Long duration Human space missions - Can we survive them?

GCNRevenger · 2005-03-30 14:42:51

Yeah, and the unfilterd UV light from the sun would make them crunchy and brittle.

dicktice · 2005-03-30 16:55:51

Damn it GCNR ... and just as I was picturing Grypd's space laundry as having a little airlock, shaped like a washing machine loading door, too!

Grypd · 2005-03-30 16:59:51

Then we put out clothes which are resistant to Uv and those should be relatively easy to make and the UV would help with killing the germs

SpaceNut · 2005-05-12 08:00:00

Well back to topic:
NASA turns to local doctor for astronauts' muscle strength
Well it is assumed that some gravity is better than no gravity but inaddition to the duration its the amount of time to recover that is a question. Can we shorten that recovery time by the short term use of artificial gravity by rotation or is extreme exercise enough?

dicktice · 2005-05-12 09:29:14

Well, whatever this new NASA study comes up with, exercise will be an essential part of the solution. So, the Skylab circumferential running track capability should be a part of any future microgravity habitat pressure hull configurations--with as large as possible inside diameter health section, including a rotatable "funhouse" end wall for ongoing centrifuge experiments.

RobS · 2005-05-18 12:50:30

Here's another article about artificial gravity:

http://www.space.com/businesstechnology … Artificial Gravity: NASA Spins Up New Study

Notable quotation: "Young has long been a research advocate for artificial gravity. He notes that a short radius centrifuge spinning at high rates -- upwards of 180 degrees per second – while practical, has its challenges too.

"At MIT, under National Space Biomedical Research Institute sponsorship, Young and his research colleagues have shown that astronaut surrogates can adapt to the initially sickening Coriolis effects of head turns during centrifugation, even at high speeds."

They're talking about 30 revolutions per minute, too! I wouldn't want to do that, but it sounds like 4 or even 6 rpm is practical.

-- RobS

Chazbro38 · 2005-05-21 13:52:42

There is of course one simple solution to all of these issues. I call it the management of manned deep space flight hygiene. Minimize exposure time to cosmic rays, zero-g effects and isolation thorough the use of powerful propulsion systems that get you to Mars in the shortest amount of time possible. It removes the need for extensive radiation shielding and or complex rotating structures.

I think you'll find that for the short term this is the only realistic way to go.

Charlie

Mad Grad Student · 2005-05-21 15:26:19

The problem with using a "powerful propulsion system" (I assume you mean something like high-thrust ion engines or VASIMR plasma propulsion) is that there aren't any off-the-shelf mature was to do it for a Mars mission. If you want to keep the development time for such a mission under ten years, which will likely be the maximum politically acceptable time, the only currently viable options are chemical and perhaps nuclear rockets. With either option the trip time will be about six months at minimum both ways, but nuclear thermal rockets will allow more payload capacity.

This should be perfectly acceptable even if no simulated gravity system is used. We know that if they keep up a rigorous daily exercise regimen astro/cosmonauts can be reasonably fine after returning from stints on Mir longer than a year. Adjusting to one third Earth gravity after half this time in zero-g should be no problem at all, the only potential problem here is what kind of condition the crew would be when they return to Earth. Simulated gravity shouldn't be too difficult of a design problem in any case. By slinging a tether between the hab and a spent kick stage you can create huge spin arms that allow Martian gravity to be created by spinning at a more reasonable rate of 3-4 rpm. Tethers can break of course, but even if such an event occured it would not be as though something mission-critical were compromised.

Radiation is not as great a problem as some scientists studying it would like it to be. IIRC, Mars Odyssey recorded the radiation environment in Mars orbit to be just about twice as heavy as that of the ISS. While that won't win any safest workplace awards, it also should not compromise a 2-3 year long mission. On the surface, where a conjunction-class mission would be spending more than half its time, the radiation would be far less considering the atmosphere to block half of all radiation from the universe and all of Mars to block the other half. I would love to learn more about radiation and we do need to be careful ensuring that the crew is not put into a dangerously active environment, but these are not mission-killing difficulties. Chemical rockets are just fine for going to Mars.

RobS · 2005-05-22 15:27:58

We don't need fast propulsion to get to Mars. I agree it would be nice to have, but I suspect it will cost tens of billions of dollars to develop.

I suspect artificial gee isn't THAT hard to create, but it does have one problem: since you could lose it, you have to design your voyage for zero gee anyway. ISS has no way to wash clothes; they use them and throw them away. Bathing in zero-gee is not very convenient. It is harder to eat and cook in zero-gee, too. But since a Mars voyage could lose its artificial g, we can't just send along a Maytag clothes washer; if they lost their gravity they would have no easy way to wash clothes for several months! So you have to design for zero gee anyway.

-- RobS

Chazbro38 · 2005-05-22 17:40:08

Ion drive was just unproven until it was used as the primary propulsion system on the Deepspace One technology demonstration mission. NASA (or someone else) will be have to bite the bullet on VASIMR the same way so that we can move on. The Isp for ANY chemical propulsion system is totally inadequate for practical manned deepspace flight. If we are to go to Mars, the rest of the solar system and the stars we will have to prove out VASIMR or another similar propulsion technology in any event so we might as well get to it.

RobS · 2005-05-23 00:00:53

1. Chemical propulsion IS NOT inadequate for Mars flights. It's perfectly adequate. We know how to use it to get to Mars in six months and back in the same length of time. The NASA Design Reference Mission uses it (though ion and nuclear options also exist).

2. VASMR is not only unproven; you can't power it adequately. It needs thousands of kilowatts of power. No one can build a reactor to make 100 kilowatts yet, let alone thousands. ISS has solar panels able to make 100 kilowatts; no one knows how to scale them up to make, say, 10,000 kilowatts (though new materials will make that easier in a decade or so).

We also know solid-core nuclear propulsion will work, and the politics to approve are probably doable. Solar thermal is another alternative able to give an ISP of 800 or so, though thrusts would be in the 100 pounds range so you'd need to raise your ships to a highly elliptical orbit gradually and then use chemical for the rest.

-- RobS

SpaceNut · 2005-06-03 09:09:23

Canadian scientists contribute to European study of the body at rest

In the longest bedrest study for women ever conducted in Europe, 12 women have been confined to bed and monitored for 60 days at the French Institute of Space Medicine and Physiology space clinic in Toulouse (MEDES).
The women were confined to bed from March to June 2005, lying with their feet slightly higher than their heads, at an angle of about six degrees. This position prompts changes in the body similar to those experienced by astronauts in the microgravity of space, such as a loss of muscle mass, reduced strength, decrease in bone mass and weakening of the cardiovascular system.

Why only women?

RobS · 2005-06-03 10:15:30

Probably to keep variables caused by gender constant.

-- robS

Chazbro38 · 2005-06-03 21:40:02

For anything other than Cis-lunar travel, chemical propulsion is ABSURD. Six months or more each way to Mars isn't particularly feasible either(I've been on multiple patrols on nuclear-powered ballistic missile submarines for three months at a time and thats pretty close to the limit). Nuclear electric propulsion is over 10 times more efficient than chemical rockets so clearly either Ion drives or VASIMR or the only realistic alternatives at this time. A nuclear electric propulsion system could propel and power at least ten times as much payload science as any chemical system of comparable mass. In a nuclear electric propulsion system, a nuclear reactor produces heat, a power-conversion system converts the heat to electricity, and an ion thruster (or VASIMR) uses the electricity to propel the spacecraft. The new generation of Nuclear Electric Propulsion Systems(NEPS) are designed to last seven to 10 years in space and are about 15 times more efficient than the Space Shuttle Main Engines.
"The more efficient the engine, the less fuel the spacecraft has to carry. As for nuclear reactor technology I refer everyones attention to RAPID (Refueling by All Pins Integrated Design) The 200 kWe uranium-nitride fueled lithium cooled fast reactor concept (RAPID-L 1) The 200-kW (electric) uranium-nitride-fueled lithium-cooled fast reactor concept "RAPID-L" to achieve highly automated reactor operations. RAPID-L is designed for space based power systems. It is one of the variants which enables quick and simplified refueling. The essential feature of the RAPID concept is that the reactor core consists of an integrated fuel assembly instead of conventional fuel subassemblies. In this small-size reactor core, 2700 fuel pins are integrated and encased in a fuel cartridge. Refueling is conducted by replacing a fuel cartridge. The reactor can be operated without refueling for up to 10 yr. RAPID-L Operator Free Fast Reactor Concept Without Any Control Rods.

People should check their facts before they post on this topic.

Charlie

SpaceNut · 2005-06-17 11:30:59

Well the Twelve women recently completed 60 days of voluntary bedrest now;
Actively seeking twelve new volunteers! Female volunteers prepare for a second 'bedrest'

For phase 2 of the study, which is due to begin in September, ESA, the French space agency CNES and the MEDES Institute are looking for twelve new female volunteers from the European Union.

GCNRevenger · 2005-06-17 12:01:40

For anything other than Cis-lunar travel, chemical propulsion is ABSURD. Six months or more each way to Mars isn't particularly feasible either(I've been on multiple patrols on nuclear-powered ballistic missile submarines for three months at a time and thats pretty close to the limit). Nuclear electric propulsion is over 10 times more efficient than chemical rockets so clearly either Ion drives or VASIMR or the only realistic alternatives at this time. A nuclear electric propulsion system could propel and power at least ten times as much payload science as any chemical system of comparable mass. In a nuclear electric propulsion system, a nuclear reactor produces heat, a power-conversion system converts the heat to electricity, and an ion thruster (or VASIMR) uses the electricity to propel the spacecraft. The new generation of Nuclear Electric Propulsion Systems(NEPS) are designed to last seven to 10 years in space and are about 15 times more efficient than the Space Shuttle Main Engines.
"The more efficient the engine, the less fuel the spacecraft has to carry. As for nuclear reactor technology I refer everyones attention to RAPID (Refueling by All Pins Integrated Design) The 200 kWe uranium-nitride fueled lithium cooled fast reactor concept (RAPID-L 1) The 200-kW (electric) uranium-nitride-fueled lithium-cooled fast reactor concept "RAPID-L" to achieve highly automated reactor operations. RAPID-L is designed for space based power systems. It is one of the variants which enables quick and simplified refueling. The essential feature of the RAPID concept is that the reactor core consists of an integrated fuel assembly instead of conventional fuel subassemblies. In this small-size reactor core, 2700 fuel pins are integrated and encased in a fuel cartridge. Refueling is conducted by replacing a fuel cartridge. The reactor can be operated without refueling for up to 10 yr. RAPID-L Operator Free Fast Reactor Concept Without Any Control Rods.
People should check their facts before they post on this topic.
Charlie

"People should check their facts before they post on this topic"

Why yes, I think so Chazbro... starting with you:

First off six months to Mars is not unreasonable, it is rough on the mind and body, but astronauts and cosmonauts have done it for years. I think that six months is near the limit, but it is obviously possible.

Second, you have catagorically ignored the real problem with using a nuclear fission reactor to run a VASIMR engine, which is not how many kilowatts is consumes, but rather how much those reactors and their converters weigh per-kilowatt.

A VASIMR engine is going to require at the minimum somewhere on the order of 3,000 kilowatts of electric power for a manned ship of reasonable size to go much faster then chemical rockets. More energy, like 10,000-20,000kWe would be nice... The trouble is the reactor(s) powerful enough to make that kind of energy, when you add on the mass of the converters, radiators, and radiation shields will be so heavy that it will weigh down your ship and not help your trip time much.

This is not counting the mass of the VASIMR engine itself, which is not trivial either, and could prove to be quite heavy itself. Superconducting magnetic solenoid coils, wrapped with liquid hydrogen pipes (if not actually in the fuel tank!), the electric converters and their cooling systems, the actual microwave generator and its cooling systems, fuel handling equipment, and a cryogenic cooler for when the engine is shut down would be nice too.

Oh, and if you do go with an Ion engine or a VASIMR engine, you will have to trade that big payload improvement for the big reduction in trip time, so you will wind up having a much more expensive space ship for the same payload I bet.

Also I think that Rob here is still basically right, that no reactor - especially not the RAPID series - are anywhere near big enough to really power a manned spacecraft with a VASIMR engine. One of RAPID's "essential features" is that its too heavy, like all solid-core reactors.

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As far as using an ion tug to push your ship to a high orbit just shy of escape velocity, you really can't shorten the trip that much versus chemical, since you can't use the ion tug to push you any faster then this high orbit's velocity, so you would be stuck with chemical for any speed improvements. Plus, the fuel boiloff would be problematic for a 3-6mo spiral out of Earth orbit.

PS: Oh, and NASA DRM does indeed call for the use of solid-core nuclear rockets in order to increase payload mass that can be carried with the lighter-duty Magnum heavy lift rocket.

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My favorite engine, though I am of course biased by the sheer elegance of the concept, is the gas-core nuclear thermal rocket. It is probobly the only option besides VASIMR to achieve short interplanetary transit times, but it is probobly just a little bit beyond out current materials technology. At the moment, solid core NTR is the only enhanced-Isp/high-thrust engine that doesn't break the payload or fiscal budgets.

RobS · 2005-06-17 22:20:29

Not to mention the tens of billions of dollars of development cost--multi-megawatt nuclear reactors in space won't be cheap--and the political complications of launching BIG nukes into space. If a puny 100 kilowatt-electric reactor masses five tonnes right now for Zubrin's Mars Direct, how much will a 3,000 kilowatt reactor mass; fifty tonnes? That's twice as large as anything we can launch into space right now.

And how much will the ion engine mass? Consider this information: NASA TM-2002-211970 (Timothy Sarver-Verhey et al), describe an 11.3 tonne solar-electric vehicle using nine 50-kw gridded ion thrusters and 12.2 tonnes of xenon to move 36.6 tonnes of payload to Earth-Moon L1 in 270 days (9 months!). The vehicle would have thin-film solar arrays totalling 2,685 square meters (mass 0.33 kg/m2 or 900 kg). Arrays and engines would have a 2-year design lifetime. The design includes a 2.2 tonne margin for the ion engine mass (it could be as much as 13.5 tonnes, or if it is 11.3 tonnes the payload is 38.8 tonnes).

If a 500 kw ion engine masses about 12 tonnes, how much will a 3,000 kw ion engine mass; 72 tonnes? Let's be conservative and say 36 tonnes. We now have a 50-tonne reactor and a 36 tonne engine to push what; 50 tonnes of vehicle and crew? It will need maybe 30 tonnes of xenon at $10 million per tonne. How is that cheaper than a chemical engine and about 100 tonnes of fuel, which may very well mass less than reactor + ion engine + xenon? I'm afraid this technology has a long way to go before it will help us very much.

-- RobS

Yang Liwei Rocket · 2005-07-15 18:45:59

SpaceNut wrote: It appear that we have a new reason to think out long duration missions in the developing of cateracts due to high energy radiation particles and that we must do more research into protecting the astronauts vision since they are at risk for such damage once leaveing Earths protective fields.
I have twin cataract lens implants, which are essentially plexiglas, impervious to radiation particle damage, and they are just wonderful, in that they have corrected my extreme nearsightednes so I can fly without glasses (except bifocals, of course, since there is no accomodation for closeup reading . . . which of course, at my age, was gone anyway). Next objection?
We obviously need to work on shielding people from that radiation. There are several ways to deal with this problem. It ranges from both passive to active shielding to making the travel time less by developing new types of drive engines that can propel our space ship faster. Then there is the biological method of cell repair. We will probably use all four methods when every things has been said and done.
Larry,

Here is the trouble, there is no longer a big Space goal like the days of the Moon landings and the Space race began when Soviet-Sputnik and Russian Yuri went into Space but died when Americans landed on the Moon with Apollo and Russia's industry fell down with the collapse of the Soviet Empire. American astronauts when onto the Moon, since Apollo no human has been back, and to add insult to injury, there's American people who are tryingtell us that it was all a hoax.How much will Mars cost, some say $200 billion over the next 10 years, others say 500 $ billion over 20 years. The trouble with fuel supply, bulk of water and problems with long time exposure to low gravity and radiation have yet to be resolved properly. Sending stuff to the Red Planet is still rather a hit or miss proposition, the USA have lost many craft, Russia only landed one and it tranmitted for a few mins while ESA have only done Mars Express and the Beagle lander went crunch. In Space manned missions to Space stations, astronauts the Moon, and cosmonaut spacewalks have been very good but crewed missions to Mars have a single overwhelmingly big disadvantage over robotic missions and that is the people ahve to go back home again in a return flight, and it means you have to stay on Mars for 490 days, until Earth and Mars are lined up for a second launch window meaning one cannot do a nice American-flag mission in Apollo style. Currently on Mars it is so much easier and cheaper to send machines, is this why the Russians sent their Rovers to the Moon ?

dicktice · 2005-07-15 19:43:24

Sorry, my mistake, see below:

dicktice · 2005-07-15 19:46:09

Naw, the electronics of that era wasn't up to the miniaturization required for semi-autonomous control from Earth of any conceivable rover on Mars, neither by NASA nor the (then) Old Soviets.

Mad Grad Student · 2005-07-16 23:27:46

Here is the trouble, there is no longer a big Space goal like the days of the Moon landings and the Space race began when Soviet-Sputnik and Russian Yuri went into Space but died when Americans landed on the Moon with Apollo and Russia's industry fell down with the collapse of the Soviet Empire. American astronauts when onto the Moon, since Apollo no human has been back, and to add insult to injury, there's American people who are tryingtell us that it was all a hoax.How much will Mars cost, some say $200 billion over the next 10 years, others say 500 $ billion over 20 years.

NASA is working harder towards a crystal-clear goal right now than it has been any time in the past 36 years. The VSE has survived for a year and a half now, and is picking up more momentum by the day. Nearly every review of the NASA's current objectives (return to the Moon, maybe later to Mars) has given it their resounding approval. Real progress is happening towards our return to the Moon, progress that will become more visible as time goes by. Most important, NASA's budget is gently inflating with hardly a peep of protest out of Congress. NASA most definately has a goal in front of them, and is making headway towards it.

Going to Mars will cost nowhere near $200 billion, let alone $500 billion, or the absurd $600 billion price tag of Bush-I's SEI. Under the ideal best-case scenareo, $20 billion over the next ten years could take us to the red planet. More realistically, such a project will cost between $60 and $80 billion, depending on how efficiently NASA can utilize its resources and how extensive a mission they desire. A Mars mission is technologically and politically doable, the only major obstacle I see to its exection would be too great a focus on the Moon. As long as we can avoid having the CEV becoming a "Lunar shuttle" of sorts, it can be done.

There's no point in looking at the reliability of unmanned missions to try to figure out the odds of a successful manned mission. During the 1960s the Surveyor and Ranger robotic probes sent to the Moon had a horrific failure rate, and yet every Apollo mission came back safe and sound. The extra precautions taken to ensure the safety of the crew, not to mention the adaptability of real, live humans, greatly increases the odds of success of a manned mission over an equivalent robotic excursion. It will always be safer and cheaper to launch unmanned missions than their manned counterparts, and the sciece return brought by robotic missions will always be laughably pathetic compared to that of human versions.

Going to Mars will not be an easy venture, but it is well within our technological capabilities. We went to the Moon in an era when a computer the size of a room had less computational power than a hand-held calculator. Missions to Mars are absoltuely feasible, and shouldn't turn out to be that expensive either.

Yang Liwei Rocket · 2005-07-17 00:26:28

I am not bashing NASA or the USA, for me it doesn't matter if Russians, Japanese, Europeans or Amercians want to send craft to a planet like Mercury, what matters to me are the space results, a great mission and the space science. When NASA landed Americans on the Moon it not just made the USA proud but the people of the world thought it was great for mankind. Mad Grad Student I understand what you're saying, and agree with much of what you said. You have made some good points but Is it all so clear or are there questions to be asked, the NYtimes CNN and Washington post have asked about how valid such stuff is, Steven Weinberg criticises the use of manned space missions, and Glenn has been critical of plan Bush to the Moon/Mars. I see many problems with the vision to Mars from President Bush, and I maybe have about 6-7 major questions to ask. But I will address 2 of the big questions in this post.

Two of my major question would still be the ONE : budget and TWO: dealing with internal sceintific/political conflict, I see the trouble because the Shuttle return, development of a CEV and SDR are all part of these goals and pushing Shuttle to finish ISS, all of this will be a major cost and it is part of the total Mars package deal . Space flight is both a scientif jounry but to being with there is a political game to understand and winning public support from the taxpayers. Form the Bush goal we had a vision for Moon landing, finsihing the space station, bringing back the Shuttle and Right now NASA has not been back into Space for 2 1/2 years, they are not ready for lunar flight and if they can't launch Shuttle soon they will lose a launch window and may depend on Russian Soyuz, ESA's ATV or Russian Progress for their lifts and payloads. This is why I say there is internal political/scientific strife and contradictions. The Bush vision asked for the return of Shuttle and manned flights after the last disaster. Considerable costs are incurred by NASA in maintaining the aging Space Shuttle. During the last decades up to 1/3 of NASA's budget had to be invested in the Shuttle to keep it flying for year 2005 another 5 billion are allocated for the Space Shuttle constituting 30 % of the entire US-space budget and NASA's funding of many research projects has been cut in the recent years and months in order to free money from missions like JIMO, Ulysses, Voyager. The cancellation of other missions has done great for money cutbacks but not for other members of the science community, it has lead to heat over Voyager, people asking about JIMO and the Hubble fan Club are starting to dislike manned missions because of the HST cancellation. A single Space Shuttle launch costed more than 600 million dollars to run, it is getting more expensive due to the whole overhaul and new safety checks and development of the SDV and CEV is going to be very costly.

GCNRevenger · 2005-07-17 08:13:23

" and development of the SDV and CEV is going to be very costly."

Why?

There will be a fundimental difference in how NASA at least tries to handle funding from here on out, which is really pretty simple to understand. Shuttle has been NASA's life support for thirty years, bringing in half the agencies' money (if you include ISS and HST), and so was in their interest to make it as expensive as possible. Now things are different, under Bush's plan the end of Shuttle will be almost irrevokable by the end of his tenure, and so NASA will need some other program to justify its exsistance. VSE is that plan, as just operating ISS could not possibly be enough, and it has a hard-and-fast goal: Moon and Mars. NASA will either accomplish VSE, or die trying... Which is probobly a pretty good motivator for fiscal responsability.

I would also like to note that for planetary sciences, there is no substitute for human boots on the ground. Take the MER rovers for instance, everything they have done for the past year, all their accomplishments and science, all of that... could have been done in a few days by a geologist in a rover. Maybe even just one day. I also think that if we are going to look for life, then sending robots to try is futile... where are the bacteria going to be, near the surface with the peroxide-laced salty soil, the flesh-charring ultraviolet radiation, and the tenuous dessicating dry atmosphere? We will have to drill, and people are much better at drilling then robots.

Chazbro38 · 2005-08-12 23:46:23

"People should check their facts before they post on this topic"

Yep and I meant it—this especially applies to people like GCN Avenger whose post indicate he has absolutely no ACTUAL HANDS ON EXPERIENCE with any of the science and technologies that he babbles on about.

If he bothered to do even a google search, much less actual research, he would know that a six month coast through deep space by a human crew is universally considered by all acknowledged experts in the field as being a human factors show stopper, both because of GCR and physiological deterioration due to prolonged exposure to zero-g. GCN has cause radiation induced cataracts on at least 36% of the entire astronaut corps to date and those astronauts that have been in space for more than five weeks at a time have all complained of suffering from debilitating side effects from prolonged exposure to zero-g for as many as four weeks after returning to earth. What information there is available on Cosmonauts trends towards significantly worse effects since the Russian space program has admitted using some of its Cosmonauts as experimental test subjects to push the boundries of human endurance. All of this information is very public and accessible to anyone who isn’t too lazy verify his facts before posting.

As for GCN Avenger’s dismisal of VASIMR once again your lack of ACTUAL HANDS ON EXPERIENCE with nuclear reactor technology couldn’t be more apparent. The power for a VASIMR propulsion system can easily be provided by a sodium-cooled fast spectrum reactor
Which is a low-pressure, self-cooling reactor. It will generate 10 MW of power for 30 years before refueling and it already exists and is operating. There are no complicated control rods to move through the core to control the flow of neutrons that sustain the chain reaction; instead, the reactor uses reflector panels around the edge of the core. If the panels are removed, the density of neutrons becomes too low to sustain the chain reaction. A side benefit is that the plant will generate enough excess power that some could be used to produce hydrogen & Oxygen through electrolysis.

As someone such as myself who is a veteran of the United States Navy’s Submarine service and is intimately familiar with the experience of living and working within a few feet of a multimegawatt nuclear reactor for months at a time, I can tell you that there are several, currently existing nuclear reactor technologies that can readily be adapted to power VASIMR propulsion systems---which is sadly more than I can say for Gas core reactor technology which, because it has never actually existed outside of a computer model, is totally worthless as a solution to anything in the real world.. By contrast, sodium-cooled fast spectrum reactor technology has existed in operational reactors (some even on submarines) since the 1950’s.

GCN Avenger’s posts on these topics indicate that he has a real serious need to get out and get real world experience with these technologies…..a person can’t just read about them in a book or watch a Star Trek episode or whatever it is that he does then post like you are some sort of a subject matter expert. Every time you post you reveal glaring fundamental errors that indicate how poor your grasp of the technological material really is.

Chaz bro

Austin Stanley · 2005-08-13 01:29:20

I posted a similar reply on your other topic, but I'll briefely repeat and expand here. What is the specific power of this reactor? The only statistics I could find for a similar sort of reactor were 200W/kg. And this reactor was not apparently designed for space, with the heavy radiators necessary for such an enviroment taken into acount. It's specific power is good, but not revolutionary. Other space reactors currently on the drawing board already have this level of performance if not better. In fact IIRC it is about what I have used as a refrence for most Nuclear powered space reactors.

This would mean you would need a 50mt reactor of this type to power a typical 10MW VASIMR engine for the quick trip to Mars. This is in addition to mass of the VASMIR engine itself and the hydrogen propelent you would use as fuel. Thus such a system is impracticle for intial use on any Mars Voyage. Although it might be usefull powering a larger ship such as a cycler. But extensive in-orbit construction would be required. Realy though, reactors with much higher specific power are necessary to make such missions practical, such as GCNR or fusion reactors both of which would probably have specific powers >1kW/kg are required to make VASMIR practicle. Of course the question then is, if you have such powerful reactors, why not use them directly for propulsion instead of VASMIR?

I also wouldn't be so hastly to assume that everyone here has regected the use of liquid metal cooled reactors of various types in our planning. We have. In fact not to long ago GCRNevenger and I debated the merits of a nuclear power/vrs solar thermal for powering the extraction of oxygen from moon rocks. I belive he brought up just the system you propose due to it's sacrifice of electric specific power for better thermal specific power. (I still advocate Solar Thermal BTW)

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#126 2005-03-30 14:42:51

Re: Long duration Human space missions - Can we survive them?

#127 2005-03-30 16:55:51

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#128 2005-03-30 16:59:51

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#129 2005-05-12 08:00:00

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#130 2005-05-12 09:29:14

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#131 2005-05-18 12:50:30

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#132 2005-05-21 13:52:42

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#133 2005-05-21 15:26:19

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#134 2005-05-22 15:27:58

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#135 2005-05-22 17:40:08

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#136 2005-05-23 00:00:53

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#137 2005-06-03 09:09:23

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#138 2005-06-03 10:15:30

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#139 2005-06-03 21:40:02

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#140 2005-06-17 11:30:59

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#141 2005-06-17 12:01:40

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#142 2005-06-17 22:20:29

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#143 2005-07-15 18:45:59

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#144 2005-07-15 19:43:24

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#145 2005-07-15 19:46:09

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#146 2005-07-16 23:27:46

Re: Long duration Human space missions - Can we survive them?

#147 2005-07-17 00:26:28

Re: Long duration Human space missions - Can we survive them?

#148 2005-07-17 08:13:23

Re: Long duration Human space missions - Can we survive them?

#149 2005-08-12 23:46:23

Re: Long duration Human space missions - Can we survive them?

#150 2005-08-13 01:29:20

Re: Long duration Human space missions - Can we survive them?

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