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Comment: Re:Food is not the limiting factor (Score 3, Interesting) 279

by Rei (#48190491) Attached to: NASA's HI-SEAS Project Results Suggests a Women-Only Mars Crew

That is, of course, for a given radiation dose, which is independent of body cross section - which is relevant in real-world scenarios. If we assume an isotropic radiation exposure profile, an average male height of 174cm, an average female height of 161 cm, and asssume an equivalent profile, then a man presents a 17% higher profile to radiation exposurediation exposure, so if a woman has a 50% higher (150%) cancer risk, then it's only 29% higher for a fixed radiation flux per square meter.

However, let's look further at this. Given the smaller size of members of a female crew, you can shrink the spacecraft occupant space by 8% on each axis, or a volumetric decrease of 26%. Mass changes are more difficult to reckon. Life support, food, water, etc is dependent on metabolism, which the article shows is dramatically lower for women in space. Fuel needs are proportional to all other mass issues. Only a few things (such as computers and scientific equipment) don't trace back to crew member size and mass. Regardless, for a given launch weight, it's clear that you can afford the mass of a significantly increased amount of radiation shielding for a female crew due to the weight savings elsewhere, probably easily more than offsetting the cancer risk.

Beyond this, the average US astronaut age is 34, an age well after when most women are done having children (assuming that they even want to have children). Given that the article states the risk is from breast, ovarian, and utirine cancer, I wouldn't be surprised if many would consider full hysterectomy for the ability to travel to Mars.

Comment: Re:Compelling, but a mix still better... (Score 3, Interesting) 279

by Rei (#48190177) Attached to: NASA's HI-SEAS Project Results Suggests a Women-Only Mars Crew

Despite how radical that statement sounds, it's actually perfectly reasonable for a zero-G environment. They're not only dead weight, they're also in the way and make you require larger accomodations.

Even in Mars's gravity field a legless person would deal quite well, at least inside the facility (picture how easily you could get around without your legs if you suddenly were given 2.5x the arm strength, didn't have your legs weighing you down, and on top of that add in how most double amputees already have good arm strength to begin with). They should be able to "hop" with their arms all the way to a 2 1/2 meter ceiling without trouble, and the full arc would take a good two seconds to come back down. On the moon it'd be even easier. Of course, if they're legless, why would they even need such tall ceilings to begin with?

Comment: Re:F the UK (Score 3, Insightful) 458

by Rei (#48185113) Attached to: In UK, Internet Trolls Could Face Two Years In Jail

I agree. If by "poisoning" they mean people making insolts or dispatching flying penises in Second Life or stuff like that, then it's a bill too far. But if by "poisoning" they mean launching flickering images on an epilepsy forum to try to cause seizures, "doxxing", making legitimate rape and murder threats, etc, then I think it's absolutely justified. All too often is there the assumption that what happens online doesn't warrant enforcement, even if it's something that crosses over into the real world.

Everyone has the right to free speech, but it ceases being free speech when it crosses certain bounds (shouting fire in a crowded theatre, incitement to violence, solicitation of criminal activity, etc). All of these cases are nuanced and require careful balance, but what they should not be is ignored.

Comment: Re:Overly broad? (Score 1) 402

by Rei (#48182001) Attached to: Soda Pop Damages Your Cells' Telomeres

Exactly what I'm thinking. I respect peer-reviewed research, and take results seriously - preferably consensus positions, but on lesser researched topics, individual studies. But isn't this pretty useless without more details? Is it sugar consumption? Then diet soda doesn't count. Is it phosphate consumption? Then are all kinds of other foods also a threat? Is it caffeine? If so, then coffee is a threat and caffeine-free soda is fine. Is it other lesser ingredients, such as certain flavorants or colorants? What element in their test soda is so harmful that it has such a dramatic effect? Surely it's not all ingredients, or the act of consuming them at once...

Comment: Re:Baby steps (Score 1) 348

by Rei (#48179831) Attached to: White House Wants Ideas For "Bootstrapping a Solar System Civilization"

Wrong. I said mass manufacture - you don't have to re-engineer curiosity from scratch and hand-build it every time. And if you can pay to build a super-heavy-lift vehicle, or tons of smaller (but still very large) launches to get your ~100 tonne manned Mars round trip spacecraft into orbit, then you can launch a 100x 889kg curiosity rovers.

You literally can launch about 100 mass-manufactured curiosity-sized rovers for the cost of one manned mission. The scientific bang for your buck is way, way, way higher with robots.

And FYI, if your goal is to be able to help people "live on another planet", then you absolutely should not be supporting wasting money on a trip to Mars on today's way overpriced launch systems. You should be supporting spending it on developing novel systems for orders-of-magnitude reduction of launch prices, be they scramjets, launch loops, coilguns, metastable fuels, nuclear thermal propulsion, or in general insert-your-favorite-potential-cost-reducer-here, so that it doesn't cost an impractical amount of money to send people there. (never mind that we're not even centuries away from being able to recreate a full self-sustainable tech tree on Mars.. see earlier in the thread)

I always find it funny to hear people the same alt-space fanboys complaining vitriolically about how maintaining ISS is a huge waste of money but then insisting that we set up a manned outpost that would cost orders of magnitude more to maintain ;)

Comment: Re:Baby steps (Score 1) 348

by Rei (#48175493) Attached to: White House Wants Ideas For "Bootstrapping a Solar System Civilization"

What "all purpose robot"? A robot or person's capabilities are limited by what scientific equipment they have on hand, not by whether they can digest corn or catch a cold. I'm talking about a robot like Curiosity. A person could mass-manufacture and dispatch a hundred Curiosity rovers to every corner of Mars for the cost of one manned mission and would collect dozens of times more data.

Comment: Re:Baby steps (Score 1) 348

by Rei (#48175481) Attached to: White House Wants Ideas For "Bootstrapping a Solar System Civilization"

Ref. It took 30 seconds. Please don't ask other people to use Google for you, you're (presumedly) an adult and should be able to manage these sort of things on your own.

But in order to avoid thermalizing your fission fragments the reaction is going to need to be in near-vacuum

The reaction is done in a near vacuum. But that doesn't mean that there's almost no fuel. Fission fragments and neutrons behave totally differently, fission fragments are positively charged and respect Lorenz force, neutrons are neutral and do not, so it's easy to separate the two (as well as from the fuel, which becomes negatively charged and is not moving at relativistic velocities).

These things have been fully simulated, there's nothing unreasonable about them.

but our best neutron mirrors can only get total reflectance at angles of incidence of less than a single degree

I have no clue where this is coming from. Neutron reflectors (more properly thought of as scatterers) can scatter back, and in fact moderators produce a relatively anisotropic thermal neutron flux. The current proposal for a dusty fission fragment reactor involves U235 fuel and a moderator in the shell of the reactor.

Comment: Re:Baby steps (Score 1) 348

by Rei (#48172161) Attached to: White House Wants Ideas For "Bootstrapping a Solar System Civilization"

Oh please, be serious. It's humans running the robots who make the decisions. The only benefit a human on Mars has is latency. But that's a really silly benefit, given that there's no urgency to get the data and just travel there takes months and the limiting factor on how much data you'll collect overall is how long your scientific equipment lasts. And no, an astronaut on Mars isn't going to be repairing a broken mass spectrometer or the like, it's a silly concept. And it'd, as noted, be orders of magnitude cheaper just to send a second robot.

Comment: Re:Power Source (Score 2) 348

by Rei (#48167453) Attached to: White House Wants Ideas For "Bootstrapping a Solar System Civilization"

I totally disagree. A dusty fission fragment reactor has been demonstrated using a non-nuclear substitute fuel, which demonstrated proper containment and thermal management. And modelling shows that such a configuration should produce a collimated fission fragment beam. So what's so grossly impractical? Have you come across a paper indicating that it's impractical? Because I sure haven't.

My previous comments apply to NEP

I'm not talking about NEP. I'm talking about generating a RF plasma and funnelling it through a nozzle, like in VASIMR, but with primary heating being from an IR nuclear lightbulb. And even if I wasn't, commentary on conventional nuclear reactors vs. solar is inapplicable when one is talking about totally different type of reactor.

Comment: Re:A 'SimCity' CAD design game (Score 1) 348

by Rei (#48167417) Attached to: White House Wants Ideas For "Bootstrapping a Solar System Civilization"

Hmm... I'm not sure what you're thinking about doing with CAD, but a Sim that handles real inorganic (and potentially simple organic) chemistry and materials properties could be incredible for enabling the crowd-sourcing of simplifying the tech chains of refining and production, which on earth are just ridiculously long and totally impractical to just migrate to Mars. The users would be given a realistic distribution of raw Martian minerals, and would have to feed the 3d printers / molders / CNC machines / lithography / robotic assembly that makes products. These products would include a (long) fixed set of needs to keep colonists alive and comfortable, as well as spare parts for your refining / mining equipment and the manufacturing hardware's equipment. Users could then try to produce as much of a colony's needs as possible with as little imported hardware as possible.

Simulating wear and corrosion on the refining, transport, and mining hardware would be a must. I think requiring the users to design the full details of the 3d printing and other manufacturing hardware would be overkill, but they should be able to choose what materials different "major parts" for them are made out of and what they want to supply as raw materials, which would affect wear / corrosion rates / efficiency / etc. Game consultants should include a wide range of people with real-world experience in different industries to make sure it's realistic, and the game should be launched with a variety of real-world pieces of Earth mining and refining hardware so that new players have something to start out with and tweak (albeit starting out heavily reliant on imports from Earth). As each person designs a new piece of hardware and tries it out, it should be saved to a global database, along with a history of what it's been taking in (raw materials, parts, etc) and producing as an outputs. Others could then search through the global database for equipment that does a function that they need to incorporate into their hardware.

The game could run in a MMO mode or single-user sandbox mode. In MMO mode there would be multiple users each with their own mine, refining center, manufacturing center, or whatever they want to build) on Mars, while in single-user mode a user would have their own whole planet to play with on their own. Once they get a production line running they can dispatch transport to carry materials or goods to where they're needed, there can be mishaps along the way, etc - all of the elements of your typical enjoyable Sim game - except with real-world chemistry and mechanical properties underlying key aspects. The victory condition would be total manufacturing indepence from Earth. The loss condition would be overstraining Earth's ability to supply you, leading to shortages and colonist deaths.

I think something like that could, if well designed, be both potentially fun for users and useful for engineers designing real-world infrastructure.

Comment: Re:Begin planning use of Lockheed's fusion power (Score 2) 348

by Rei (#48167303) Attached to: White House Wants Ideas For "Bootstrapping a Solar System Civilization"

Great! Now you just need to invent an actually functional confinement method for the absurdly-hot gaseous/plasma nuclear fuel to stop it from destroying its containment vessel or leaking out its fuel in short order. And while you're at it, you should probably go ahead and invent a way to stop the quartz / fused silica bulb from undergoing blackening when exposed to a neutron flux, something it's so prone to doing that people deliberately expose quartz to nuclear reactors to make opaque black quartz for jewelry. And of course, a way to start the whole thing, a process that's been so problematic that they've been investigating bombardment by sizeable amounts of bloody antimatter as a potential solution.

Easy as pie, surely! Riiight around the corner.

What isotope are you thinking of as fuel? Unicorn-235?

Never buy from a rich salesman. -- Goldenstern