Re: the SLS's LH2-fuelled upper stage will always be more efficient
Not true. SEP(solar electric propulsion) in its current iteration is up to 10 times more propellant efficient, with theoretical margin to become an additional 10 times better.
168 posts • joined 16 Mar 2016
Not true. SEP(solar electric propulsion) in its current iteration is up to 10 times more propellant efficient, with theoretical margin to become an additional 10 times better.
Because with LOC(Loss of Crew) estimates that make Shuttle look safe, any crew riding on SLS/Orion has a very good change of having screws(and other spacecraft bits) involuntarily inserted.
Scoff all you want, the remaining microbes on Ceres will lead to unexpected profits. I need $500 million to test my 5 tonne lander bringing back Lunar samples, then it's on. It being research on every hunk of rock with equal or lower gravity than Ceres, meaning almost everywhere humans can go with current technology, including Psyche 16.
You do realise Goodwin's Law has been extended to include references to "Snowflakes", right?
Actually "Snowflakes" is a corollary. AFAIK this particular corollary has not yet been rigorously defined. Feel free to create one. This information will be very useful as our AI develops psychohistory.
Based on the little Martian exploration we've done, it appears that it took billions of years for the solar wind to create what we see today. Yes, the solar wind will eventually strip any Martian atmosphere, assuming we don't simply* develop an artificial planetary magnetic field. This will take millions of years. Unless your definition of long term human use is in time frames longer than humans have existed for, you have not stated a case against long term human use of Mars.
* Simple for a civilization with the technology to construct a colony on anther planet than is large enough to justify the effort in nuking the poles. We know how to build Dyson-Harrop satellites today. Dyson-Harrop satellites can harness solar energy to create large magnetic fields in space. The solar wind is made up of charged particles, principally protons and electrons. Charged particles can be influenced by magnetic fields. A constellation of Dyson-Harrop satellites in Martian orbit** therefore can deflect the solar wind. I expect, if a better method is not developed, this style of system can be refined to capture the solar wind. As protons plus electrons equals hydrogen, this is one potential way to import lost-cost hydrogen(We also end up with helium and traces of heavier elements) to Mars. The same system could also be used to give the Moon it's own magnetic field, allowing a Lunar atmosphere.
** You may have seen the proposal for a similar shield placed at the Sun Mars L1 point. This doesn't work because the solar wind hits from the side. The solar wind is influenced by the Sun's magnetic field, which is dragged by the Sun's rotation. The Sun's magnetic field, when viewed from above the orbital plane, looks like a pinwheel.
My expectation is that, if we look at a longer sales period, we should see a peak in sales right before credits end and a valley right after. If I had been in the market for an EV in Georgia as the end of the credit approached, I would have bought sooner so I could still get the credit. I expect most people would do the same. Looking at sales from the months before the credit ends and the months after tells us nothing. What we want to know is how long it takes sales to recover at the new higher price point.
Unfortunately, when I search for EV sales data for Georgia, all that comes up are articles lamenting the valley in the first months after credits ended. What I'd like to find are sales figures from at least 6 months before and after the credit.
Marvin the Martian was a Warner Bros creation. We know Marvin hasn't been assimilated yet because he hasn't been forced to give up his quest for galactic domination to become a talk show host.
Based on what I found scattered throughout the Reddit AMA, the plan is to use methalox, not hypers, for control thrusters. These will be fed by the main fuel and oxidizer tanks using a pressure fed system. Cryo-cooling systems will not be used for the initial BFS flights. Instead boil-off will be controlled by venting.
Methalox cryo-cooling is a mostly solved problem. Musk acknowledged that it will be added so I expect there volume and mass reserved in the BFS designs to accommodate the system.
"Wouldn't the mere fact that there is at least *some* atmosphere on the Mars-side of your suit/vehicle/etc, compared with the vacuum encountered on the Moon or in orbit, make the design of said suits/vehicles a bit easier thanks to them not needing to cope with such a steep pressure differential?"
Yes. The pressure a suit has to contain is indeed nearly identical for Mars or the Moon, as others have pointed out. This isn't the end of the story though. Any useful pressure suit will leak. On Mars, we can recapture lost gases by compressing the tenuous atmosphere. This isn't possible on the Moon. It's far cheaper to refill our suit by compressing the Martian atmosphere than it is to ship carbon and nitrogen from Earth to the Moon. Economics dictate that the Lunar suit must leak less, therefore more we expect it to be more complex.
Just because you fail to see how an atmosphere makes things easier doesn't mean that having an atmosphere makes things easier. Here is a very brief list of key advantages.
Areobraking - The amount of energy needed to send a craft from Earth to land on Mars and the Moon are similar because the Martian bound ship doesn't have to use fuel to cancel orbital velocities.
Micrometeorite shielding - Specs of dust are an impact hazard on the Moon. The Martian atmosphere eliminates this potential threat.
Radiation shielding - The Martian atmosphere provides far more than the Lunar lack-of-atmosphere.
Temperature regulation - The Martian atmosphere traps enough heat that we can deal with the night time cold. Even with a P-238 heating element, the most recent lunar rover began malfunctioning after only one Lunar night. Solar powered robots without a P-238 heating element can survive over a decade on Mars.
Extractable resources - The Martian atmosphere is an easily processed source of carbon and nitrogen. Virtually all of the chemistry we use involves carbon and nitrogen. A colony will require tons of carbon and nitrogen reserves per person. Based on current knowledge, there are no extracable carbon or nitrogen sources on the Moon.
The last point is very important. Each colonist will require a carbon reserve of 12+ tonnes for the agrarian sector of the economy. When we start adding other economic sectors, such as textiles, plastics, and metallurgy, the per-colonist reserve necessary grows rapidly. On Mars CO2 capture and recycling doesn't have to be perfect. We can simply compress more atmosphere if we need more carbon. Every loss on the Moon has to be replaced with imports. Capturing the CO2 emmissions from aluminium production is going to add mass and complexity, with necessary higher price tag, of Lunar equipment compared to equipment that does the same job on Mars.
The only advantage that the Moon has, and this isn't based on current technology, is travel time.
So you want to replace one set of socialist programs with the set of socialist programs you prefer.
That will go over really well. /sarc
Wouldn't it require less waiting to design and build a working fusion power plant?
We'd all love to have materials that could be used to make solar panels with the ability to withstand the expected radiation levels inside a fusion core. AFAIK, no one has discovered the right materials yet.
You'll have to describe how you envision wind turbines functioning inside a fusion reactor core. I can't think of any way to make the extra effort worth the trouble.
What is MEGA?
What do you mean I should know? Let me have my computer, I need to Ask Jeeves.
We know where to find water, carbon dioxide, and nitrogen on Mars. We'll need to take the tools necessary to collect these. We'll also need a bubble in which we can grow crops. From here it is relatively straight forward. Step one, grow grains and hops. Step two, brew beer. Survival necessities solved.
Obviously this is an over-simplification. So far I haven't found any product that can't be made on Mars.
Before we consider going to the Moon we need to look to see if we can find carbon and nitrogen hiding somewhere. After we find possible resources, we then have to figure out if they are extractable.
We've already figured out how to extract the carbon and nitrogen we'll need on Mars. We've found carbon and nitrogen on Ceres. Either of these are currently better options than the Moon.
It just so happens the Japanese have plenty of tritiated water they have no use for. I wouldn't be surprised if they'd pay someone to take it off their hands.
He3 isn't as rare on Earth as most people claim. He3 is expensive on Earth because there is virtually no demand. If we ever get working fusion there will be demand and people will start separating the various isotopes. This will lead to a dramatic drop in terrestrial prices for He3. Shipping costs from the Moon have to drop by at least an order of magnitude, more probably three orders, for any profitable He3 extraction, assuming fusion power plants become available.
When a business case doesn't have any sizable revenue for at least three decades, it is not a business case.
Bubbles of course.
Sadly only the five others who were there for that DnD game will fully appreciate the joke and, AFAIK, none of them regularly read El Reg.
The chances of finding that comment on a Mars story are a million to one, yet it appears nine times out of ten.
Theoretically we could but, since we gave up valve research for silicon, we never miniaturized valve tech.
It's been 20+ years since I've used CAD software so my skills have atrophied. I initially assumed that it wouldn't be that difficult to relearn. That has not been the case. Now that I know it isn't just me, I would like a solution. The current plan is to bring at least one more person. This creates two problems. First, capital is extremely limited and paying a salary blows my budget. Second, I want things done right so I prefer to do as much as possible myself. I prefer to finalize the design, then have a licensed engineer sign off on the government required paperwork.
Aside: I did a test using my GF as the guinea pig. In her case, 22% is far too low. She gave up on the flat UI so I have no clue how much worse flat is for her. The test was done using two different subjects as using the same basic content would have skewed the results in favor of the second page. Both subjects were outside of her knowledge base.
Metro worked very well
Vista is preferable to Metro.
Thanks for reminding me what a usable web page looks like.
Great job formatting your comment so that your point was obvious. I regret that I have but one upvote to give.
Since it is possible to buy cheap smart phones I have to question whether securely wiping this phones so they can be reused is worth the trouble, if our goal is to get as many phones into the hands of the poor as possible. Simply put, I would love to see the refurbishment costs compared to binning the phones and buying new ones for the poor. Simply having sunk costs is not a reason to help fewer people with the same number of tax dollars.
Space tourists are going to expect others to be able to clearly see their face. With this design no one can tell it is you in that selfie. Add in the expectations created by Hollywood, namely lights inside the helmet, and it should be obvious to everyone that this suit version is going to be a commercial flop.
As long as only NASA(and partners) astronauts are the only people using this it won't be a huge problem.
Are you talking about this plutonium sale?
I guess someone could separate weapons grade plutonium from MOX but I have to wonder why anyone would bother. There are far easier ways to build a bomb.
No, I am not telling you what they are.
Me too...unfortunately I reckon that no matter how long I studied and how much I trained, I'd still never be able to understand more than one word in five.
Give your self some credit. I'm certain you'd be able to understand the various definitions of the words. What is uncertain is which definition to use.
What we have here is a case where most people are complaining over a document they haven't read. Of the small subset of people who have actually read Damore's piece the general consensus is that it is fairly well written and we should be debating the specific points. The few that don't have this opinion seem to be the bigots at both ends of the political spectrum.
At one point I expected far better from El Reg. I used to come to this site expecting to learn useful information. Now it seems like the standard is to be less informative than Buzzfeed.
Thanks for linking the Atlantic piece.
Ponies are indeed tasty.
Are you sure about that?
Earth microbes have evolved to compete on Earth. I find it highly doubtful that Earth life will be able to out-compete Martian(or any other location) life in its native habitat.
That said, we want to identify and understand alien life before we start mixing. We wouldn't want the microbe that produces the cure for cancer to die before we find it.
It means that Orbital ATK is not planning any manned spacecraft that can reach GSO.
As any fule kno Orbital ATK is the bestest rocket company ever. If they aren't able to get a person to GSO then no one can. Therefore, in order to extend the range of space walk technology the only solution is to give Orbital ATK $xxx billion to build a new rocket or drop the matter completely.
You have to explain why customs can look up your arse for drugs, but should leave your phone untouched.
The better question is why customs can perform anal drug inspections to begin with. Just because one failed program(Let's face it. If I really wanted to I could find any type of drugs I want.) exists does not justify using it as a model for other police action.
Downvoted because the US media is under the impression that every headline must contain the T word. I literally spend a lot more time filtering out unless crap from news feeds.
Note: I am merely explaining my downvote.
I was ready to click upvote until I got to, "ITER is too important to be cocked up by politicians." Perhaps things are different where you live, but, around here the more important something is the more likely it is to be cocked up by politicians.
We don't need to have a person to tend a craft in Lunar orbit any more. There are these things called computers which can automate all of the necessary tasks. Computers have gotten much smaller in the last five decades, so much so, they can fit on spacecraft.
Not that spending the resources on a lander of one is a good use of scare resources.
Actually there are things that can be done.
First, don't spend 3 years traveling to Mars. Go faster, and get there in 3-4 months. This cuts the exposure by an order of magnitude.
Second, ~3 cm of water cuts radiation level in half. The crew is going to need water so put the storage around the outside of the habitable area. Have a panic room with thicker shielding for solar storms.
Third, don't use metal as the primary material in the bulkheads of habitable areas. Metals, when struck by high energy particles, emit secondary radiation. Inflatable sections, much like what Biglow is playing with, don't have the same problems with secondary radiation.
Radiation is not a big problem in most of the inner solar system. We don't want to hang out in the Van Allen belts or get too close to the Sun but we aren't planning on spending a lot of time in either place.
When exactly did humans get so bad at noticing difference. When I were a lad we could tell the difference at 2%, if we didn't expect it. If a person knew that there was a difference that amount was less.
Methinks that 10% number is marketing gobbledygook.
Since transits only last a fraction of a day, all the stars must be monitored continuously, that is, their brightnesses must be measured at least once every few hours. The ability to continuously view the stars being monitored dictates that the field of view (FOV) must never be blocked at any time during the year. Therefore, to avoid the Sun the FOV must be out of the ecliptic plane. The secondary requirement is that the FOV have the largest possible number of stars. This leads to the selection of a region in the Cygnus and Lyra constellations of our Galaxy as shown.
Satellites use hypergolics. The most common fuel combination is monomethylhydrazine fuel and textroxide oxidizer. Lunar fuel plant designs are based around hydrolox. ISRU availability of nitrogen and carbon on the Moon is limited to trace amounts. Refueling satellites using Lunar fuel will require importing both nitrogen and carbon.
We want hydrogen, not oxygen, for spacecraft shielding. If we want to go the bulk mass route and use unprocessed rocks, grabbing an asteroid requires far less Dv. The trouble with the bulk mass route is we end up using a lot of fuel to get rock to the destination. That rock isn't useful for much else without processing. If we were building dozens of ships and stations it could make sense to build a rock processing center in space. We're not building dozens of ships and stations. At this stage is HSF it makes the most sense to send water to any stations/ships we build. At least there are multiple uses for the water.
The Moon simply is not a good source of resources. To change this we either need to import carbon and nitrogen(Assuming we don't discover extractable local sources in the quantities needed). Depending on the labor force needed to operate an industrial mass-production facility(Robots are great but, for the foreseeable future, we still need the guy with the spanner.) and the supply chain it is questionable whether we would have enough hydrogen for local uses. If we are going to the Moon using tax dollars it has to be because people actually want to live on the Moon. If casino owners want to set up Lunar Vegas on their own dime that is fine with me.
I am hoping the Sabre engine will fly. I don't see what exactly Skylon has to do with a discussion about the Moon versus Mars. Skylon is a space plane to LEO. When(think positive) it is operational it should lower the cost to Earth's surface to LEO. If anything it will make it more difficult for Lunar exports to compete.
Because I don't think I've covered it, which means it will probably come up, hydrolox(H2/O2) is not suitable for use as a satellite fuel. The current goal for "long-term" hydrogen storage on orbit is seven days(ACES developmental second stage).
Obviously we need fertilizer for our crops. Initially the rocket fuel plant will provide a large portion of our buffer gases(Nitrogen and argon being roughly 5% of the atmosphere). Trace elements such as phosphorus and sulfur are available in the Martian dust(Ideally we will find more concentrated sources but we have the elements we need). While I haven't fully examined everything need to make fertilizer all of the ingredients are available on Mars.
Yes, plants require oxygen. That doesn't really matter. Food crops will provide roughly twice the oxygen humans need. Crops grown for other purposes, fibers like cotton for textiles and cellulose for plastics production, further enhance the oversupply of oxygen. Inside we have far too much total oxygen. The little bit plants require is already available so there is no reason to be overly concerned.
Outside we already plenty of oxidizers available. What we really need on Mars is fuel.
I ain't Spartacus,
The answer is because we can. Once we get there we know we will learn valuable things but, because we don't yet know what those things are, we have no clue how to monetize them. At this point all that we can do is determine which short-term goals won't be able to turn a profit.
Excepting tourism all of the Lunar options you list require markets that don't yet exist. Our current satellite fleet was not designed to be repaired, serviced, or refueled. Much of the planned research into developing industrial processes got delayed when Shuttle cancellation was announced, and is still on hold. While you didn't mention it, I will add that He-3 mining requires fusion, which is still two decades away.
Honestly my preference is to go to as many places as we can. The problem is that there simply isn't enough money. Since we can afford to start one colony, assuming we don't use the traditional supply-side oriented funding techniques, the question is which target provides us with the best options for developing a local economy? Based on the information available, developing a local economy appears far easier on Mars. As ships that can travel from Earth to Mars will be able to easily do the Lunar trip(A Lunar specific lander is desirable though.) private enterprise can go to the Moon once there is demand for products they can make.
As others have noted this is just a re-release of last year's presentation. Rumor(Well Musk did twit that it is coming but I stubbornly refuse to use twitter as a source) is that Mars Plan V2 is coming out soon.
It would be much cheaper to send him by himself.
While I'm not one to be overly concerned with planetary protection that is far too much contamination risk.
We don't want to land on the water supply. The heat from rocket exhaust is not conducive to keeping ice solid. I work under the assumption that a Martian spaceport will be 10-15 km from our primary ice mining operations. We're most likely going to be stuck lugging fuel or water around. CO2 collection is far less site-specific.
Please note that this is an assumption that will change based on site surveys. We could find the Martian equivalent of a peninsula. While fuel production still needs setbacks(one does not land rockets on top of solar panels and we can't neglect transmission losses) it is possible we will find a location that allows for transportation distances of less than a km. Since we have yet to begin investigating potential landing sites it is safest to include more fuel transportation in the mass budget.
When deciding on where to place the location there are two factors. How much Dv it will take to get there and what resources are available. The Moon's lack of atmosphere means that the total Dv to reach either destination isn't markedly different(Areocapture and areobraking really are that valuable). There are more identified resources on Mars than the Moon. If humans have problems with values of G between 0.16% and 0.99%we expect them to be worse at lower G levels(As we have no data this is just a guess).
Historically the number of colonists who have returned to their homelands is nearly 0%. Since, at current transportation costs, there will be very little in the way of physical goods returned, the added return costs are not a major consideration.
At the end of end of the day what matters is what resources we have available, how difficult it is to utilize those resources, and who will use those resources. On the first two points, based on everything we know, Mars wins. On the third point the Moon has a slight edge. Short travel times mean that we expect tourists in addition to the colonists. So far I've not been able to find production techniques that allow the expanded customer base to make up for the higher costs of local production. For long-term growth the target we want is Mars.
If you happen to have a business model for the Moon I have yet to consider, I could be convinced going to the Moon first is worth the effort. Please be aware the export cases commonly used, fuel depots and computer chip manufacturing to name a couple, require customers and a comparative advantage that overcomes the cost which do not exist unless we are undertaking a larger project, like colonizing Mars. For now the Moon is a path to nowhere economically.
We also have to consider that virtually all of the equipment for Mars and the Moon is similar, just more robust for the longer trips required to reach Mars. Design for Mars and we end up going to the Moon as well by default. Personally I'd prefer to target a more difficult destination(Both the Moon and Mars can be expected to be water importers) but few others are willing to consider targets like Ceres.
The estimate is that each ITS return will require 40,000 m² of solar panels.
As ITS is still a paper rocket this figure is for reference purposes only. It does give us a sense of the scale needed, which, at this point, is what we need.
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