New Mars Forums

Sorry for the double post, forgot about Commodore here.

Hmm... I guess I have to read the article, because what you are saying doesn't make sense to me.  Does the cycler stop somehow at L1?  Does the shuttle meet it stoped at L1 or does it rendevous with it out in space?  I guess most importantly, how and where does the shuttle match orbit with the cycler?

I agree with what you are saying though.  The current CEV won't cut it.

If you are spending this much refurbishing/refuling the shuttle.  Why not just spend that money on refurbishing/refuling a traditional interplantary transfer vehicle (ITV) instead?  The engines an ITV would require aren't that diffrent (a little bigger) than those the shuttle would need, and it's Hab is only say, 4 times as big?  LSS system requirments fairly similar and what not.

Sure, but my point is if something goes wrong with docking (a broken hatch on the CEV for example, that would be tricky) your dead.  Missing your orbit would be another no-solution docking killer.

Resupply doesn't worry me that much.  A solar sail or ion tug could eventualy catch up with the cycler and resupply it.  This does add additional costs to the system though.

Even those millions of pounds of high explosives have an abort option (minus the shuttle), the cycler does not.

Of course I'm sure you could find some people quite willing to be shot out of a cannon onto an airplane if you made them the right offer.  (Like being on Fear Factor).

You hit my point exactly.  The cycler is fine (if a bit expensive) it's the shuttle that makes the thing difficult.  It has to be cheap, very powerful, and light.  But of course as the adage goes you can only have two of those.  It has an exceedingly difficult job, it has to be able to match speed with the fast moving cycler very quickly (before it's limited life support runs out), so it must be very powerful.  The redevou demands some sort of high thrust engine, either chemical or as you say some nuclear thermal option.  Unfortuantly chemical's low thrust means it can't be light (though it might be cheapish) and nuclear option means it probably can't be cheap (though it might be lighter).

But after further consideration, I don't think a powered abort is realy possible either way.  To do a powered abort it has to carry a signifigant fraction of the TEI/TMI delta-V with it.  Even with a NTR this is still going to be A LOT of propelent, and it increases the mass which increases the amount of propelent necessary to catch the cycler in the first place.  Without some sort of VERY high ISP high thrust engine such as GCNR/NSWR/Orion I just don't think it is going to be possible.  However, none of these engines are going to be cheap either.  Without some other magical way to stop in space (and I am open to suggestions) the crew is going to be in it for the long hall.  And if you have to provide for that, you might as well go on and forget the cycler and send them in the shuttle in the first place.

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As for the difficulty of rendevou I don't think it's impossible to pull of, but it will be considerably more difficult than any we have done before.  The craft are going to be docking at a MUCH higher delta-v than we have ever done before.  While their relative delta-V's may no be that diffrent (on the other hand to save some propelent they might well be) the high delta-V makes errors in positioning much more critical.  An error is twice as big when you go twice as fast.

More critical however is the short and critical time frame to pull it off.  Unlike previous docking missions both craft are on a hyberbolic (or nearly hyberbolic) orbits, possibly diffrent ones which only intersect for a limited period of time.  Unlike the most previous rendevous missions there isn't an (realitivly) unlimited number of tries you can take before you do it.  There is a time window that must be delt with, either you meet it, or you fly into empty space, no fun.

But like you said rendevous is not the only reason you need some sort of abort option.  Any malfunction that prevents the docking will cause disaster.

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To me they cyler approach seems most like shooting someone out of a cannon to catch a ride on an airplane.  Not a very smart thing to do.

We've talked about cyclers quite a few times, and my feelings about them haven't changed much.  In the short term at least I don't see them as worth the expense.

You see when a cycler approaches Mars or Earth it is still moving at essentialy the necessary velocity to fly back to Mars or Earth.  It can't stop, it going to fast, and breaking it into orbit would defeat the point of a cycler.  So you have to catch it.  To do this you have to rendevou at essentialy the same speed the cycler is going, which means you have to spend nearly as much energy as if you were going to send your payload to Mars/Earth anyways.

This creates to problems.  First  such a high speed rendevous is very difficult to plan and carry out, your time frame is relativily short and you only have one chance at it.  Secoundly, if you miss the rendevous you have essentialy no abort option.  Your rendevou craft is traveling fast enough to send it away from your planet for a very long time.

So the advanatage of a cycler is very limited.  Essentialy you get two things.  The ability to operate a larger craft with a higher Life Support efficancy, saving on your consumables for the voyage, and some small propulsive savings and the ability to use a small cheap redevous craft to meet the cycler instead of the large vessle that you would need to make the voyage on your own.

However currently the savings you would get in life support effeciancy and delta-V are very small for near term missions.  The diffrence in 90% vrs 99% closed life support for 6 people or so is not that great.  And if you want an abort option for the redevous craft it either has carry enough propelent to slow down to a reasonable return time, or enough life support to support the crew untill the come back around naturaly, it might need some way to re-enter/aerobrake as well.  This eliminates any advantage the redevou craft might have in the first place.

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To me the solution to reducing the cost of the voyage to Mars in back is to improve the engines and to develop reusable transfer vehicles.  Cyclers just don't make any sense to me.  Especialy not currently, maybe someday if/when we are sending 100s of people an opposition to Mars they might be logical, but even then I have my doubts.  The more people you send the more important an abort option becomes and that just destroys your advantage.

I'm not at all convinced that these advantages of He 3 are going to give it enough of an edge to displace conventional fusion fuels.  D-T and even better yet D-D fusion fuel is effectivly free while He3 is going to cost millions to billions a gram.

And relisticly the the advantages He3 has are not that great.  It's advantage in power per unit fuel mass is worthless on the earth, where its mass is so low (in comparion to coal or even nuclear) to be meaningless.  It has lower neutron emission but is still not totaly aneutronic, due to the side reactions D-D and D-T, producing about a tenth as much neutron radiation as D-T fusion.  This is still alot of radiation.  It's higher plasma density might let your reactor be smaller, but necessarily that much smaller.  It still has to be able to withstand high energy neutron radiation.  He3 reactors are also often assumed to be smaller because they use higher field densities then D-T reactors, but this is an unfair assumtion since a He3 reactor requires such a field for it's operation and a D-T reactor would similary benifit.

So in the end you get potential better and easier energy conversion by converting the energized protons to electricity, a longer period of time bettwen having to overhall the reactor due to neutron radiation, and you don't have to breed tritium.  You still have to worry about disposal of radioactive parts (a minor concurn) and the D-D side reactions actualy produce tritium so you still have to worry about that as well (another minor concurn).  I doubt anyone who couldn't already produce all the tritium they wanted to would be getting their hands on He3, but you could probably use it in a thermonuclear bomb as well.  In the end these advantages are not enough to outweigh the massive costs of importing the stuff.  Heck, it probably would be less expensive to just collect the He3 from Tritium decay in the end anyways.  Also, if He3 fusion proves to be possible, I see no reason that D-D fusion coudn't also be done, which has many of He3's advantages and fewer of D-T's drawbacks.

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As for fighting on the moon, I doubt it will ever come to blows.  Any fight in space would quickly spill over here on the earth.  The US can currently "win" a nuclear engagment with China pretty easily, but I doubt it would ever happen.  As they used to say about the Russians, probably also applies to the Chinese.  "They love their children just as much as we do."  Meaning neither of us wants to see a nuclear war.

Is there realy anything to fight over?  A fair question.  The moon is plenty big, but BWhite might be right that the resources might be concentrated in a few strategic locations.  But then again it might not.  Even if water only exists in economicly recoverable quantities on the poles, there are lots of craters up there and each could give alot of water.  Platnium is likely to be scattered about as well.  Because the moon doesn't have an atmosphere to sheild it from some strikes or tetonic action, or weather to move the stuff around after it hit, there are probably plenty of platnium rich strikes to be mined.

I agree with the points about how territory will be "claimed."

With helium-3 in the parts-per-BILLION range, we won't be extracting that much just from baking rocks to get oxygen.  Large scale water extration is closer to what we need, but even then we still won't be extracting in nearly the quantities.  If we could find water concentrations of ~1% in shaded regions, the 1,000 tons or so we would need to process to get 100 tons of water would only give us like 10 grams of helium-3.  So to extract it in economic quantities we are going to have to mine/process some very large streches of the lunar surface.

Your comments about effeciancy may have some merit when dealing with space reactors, but little when dealing with terrestrial reactors.  Conventional fusion fuel is dirt cheap in comparision to the amount of energy it can produce.  If fusion power becomes practical and Deutrium extraction and Tritum production go large scale this will be even more true.  Helium-3 being able to produce marginaly more energy per unit is not going to able to offset this tremendous advantage.  Since concentional reactors are still strugling to reach breakeven it still to soon just how much of an advantage He-3 is going to give you, but it certianly isn't going to realise the multiple order of magnitude increase you would need to be economicly competitive.

The key benifit of both nuclear and fusion power is that the fuel costs are insignifigant.  Enriched uranium consists of about 16% of fission costs, compared to 38% for coal and even higher amounts for oil and natural gas.  Fusion fuel in comparison is expected to make up less than 1% of the cost.

This argument has some merit, but not for the reasons you state.  Without fast neutron radiation there is less worry about the degredation of the containment ring.  This is likely to be very important as examining the machinery for degredation and then fixing and/or replacing it is likely to be one of the major costs associated with fusion power.  However, I still don't think this is enough to offset He-3 very high costs.  Especialy since side reactions that take place during He3-D fusion still produce some neutron radiation.

Changing the body's orientation doesn't solve the problem, just changes when and where it occurs.  A person lying prone might not have as much trouble during turns, but would have more sever problems during dives and climbs.

As for other mechanical means of assistance, there is some potential here, but not alot.  An artifical heart for example, is not only complicated and extreamly dangerous (what if it were damaged/punctured, you could bleed out in secounds!) but also causes it's own complications.  Increasing the blood pressure to the levels necessary to pump the blood to the brain also increase the risk of a fatal stroke.  Mechanical systems can suffer from the same problem, and there is a limit to how much pressure can safely be applied to the lower extremities.  Also an issue is how fast your system can react.  Fighters can go into multi-g turns very rapidly, and your mechanical system may not be able to react fast enough.

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When I was talking about UAV, I was thinking primarily about autonomous robots.  However the USAF style of air-combat is well suited to the introduction of either kind.  Stealthy UAV will procced to the target directed/controled by the airborn radars on AWACS and other airborn control vessles.  If the AWACS determine that it is a valid target, the UAV well be set loose to attack the target on their own.  Since most modern air-combat is beyond visual range anyways, dogfighting skills wont even have to come into play.  They will just launch their missles and burn off.  Similar mission profiles can be used for boming/ground attack runs as well.

As I said previously, I am in favor of some dramatic cut backs in the US military, but the F-22 is the wrong program to cut.  I mean, we have already spent the billions to develop it, it would be foolish to back out of the deal now after spending all that money.  As discussed previously the proliforation of good 3rd and 4th generation Russian fighters along with deadly beyond visual range missles put our opponents on a more even footing than ever before.  This threat is combined with the fact the increased avalability of some truly deadly russian SAM, such as the SA-10/SA-20 which can even intercept balistic missles, demand a new 5th generation of fighters.  The US is not alone in this line of thinking, the EU has also put down some serious cash developing the Eurofighter, their 5th generation fighter design.

Our stealth weapons like the B-2 and the F-117 are still very good, but they are both bombers, and as such can not deliver air-superority.  A B-2 cannot stop a fighter from delivering a bomb or anti-ship missle.  It cannot defeate a fighter in the air, that task must be performed by a fighter, which are going to be increasingly vunerable.  Also, the F-117 (and probably the B-2 as well) are not invicible due to their stealth.  An F-117 was shot down over Yugoslavia by a Russian SA-3.  Which makes me worried because the much more advanced SA-20 series is being put on the export market.  We only have 55 of the F-117 and 21 of the B-2's anyway.

As for SEAL's jumping out of C-5's at 35,000 feet as an anti-missle battery measure, you must be out of your mind.  I don't know if HALO jumps are actualy possible at that altitude, but it is certianly WAY above the normal alttitude for jumps.  Jumping at this alttitude is very risky by itself, but its small in comparison to what those poor guys will face on the ground.  Despite what your video games may have taught you, even a high trained group of men like the SEALs, Green Berets, or Rangers will be hard pressed to deal with the defences at a minor SAM site.  It's just common sense, a dozen or so guys (at best) are no match for the platoon or so that would be guarding and operating the SAM site.  Besides many modern SAM weapons are mobile, so the SEALS would have to go traipsing about behind enemy lines for an extend period trying to track it down.  Making their already difficult to impossible job even harder.  Even if the site was stationary, it could be tough for them carry enough ordince to get the job done anyhow.

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I disagree on the DDX/CGX/LCS though.  Not that their necessarily a bad ideas, but just that it would take to long and cost to much to replace the US destroyer/cruiser fleet.  And it doesn't eliminate (or realy even greatly reduce) our vunerability to anti-ship missles.  A destroyer or worse yet a cruise or a carrier is a big, slow moving radar blip, no matter how you dress it up.  If you can get a fighter close enough and/or determine the position of a carrier group well enough to launch an anti-ship missle at it, the missle isn't going to have any trouble finding it's target, stealth features or not.

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Like I said before, the EU is currently working on developing a new carrier program.  In fact both the French and British are currently working on new carrier designs.  We should just sell them a couple of our older Nimitz class vessles instead.  Throw in a couple older Ticonderoga class cruisers and destroyers to sweeten the deal and we could kill two birds with one stone.  Freeing up US money and generating enough revenue from the sale to fund our mission to Mars to boot!

I tend to agree.  Here is how I would cut back the US Armed Forces.

USN

Currently fields 12 Carriers, I would cut this back to 6.  The following carriers would be decomissioned and/or sold off to other friendly countries, like Europe, Australia, and maybe India.  While the Nimitz class is very good, it is no longer so cutting edge that we should fear selling one of them to one of our close allies.  But even the oil fired Kitty Hawk and JFK are vastly superior to any other carrier out there, including that French POS.

USS Kitty Hawk (CV-63)
USS Enterprise (CVN-65)
USS John F. Kennedy (CV-67)
USS Nimitz (CVN-68)
USS Dwight D. Eisenhower (CVN-69)
USS Carl Vinson (CVN-70)

The remaining 6 more modern Nimitz class (or Theodore Roosevelt subclass) carriers would be retained.  Although further production would be halted after the George W Bush enters service.  Instead the one of these (or one of the retired ones) will be refited when modernizing is necessary.  This will allow the US to deploy 2-3 carriers at any one time easily, and up 5 in an emergency.

I'm not as up to date on the numbers and deployment of the rest of the USN but I figure most of the rest of our forces could be cut in half as well, with the the potential to sell at least some of our ships to our close Allies.

As for the Airforce, as GCNR says, there is room to be cut in our strategic bomber fleet.  The US currently deploys 85 B-52s, 67 B-1s, and 21 B-2s.  I still think all of these bombers have a roll to play in our armed forces.  The B-52 as a cheap bomb/cruise missle truck.  The B-1 as a low-altitude penetrating bomber/bomb truck.  The B-2 as a long-range penetration bomber and strategic deterent.  The introduction of JDAM and other cheap precision GPS guided bombs have made these bombers even more leathal than before, and the remain one of the cheapest ways to put bombs on a target.  However, again we are overbuilt for our current situation.  I would reduce the number of B-52s and B-1s to about 24, with another 24 left in active reserve.  I would keep the number of B-2's the same since we spent so much to by the darn things we might as well use them.  I would keep our current inventories of fighter air-craft as is.

The Marines and Army I would leave alone as they are pretty much fully deployed currently.  I would halt development of the new ambipous APC for the marines, although it may be to late as it is close to deployment I think.

I haven't looked to far into the process, but it may be quite difficult to liberate the oxygen from the Moon's minerals through simple heating alone.  Obviously if you apply enough energy it will eventualy decompose, but we could be talking about ALOT of energy here.  The lattice energy of FeO is nearly ~4MJ/mol.  Applying so much energy directly may not be practicle, so reducing the oxides with hydrogen makes sense.  The operation is perhapce more complicated, and you do have to import the hydrogen, but it can be recycled.  I'm not sure which option is actualy perferable, but more research has been put into reducing the soild with hydrogen than simple decomposition.

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I guess you could electrolise the molten rocks as well, but this would take not only alot of heat energy, but also a considerabl amount of electrical energy.  But on the plus side you would get pure iron in addition to then oxygen.

Perhapce some pathogen's will contaminate any non-sterile vessle, but the amount will be so vanishingly low that it can probably be ignored.  Bacteria and viruses are primarily trasmitted via some sort of infectious material (mucus and what not) or something that was contanimated by the material and not properly cleaned.  This should not be an issue on a clean spaceship.  And without contact with new inficted people there is little chance of any new pathogen's being introduced into the enviroment.  Infectious diseases don't just spring out of nothing or rain down from the sky, they are transmited from person to person (or animal to person).  People generaly just don't get sick spontaniously, they catch the infection from someone else.

The effects of antibiotics are wholy independant of the immune system.  Antibiotics generaly destroy cell walls of bacteria causing them to disolve and be devowered and filtered by the body.  Certianly the body's immune system benifits from the weakening of the infection, but the two operate independantly of eachother.  Perhapce you are confusing them with antibodies, a critical componet of the immune system?

I seriously doubt that food poisning is going to be an issue, all the food brought on board must be preserved in some way (freezdrying primarily) that prevents the transmition of infectious material.  And while accidental contamination is a risk, it's a minor one.  Very few people catch colds from infected doornobs, it's just not a good disease tranfser mechanisim.  Simple cleanlyness, like washing hands before and after meals, restroom, and proper clean-up of food and what not also drasticly lowers this risk.  So while a risk of infection may exists, it's extreamly low.

Cancer doesn't just develop overnight.  Rember that the ride out and back aren't very long from that point of view.  Also, the concurns with the immune system seem to be confined to T-cells and their roll in fighting infectious disease, not the body's ability to recognize and eliminate cancerous cells, which is seperate.  Cancer is not a primary worry of AIDS paitents who suffer similar (although probably more sevear) T-cell deficencies.

And while no one has long term exposure to cosmic radiation, it's not like it is any diffrent than any other sort of radiation of similar magnitude.  And the data we have on that shows that the increased risk of cancer is mild (<10%) and the chances of developing it spontaniously during the mission slim to none.

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Key points. 
#1.  A spacecraft should be a very clean enviroment, there is little infectious material to come in contact with and this material (and the kinds of infectiouns) will not change over the duration of the mission.
#2. The concurns are primarily with T-Cells which fight infectious diseases, not cancer.  Cancer developes over a longer period of time anyways.
#3. The body has several layers of immune defense not reliant upon T-Cells which will still be effective.  Our primary (and most effective) line of defenese, out skin and mucus membranes are not effected at all.
#4. Many people on Earth live active lives despite similar T-Cell deperesion due to AIDS or other immune disorders, some self inflicted (for transplants).
#5. Antibiotics, which can cure practicaly all bacterial infections, and antivirals can also help to support/suplant the human immune system if necessary.

I don't know how well they would be able to hide it.  US (and probably Russian) spy satilities/radar stations can and will detect any major launches, track them, figure out the kind of rocket, and what happens to it.  This is one of the byproducts of the cold war.  It's impossible for the Chinese to launch any orbital craft without alerting us.  Which they would probably do anyways so as to avoid any misunderstandings.

Now they could lie about who or what was on the craft, but covering up their fate isn't going to happen.

Sure you could make some money by selling rights to Television companies and what not.  If the landing on Mars was successfull you might even be able to turn it into a media super event, like the Superbowl.  However even if all this was wildly successful you would probably be talking about hundreds of millions of dollars, not the billions and tens of billions you would need.  It could surely help the funding of the effort, but it's not going to cover it itself.