My opinion and as it turns out, the actual proposal, is to open one of them and leave the others unopened. We don't know when there will be the opportunity to get more of them and there probably will be even more sophisticated equipment available in the future. So I wouldn't open them all. But saving them until they're useless is also a bad idea (that's usually what happens with my consumables in video games).
The thread for space cadets!
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My opinion and as it turns out, the actual proposal, is to open one of them and leave the others unopened. We don't know when there will be the opportunity to get more of them and there probably will be even more sophisticated equipment available in the future. So I wouldn't open them all. But saving them until they're useless is also a bad idea (that's usually what happens with my consumables in video games).
hobbsyoyo
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Great idea!
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Engineers have tested the first air-breathing electric engine. This technology will allow a spacecraft to skim the atmosphere without need for fuel for as long as the engine holds out. Basically, in very low orbits there is enough drag to bring down satellites in short order. But there's a lot of good science you can do at this altitude, so scientists want to be able to work in that regime. There have been atmosphere-skimming missions before but they were very short lived. There was an electric-powered satellite that managed to stay up for a few years until its propellant ran out. This system would allow a probe to stay up indefinitely. I do think however, that the use of ionized oxygen will create a ton of wear on the engine but here's hoping they can solve that problem so that the system can work longer than a conventional electric propulsion system.
https://phys.org/news/2018-03-world-first-air-breathing-electric-thruster.html
It's pink because it's using nitrogen and oxygen instead of xenon.
warpus
Sommerswerd asked me to change this
That's neat. I wonder if space stations like the ISS could use this technology to fix their orbit without having to get supplies from the surface?
The engine is designed to work at 200 km altitude. The ISS orbits at a height of about 400 km. Since air density decreases exponentially with height, I don't think you have any hope of using it at 400 km without a complete redesign. I was going to estimate the relative pressure at these two altitudes, but discovered that I don't know enough of thermosphere physics to make an estimate in which I would have any confidence.
That said, if you have such an engine and are designing a space station, you could just design it to operate it at 200 km.
But while fuel is a major part of the resupplies, it isn't the only one. The amount of water the Progress resupply missions bring is on the same order of magnitude as the fuel. So even if you eliminated the need for fuel, you would still need quite a few resupply missions.
hobbsyoyo
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Another massive problem for lowering the orbit is that the ISS's solar panels are essentially giant drag plates. I mean you'd already need a much bigger thruster than what they developed to keep the station up at 400 km (assuming it could suck up enough air, which it can't). But if you were trying to operate it at 200 km, you'd need a massive cluster of thrusters which would in turn need even more solar panels. I'm not really sure you could do it from a practical standpoint. And of course the problem of gradual erosion from atmospheric molecular collisions would be much, much worse at that altitude so you'd be having to replace those monstrous solar panels regularly along with other components.
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Re: Stratolaunch
So apparently they are thinking about designing a re-usable space shuttle (codenamed Black Ice) in Stratolaunch to serve as the payload-delivering stage. It would be about twice the size of the actual space shuttle but would almost certainly have only a fraction of the payload capacity since it would have to carry all of the fuel for getting to orbit internally. In any case, a big space shuttle makes a lot more sense for this massive plane than a bunch of tiny little rockets.
https://www.washingtonpost.com/news...ttle-called-black-ice/?utm_term=.df2eac03a26a
warpus
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Sounds expensive. Seems to me that everybody should be trying to come up with designs to compete with the BFR, not build giant space shuttles
hobbsyoyo
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I think BFR is probably overkill for the market. That's the reason that SpaceX designed a smaller version of their next rocket because they deemed the one they presented in 2016 to be too big to service the market. The new BFR is supposed to be a compromise in that it's just big enough for Mars colonization but not too big for the current commercial launch market. In the end, really, I think that their business case is going to depend on hauling dozens of their own internet satellites up in one go and in the market responding to the capabilities of the BFR to produce bigger satellites. If the latter doesn't happen, then they will be entirely reliant on their internet spin-off to make money.
I think New Glenn and Falcon Heavy are really about as big as the market can utilize to be honest. And the trend over the last 5 years or so has been toward smaller satellites. On the communications side, they are incorporating electric propulsion which has allowed them to shrink quite a bit. And of course electronics in general are getting smaller and more efficient which also helps. For everything but communications, there has been a big push to build up distributed fleets of CubeSats and other small sats that are less capable than the bigger birds but far, far cheaper. And for a lot of applications, dozens of tiny satellites are more valuable than a single huge satellite.
That's why I think Virgin Orbit, Rocket Labs and a few other small sat launchers have a bright future because they're catering to that trend for smaller satellites which right now kind of get shafted on the ride-share market.
Of course, if manned interplanetary spaceflight becomes a reality then NG and FH are too small and you really will need BFR-like rockets to service that market.
I think New Glenn and Falcon Heavy are really about as big as the market can utilize to be honest. And the trend over the last 5 years or so has been toward smaller satellites. On the communications side, they are incorporating electric propulsion which has allowed them to shrink quite a bit. And of course electronics in general are getting smaller and more efficient which also helps. For everything but communications, there has been a big push to build up distributed fleets of CubeSats and other small sats that are less capable than the bigger birds but far, far cheaper. And for a lot of applications, dozens of tiny satellites are more valuable than a single huge satellite.
That's why I think Virgin Orbit, Rocket Labs and a few other small sat launchers have a bright future because they're catering to that trend for smaller satellites which right now kind of get shafted on the ride-share market.
Of course, if manned interplanetary spaceflight becomes a reality then NG and FH are too small and you really will need BFR-like rockets to service that market.
warpus
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It surprised me when I first read that the BFR will render the falcon heavy obsolete, because that was my first thought.. "If the falcon heavy is being discontinued, how are they going to send up smaller payloads?" So I assumed their plan is to not hope for larger satellites, but rather to send up multiple payloads all at once? Would that not work? Seems odd that they're going this route if that's not possible. Might as well keep the falcon heavy around then.
Thorgalaeg
Deity
How many tons would be needed to launch to build a permanent base in mars? Including potato sacks.
I think the plan is that the BFR is cheaper to launch than a Falcon Heavy. If they achieve that, there is no point in keeping the latter around. As long as there is no cheaper alternative, it doesn't matter if the BFR launches half-empty. And even if the BFR will be more expensive to launch than the Falcon Heavy, SpaceX might still decide to discontinue the FH to generate business for the BFR and to save costs by having one production line instead of two. Customers would just have to pay for the BFR if there is no alternative.
The only danger of this strategy would be competitors building smaller and cheaper rockets that still can carry about everything customers want to send to space (and are also able to saturate the market). But I don't think that is going to be the case in the near future.
hobbsyoyo
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What Uppi said is the plan. I'm just dubious as to whether or not the cost savings will be as dramatic as they predict. However, this system will be built from the ground up with rapid reuse in mind which will make a huge impact on operating costs. And the fuels it will use will also be pretty cheap - Texas will actually pay companies to find uses for natural gas in some cases. Also the ability to land back on the launch mounts will itself be a massive cost savings - and SpaceX claims they already are approaching the necessary accuracy with the Falcon system.
Also, there is a ton of movement on the small sat launch services provider side right now so you really can't dismiss that segment of the market being lost to SpaceX - and SpaceX doesn't go out of their way to service the rideshare market to begin with.
Let me get back to you on this. I'll have to do some digging. I could find a source that would spell it out but I want to see if I can do a calculation myself and then compare it to more rigorous studies. My initial WAG (technical term actually used in aerospace - wild *** guess) is about a 1,000 metric tons for a very small settlement.
About permanent settlement on Mars - wouldn't weak gravity be a major obstacle for creating it? I read somewhere that people who spend long time on space stations, like a year or so, had serious health complications. And that were trained professionals. Imagine now people spending decades, or even born on Mars. Other problems are at least technically solvable, we can bring supplies, shield the base from radiation, etc., but what we can do with near weightlessness?
Thorgalaeg
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I think that health problems would come mainly from radiation. Low gravity is not very problematic as long as there is some. Problem is zero gravity.
Only 1000??? So 3-4 heavy launches? So ,the cost of 3-4 big airliners o a bunch of fighters?Inconceivable. We should have cities in Titan already.
Broken_Erika
Play with me.
Don't forget Chainsaws. 'Cause if your gonna have a mars base, it's gotta have a good supply of chainsaws.
"Leaving our Earth we promised
That apple trees will bloom on Mars"
From the song written in 1963
Spoiler :
hobbsyoyo
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Yeah it's the #1 problem in my opinion. You hit the nail on the head - everything else is a 'solved' problem more or less in that they mostly just take money and willpower to overcome. Reduced gravity is another thing altogether. We have a bit* of data on weightlessness and a ton of gravity on 1 g but no data on .3 g. We really have no idea how bad it will be long term - especially for babies born there. The ISS was intended to have a centrifuge lab to test this stuff in animal models but it was cancelled. There are no plans that I know of for <1 g test labs in orbit so likely the first data we'll get will be when people start going over there which is bad.
In science fiction they often get around this through drugs or one-person centrifuges that people use daily to strengthen their bones but who knows if that will be sufficient. Also, the trip out to Mars doesn't have to be super long and people can cope with a few months of weightlessness. But for some trajectories you're talking 9+ months of one-way travel which would be pretty detrimental.
*Despite decades of spaceflight, the vast majority of our astronauts have spent less than a month in space each and there have only been a few hundred astronauts in total. Thus the data set is so laughably small and incomplete that its hard to draw a lot of conclusions from it. There are a lot of things we do know but without more data I don't think we can make a lot of definitive statements on the long term effects of <1 g other than it's generally bad for your body.
Like I said above, we actually have 0 data to draw the conclusion that low gravity is fine. Given that only a dozen astronauts have experienced less than 1 g on the Moon (and only for 2-3 days at max), we really don't know anything about what it would do to our bodies.
Well that's why it's a WAG. I'm also looking at the problem from a minimum viable product viewpoint - so I'm trying to think of the minimum mass it would take to set up 3 or 4 people to live on Mars indefinitely. If you are interested in a bigger population then let me know and I'll adjust. But here's the partial set of assumptions I'm working from -
I'm thinking of an initial colony of just 3 or 4 people that could live indefinitely. The colony could grow slowly after the initial set up phase but the colony would self sufficient such that those initial people don't need anything else from Earth to live and so long as the transfer rate of new colonists is slow, they can continually add capacity to the colony through sourcing of local materials to allow for slow, controlled growth through immigration and organically. Most of the stuff they will bring will be excavation equipment and the vast majority of their raw material inputs will have to come from Mars itself. I'm also assuming they land in a relatively rich area with easily-accessible subsurface water and useful mineral deposits. Also, every piece of equipment they will bring will be mass-optimized, so I'm assuming a ~50% across the board cut to the mass of things like excavators.
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Thorgalaeg
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My totally baseless assumption is that they will be fine as long as remain in mars. But will be unable to return earth after a few years. They will not want anyway. Will want to stay in mars and become independient martians and we will have to apply the article 155 of the solar constitution.
hobbsyoyo
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I'm not actually convinced that's true. I like to think we can solve the problems that low-g life will incur but I don't know that for a fact. My biggest worry is actually gestation - will babies grow too large in the womb due to the reduce gravity? Who knows? I think centrifuges will be the short term solution to this problem (if it turns out to be a problem - again we can't say with certainty) but it will be pretty inconvenient for people. Drugs and gene therapies will be easier I think though they may come with terrible side effects.
Thorgalaeg
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Babies already grow floating in the amniotic fluid. I doubt the fetus would notice anything.
Anyway is there any ISS experiment about gestation of mamals in space? It would be interesting to know if cells needs gravity to know the direction they must grow to. Wouldn't be the case in mars anyway as there is some gravity there.
And if kids get to big there is a thing called cesarean. It would be needed in the first generation of martians only though as in the next ones mothers would be as big as his giant childs. So we would have two species of humans in not time. Tall weak martians and short strong earthlings. Now you can crush my overoptimistic views.
Anyway is there any ISS experiment about gestation of mamals in space? It would be interesting to know if cells needs gravity to know the direction they must grow to. Wouldn't be the case in mars anyway as there is some gravity there.
And if kids get to big there is a thing called cesarean. It would be needed in the first generation of martians only though as in the next ones mothers would be as big as his giant childs. So we would have two species of humans in not time. Tall weak martians and short strong earthlings. Now you can crush my overoptimistic views.
