New Mars Forums

I think this is the second time in recent months that the idea of using a kind of centrifuge on the surface of Mars has come up. I had never considered this concept before somebody else mentioned it, thinking that you could only really use rotation for artificial gravity in the (effectively) zero-g environment of space.
   Not so, of course! I'd forgotten about inclined floors and simple vectors to attain the gravity you need.
   In your scenario, Bill, as calculated by CC, the floor of the 'train' or centrifuge would incline at about 61.5 degrees to the horizontal. Surprisingly, though, the 0.7g of horizontal centripetal acceleration in conjunction with the 0.38g downwards acceleration, will give the occupants only about 0.8g, standing on the inclined floor. Maybe that's all you were looking for anyway, I don't know.
   Surprisingly, to get the full 1g effect for the occupants, the centrifuge would have to develop 0.94g horizontally (! ) and the floor would need to incline at 68 degrees to the horizontal. The 'carriages' would be hurtling around the circle at 138 kms/hr, covering the full circumference every 26 seconds!
   The buried loop with gimballed carriages sounds ideal, because you could adjust the gravity from 0.38g up to whatever level you want, simply by altering the speed. The gimbals would automatically adjust the inclination of the floor.
   CC's inclined rail system is probably easier to build, but the inclination of the rails would have to be set for one speed and one gravity only. And, as CC mentioned, if people are going to spend appreciable amounts of time in such a device, radiation shielding becomes a problem for the exposed version.
   I really like your plan, Bill! Getting people to spend their evenings and sleep periods in artificial Earth gravity, right there at the settlement, would ensure they remained in good physical condition. But would you have trouble persuading them, after a strenuous day out on the surface, to subject themselves to what would feel like 2.6 times their 'normal' weight?! Some of them might say: "I'm here for good. I'm a Martian now. I might as well just accept the conditions of my adopted world. Sure that blasted train is OK for people planning on going home to Earth, or the body-builders who enjoy feeling like superman when they step out into Martian gravity each morning! But me? ... I'm not interested!"
   And with CC's plan for expectant mothers, how much of their 9 month pregnancy do you think they'll need to spend in this high speed contraption?
   And what about people getting on and off all the time? Would that make you dizzy, even if you have adjusted to the Coriolis effect?
   I suppose it could be done. But would it ever be a practical proposition?
                                           :0

HEAVY STUFF, man!!
   That's not naturally grown material you're smoking, Scott! That's some kind of hydroponic sh*t!
   For God's sake, lighten up before they close down this website and take us all away for questioning.
                                   

Hi Mark S and Nirgal !!

   Mark, I'm not familiar with the "cropped out" image you mention, but even the better known images released by NASA seem to have been deliberately degraded or distorted.
   When the first so-called high resolution MGS images came out, at least one I remember was upside down, elongated (stretched), and washed out, as though seen through gauze or something. As NASA said at the release, it looked like a shapeless mesa. ... But then, so would a photograph of your mother, if displayed the same way!!
   They later released what they described as 'confirmation' of the shapelessness of the Face, in the form of a MOLA image. Now anybody with some slight knowledge of the MOLA instrument will understand that its vertical resolution is very good (that's its job! ), but laterally, its resolution is poor. The image they showed, therefore, made the Face look like a bowl of oatmeal! But the press and the hapless (and generally clueless) man-in-the-street, were fooled into accepting this 'blob' as some kind of superior quality image which finally laid to rest any notions of artificiality. In fact, its resolution was orders of magnitude worse than the visible light images it was supposed to debunk!
   Now, I don't classify myself as a wide-eyed, drooling sucker who falls for every flying saucer story he hears. In fact, I like to think I'm as hard-headed and practical as the next person. But surely you have to admit that NASA's treatment of this whole Cydonia thing has been less than open and unbiased? It honestly doesn't look like even-handed and transparent behaviour to me, at any rate.
   And yes, Nirgal, I've found the same problem with images being impossibly slow to download from the Enterprise Mission site. I assumed this was because of huge demand from thousands of interested individuals all hitting the site at the same time(? ). Would that explain it?
   Anyway, from what I did see, there are apparently buried  artificial structures all over the Cydonia region. I can't see how these geometric and detailed shapes could be artifacts of the imaging process, either. Unlike some of the earlier way-over-the-top, magnified-to-blazes Enterprise images where the pixels themselves were being identified as buildings(! ), these images are going to be hard to dismiss as anything other than artificial (I think). Although Josh may have something to say about all this!!
   So, a summary of my position on this is that I'm now leaning quite markedly towards the artificiality hypothesis, but I'm waiting to hear a plausible alternative explanation from the imaging gurus.
   Where are ya, Josh?! Save me from the lunatic fringe!!
                                       

Hi Pat!
   I am aware of light's zero rest-mass, a concept I thought of as theoretical only, until recent laboratory success in slowing light to a virtual standstill.
   But the pressure of light on a solar sail obviously indicates photons have momentum. As far as I can tell, you can't have momentum without mass, right?
   I've never seen a layman's guide to how the mass of photons varies with speed and have always blithely accepted that somewhere between 0 kps and 300,000 kps, light just acquires the mass necessary to exert pressure!
   Perhaps you can give me (and maybe others amongst us? )
an "idiot's guide to mass variability in photons" ?!!
                                       

P.S. Thanks for confirming for us that the mass of our
       astronauts aboard their starship doesn't actually increase
       ... at least in their frame of reference. We can all now
       sign up for that first mission to Alpha Centauri without
       worrying!

P.S.
   I just remembered another thing about travelling at 0.9999c.
An outside observer would perceive the physical dimension of the craft, in the direction of travel, to be getting smaller.
   As the craft approaches closer and closer to light speed, its forward/backward dimension would appear to approach zero! ... But only in the frame of reference of the outside observer.
   Again, the crew on board our craft would be blissfully unaware of any reduction in the volume of their living quarters. In their frame of reference, their tape measures would reveal not a jot of difference in the length of their ship.
   I feel this constitutes more evidence to bolster my case that no increase in mass would be noticed either.
   [Still waiting for a withering attack, though!!]     

I think it must be the axe.

Hi Gibbon!
              Even if you could beam energy to your spacecraft so that no fuel, as such, is required, you will still need some material to use as reaction mass. i.e. You still need something with mass that can be thrown backwards in order for the spacecraft to go forwards.
              In a way, this places almost as much of a constraint on the craft as does the requirement for fuel. This is because you can run out of reaction mass in much the same way as you can run out of fuel itself!
              You're either going to need a gas station or a mass station!!
                                         

P.S. Hence the current search for a propellantless propulsion
      system.
      Which reminds me ... has anyone heard anything about
      NASA's test program with the Podkletnov gravity device?

Turbo, I think it's fantastic that you've built such a device!
  I did some mathematics on the figures (simple mathematics ... I'm no rocket scientist, I hasten to add! ) and found that achieving 6kms per second over a distance of 18 feet, takes an acceleration of approximately 334,000g !!
   Is there any problem with the projectile deforming under such acceleration? Or does the field act on every part of the projectile simultaneously, thus causing no internal stress at all?
   Do you get your professor to catch the projectile for you?!
                                       

Thanks, Adrian!
   Your response is just the sort of information I enjoy getting. As one would expect from a biologist, you have put forward a well-reasoned argument which I find persuasive.
   I can accept that even if contamination has occurred, it may well be that it has been naturally 'contained' by the very nature of the environment. Or, at least, slowed to a crawl in its propagation.
   This is food for thought which I will chew over and keep 'on file' as I gather more information in my web-browsing and other reading. You've stopped me in my tracks and I will reconsider the space-probe contamination issue in the light of what you've written.
   I don't think, however, that it changes my views on impact transfer of life between Earth and Mars over the ages. I still think a thriving biota will be found on Mars, though I will give more thought to my position on the effect of more recent, human-mediated biological additions to the mix!
   And yes, Josh, I see your point about those areas of Mars where the solar wind is effectively deflected by the remnant crustal magnetic field. If there is a sub-surface biota, perhaps microbes will be found closer to the surface in these areas because of the lesser radiation. Incidentally, is a water-rich regolith more impervious to radiation than a dry regolith, i.e. is water (or ice) a significant radiation shield?

Trust a Frenchman to cut through all the bulls***t and get to the nitty-gritty ... such a practical people, the French!
   CC, I've often thought it must be possible to find a few million people willing to reach into their pockets to support a private space initiative. I know I would DEFINITELY do so myself if I thought it was a serious effort.
   Is there any practical way of organising such a project?
                                      :0

Thanks everyone, for responding to my comments.
   I THINK I get your drift, inasmuch as I comprehend that less contamination is better than more.
   What I'm thinking is that bacteria divide every so many minutes (Adrian, as a biologist, will be in a position to provide details on this), which means that during a period of weeks or months they can multiply enormously. This is almost a geometric progression (not quite, because of natural attrition, food supply considerations, etc.) and it means that a few bacteria, or even just one bacterium, has the potential to become untold trillions of trillions in a relatively short period.
   If I can just reiterate the idea that past probes have contaminated Mars. I am referring particularly to Soviet probes. The Mars-2 lander, in 1971, crashed onto the surface, as did Mars-6 in 1974. Mars-3 successfully soft landed on Mars in 1971, but communication was lost after only 90 seconds.
   There was great competition between the USA and the USSR in those days. There were even instances of Soviet craft being rushed to the launch pad to try and overtake an American Mars probe already on its way to Mars! How rigorous were the biological contamination precautions? How much money would you be willing to bet, that not a single Terran organism was present on any of those three Soviet probes I've mentioned? I can tell you honestly, I wouldn't bet a cent!!
   It was established back in the 1960s, using 'Mars jars' in which Martian conditions were duplicated, that many kinds of Earthly bacteria and moulds are perfectly capable of surviving, and even prospering, in the environment of Martian regolith. Carl Sagan pointed out that Earth microbes or their spores, attached to grains of dust, could readily be transported around the Martian globe by the incessant winds. '"In this way", he wrote, "descendants of just one micro-organism could, in theory, give Mars in a few years as many microbes as exist on Earth."
   Some Earth microbes have probably been dividing and spreading on Mars since 1971! That's 31 years!! And we're not counting any bugs which have arrived since then on American probes, however hard they may have tried to sterilise those. There probably isn't anywhere on the planet that doesn't have a healthy colony of something from Earth growing happily in the soil or under the rocks!
   I hate to go on and on like a broken gramophone record, but I think we're locking the gate after the horse has bolted!
                                   ???

I disagree with the notion that we can "avoid contaminating the surface as much as possible". (Please excuse me using your words, Phobos. I certainly don't mean to belittle your valuable contributions in any way, but your words exemplify the concept I think needs examining.)
   First of all (yes, I'm back up on my soap-box again! ), I think Mars has had life at least as long as Earth.
  Secondly, even if I'm wrong, we've sent contaminated probes to Mars in the past anyway. So we've almost certainly broken any quarantine that may have existed.
   Thirdly, and this is my main point, even if everything I've said up to this juncture is nonsense, you simply cannot send humans to Mars and avoid contaminating the place with bacteria and moulds. It can't be done!
   Eliminating ALL bacteria in a given space is impossible without using extraordinary means such as powerful chemicals and/or high levels of lethal radiation. An astronaut has to get into an airlock in the Hab in order to get out onto the Martian surface. His/her suit is covered in microbes of different kinds and so are the walls of the airlock. Then you have to open the outer door and step onto the planetary surface outside. There is no practical way to avoid some of those microbes getting out onto the surface with the astronaut.
   Most will die in the inhospitable conditions they encounter, but some will make it to the surface, perhaps in dormant form, and maybe find their way into the subsurface water-table. And this scenario takes no account of any outgassing (leakage) from the suits used and the Hab itself, and any means devised to dispose of human wastes.
   Some contamination is inevitable. And, given the reproductive powers of bacteria, some contamination might just as well be massive contamination!
   Human missions mean major contamination and we'll just have to get used to the idea. It's time to face reality.