You’re citing the high failure rate of unmanned missions as an argument for sending manned missions instead? … Seriously??
I know, right. Imagine how much testing, R&D, and redundant mass you have to bring along to raise that chance of success from 50% to 95% or whatever would be considered an acceptable risk for live astronauts. That extra testing and those extra dead weight subsystems raise the cost enormously over the per kilogram cost of sending robots.
No, it was signed by the Republic of China (free China, on Formosa), not the People’s Republic of China (Red China, on the mainland).
That is an ideal situation for the People’s Republic of China – they claim to have been the ‘real’ Chinese government since 1949, so they honor that treaty. But if they ever decide it would be to their advantage, they could just say that treaty was signed by a corrupt, deposed former regime.
You misunderstand me. I mean spin the whole damn ship. No reason not to.
Oh, and yes, I meant a lot of water. Like, a layer several feet deep. It might necessitate using the moon as a slingshot, in order to reduce fuel consumption.
One thing that has not been addressed is all the shit in space. There is a fair bit of stuff out there. Automated probes tend not to be bothered as much by it, but a mission requiring structural integrity over a path of around 2 AU in forward distance at about a million miles a day, you need to have a pretty good umbrella ahead of the bow to keep tiny holes from permeating the hull. Not sure how spin would affect the effectiveness of that.
Other than, you know, structural stress. Spaceships are not normally built with enough reinforcement to be spun. The second problem is size. It has to be physically long enough along the spin axis dimensions or the crew will be nauseous all the time.
Anyways, all these problems can be solved. However, the groups who have solved this problems in the past have needed over 100 billion dollars to put a station in very low orbit that does not spin, does not have long duration life support, nuclear power, or radiation shielding. That credible organization - a conglomerate of several national space agencies, though NASA is the main one - will need something like 250 billion to a trillion to do a Mars mission.
Spending 250 billion to a trillion to put 10 or so human beings on a far away rock does not seem like a good use of discretionary funds. You could use the same money to develop and pay for dozens of nuclear reactors, thousands of miles of new highways, hundreds of new pharmaceutical drugs (if the Federal government were paying the bill, they could pay for development of replacement antibiotics since the current crop is becoming ineffective), etc etc etc. A manned Mars mission could have been done in the 1970s/early 1980s. Congress decided against it for similar reasons.
Yes, some day colonizing another planet will be a worthy goal. However, a mere trillion dollar Mars mission is not enough to start a self sustaining colony. Before we can ever build such colonies, we need radically more advanced technology in other areas. If people really wanted such colonies as soon as possible, they’d spend the money where it matters - on developing more compact, self replicating machine tools and factories.
In regards to spinning the ship, that is what I get for using the images of 2001 and 2010 movies where only part of the ship spun.
Point taken on that. I assume that there would be little dizziness from that as there would be no perspective to make someone dizzy.
The water shielding I remember reading about many years ago in an Asimov novel, I believe.
However, when I learned that water is only okay again gamma radiation (It needs dense material for shielding), the amount of water necessary I thought would require too much to be effective on a space ship for Mars
However, I am probably wrong on that as well.
You have to consider the counter-force. On a helicopter, you have the tail rotor to handle that. On a spaceship, you would need a counter-rotating mass to cancel the rotation of the crew chamber (because even bearings would impart rotation to the ship), so you would be sending extra mass, which I suppose could be supplies for Mars, but then you would have to spin the thing down when you got there. Spinning down a ship on arrival would just involve a long burst of hydrazine from a control jet. And constructing it to handle the spin stress would not be a great deal more difficult, I think, than constructing a durable ship in the first place. Most likely, the transport ship would remain in orbit around Mars for a year, the descent ship would be on one of the barges (or the barges themselves).
What was the failure rate of unmanned missions to the Moon (rhetorical question…here is the same list for the Moon)? The failure rate of manned missions was 1. So, yes…seriously. Do you think that the same level of redundancy and care go into an unmanned probe as a manned mission??
[QUOTE=Habeed]
I know, right. Imagine how much testing, R&D, and redundant mass you have to bring along to raise that chance of success from 50% to 95% or whatever would be considered an acceptable risk for live astronauts. That extra testing and those extra dead weight subsystems raise the cost enormously over the per kilogram cost of sending robots.
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We already know that a manned mission would cost more. There would be greater risks (some of which can be mitigated, some which can’t). The question was ‘Is there any reason to send a manned mission to Mars?’ and the answer is yes…manned missions would be able to do more than unmanned missions and in less time. You are just reiterating the ‘but it costs more!’ as if anyone is arguing that point.
At any rate, as I said, this is a debate, not a GQ type question with a GQ type answer.
Getting a little off topic, but I don’t remember ever seeing the Discovery in 2001 spinning but it had to have part of it spinning as the astronauts were working in gravity in parts of the ship.
The Russian ship in 2010 definitely did have a spinning section.
Why would it be necessary to stop the spin when reaching Mars? Could it not just keep it spinning and then leave from the non spinning part of the ship.
Of course, this means that there would have to an access point between the spinning and non spinning sections
Yes, I guess it would be best to have an entire spinning ship to keep things simple
… calling the driverless car contingent over to this thread to comment on why sending people to Mars wont be needed in the future (robotics and technology will be able to do a better job than us, more safely, and cheaper)…
…and all we need to do is send a bunch of mapping robots with humans over there to map out everything in order to make the driver-less cars work properly and have GPS maps available to them on Mars. 
When we see the first large scale deployment of driver-less cars that can basically drive anywhere in the continental US (or Europe, or Asia, etc) then that will prove we can do that anyway. But driver-less car technology isn’t going to solve all or even most of the issues with sending rovers to Mars to do large scale science in an area more than a few 10’s of kilometers per decade.
XT, I guess I am trying to see if there is a cleft in the logic here:
- Driverless cars are going to be safer and more efficient than people drivers = Robotic probes are safer and more efficient than sending astronauts.
Or, is it that while we are reasonably assuming technology will eventually solve earthbound problems like driving, we should not take people out of the equation for space exploration?
I think you are talking around the point.
The fair way to evaluate the alternatives is to look at what can be produced for a given expenditure of money and resources. This approach, many here contend, is what leads to the conclusion that the sensible answer to the question is “No, you’ll get better results by concentrating on robotic missions.”
So, your argument is; NASA could have saved a lot of time and money if they had skipped all those unsuccessful unmanned missions and just started with the successful manned trips.
My thoughts exactly. I think the resistance to completing these R&D efforts close to home instead of including them in the mission plan may be based on a fear that the list of reasons to send a manned mission to Mars will dwindle down to just … It’s a real neat idea.
No, that’s not my argument.
[QUOTE=Xema]
The fair way to evaluate the alternatives is to look at what can be produced for a given expenditure of money and resources. This approach, many here contend, is what leads to the conclusion that the sensible answer to the question is “No, you’ll get better results by concentrating on robotic missions.”
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I disagree, but since it’s a debate and not a GQ answer that’s fine. I think, based on the limited data we have from manned landing on the moon verse what was collected on Mars in several decades that human exploration pretty obviously can and does do more in a concentrated time than the actual, real robotic missions we’ve sent to Mars have done. We traveled further, got more samples and brought more science back…and this was for a few trips with a few 10’s of hours on the surface, not all of which was spent exploring. A Mars mission would have several astronauts on the surface for a year or more with all of the equipment they would need to do a large amount of science both on the planet and brought back when they return. So, no…I don’t think we’ll get a better result concentrating on robotic missions to the exclusion of manned missions. The BEST result is to do both…do robotic missions as we have in the past because that’s what we COULD do, and do a manned mission at some point to really dig into the science and exploration of Mars. YMMV and obviously does, but you and your side hasn’t shown definitively in a GQ way that robotic missions preclude manned missions…just like, obviously, I haven’t convinced anyone in this thread (or any of the myriad threads like this we’ve had in the past) that manned missions are necessary too.
They are solving two very different problems, so I don’t see the correlation. Robotic probes are certainly safer than sending astronauts and they cost less, and if they are the only viable choice you have they would certainly be better than doing nothing. We get quite a lot out of them and they have been great tools for exploration. But actual humans on Mars would be able to do orders of magnitude more in the time they would have on planet.
Like I said, it’s two different problems. If your point is we could or would build better rovers in the future then I agree…we already are doing that. But they won’t be as good as an actual human explorer any time soon (or maybe ever) since humans are more flexible and capable (millions of years of evolution as explorers and such ;)).
The robots have told us that it is a dead, lifeless, cold desert planet. We’ve sampled the soil. We’ve sniffed the atmosphere. We’ve taken hundreds, if not thousands, of pictures.
Honestly, I think we know all we need to know about Mars now. Sending humans would be an enormously dangerous task, and there would be very little payback.
Dizziness has almost nothing to do with your eyes. So the presence or absence of a perspective is irrelevant.
If we made a wheel-shaped ship a few thousand feet across and spun it slowly, folks could walk around on the inner surface of the outer shell and feel something very close to normal earth gravity.
If we made the same ship 40 feet across and spun it quickly, like the squirrel-wheel scene in 2001, folks would go ass over teakettle or barf if they turned their head left or right while walking. Much less did a quick about-face and started walking the other way. Just walking in a straight line along the perimeter with head and eyes caged forwards would be disorienting as hell.
The reason is that while the instantaneous force from head to foot may be a constant value around 1 G, there’s also a continuous rotating acceleration about the spin axis. Which is tolerable to the human balance system as long as you don’t change anything. Walk faster or slower or turn your head or walk crosswise to the rotation and really crazy shit happens instantly.
As well, the G-force depends on the radius. On a thousand-foot radius wheel your head is at 995 feet and your feet are at 1000. That is a small enough difference percentagewise that you’ll probably not notice that “gravity” feels 0.5% less at your head than your feet.
On a 20 foot radius wheel, your head is about 25% of the way to the center and feels about 25% less “gravity” than your feet do. That’d be weird. Make it a 10 foot radius, which is a bigger cross section than any space hunks we’ve orbited yet, and now your head is feeling 50% of the “gravity” your feet feel. Thataway lies perpetual dizziness & nausea.
The most plausible approach to centrifugal ship design is a small can for the people and a separate counterweight connected by a long (multi-hundred or thousand foot) tether. Then spin the whole thing slowly like a set of bolos. The problem is that’s not a dynamically stable configuration and would take constant small thruster nudges to keep from twisting into crazy 3D motions.
All this stuff is hard – crazy hard. Which is why it costs $trillions if it can be done at all. We could certainly invest the money to advance the tech, which will eventually lower the marginal costs. So far we don’t have the economic oomph to pull this off.
I agree. There’s no fossils or anything but rocks of a particular elemental composition appropriate for Mar’s place in the solar system. There are a few mysteries (why does it look like there are canals), but the explanation for those mysteries is more than likely quite boring (flowing CO2 or something)