to reject the astronaut's metabolic heat. Our suits currently do this by means of an undergarment that circulates a coolant over the astronaut's body and then passes that heat to space by means of sublimating small amounts of water.

Mechanical protection from debris strikes or puncture is provided by layers of material that provide specific tensile strength and hardness. Kevlar and other materials provide resistance to puncture. Mylar and alternating hard/soft layers provide attenuation from impacts. These also do double duty as the thermal insulation.

Pressure retention is accomplished by a pneumatic envelope that is reasonably gas tight. The pressure garment is composed -- in modern space suits -- of some rigid pieces and some flexible pieces made of Neoprene or silicone rubber containing integrated restraint layers. It is possible, but impractical, to make a suit entirely out of rigid elements.

Breathable air is provided generally to the head and face area only, although it may be circulated through the suit elsewhere in order to achieve comfort. As with all such systems, the suit must supply oxygen at the correct partial pressure and remove the carbon dioxide. Currently CO2 "crackers" are not compact enough to carry on a space suit. Chemical means are used to remove CO2, and the oxygen supply comes from a pressurized tank.

There must obviously be a supply of electrical power to operate the machinery that maintains the thermal and chemical environment.

It is usually not sufficient merely to satisfy the astronaut's biological necessities. He must be useful in space too, and so dexterous gloves must be engineered, and the astronaut must have attach points for tools, some means of communicating with his colleagues, and a source of light.

Are there any photographs/pictures/film available from any Russian missions?

Yes, although less of it is online. The Soviet space program was more secretive than the U.S. program, and only since the 1990s has enough of it been made available to western researchers to allow us to begin building an accurate picture of it.

Do the Russians still have a space program?

Yes, but it is fundamentally different now than it was in the 1960s and 1970s.

What is Time Dilation?

It is an effect of relativity where, at speeds that are a significant fraction of the speed of light, time will appear to pass more slowly for you inside the spaceship than it will for those outside the ship.

[skinbath]

JayUtah;

Many Thanks for taking the trouble to respond,( and in language I can understand too ).I`m sure I won`t be the only one to have been helped by this.

[JayUtah]

You're welcome. I should probably explain a few technical terms. "Linear" design is one in which each component in a system has fundamentally only one job. To approach a problem with linear design means to take, for example, the propulsion aspect and design a fully independent system to solve that aspect. Then you take up, say, electrical supply and design a fully independent system for that aspect. Linear designs tend to be very predictable and safe, but they're also wasteful, inefficient, and often unnecessarily redundant. Apollo, for example, integrated breathing oxygen with the oxygen used to generate electricity into one oxygen system, and then used the heat from the electronics to heat the cabin. Non-linear designs can interact in various undesirable (and often unforeseen) ways. Apollo 13 ran into problems from just the non-linearities described above.

Another good example is the Bear River ride at Disney's California Adventure. Water rides require a large reservoir of water nearby from which to add and subtract water quickly to the water level in the ride. For that reason water rides are normally placed on the edge of the park so that the reservoir can be located outside the wall. Splash Mountain, for example, is put up against the famous Disneyland berm. But they wanted Bear River Mountain to be in the center of California Adventure as a visual icon. The reservoir for the ride is actually the "tidal pool" located next to the Cannery Row area. The designers had envisioned a pool that rose and fell to mimic the tide. And, coincidentally, the nearby ride had need for a large body of water whose level could rise and fall. Non-linearity solves the problem.

[skinbath]

Jay,can you take the time to elaborate here?

Linear designs tend to be very predictable and safe, but they're also wasteful, inefficient, and often unnecessarily redundant.
Apollo 13 ran into problems from just the non-linearities described above

Do you mean for example that :-

a)wasteful because they take up a certain amount of space that could be put to better use by another essential function?

b)inefficient in that they are used for just one particular function/service? And are a drain on resourses?

c)redundant (as above) and because once the function/purpose for their inclusion is over (perhaps,say,the function takes place very early in a mission) they are "dead weight" so to speak?

Can you describe some of the problems regards the above that affected Apollo 13?And what lessons were learned and applied to the later missions?

Are there any "back ups" or are most support systems "stand alone"?(I`m only just getting my head around some of the terminology so please bear with me )

Thanks,

[skinbath]

Jay wrote:-

There are many strategies for supplying breathable oxygen in space. For short missions it can simply be carried in compressed or cryogenic form. If your ship designs are non-linear, you can set it up so that oxygen is a by-product of some other reaction. For long-term purposes, and where a reliable source of electrical power is available, you can "crack" exhaled carbon dioxide and recover the oxygen from it.


Am I right in thinking that this is a dwindling resource and therefore can only be used on missions with a limited/specific timeframe?

If so would this apply to the space station or is the oxygen resupplied or a combination of cracking and resupply?

[PhantomWolf]

skinbath said:

Jay,can you take the time to elaborate here?

Linear designs tend to be very predictable and safe, but they're also wasteful, inefficient, and often unnecessarily redundant.
Apollo 13 ran into problems from just the non-linearities described above

Do you mean for example that :-

a)wasteful because they take up a certain amount of space that could be put to better use by another essential function?

Yes. If you have three systems that work independantly rathger then two that can do the job togther s side effects of each other, you are wasting space, as well as resources such as power.

b)inefficient in that they are used for just one particular function/service? And are a drain on resourses?

Yes.

c)redundant (as above) and because once the function/purpose for their inclusion is over (perhaps,say,the function takes place very early in a mission) they are "dead weight" so to speak?

They can cause redundancy because other systems may provide the same function as a side effect. Consider Apollo where they used the heat from the electronics to heat the capsule. A seperate heating system would have been redundant. It would have wasted room and resources and it would have be an inefficent way of using the resource availible.

[skinbath]

Thanks Phantomwolf,

I`m beginning to make sense of a number of issues,albeit slowly, .

I now understand (in a laymans way) the reasoning and sense (and more importantly,the distinction between linear and non linear) here.

What then are the guidelines here?,i.e.if a function can be either linear or non linear,but linear is more reliable how would a choice be made?,(I know this may sound silly as obviously whichever comes closest to 100% reliability) any compromises made?A sobering thought!

[Data Cable]

Put it this way. When you have completely compartmentalized systems which do not interact with each other, it's much easier to predict what sort of problems might arise within those systems. When systems start interacting with one another, the complexity increases, as does the number of things which can go wrong, and it becomes more difficult to predict potential failures, and/or the effects thereof for the overall system.

[PeterB]

Skinbath

One of the linearity problems on Apollo 13 was to do with heating the spacecraft. As PhantomWolf said, the Command Module was warmed by the excess heat from the spacecraft's electronics. But because they had to switch off the CM's electrical systems until they were about to re-enter the Earth's atmosphere, the CM quickly cooled down. Likewise, because they were trying to stretch the electrical life of the LM, they operated only a small number of electrical systems, thus generating little heat.

The original accident in the Service Module was an oxygen tank explosion. The oxygen was used by the crew for breathing, but it was also used to power the CM's fuel cells. So with no oxygen, the fuel cells had to be shut down, removing the main source of electricity for the CM. But the by-product of the fuel cell was water for drinking and for cooling the electronics. Therefore, the crew had to ration their drinking water.

In other words, the loss of oxygen meant the crew were short of drinking water and were cold.

[skinbath]

Thanks for your replies guys, .

[JayUtah]

What then are the guidelines here?

When I figure that one out, I'll get a Nobel Prize in physics, or whatever category engineering falls under. Deciding upon an appropriate degree of linearity in a design is where the engineer's individual skill lies. There is no deterministic method.

Engineering, at its most abstract, is problem-solving within constraints. There are constraints that arise from the requirements of the problem. There are constraints that arise from the natural world. There are constraints that arise as side-effects of proposed solutions. And then there are constraints that arise from the practicality of arriving at and implementing the solution -- these are generally schedules and budgets.

If I asked you to build a car, I might specify that the car have a cruising speed of 30 miles per hour and a range of 100 miles. Those are constraints that arise out of requirements.

Constraints that arise out of the natural world are those that have to do with thermodynamics, mechanics, and other "laws of nature" that I have to obey. Internal combustion engines, for example, work according to certain properties of materials for strength and heat transfer. I may investigate a wide range of materials, but I cannot simply make the rules themselves go away.

Side-effect constraints might be the vibration, heat, and exhaust products from an internal combustion engine. If vibration caused me problems elsewhere in the design, I might consider a different kind of motor in order to provide an overall better solution.

The practical constraints would be the development budget and schedule. If you gave me $100,000 to develop it and another engineer of equal skill $1,000, there will be a difference in the quality of engineering. If you gave me six months to do it and you gave another engineer 3 days to do it, you will also see a difference in the solution.

Reliability is a constraint. Specifically, it is a "quantity" in the design that may vary and may be subject to negotiation based on the importance of other competing constraints. Regardless of management assurances, you never get an a priori set of fully-balanced constraints. And you never have a harmonious set -- these constraints by their very nature oppose each other.

The word generally thrown around in this context is "satisficing", which is a weaker form of optimization. One does not look for the best solution necessarily, but one that is good enough.

If a customer requires high reliability, then I would be tempted not to introduce nonlinearities into the design. However, that would come at a price of efficiency, mass, cost of operation, and higher unit cost. The resulting system would be larger and heavier, use more energy than is strictly required (and thus cost more to operate), and cost more to build.

If the customer also requires high efficiency, low mass, or cheap unit cost, then a suitable design may require considerable research and development into materials and processes that may not be common. That incurs a longer schedule and a higher development budget.

If the customer is unwilling to budge on any of his constraints, then he is often shown the door. This is the business side of engineering. Engineers roped into solving completely preconstrained problems rarely find success.

100% reliability is just not attainable. And so the question is how much unreliability you are willing to tolerate. This means, unfortunately, putting callous valuations on all kinds of things, including human life. But luckily not all engineering must practically deal with safeguarding human life; and where it is dealt with it usually commands high priority.

Reliability is often simply the failure rate of a mechanism, regardless of what is at stake. Since reliability has an ever-escalating cost, high unit reliability is not always the way to go. If a light bulb has a service life, on average, of 500 hours and costs $1.00, you might prefer that type of light bulb over one that costs $10.00 and has a service life of 4,000 hours. You get more service hours for your buck with the cheaper bulb -- you just buy lots of them. But if the light fixture is at the top of a pole and entails considerable risk to change it, then the "cost" of the replacement operation itself has to be factored into the decision. You may decide to go with the more expensive bulb simply to reduce the number of times you have to climb the rickety ladder, even if the trade-off is that you pay more for each hour of illumination from it.

That said, there are methods that come out of statistical probability for analyzing a design, given individual component reliability and the conceptual topology of the (known) interactions. But that just gives you an objective set of metrics upon which you still have to reason and negotiate. And they are particular to each specific design.

[skinbath]

When I figure that one out, I'll get a Nobel Prize in physics, or whatever category engineering falls under.

You`ve already achieved pretty high status as your membership category reminds us ; may I go as far as saying that if not yet in sight then maybe just over the next hill,or the one just beyond;Further is our destination !

Thanks for your reply Jay and thanks for using easy to understand analogies.Part of the problem for me is that I lack even a basic understanding of terminology,but,I`m working it.

[golfhobo]

Skinbath: I'm certainly no 'astroexpert' but let me point one thing out. One 'term' that bears further consideration is: REDUNDANT

At first it might appear that one would not want to waste space or energy on redundancy, yet in the space program, where life must be sustained in a hostile environment and separated from the local stockroom, redundancy is often the goal and is crucial.

The most common use of the word redundancy in space flight is for a back-up system in case the main system fails. In the case of the integrated systems mentioned above that provide oxygen, heat and fuel; if the system fails ALL related functions fail. This could be catastrophic. Often it is desired to have a linear system to back-up each function of a nonlinear system, and at times another linear or non-linear system to back up THAT one. True it wastes space, but it may preserve life.

The most critical issues are of course, preserving life and getting back home. To go into space without redundant systems for both would be like shooting craps. Although the goal and purpose of the engineer is to reduce waste and inefficiency, it cannot always be achieved at the expense of redundancy.

So, although unecessary redundancy is inefficient and wasteful, redundancy itself is critical. In understanding space flight or any other discipline, especially science based, it is important to NOT assume the common definition of words.