More important, how do you handle the radiation environments which are brutal.
What's the point of manned missions to gas giants?
Nevertheless http://trajbrowser.arc.nasa.gov says that the DeltaV to eg. Vesta is higher than to Jupiter which somehow suprises me. Is it due to the fact that you need to "slow" down when arriving at Vesta, while there is no such need when caught into Jupiter's potential well?
Ceres is where we should go after Mars. Much closer, could be really interesting.
Quote from: xanmarus on 11/01/2014 06:01 pmWhat's the point of manned missions to gas giants?Not the gas giants themselves, but Europa, Ganymede and Callisto. Besides Mars, the most suitable places to be in the solar system - and with a lot more resources than Mars. The natural next step if a Mars colony is successful.
Why not Venus? I have seen intresting suggestions for in air floating hab
Quote from: docmordrid on 11/01/2014 07:53 pmMore important, how do you handle the radiation environments which are brutal.Easier to shield than GCR is. But anyway, just visit Callisto instead which has far lower radiation levels.
Quote from: PerW on 11/02/2014 05:51 pmWhy not Venus? I have seen intresting suggestions for in air floating habWell, you beat me to it!The proposed BFR + second stage should be capable of launching a couple of Ba330 or a single [conceptual] Ba2100 to low Venus orbit. After that, a couple of MCTs might handle the logistics of such orbital station. Not sure if it makes sense for a manned program though, unless it is used for some sort of buoyant station in the atmosphere. I've seen some speculation on the feasibility of tethering a habitat 80 km above Venus surface, but it sounds far fetched to me. Even more than a Mars colony, in fact.
Why? Because a round-trip to Saturn is much further (more than twice as far from Earth) as Jupiter. And a trip to Jupiter is already a long trip. That's why you'd probably go to Callisto before Titan.
I was talking about visiting Callisto first vs visiting Titan. But you're already at colonization??
I suggest that the design of any manned spacecraft to the gas giants will depend mostly on the destination chosen. Planetary landers are specialists. A vehicle designed to land on Callisto will be substantially different from one sent to Titan. Any manned lander sent to the gas giants will be substantially different from MCT although it could quite easily incorporate many of MCT's systems. The same sort of "one size fits all" argument came up when people were proposing landing Dragon on the Moon or Venus etc. On the other hand a spacecraft intended to visit and orbit the moons and smaller bodies would be more generic in its design than any lander. These design trends are already present in current unmanned planetary spacecraft.
I'm with llanitedave on the matter of gravity wells for human space settlement. Keep away from them. Especially keep away from Titan with its dense, murky almost cryogenic atmosphere that could freeze an unprotected human solid in seconds. A great place to do research, a bad place to live.
Going by gravity, gentlemen, would then mean Elon shouldn't bother colonizing Mars at all.
I have long thought that an important economic step in establishing a space based economy comes from finding an ice trojan of Jupiter (or Saturn) that could be moved through a series of low energy maneuvers using some of its own mass as reaction mass in an NTR or STR to end up ( taking a fairly long time) in Earth orbit. The value of that resource there would be immense and enabling. If a Muskesque Martian Colony exists, then sending one of these into Mars orbit also makes sense.Of course we might then go all space opera and have ice pirates too!
Also left unmentioned is that for all of its issues with cold, your blood will not boil on Titan even if your suit springs a leak. On Callisto, Europa, Ceres and even Mars, you cannot say the same.
Quote from: Hyperion5 on 11/07/2014 04:37 pmAlso left unmentioned is that for all of its issues with cold, your blood will not boil on Titan even if your suit springs a leak. On Callisto, Europa, Ceres and even Mars, you cannot say the same.While I agree with your point (vacuum is deadly) one's blood doesn't really boil; the body can provide enough pressure to prevent that.
How long can a human live unprotected in space?If you don't try to hold your breath, exposure to space for half a minute or so is unlikely to produce permanent injury. Holding your breath is likely to damage your lungs, something scuba divers have to watch out for when ascending, and you'll have eardrum trouble if your Eustachian tubes are badly plugged up, but theory predicts -- and animal experiments confirm -- that otherwise, exposure to vacuum causes no immediate injury. You do not explode. Your blood does not boil. You do not freeze. You do not instantly lose consciousness.Various minor problems (sunburn, possibly "the bends", certainly some [mild, reversible, painless] swelling of skin and underlying tissue) start after ten seconds or so. At some point you lose consciousness from lack of oxygen. Injuries accumulate. After perhaps one or two minutes, you're dying. The limits are not really known.You do not explode and your blood does not boil because of the containing effect of your skin and circulatory system. You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly. Loss of consciousness occurs only after the body has depleted the supply of oxygen in the blood. If your skin is exposed to direct sunlight without any protection from its intense ultraviolet radiation, you can get a very bad sunburn.At NASA's Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in '65. He remained conscious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain. The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds. The subject regained consciousness at around 15,000 feet equivalent altitude. The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to boil.
Titan's air may be a better conductor of heat & cold than the air around Antarctica, but it's not so thick that it'd freeze you solid in seconds. For that sort of issue you'd need to chuck someone into one of Titan's liquid methane lakes or rivers.
Quote from: Hyperion5 on 11/07/2014 04:37 pmGoing by gravity, gentlemen, would then mean Elon shouldn't bother colonizing Mars at all. That's another thread, or course, but I'd be tempted to make that argument. Don't tell Mr. Musk, though, because his big dream, even if I think it's misplaced, is doing us all a whole lot of good in the meantime.
Your lungs can withstand maybe a couple psi, so you can hold your breath in vacuum a little bit (if you're breathing pure oxygen), which could help quite a bit.
Quote from: Robotbeat on 11/10/2014 12:17 pmYour lungs can withstand maybe a couple psi, so you can hold your breath in vacuum a little bit (if you're breathing pure oxygen), which could help quite a bit.Uh, no... Not unless you want to have your lungs blown out your nose and explode You let it ALL out or your in serious trouble. You should have a about half a minute or so of conscious activity available if you were pre-breathing pure O2.Randy
Your lungs and nose, etc, can withstand 1-2 (perhaps 3 for some) psi of pressure differential. That's a verifiable fact. It can be shown with a simple experiment.
Quote from: Robotbeat on 11/13/2014 12:04 am Your lungs and nose, etc, can withstand 1-2 (perhaps 3 for some) psi of pressure differential. That's a verifiable fact. It can be shown with a simple experiment.How do you retain 1-3 psi in your lungs? Sounds risky.Edit: Fixed quote
I think "2001" got this one right; "Gravity" certainly didn't...
200-220 MT of refined high grade material to LEO at a time with a fully reusable launcher and in space manufacturing with concepts like spider-fab and 3D electron beam welding printing changes the equation. Makes one wonder what could be built.A 10 meter center cylinder with 2 6 meter diameter torus's at 75m and 150m radius and 8 spokes, 1 cm thick would require 6 200 MT BFR Launches and provide 62X the interior volume of the space station. 0.5G on the inner ring and 1.0G on the outer ring.Another thread perhaps. Does anyone know a good one to discuss this?
Quote from: RanulfC on 11/10/2014 11:35 pmQuote from: Robotbeat on 11/10/2014 12:17 pmYour lungs can withstand maybe a couple psi, so you can hold your breath in vacuum a little bit (if you're breathing pure oxygen), which could help quite a bit.Uh, no... Not unless you want to have your lungs blown out your nose and explode You let it ALL out or your in serious trouble. You should have a about half a minute or so of conscious activity available if you were pre-breathing pure O2.RandyYou ignored what I said. Your lungs and nose, etc, can withstand 1-2 (perhaps 3 for some) psi of pressure differential. That's a verifiable fact. It can be shown with a simple experiment.
Hyperion: oxygen pressure at Everest is 1psi. Oxygen is only toxic at very high pressures (multiple atmospheres), ie while diving, so isn't relevant to this discussion.Speaking of, this is off-topic. What was supposed to just be a drive-by comment derailed the thread. I've proven my point so will say no more.
Quote from: Hyperion5 on 11/07/2014 04:37 pm Titan's air may be a better conductor of heat & cold than the air around Antarctica, but it's not so thick that it'd freeze you solid in seconds. For that sort of issue you'd need to chuck someone into one of Titan's liquid methane lakes or rivers.contact with the ground would be a bigger problem in the first instance. Have you ever stuck your hand in liquid nitrogen? I have done before for several seconds and it just boils. conversely I picked up a bit of frozen ethanol that we plucked out of the same dewar (we were playing with it) and I got a blister on my finger.
Quote from: Robotbeat on 11/13/2014 08:25 pmHyperion: oxygen pressure at Everest is 1psi. Oxygen is only toxic at very high pressures (multiple atmospheres), ie while diving, so isn't relevant to this discussion.Speaking of, this is off-topic. What was supposed to just be a drive-by comment derailed the thread. I've proven my point so will say no more.Your point was meant to emphasize that surviving the near-vacuum of Callisto is not as bad as it seems, especially relative to Titan's cold. ...
Back on topic I don't think MCT could handle the thermal environment or the duration of missions much beyond Mars.
Thermal, maybe, but if MCT can carry supplies for 100 people for 3-4 months, it could probably support a small crew for several years.
I think the bigger problem will be power - I expect MCT to be solar powered, which is fine for Earth-Mars and might even work out to the asteroids (a smaller crew might mean less power needs) but beyond that...
Also, delta-v needs and refueling. MCT will probably depend on aggressive aerobraking and refueling at the Mars end.
Quote from: Vultur on 11/14/2014 04:26 amThermal, maybe, but if MCT can carry supplies for 100 people for 3-4 months, it could probably support a small crew for several years. Agreed. MCT's have all the right pieces to support a small crew on longer 'exploration' missions. Quote I think the bigger problem will be power - I expect MCT to be solar powered, which is fine for Earth-Mars and might even work out to the asteroids (a smaller crew might mean less power needs) but beyond that... Agreed. Anything further out needs nuclear power.