I'm looking into the mini-magnetosphere too, but I don't think a plasma bubble shield is viable once landed on a celestial body, though I don't know enough to rule it out yet.What I'm looking into is whether an ITS in a high ionizing radiation environment could be modified to protect suited astronauts enough to allow a flags and footprints mission as depicted below. I think in this case the body landed on is Europa. If so the daily dose there is 54 rem this is about what the NASA astronaut dose is for a year.
Read an article somewhere that running a superconducting cable around Mars' equator powered by a good sized nuclear fission plant would produce a planetary mag field...
Quote from: philw1776 on 09/28/2016 11:50 pmRead an article somewhere that running a superconducting cable around Mars' equator powered by a good sized nuclear fission plant would produce a planetary mag field...Too add to this I vaguely remember reading somewhere that the time taken to erode an unshielded terraformed Martian atmosphere was about 1 million years. Not a time scale significant to an individual but definitely significant on a species level. Again no sources or maths to back this up, yet.
What I'm looking into is whether an ITS in a high ionizing radiation environment could be modified to protect suited astronauts enough to allow a flags and footprints mission as depicted below. I think in this case the body landed on is Europa. If so the daily dose there is 54 rem this is about what the NASA astronaut dose is for a year.
I think it is likely that any ITS designed for the deep solar system (Jupiter and beyond) will have some significant changes done for the crew area, to improve radiation protection and other systems.
What about the "plasma bubble" idea for mini-magnetosphere? If you can generate a plasma bubble that's a few hundred meters across, then that could protect your ship:
Quote from: sanman on 09/28/2016 11:40 pmWhat about the "plasma bubble" idea for mini-magnetosphere? If you can generate a plasma bubble that's a few hundred meters across, then that could protect your ship:To shield from radiation you'd need a extremely high optical density plasma that could absorb relativistic particles. If we could do that, ITER and NIF would have already succeeded.NIF is the furthest along with alpha heating (means it absorbs X rays - which are a fraction of the optical density to absorb relativistic protons/alpha particles). Only works for seconds, takes huge apparatus, size of plasma in centimeters (or less!).Simply - "no". What would you need here to work as a shield ? Something that would constructively cancel inbound particles momentum on itself. So you'd need to know in advance where it would be, what momentum vector it has, and cancel (thermalize) much of the energy.If you figure it out, there are a lot of smart people who'd love to know too ...
Quote from: Space Ghost 1962 on 09/29/2016 12:29 amQuote from: sanman on 09/28/2016 11:40 pmWhat about the "plasma bubble" idea for mini-magnetosphere? If you can generate a plasma bubble that's a few hundred meters across, then that could protect your ship:To shield from radiation you'd need a extremely high optical density plasma that could absorb relativistic particles. If we could do that, ITER and NIF would have already succeeded.NIF is the furthest along with alpha heating (means it absorbs X rays - which are a fraction of the optical density to absorb relativistic protons/alpha particles). Only works for seconds, takes huge apparatus, size of plasma in centimeters (or less!).Simply - "no". What would you need here to work as a shield ? Something that would constructively cancel inbound particles momentum on itself. So you'd need to know in advance where it would be, what momentum vector it has, and cancel (thermalize) much of the energy.If you figure it out, there are a lot of smart people who'd love to know too ...Tell CERN & ESA before it's too latehttp://www.sr2s.eu/"The aim of the (SRS2) project has been to develop, validate and increase the Technology Readiness Level (TRL) of the most critical technologies related to a magnetic shielding system for protecting astronauts’ lives during long duration space missions.Long duration permanence in deep space or on the surface of planet not protected by a thick atmosphere and/or magnetosphere represent a challenge which remains, as today, unsolved. Long term exposure to Galactic Cosmic Rays (GCR) and Solar Energetic Particles (SEP) is thought to cause a significant increase in the probability of various type of cancers. Means to adequately shield the astronauts from the ionising radiation are required in order to realistically plan for exploration missions to Mars"
If nuclear reactor was installed on ITS, then you probably don't need the solar panels anymore. (Could reactor be installed somewhere in aft section, below the methalox tanks for better shielding?)
Oh, and to give you the idea how much flux we are talking about, remember that when a SC like Juno dives into the radiation field, the metal of the SC warms up significantly. It's really a massive amount of radiation. Quote from: philw1776 on 09/29/2016 12:32 amQuote from: Space Ghost 1962 on 09/29/2016 12:29 amQuote from: sanman on 09/28/2016 11:40 pmWhat about the "plasma bubble" idea for mini-magnetosphere? If you can generate a plasma bubble that's a few hundred meters across, then that could protect your ship:To shield from radiation you'd need a extremely high optical density plasma that could absorb relativistic particles. If we could do that, ITER and NIF would have already succeeded.NIF is the furthest along with alpha heating (means it absorbs X rays - which are a fraction of the optical density to absorb relativistic protons/alpha particles). Only works for seconds, takes huge apparatus, size of plasma in centimeters (or less!).Simply - "no". What would you need here to work as a shield ? Something that would constructively cancel inbound particles momentum on itself. So you'd need to know in advance where it would be, what momentum vector it has, and cancel (thermalize) much of the energy.If you figure it out, there are a lot of smart people who'd love to know too ...Tell CERN & ESA before it's too latehttp://www.sr2s.eu/"The aim of the (SRS2) project has been to develop, validate and increase the Technology Readiness Level (TRL) of the most critical technologies related to a magnetic shielding system for protecting astronauts’ lives during long duration space missions.Long duration permanence in deep space or on the surface of planet not protected by a thick atmosphere and/or magnetosphere represent a challenge which remains, as today, unsolved. Long term exposure to Galactic Cosmic Rays (GCR) and Solar Energetic Particles (SEP) is thought to cause a significant increase in the probability of various type of cancers. Means to adequately shield the astronauts from the ionising radiation are required in order to realistically plan for exploration missions to Mars"GCRs are often neutral, and do cleave proteins. They can only be scattered. SEP's are charged and have higher flux.Lots of science is spent tilting at windmills. Sometimes they succeed. We've been attempting controlled fusion for longer than I've been alive. Lets not plan on anytime soon for that, ok?add:Oh, and those people are among the ones who'd like to know, how you did it.
Sailors aboard nuclear submarines get a lower dose of radiation than people working a 9-5 office job, even with the bunks right next door to the reactor compartment.
Okay, but terrestrial isn't as mass-constrained as space hardware. Hopefully proper design would mitigate risks.
Big problems with SR2S, it's a large system and only protects the volume that it contains. Your walk is only going to be a few meters before you need to move the system. Perhaps it could be fitted to a rover but not a suit.
The prospects of those Europa explorers coming home with much more than a couple of selfies is looking remote.
Compute the gyroradius of a N Mev proton of alpha particle. You'll find you need a unhealthful magnetic field strength to encompass such a ship.
And:https://gravityandlevity.wordpress.com/2015/01/12/how-strong-would-a-magnetic-field-have-to-be-to-kill-you/
And:https://www.sott.net/article/282845-The-effects-of-magnetic-fields-on-the-body
Quote from: Space Ghost 1962 on 10/03/2016 12:30 amAnd:https://gravityandlevity.wordpress.com/2015/01/12/how-strong-would-a-magnetic-field-have-to-be-to-kill-you/Yeah, I read that when I was looking it up. It's clear that insanely strong (magnetar level) fields would be fatal. But there doesn't seem to be any real knowledge between the ~8 Tesla humans have been exposed to (or maybe the slightly higher levels mice have been exposed to) and those ~100,000 Tesla magnetars.QuoteAnd:https://www.sott.net/article/282845-The-effects-of-magnetic-fields-on-the-bodyThis website doesn't look reliable, anti-vaccination stuff and such.
I thought it was mentioned but I don't remember where that the ITS should have its rocket end pointed to the sun and the windows pointed out to space to minimize radiation exposure to the occupants. Engines and tanks of LOX and LCH4 make good radiation blockers.
Elon Musk actually said it in his presentation, but it's nonsense. Most of the dangerous radiation in space are galactic cosmic rays and solar particle events from coronal mass ejections. In both cases the radiation is mostly isotropic, so the spacecraft orientation will not really matter. (my job is solar particle radiation research)
I suspect that it will be the other way around - prop tanks on the shady side to keep them from boiling off. Which would then mean that the window would be permanently in the glare of the Sun. Cheers, Martin
Quote from: obsever on 10/06/2016 04:24 pmElon Musk actually said it in his presentation, but it's nonsense. Most of the dangerous radiation in space are galactic cosmic rays and solar particle events from coronal mass ejections. In both cases the radiation is mostly isotropic, so the spacecraft orientation will not really matter. (my job is solar particle radiation research)So whats the truth? I would assume solar radiation(flares etc) would be pretty much from the sun only. I can see cosmic being pretty isotropic. Though even that has some galactic orientation depending on charge or no charge for the particles.
I would have thought coronal mass ejections would produce nonisotropic radiation.
Does that mean the only way to safeguard against that possibility is to have a "radiation room" of some sort surrounded by water tanks?
There's got to be some maximum direction even if not everything comes from there.
I would have thought coronal mass ejections would produce nonisotropic radiation. Does that mean the only way to safeguard against that possibility is to have a "radiation room" of some sort surrounded by water tanks? Or would even that be ineffective?
Quote from: guckyfan on 10/06/2016 04:40 pmThere's got to be some maximum direction even if not everything comes from there.Now that I think about there is always two tales to a comet.One from light pressure.One from the solar wind.They look to be about ~15 deg apart from one another.
Stacking the bunks beds x3 would boost free floor space as you could then fit 6 pax in a 4 pax cabin and 9 pax in a 6 pax cabin.These images have 9 beds in a 3x3m (9m^2) space. History has proven that sort of sleeping space does work. From the images, I could do 4-6 months sleeping in space in a bunk that size. Which says a lot more than 50 pax could fit on each of the BFS 2 accommodation floors.
How much protection from radiation would the 2 unpressurized decks of densely-packed cargo provide (as a baseline to whatever additional protection offered by a solar-storm-safe-room)? Significant or negligible?
Quote from: TheTraveller on 10/03/2016 05:06 pmStacking the bunks beds x3 would boost free floor space as you could then fit 6 pax in a 4 pax cabin and 9 pax in a 6 pax cabin.These images have 9 beds in a 3x3m (9m^2) space. History has proven that sort of sleeping space does work. From the images, I could do 4-6 months sleeping in space in a bunk that size. Which says a lot more than 50 pax could fit on each of the BFS 2 accommodation floors.When I see this sort of stuff, it makes me wonder if people are thinking too much about how we do it in gravity. On this trip 'bunks' and 'cabins' are really going to serve two major purposes, privacy and sound suppression. Both of these purposes can be served with detachable/collapsible/flexible dividers (quilted fabric that attaches with velcro as one example). Rigid, walls, bunk beds, and mattresses aren't actually needed in zero-g. I think instead of picturing a permanent 'floorplan' it might be better to think in terms of sleeping accommodations that can be stowed when not needed and spaces that can be reconfigured for flexible use and to reduce claustrophobia.
This is going to sound dumb (and maybe it is, or at least funny), but there's a significant amount of self-shielding simply by having a hundred people close together in a big huddle. Significant shielding even for the people on the outside (they're still half-shielded).Food and water also work great.So if you just had a massive game of "sardines" in the pantry, you're good.
Quote from: Robotbeat on 10/07/2016 02:04 amThis is going to sound dumb (and maybe it is, or at least funny), but there's a significant amount of self-shielding simply by having a hundred people close together in a big huddle. Significant shielding even for the people on the outside (they're still half-shielded).Food and water also work great.So if you just had a massive game of "sardines" in the pantry, you're good.The highest shielding this can provide consistently to all passengers is 50% of the incoming radiation, presupposing an infinite number of passengers and no issues with ventilation. This is highly unsatisfactory, because incoming radiation may be more than twice a lethal dosage.
Quote from: Burninate on 10/07/2016 02:13 amQuote from: Robotbeat on 10/07/2016 02:04 amThis is going to sound dumb (and maybe it is, or at least funny), but there's a significant amount of self-shielding simply by having a hundred people close together in a big huddle. Significant shielding even for the people on the outside (they're still half-shielded).Food and water also work great.So if you just had a massive game of "sardines" in the pantry, you're good.The highest shielding this can provide consistently to all passengers is 50% of the incoming radiation, presupposing an infinite number of passengers and no issues with ventilation. This is highly unsatisfactory, because incoming radiation may be more than twice a lethal dosage.yeah, in a vacuum far outside the ship. Even the ship itself provides significant shielding.As I said, if you're surrounded by your food/water rations and your fellow passengers in a small space, you'll be fine.
Quote from: ThereIWas3 on 10/03/2016 09:02 pm...Millions to the person who perfects an efficient zero-G shower.How about a "Bath Bag"? Essentially, a large bag that a person would get into, sticking their head out through a hole that has elastic around it to "seal" it...
...Millions to the person who perfects an efficient zero-G shower.
Something that I haven't seen discussed is Electro-Magnetic Shielding...
Can I ask for a consensus as to whether Magnetic or other shielding techniques (outside of the physical barrier type), are feasible in the next 10-20 years, on a scale to protect ITS sized space craft in Space. NOT crew, leaving the confines of the space craft. Yes or No... I'm looking for learned opinion on this. No hand waving. Is it "magic, unicorns and fairy dust" or something that is way out, 100 + years, before a practical application is possible... Star Trek wishful thinking...Gramps
If we model ITS as a spherical shell of 30m in diameter, its effective shielding with 150t of dry mass is 5g/cm^2, but most of that is probably carbon fiber and epoxy, which are significantly better per weight than aluminum, Which makes up partly for the fact the mass isn't evenly distributed. So already, you have enough shielding to weather the worst solar storms recorded. Plus you have landing propellant and especially a whole bunch of food and water.If we assume 200kg of food, water, and other consumables per person, you could have a shield 2m by 0.5m that's good for 20g/cm^2 of highly effective shielding. Arrange in a spherical phalanx with the other passengers, you have better shielding than is listed in this graph, which assumed crappy aluminum.As you can see, solar flares would pose zero immediate mortal danger just by using the mass already on hand. Also, flares mellow out as they get further from the Sun, and these are basically the worst flares recorded:
Musk mentioned short transits to Mars. I remember an old presentation (non SpaceX) where a short (3 months) transit would make more sense in terms of food, water and reduced radiation.An 8 month transit makes sense for a probe but with consumables for people it pays off to spend more fuel and do a faster transit.It is an optimization between fuel and consumables + radiation shielding.My bet is that part of radiation mitigation will be achieved by short transits.
Quote from: Robotbeat on 10/07/2016 03:32 pmIf we model ITS as a spherical shell of 30m in diameter, its effective shielding with 150t of dry mass is 5g/cm^2, but most of that is probably carbon fiber and epoxy, which are significantly better per weight than aluminum, Which makes up partly for the fact the mass isn't evenly distributed. So already, you have enough shielding to weather the worst solar storms recorded. Plus you have landing propellant and especially a whole bunch of food and water.If we assume 200kg of food, water, and other consumables per person, you could have a shield 2m by 0.5m that's good for 20g/cm^2 of highly effective shielding. Arrange in a spherical phalanx with the other passengers, you have better shielding than is listed in this graph, which assumed crappy aluminum.As you can see, solar flares would pose zero immediate mortal danger just by using the mass already on hand. Also, flares mellow out as they get further from the Sun, and these are basically the worst flares recorded:An issue is that radiation dose monitoring was going on only for about 4 solar cycles, and the Sun likes to surprise us sometimes. This study included an estimate for a hypotetical SPE that could have accompanied the "Carrington Flare", the strongest solar flare ever observed (in 1859):http://www.swsc-journal.org/articles/swsc/pdf/2014/01/swsc130038.pdfThe radiation dose from such event could be deadly with 5 g/cm^2 shielding and with 20-30 g/cm^2 shielding (7-11 cm of Al, typical for ISS Columbus module according to the paper) would still exceed the 30-days limit recommended for ESA astronauts, although the colonists might perhaps accept such risk.
This graph shows it most clearly as it gives a range of materials from hydrogen to lead.As you can see on the right, even the smallest hydrogen shield reduces the radiation dose. Whereas for aluminum, there's a large portion of the right curve where the aluminum makes you worse off, but eventually helps some as you approach 30g/cm^2. For lead, it's the entire curve to beyond 30grams/cm^2 where it makes the effective dose much worse. Carbon fiber composite would be somewhere near water as far as effectiveness. As you can see, it's better than aluminum.
Carbon fiber has a very high hydrogen content and should shield similar to water for the same mass/area.
See this post for more details (follow the quote link to see the image):
Quote from: envy887 on 10/07/2016 08:05 pmCarbon fiber has a very high hydrogen content and should shield similar to water for the same mass/area.First sentence in wikipedia on carbon fibre: "...composed mostly of carbon atoms."Not any hydrogen really.
QuoteSee this post for more details (follow the quote link to see the image):Thanks, interesting thread. I'll have a closer look. From a quick look at that post, the plot refers to GCR, which is composed mostly from heavy nuclei contain a lot more heavy nuclei than SEP.We were talking about SEP events, which are composed >90% percent of protons so the implications on shielding materials are very different. I think g/cm^2 is a good parameter to use in this case.In any case, with the amount of cargo carried on the ITS I'm already quite convinced that making an ad-hoc radiation shelter from food supplies, etc., should reduce the risk from SEP events to reasonably acceptable levels.But now that you brought up GCR... that is potentially a lot nastier problem. I don't have much experience with GCR modelling, but a colleague of mine who has some is saying that with any amount of shielding (even low-Z materials) you always get a lot of secondary radiation and it's impossible to reduce that. He for sure doesn't have experience with spacecraft of ITS size (because no one does) and possible solutions such size might offer, but dealing with GCR might be an interesting challenge.Edit: I think developing something like this might be the best solution: https://www.newscientist.com/article/dn26840-anti-radiation-drug-could-work-days-after-exposure/
Quote from: obsever on 10/07/2016 04:42 pmQuote from: Robotbeat on 10/07/2016 03:32 pmIf we model ITS as a spherical shell of 30m in diameter, its effective shielding with 150t of dry mass is 5g/cm^2, but most of that is probably carbon fiber and epoxy, which are significantly better per weight than aluminum, Which makes up partly for the fact the mass isn't evenly distributed. So already, you have enough shielding to weather the worst solar storms recorded. Plus you have landing propellant and especially a whole bunch of food and water.If we assume 200kg of food, water, and other consumables per person, you could have a shield 2m by 0.5m that's good for 20g/cm^2 of highly effective shielding. Arrange in a spherical phalanx with the other passengers, you have better shielding than is listed in this graph, which assumed crappy aluminum.As you can see, solar flares would pose zero immediate mortal danger just by using the mass already on hand. Also, flares mellow out as they get further from the Sun, and these are basically the worst flares recorded:An issue is that radiation dose monitoring was going on only for about 4 solar cycles, and the Sun likes to surprise us sometimes. This study included an estimate for a hypotetical SPE that could have accompanied the "Carrington Flare", the strongest solar flare ever observed (in 1859):http://www.swsc-journal.org/articles/swsc/pdf/2014/01/swsc130038.pdfThe radiation dose from such event could be deadly with 5 g/cm^2 shielding and with 20-30 g/cm^2 shielding (7-11 cm of Al, typical for ISS Columbus module according to the paper) would still exceed the 30-days limit recommended for ESA astronauts, although the colonists might perhaps accept such risk.g/cm2 is a VERY poor way to compare materials. 5 g/cm2 of water is better than 20 g/cm2 of aluminum. Carbon fiber has a very high hydrogen content and should shield similar to water for the same mass/area.See this post for more details (follow the quote link to see the image):Quote from: Robotbeat on 08/19/2016 12:56 pmThis graph shows it most clearly as it gives a range of materials from hydrogen to lead.As you can see on the right, even the smallest hydrogen shield reduces the radiation dose. Whereas for aluminum, there's a large portion of the right curve where the aluminum makes you worse off, but eventually helps some as you approach 30g/cm^2. For lead, it's the entire curve to beyond 30grams/cm^2 where it makes the effective dose much worse. Carbon fiber composite would be somewhere near water as far as effectiveness. As you can see, it's better than aluminum.
Quote from: envy887 on 10/07/2016 08:05 pmQuote from: obsever on 10/07/2016 04:42 pmQuote from: Robotbeat on 10/07/2016 03:32 pmIf we model ITS as a spherical shell of 30m in diameter, its effective shielding with 150t of dry mass is 5g/cm^2, but most of that is probably carbon fiber and epoxy, which are significantly better per weight than aluminum, Which makes up partly for the fact the mass isn't evenly distributed. So already, you have enough shielding to weather the worst solar storms recorded. Plus you have landing propellant and especially a whole bunch of food and water.If we assume 200kg of food, water, and other consumables per person, you could have a shield 2m by 0.5m that's good for 20g/cm^2 of highly effective shielding. Arrange in a spherical phalanx with the other passengers, you have better shielding than is listed in this graph, which assumed crappy aluminum.As you can see, solar flares would pose zero immediate mortal danger just by using the mass already on hand. Also, flares mellow out as they get further from the Sun, and these are basically the worst flares recorded:An issue is that radiation dose monitoring was going on only for about 4 solar cycles, and the Sun likes to surprise us sometimes. This study included an estimate for a hypotetical SPE that could have accompanied the "Carrington Flare", the strongest solar flare ever observed (in 1859):http://www.swsc-journal.org/articles/swsc/pdf/2014/01/swsc130038.pdfThe radiation dose from such event could be deadly with 5 g/cm^2 shielding and with 20-30 g/cm^2 shielding (7-11 cm of Al, typical for ISS Columbus module according to the paper) would still exceed the 30-days limit recommended for ESA astronauts, although the colonists might perhaps accept such risk.g/cm2 is a VERY poor way to compare materials. 5 g/cm2 of water is better than 20 g/cm2 of aluminum. Carbon fiber has a very high hydrogen content and should shield similar to water for the same mass/area.See this post for more details (follow the quote link to see the image):Quote from: Robotbeat on 08/19/2016 12:56 pmThis graph shows it most clearly as it gives a range of materials from hydrogen to lead.As you can see on the right, even the smallest hydrogen shield reduces the radiation dose. Whereas for aluminum, there's a large portion of the right curve where the aluminum makes you worse off, but eventually helps some as you approach 30g/cm^2. For lead, it's the entire curve to beyond 30grams/cm^2 where it makes the effective dose much worse. Carbon fiber composite would be somewhere near water as far as effectiveness. As you can see, it's better than aluminum.I'm gonna need a citation on that.https://three.jsc.nasa.gov/articles/CucinottaKimChappell0512.pdf suggests that aluminum at the same cross-sectional mass will give a dose of about 10-20% higher than water, by table 6 and 7.
I'm looking at figure 4 on GCR-spectrum shielding from page 24 of http://asgsb.indstate.edu/bulletins/v16n2/v16n2p19-28.pdf , the one that was snipped into an attachment... and I'm not seeing it. The line for water and the line for aluminum are not that far from each other.
The effects are highly non-linear, so saying "equivalent mass per area" doesn't mean much in terms of dose. I'm comparing the effective dose of GCR through 20g/cm2 Al and 5 g/cm2 water and they look like the same dose on the chart.
If we assume 200kg of food, water, and other consumables per person, you could have a shield 2m by 0.5m that's good for 20g/cm^2 of highly effective shielding. Arrange in a spherical phalanx with the other passengers, you have better shielding than is listed in this graph, which assumed crappy aluminum.As you can see, solar flares would pose zero immediate mortal danger just by using the mass already on hand. Also, flares mellow out as they get further from the Sun, and these are basically the worst flares recorded:
You are right that an anti-radiation drug is probably the very best solution, long-term. I'm hopeful we can develop something better than Amifostine.
Quote from: obsever on 10/07/2016 09:58 pmQuote from: envy887 on 10/07/2016 08:05 pmCarbon fiber has a very high hydrogen content and should shield similar to water for the same mass/area.First sentence in wikipedia on carbon fibre: "...composed mostly of carbon atoms."Not any hydrogen really.Sorry, should have said carbon fiber based composites. The fiber itself isn't hydrogenated, but the resin typically is.
Don't high-energy protons also create secondaries?
Quote from: Robotbeat on 10/07/2016 03:32 pmIf we assume 200kg of food, water, and other consumables per person, you could have a shield 2m by 0.5m that's good for 20g/cm^2 of highly effective shielding. Arrange in a spherical phalanx with the other passengers, you have better shielding than is listed in this graph, which assumed crappy aluminum.As you can see, solar flares would pose zero immediate mortal danger just by using the mass already on hand. Also, flares mellow out as they get further from the Sun, and these are basically the worst flares recorded:That chart looks like it says even the worst flare on there (Aug 72) is between "5% chance of vomiting" and "5% chance of death" at only 0.3 g/cm^2. Am I reading that wrong?
If not, do solar flares strong enough to kill by acute radiation sickness even exist short of something like the Carrington event?
Quote from: Vultur on 10/08/2016 08:28 amQuote from: Robotbeat on 10/07/2016 03:32 pmIf we assume 200kg of food, water, and other consumables per person, you could have a shield 2m by 0.5m that's good for 20g/cm^2 of highly effective shielding. Arrange in a spherical phalanx with the other passengers, you have better shielding than is listed in this graph, which assumed crappy aluminum.As you can see, solar flares would pose zero immediate mortal danger just by using the mass already on hand. Also, flares mellow out as they get further from the Sun, and these are basically the worst flares recorded:That chart looks like it says even the worst flare on there (Aug 72) is between "5% chance of vomiting" and "5% chance of death" at only 0.3 g/cm^2. Am I reading that wrong? I'm wondering what "5% chance of death" means, death by acute radiation sickness or from developing cancer later in life?
Quote from: Vultur on 10/08/2016 08:28 amQuote from: Robotbeat on 10/07/2016 03:32 pmIf we assume 200kg of food, water, and other consumables per person, you could have a shield 2m by 0.5m that's good for 20g/cm^2 of highly effective shielding. Arrange in a spherical phalanx with the other passengers, you have better shielding than is listed in this graph, which assumed crappy aluminum.As you can see, solar flares would pose zero immediate mortal danger just by using the mass already on hand. Also, flares mellow out as they get further from the Sun, and these are basically the worst flares recorded:That chart looks like it says even the worst flare on there (Aug 72) is between "5% chance of vomiting" and "5% chance of death" at only 0.3 g/cm^2. Am I reading that wrong?
I'm wondering what "5% chance of death" means, death by acute radiation sickness or from developing cancer later in life?...
Mars-bound astronauts face chronic dementia risk from galactic cosmic ray exposure
In fact, however, the study has no relevance for human Mars exploration, as the irradiation doses inflicted on the researchers’ unfortunate subjects has no relationship to what would be experienced by astronauts on their way to the Red Planet. The principal difference is that the rate that the dose was administered to the mice under study was four million times faster than that what travelers in interplanetary space would experience. In addition, the total cumulative dose delivered to the mice inside of 30 seconds was about 50 percent greater than the GCR dose that astronauts would receive over the course of a 2.5-year Mars mission.
It is shocking that the authors neglected to caveat the significance of their results by admitting these differences. Not only that, they kept the information about actual dose rates employed buried deep within the paper (it can be found in the middle of a text paragraph towards the end entitled “Animals, heavy ion irradiation, and tissue harvesting”), thereby allowing it to easily be missed by popular science writers duped into reporting the allegedly sensational implications of their irrelevant work.
Radiation and zero/reduced gravity are serious issues and Zubrin by his approach (superficial analysis and ridicule) has failed to slay those dragons. ...In The Case For Mars Zubrin claims that the increased risk of dying from cancer is about 1% and that this is much less than either the expected risk of dying from cancer of 20% or the risk to the crew from the Mars mission from other causes. He may be right, but I would want to see a peer reviewed report written by acknowledged experts in the field. Total cancer risk depends on lifestyle, by being accepted onto astronaut training and then going on a Mars mission will change the lifestyle of the crew. This effect is likely to be of the same order as the radiation effect, but it is unclear whether it is positive or not. Risk of dying from cancer is greatly effected by early diagnosis and high quality treatment. The crew both before and after a Mars mission are likely to get much better health care than the general population. These and several other factors make it difficult to produce definitive results.
That ridiculous study basically subjected those poor mice to 150% the total GCR dose of a 2.5 year Mars mission in the space of 30 seconds.Imagine a coffee drinker drinking 2.5 years of caffeine in a single cup. They'd either immediately vomit (we hope) or they'd die as they'd have FAR exceeded the ability of the body to cope with the substance.So again, that study is severely flawed and shouldn't even be discussed. I'd argue for either its retraction or its amendment.
You want good results it'll cost. You don't, then you get what you asked for.
It seems to me the discussion here is going in circles.
(For the last, a long life HSF vehicle fitted with a test cell and robotic lab animal environment management, launched on a highly elliptic orbit would be a means to that end.)
Phenolic impregnated carbon (something).Phenolic is basically a benzene ring.Lots of carbon and one oxygen and lots and lots of hyrdrogen.Sounds good.
Quote from: Space Ghost 1962 on 10/13/2016 12:36 am(For the last, a long life HSF vehicle fitted with a test cell and robotic lab animal environment management, launched on a highly elliptic orbit would be a means to that end.)But highly elliptical orbit would fly them through the van Allen belt many times. This is not a realistic deep space environment and likely lethal.
Placing them in L4 or L5 would be a better way IMO. Or L1 L2. The proximity of the moon should not affect radiation that much there.
Quote from: guckyfan on 10/13/2016 06:24 amQuote from: Space Ghost 1962 on 10/13/2016 12:36 am(For the last, a long life HSF vehicle fitted with a test cell and robotic lab animal environment management, launched on a highly elliptic orbit would be a means to that end.)But highly elliptical orbit would fly them through the van Allen belt many times. This is not a realistic deep space environment and likely lethal.Nope. Only on departure/return. Which astros would also have to do. Am talking a single "orbit", possibly leveraged with a lunar alignment coming/going.The point is to have objective physiological data.
So is there any information available about the density of Pica-X and the thickness required for 24 re-entries at hyperbolic speeds?
Quote from: Space Ghost 1962 on 10/13/2016 08:26 pmQuote from: guckyfan on 10/13/2016 06:24 amQuote from: Space Ghost 1962 on 10/13/2016 12:36 am(For the last, a long life HSF vehicle fitted with a test cell and robotic lab animal environment management, launched on a highly elliptic orbit would be a means to that end.)But highly elliptical orbit would fly them through the van Allen belt many times. This is not a realistic deep space environment and likely lethal.Nope. Only on departure/return. Which astros would also have to do. Am talking a single "orbit", possibly leveraged with a lunar alignment coming/going.The point is to have objective physiological data.So one orbit. How long can a single orbit be? I thougt you are talking several months at least.
The Moon doesn't matter. Solid angle from EML1/2 is just way too small averaged over the halo orbit.
The bottom line is that we don't have funding for appropriate basic research, that research programs are overstating results (likely on the unlikely theory that this will get them more funds...), and there's no funding for a physiological mission to gather appropriate exposure experience.Here's what I'd fund to address this: + 10-20 grants on neurological tissue radiation damage processes caused by GeV energy particles + With these processes understood, 5-10 grants on approaches to mitigate such damage (ex:tardigrades) + A long duration exposure (3-6 months) of 5-7 mammals/primates in the comparable environment (For the last, a long life HSF vehicle fitted with a test cell and robotic lab animal environment management, launched on a highly elliptic orbit would be a means to that end.)The likely return on these would be actual specimen lesions/effects in appropriate physiological context, with measurable quantitative effects, evaluated with the scope of potential mitigation as well as long term consequences of such.Beyond Mars/Moon HSF, such research would likely find support for radiation therapies for other kinds of radiation exposure/hazards.
Quote from: Robotbeat on 10/13/2016 08:53 pmThe Moon doesn't matter. Solid angle from EML1/2 is just way too small averaged over the halo orbit.Not shielding issue. Operations issues.
Quote from: guckyfan on 10/13/2016 09:09 pmSo one orbit. How long can a single orbit be? I thougt you are talking several months at least.Can be as long as almost one year (simple keplerian N body, almost anytime). Use the Moon/sun perturbations (narrow window), longer than a Mars synod.In other words, "long enough".Long enough physiologically is something like a substantial fraction of the expected HSF. Generally speaking, months.Now lets take into account what consumables and operations might limit us to (capsule). Something like 2-3 months with current capabilities. "Good enough".
So one orbit. How long can a single orbit be? I thougt you are talking several months at least.
Instead of an actual orbital mission, wouldn't it be cheaper to just do the (debunked) research properly? Hit the mice in more reasonable doses (daily? hourly?) over x months. (Poor little guys... )
Why does this thread even exist?
The bottom line is that we don't have funding for appropriate basic research, that research programs are overstating results (likely on the unlikely theory that this will get them more funds...), and there's no funding for a physiological mission to gather appropriate exposure experience.Here's what I'd fund to address this: + 10-20 grants on neurological tissue radiation damage processes caused by GeV energy particles + With these processes understood, 5-10 grants on approaches to mitigate such damage (ex:tardigrades) + A long duration exposure (3-6 months) of 5-7 mammals/primates in the comparable environment
Back to the topic at hand:Quote from: Space Ghost 1962 on 10/13/2016 12:36 amThe bottom line is that we don't have funding for appropriate basic research, that research programs are overstating results (likely on the unlikely theory that this will get them more funds...), and there's no funding for a physiological mission to gather appropriate exposure experience.Here's what I'd fund to address this: + 10-20 grants on neurological tissue radiation damage processes caused by GeV energy particles + With these processes understood, 5-10 grants on approaches to mitigate such damage (ex:tardigrades) + A long duration exposure (3-6 months) of 5-7 mammals/primates in the comparable environment this looks like it could be considered a step zero on your plan:http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2014/Ricco_BioSentinel.pdfIt is focused on yeast cells, but perhaps it wouldn't be too much of a stretch to imagine studying neurological tissue in a similar way as a next step.
Why does anything exist? You may have hit upon the ultimate question there... There is just one answer: 42 (and it's mice who are really doing the research...)
Quote from: sanman on 09/29/2016 12:54 amOkay, but terrestrial isn't as mass-constrained as space hardware. Hopefully proper design would mitigate risks.With respect to "mass constraints," you did see Elon's presentation, right? He said that the ITS would wind up being more of a "medium sized" rocket in a future stable of vehicles. And 30 years worth of submarine fuel would fit under your desk - the rest is cooling and shielding.The Shielding of Mobile Reactors (Part I)
Quote from: obsever on 10/14/2016 06:57 pmWhy does anything exist? You may have hit upon the ultimate question there... There is just one answer: 42 (and it's mice who are really doing the research...)Notice how musk put 42 engines on the booster
Quote from: Negan on 10/14/2016 05:48 pmWhy does this thread even exist?Why does anything exist? You may have hit upon the ultimate question there... There is just one answer: 42 (and it's mice who are really doing the research...)
Quotehttp://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2014/Ricco_BioSentinel.pdfIt is focused on yeast cells, but perhaps it wouldn't be too much of a stretch to imagine studying neurological tissue in a similar way as a next step.Am aware of this. Have been at presentations and asked questions, pointed out experiment flaws. Microfluidics in a deep space probe are dicey.
http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2014/Ricco_BioSentinel.pdfIt is focused on yeast cells, but perhaps it wouldn't be too much of a stretch to imagine studying neurological tissue in a similar way as a next step.
Quote from: Space Ghost 1962 on 10/15/2016 09:27 pmQuotehttp://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2014/Ricco_BioSentinel.pdfIt is focused on yeast cells, but perhaps it wouldn't be too much of a stretch to imagine studying neurological tissue in a similar way as a next step.Am aware of this. Have been at presentations and asked questions, pointed out experiment flaws. Microfluidics in a deep space probe are dicey.Why are microfluidics in deep space dicey ? A version of this is going to LEO mid next year ( barring further COPVsplosions ) https://www.nasa.gov/sites/default/files/atoms/files/powercell_fact_sheet-1aug2016-508.pdf
Environment issues.
Quote from: Space Ghost 1962 on 10/16/2016 02:45 amEnvironment issues.Everything going to deep space has environment issues, is there anything specific to microfluidics that would be specifically problematic ? Honest question
Quote from: savuporo on 10/16/2016 03:30 amQuote from: Space Ghost 1962 on 10/16/2016 02:45 amEnvironment issues.Everything going to deep space has environment issues, is there anything specific to microfluidics that would be specifically problematic ? Honest questionHonest answer. Why bother to post anything but?There are limits.
Quote from: obsever on 10/14/2016 06:57 pmQuote from: Negan on 10/14/2016 05:48 pmWhy does this thread even exist?Why does anything exist? You may have hit upon the ultimate question there... There is just one answer: 42 (and it's mice who are really doing the research...)Because a mature HSF effort that is trying to describe itself as a worthy HSF adventure (note Musk's "fun" and "entertainment" references to humans enjoying the transit) must consider radiation effects/mitigation. For that you need to confront/measure the physiological issues, otherwise "average" humans won't attempt it.This isn't the desperate Mars One or even anything like Zubrin's "extreme sports" fantasy "conquest of Mars" by a few. He's talking about a much more grand scale, and thus the rules aren't the same as before..Some narrow minded people here still have no grasp on what Musk is attempting. They try to "back fill" it into their own prior expectations, making tiny versions of ITS etc. Even Zubrin is mind-boggling stupid for the same reason. This is a lot bigger.Even our stalwart, most practiced, best qualified "space" professionals here, on this site, ... still don't get it. Still licking their stupid wounds over the Space Shuttle not living up to expectations. Well, I was part of that past too, and am able to at least grab a tiny bit of that vision. And yet not so embittered to grapple with the scope of its unsolved problems, this is one of them. As to agenda, simple - would like the human race to win. Duh.QuoteBack to the topic at hand:Quote from: Space Ghost 1962 on 10/13/2016 12:36 amThe bottom line is that we don't have funding for appropriate basic research, that research programs are overstating results (likely on the unlikely theory that this will get them more funds...), and there's no funding for a physiological mission to gather appropriate exposure experience.Here's what I'd fund to address this: + 10-20 grants on neurological tissue radiation damage processes caused by GeV energy particles + With these processes understood, 5-10 grants on approaches to mitigate such damage (ex:tardigrades) + A long duration exposure (3-6 months) of 5-7 mammals/primates in the comparable environment this looks like it could be considered a step zero on your plan:http://mstl.atl.calpoly.edu/~bklofas/Presentations/DevelopersWorkshop2014/Ricco_BioSentinel.pdfIt is focused on yeast cells, but perhaps it wouldn't be too much of a stretch to imagine studying neurological tissue in a similar way as a next step.Am aware of this. Have been at presentations and asked questions, pointed out experiment flaws. Microfluidics in a deep space probe are dicey.Look at the last few slides - that tells the story on all of this. Zero information.Anything that moves the needle helps.However, the void needs to eventually be filled with genuine in-situ physiological experiments that inform on HSF effects/mitigation. Which my example above attempts to do.If you are serious about this thread, then apply your enthusiasm/intellect/professionalism to it. Not that hard.
In the "extreme sports" context, zero radiation protection is needed. None but the ship and Mars herself.But if you want a colony and children, you need something better than nothing.
What quantity/sort of radionucleotides would need to be harvested/bred form belt material to sink into the crust by shafts sealed by depth, so that subsequent reactions would re-melt Mars core and re/start convection?Has any one done such calculations? Seems like a steady stream of tangential impactors over 1M+ years plus the core remelt would get the job done for the remainder of the solar system healthspan.
Why the heck would you do that???
Quote from: Robotbeat on 10/16/2016 06:05 pmWhy the heck would you do that???To solve the habitability problem for a few billion year or so .I might even add, "Duh."
Mars would need active management to last that long no matter what, since it'd either be far too cold (now) or far too hot (to last beyond a billion years). A superconducting ring is FAR easier/cheaper/better to do and doesn't require scouring the solar system for every last scrap of radioactive isotope.
Edit: we seem to be slightly OT for ITS Radiation protection.
The ITS will spend a lot of time on Mars, on the surface. The trip seems likely to mitigate radiation by being quick. It may be radiation mitigation near term for the ITS will be, moving out of the ITS and underground.
Quote from: Robotbeat on 10/16/2016 02:13 pmIn the "extreme sports" context, zero radiation protection is needed. None but the ship and Mars herself.But if you want a colony and children, you need something better than nothing.I am not sure that is even true. I agree this is what we must assume and work with in the beginning. But I would not be surprised at all if thorough long term research will show that we can live on the surface without any heavy shielding and without negative consequences.
Long term, IMO, 'low' (IE sub radiation sickness/sterility causing) levels of radiation will be irrelevant because we'll get something like a cancer vaccine or ultra-easy cancer treatment.We could probably have this in 20 years in an environment where biotech could really hit its exponential curve. Due to regulatory limitations, probably more like 40-50 years away.
I would worry more about micrometeorite damage with a thin carbon fiber skin. Not just to people, but to engine plumbing. (see the movie "Mission to Mars" starring Gary Sinéad)Radiation might kill you in 10 years. Micrometeorites can kill you right now.
Note: In "Mission to Mars", the actor you're thinking of is Gary Sinise.
Quote from: Vultur on 10/22/2016 05:55 amLong term, IMO, 'low' (IE sub radiation sickness/sterility causing) levels of radiation will be irrelevant because we'll get something like a cancer vaccine or ultra-easy cancer treatment.We could probably have this in 20 years in an environment where biotech could really hit its exponential curve. Due to regulatory limitations, probably more like 40-50 years away.
That is another option. I did not think about this one. I was thinking that maybe it turns out that there is no need for any mitigation. GCR is high energy but quite low level. I don't think we have good tests on that kind of radiation environment to make good models for equivalent radiation effect on humans. I think presently worst case models are used. That is reasonable but will be replaced with better models, once people have lived on Mars for a long enough time and animal tests have been done over several generations. After all people live on earth under radiation exposure exceeding recommendations and there seem to be no ill effects. But these populations may not be sufficiently observed yet so maybe not good comparison. Also the kind of radiation they are experiencing is different to GCR. So again not comparable.
If 100 people on an ITS crew vehicle are allocated 1 ton of water each (4kg per person per day including reuse), incorporating that into an envelope around the crew vehicle would allow you to achieve that 0.5m thickness for 200 square metres.
Insert appropriately cynical comment here yeah maybe, but we're actually going backwards in some medical pursuits (e.g. bacterial drug resistance) so assuming an exponential curve is a bit of a stretch.
Halving thicknesses work for gamma rays and X-rays. Not for GCR.
Quote from: mikelepage on 11/01/2016 03:53 amInsert appropriately cynical comment here yeah maybe, but we're actually going backwards in some medical pursuits (e.g. bacterial drug resistance) so assuming an exponential curve is a bit of a stretch.Antibiotic resistance isn't comparable since the bacteria are actively evolving. Radiation hazards/cancer don't work that way.
(Haven't been able to read all posts here, but...)There is a fair amount of research going back over a decade on the effectiveness of carbon based (composites and polymers) radiation shielding. So maybe the use of carbon fiber wrapped structures is not just for construction purposes or weight loss?? No real need for magnetic fields or water tanks etc.
Can I ask for a consensus as to whether Magnetic or other shielding techniques (outside of the physical barrier type), are feasible in the next 10-20 years, on a scale to protect ITS sized space craft in Space.
If we add the extra risk of poorly-understood HZE particle effects, possibly most crew members approach the 3% limit, and are restricted to one single-synod mission.
Sievert are a weighted metric for biologic effects and include the higher risk due to high energy particles. As the effects of high energy particles are not very well known, it is a safe assumption that the effects are not undervalued. Much more likely they are overvalued as a cautionary measure.
Crew Radiation Exposure EstimatesCross-posting for relevance: McGirl et al. 2016, "Crew Radiation Exposure Estimates from GCR and SPE Environments During a Hypothetical Mars Mission". In the study, female crew members under 40 approach their lifetime 3% risk limit, even on a single-synod mission with 500-day stay. That's at -7000 m elevation, beneath 15 cm of aluminum shielding.
Mini-Magnetosphere for Proton ShieldingQuote from: cro-magnon gramps on 10/07/2016 01:48 pmCan I ask for a consensus as to whether Magnetic or other shielding techniques (outside of the physical barrier type), are feasible in the next 10-20 years, on a scale to protect ITS sized space craft in Space. There's been some related research recently in artificial mini-magnetospheres. Bamford et al. suggest mini-magnetosphere protection from solar protons, as a first application. However they emphasize the complexity of mini-magnetosphere behavior in the natural plasma environment.
Quote from: LMT on 11/04/2016 04:21 amMini-Magnetosphere for Proton ShieldingQuote from: cro-magnon gramps on 10/07/2016 01:48 pmCan I ask for a consensus as to whether Magnetic or other shielding techniques (outside of the physical barrier type), are feasible in the next 10-20 years, on a scale to protect ITS sized space craft in Space. There's been some related research recently in artificial mini-magnetospheres. Bamford et al. suggest mini-magnetosphere protection from solar protons, as a first application. However they emphasize the complexity of mini-magnetosphere behavior in the natural plasma environment.Yeah, the problem with these magnetic shields is that realistic designs do not shield against GCR, just SPEs, which we already can shield against effectively using repositioned supplies at no extra mass.
we're concerned with the hard to block high energy GCRs as even if they have lower flux they have higher energy.