Jim - 2/4/2008 9:17 AMNo conspiracy just a slow news day
rsp1202 - 2/4/2008 11:23 AMWhat's the rad count on Spirit and Opportunity?Did ALSEP measure radiation levels?
Blackstar - 2/4/2008 12:27 PMQuotersp1202 - 2/4/2008 11:23 AMWhat's the rad count on Spirit and Opportunity?Did ALSEP measure radiation levels?I don't think that the rovers have radiation counters. That's partly the problem--the science program has not collected the kind of data that is required for the human exploration of Mars. There are several types of data that are needed, such as radiation and toxicology (key question: is the Mars dirt toxic to humans?).
Blackstar - 2/4/2008 10:30 AMQuoteJim - 2/4/2008 9:17 AMNo conspiracy just a slow news dayNot exactly. There's a new NRC report just released addressing this subject. See:http://nationalacademies.org/morenews/20080331.html
Blackstar - 2/4/2008 11:27 AM Quotersp1202 - 2/4/2008 11:23 AM What's the rad count on Spirit and Opportunity? Did ALSEP measure radiation levels? I don't think that the rovers have radiation counters. That's partly the problem--the science program has not collected the kind of data that is required for the human exploration of Mars. There are several types of data that are needed, such as radiation and toxicology (key question: is the Mars dirt toxic to humans?).
rsp1202 - 2/4/2008 11:23 AM What's the rad count on Spirit and Opportunity? Did ALSEP measure radiation levels?
For what its worth, you don't always need them - you can do a good estimate of dosimetry from other sources of information. One trick was to track errors in RAM/flash memory, another was for embrittlement, yet another involves paint changing color. You then cross correlate to get a common exposure.
nobodyofconsequence - 2/4/2008 2:11 PMFor what its worth, you don't always need them - you can do a good estimate of dosimetry from other sources of information. One trick was to track errors in RAM/flash memory, another was for embrittlement, yet another involves paint changing color. You then cross correlate to get a common exposure.
simonbp - 2/4/2008 2:56 PM. . . the only radiation detector yet flown . . . got fried by a solar flare . . .
TyMoore - 2/4/2008 2:49 PMI think this illustrates not only the need for more research--but also a different philosophy regarding mission architectures: either we need to think of sending larger vessels that are better shielded to protect crews, or we need to send the crew on a faster vessel so that the total radiation 'integration time' will be less.
rsp1202 - 2/4/2008 6:58 PMQuotesimonbp - 2/4/2008 2:56 PM. . . the only radiation detector yet flown . . . got fried by a solar flare . . .Kinda answers all my questions.
Blackstar - 3/4/2008 3:13 AMI listened to some solar scientists talk about this stuff once and it's rather interesting. They compare it to weather forecasting 40 years ago. They can predict some big things with greater accuracy, but one of the problems is that the prediction times are not very long. There are also some unique methods, such as looking _through_ the sun to find out what is happening on the other side (because eruptions on the opposite side are reflected through the sun and show up on the side we see). One problem with Mars, however, is that it is going to be on the other side of the sun for a good period of time during any astronaut trip, so we could detect solar eruptions that are coming toward Earth, but we might not see ones heading toward Mars--and the astronauts.There are people thinking about things like forecasting solar flares, and they think that some of this stuff is solvable, if the right money and attention is paid towards it.There are also other ways to mitigate the hazards. One possibility is developing drugs to decrease the dangers of radiation exposure. I know nothing about that area, but I'm not optimistic. Radiation slices through DNA strands, and I don't know how a drug can stop that from happening.
A_M_Swallow - 3/4/2008 4:54 AMQuoteBlackstar - 3/4/2008 3:13 AMI listened to some solar scientists talk about this stuff once and it's rather interesting. They compare it to weather forecasting 40 years ago. They can predict some big things with greater accuracy, but one of the problems is that the prediction times are not very long. There are also some unique methods, such as looking _through_ the sun to find out what is happening on the other side (because eruptions on the opposite side are reflected through the sun and show up on the side we see). One problem with Mars, however, is that it is going to be on the other side of the sun for a good period of time during any astronaut trip, so we could detect solar eruptions that are coming toward Earth, but we might not see ones heading toward Mars--and the astronauts.Sounds like a solar observing satellite is needed in a HELO orbit around Sun-Earth L2.
Blackstar - 3/4/2008 3:13 AMI listened to some solar scientists talk about this stuff once and it's rather interesting. They compare it to weather forecasting 40 years ago. They can predict some big things with greater accuracy, but one of the problems is that the prediction times are not very long. There are also some unique methods, such as looking _through_ the sun to find out what is happening on the other side (because eruptions on the opposite side are reflected through the sun and show up on the side we see). One problem with Mars, however, is that it is going to be on the other side of the sun for a good period of time during any astronaut trip, so we could detect solar eruptions that are coming toward Earth, but we might not see ones heading toward Mars--and the astronauts.
nobodyofconsequence - 3/4/2008 2:19 PMThe radiation hazard has been ridiculously played down over the years, to the point where many think it isn't a problem. What it is, is a hard problem.
nobodyofconsequence - 3/4/2008 12:19 PMNot to belabor the obvious, but the Sun has been in its inactive phase and yet had quite a number of unpredictable "events", all of which would have been fatal to a crew in a heavily shielded aluminum cylinder.
nobodyofconsequence - 3/4/2008 12:19 PM. . . the Sun has been in its inactive phase and yet had quite a number of unpredictable "events", all of which would have been fatal to a crew in a heavily shielded aluminum cylinder.
khallow - 3/4/2008 7:54 PM If the shielding is inadequate against what sounds to be routine events, then it's not "heavily shielded". It can still be "heavy" though.
Its not mass that matters - its atomic scattering cross section actually. Best per unit mass is carbon. Best per volume is water. Again for uncharged particles.
Blackstar - 3/4/2008 6:49 PM It's been played down by some people, like Bob Zubrin. It's a problem, but one that can be managed. What you do is you build in procedures and systems to reduce the risk as much as possible, and then you accept a higher level of risk.
What the "accept higher level of risk" side has been looking at is altering biological systems to cope with ionizing radiation damage in a radical way. The funding for it has been on and off and is what I've been referring to.
In a "Dr. Strangelove" kind of way, the current jerks in power like/hate it. The part they like is to be able to imagine its use with man generated radiation sources (euphamistically). They really want to"love the bomb" e.g. atomic power widespread. They think of it like a second oil empire.
rsp1202 - 3/4/2008 8:33 PM Not any more. Things have picked up.
Yes - both with the sun and extrasolar sources. We're also finding more interesting extremely high energy events that we didn't quite have the instrumentation to measure well (GRBs).
In no way has the situation gotten better for manned spaceflight. But we are getting more realistic.
nobodyofconsequence - 3/4/2008 9:07 PMWhat the "accept higher level of risk" side has been looking at is altering biological systems to cope with ionizing radiation damage in a radical way. The funding for it has been on and off and is what I've been referring to.In a "Dr. Strangelove" kind of way, the current jerks in power like/hate it. The part they like is to be able to imagine its use with man generated radiation sources (euphamistically). They really want to"love the bomb" e.g. atomic power widespread. They think of it like a second oil empire.
Blackstar - 3/4/2008 9:24 PM Ooookaaaayyyy.... Meanwhile, those of us who live on planet Earth have lost you...
Yeah, me too. I listened and didn't quite believe it either. Just what I heard between one group trying to get funded, and who they were introduced to ...
nobodyofconsequence - 4/4/2008 2:39 AMQuoteBlackstar - 3/4/2008 9:24 PM Ooookaaaayyyy.... Meanwhile, those of us who live on planet Earth have lost you...Yeah, me too. I listened and didn't quite believe it either. Just what I heard between one group trying to get funded, and who they were introduced to ...
TyMoore - 2/4/2008 7:49 PMI think this illustrates not only the need for more research--but also a different philosophy regarding mission architectures: either we need to think of sending larger vessels that are better shielded to protect crews, or we need to send the crew on a faster vessel so that the total radiation 'integration time' will be less.
TyMoore - 4/4/2008 9:04 AMAlso, nestling the pressurized crew compartments in among the propellant tanks and mission payload would help..but this will screw up the direct views (I guess you could put a bunch of TV cameras on the outside though...)
grakenverb - 4/4/2008 9:08 AMQuoteTyMoore - 4/4/2008 9:04 AMAlso, nestling the pressurized crew compartments in among the propellant tanks and mission payload would help..but this will screw up the direct views (I guess you could put a bunch of TV cameras on the outside though...)Why not just have a smaller "area of refuge" amongst the tanks that the astros could go into when radiation is detected?
HarryM - 4/4/2008 11:43 AMSeems only "shield" against Cosmic Rays is to get to and from Mars as fast as possible, via nuke propulsion of some type. Once on the surface you have 1/2 the exposure via protection of planet's bulk. Even more protection if you find a nice deep crater to have your hab, and/or bury it.At least Cosmic Rays are fairly constant though, no rude spikes like with Solar radiation. Unless a supernova goes off somewhere nearby, which is unlikely.
Blackstar - 4/4/2008 7:01 AM Quotenobodyofconsequence - 4/4/2008 2:39 AM QuoteBlackstar - 3/4/2008 9:24 PM Ooookaaaayyyy.... Meanwhile, those of us who live on planet Earth have lost you...Yeah, me too. I listened and didn't quite believe it either. Just what I heard between one group trying to get funded, and who they were introduced to ... You misunderstand. I consider what you wrote to make no sense at all.
nobodyofconsequence - 4/4/2008 2:39 AM QuoteBlackstar - 3/4/2008 9:24 PM Ooookaaaayyyy.... Meanwhile, those of us who live on planet Earth have lost you...Yeah, me too. I listened and didn't quite believe it either. Just what I heard between one group trying to get funded, and who they were introduced to ...
OK. As an alternative to traditional shielding, the idea is to deal with the problem by an alernative means. In this case, the specific research alluded to was to repair the damage due to ionizing radiation, specifically the damage to proteins. This was the form of "high risk" mentioned.
If you're interested, there's also research on materials to similarly recover structural materials from radiation embrittlement using nanomaterials. Even work on semiconductors as well.
What was weird about it was that some in the admin looked at this through the lens of use on earth with radioactive materials.
Does that connect the dots for you yet? Should I use smaller words?
nobodyofconsequence - 4/4/2008 1:30 PMDoes that connect the dots for you yet? Should I use smaller words?
Blackstar - 5/4/2008 8:43 AM Quotenobodyofconsequence - 4/4/2008 1:30 PM Does that connect the dots for you yet? Should I use smaller words? Please do. I'm stupid and don't work in the field or anything.
nobodyofconsequence - 4/4/2008 1:30 PM Does that connect the dots for you yet? Should I use smaller words?
Good for you I am happy for your unique grasp.
Mogster - 7/4/2008 6:30 AMNo one seems to know accurately how dangerous radiation exposure at different levels is to humans, I suppose its a difficult thing to quantify. If sending crews to Mars has to involve 0% additional risk (whatever that really means) then we'll never go. What would be acceptable? a 1% increased cancer risk after the mission, 5%, 10% .......
William Barton - 7/4/2008 6:53 AMFor things like increased cancer risk, the solution is to use crew who are old enough the increased risk falls inside the mortality rate for other causes. For example, for Mars sortie mission durations under 5yr, it would not be impossible to find crew members aged 60+ who were nonetheless sufficiently fit to handle the rigors of the mission. By the time they were statistically at risk for cancer, they would likely be dead from some other cause. The real danger that has to be looked at is protecting the crew from near term neurological damage from cosmic rays, which would place the mission at risk, and from rapid death due to a solar event, which would count as a LOC event.
Mogster - 7/4/2008 8:00 AMI just see the low level radiation issue as another excuse not to go.
Mogster - 7/4/2008 8:00 AMHave any of the Apollo crews shown neurological damage from cosmic rays? I've not heard of health problems from the ISS or Mir crews? I know its less of a problem in LEO but if the effects were so bad surely they'd have shown up to a degree by now.
Mogster - 7/4/2008 8:00 AMIt amazes me the Pathfinder, and the MER's flew without dedicated radiation measurement instruments.
HarryM - 4/4/2008 9:43 AMEver watch one of those cloud tanks with the rays zipping through it? They have one at the Exploratorium in SF. Fascinating.
Blackstar - 7/4/2008 7:01 AMIt's interesting to note that there are a lot of things to be concerned with. One that space advocates don't think about is pretty basic: is Mars dust toxic? If you breathe it in your lungs, will it harm you? If you think about it, walking around in a room filled with asbestos without respiratory protection is a bad idea, so it's worth asking if the Mars dust that astronauts will inevitably breathe in once they take off their dirty spacesuits will cause any harm.
HarryM - 8/4/2008 3:35 PMI guess that's what happened to Viking's experiment when they added moisture/nutrient (assuming it was not biological reaction which seems unlikely anyways), some sort of peroxide in the soil, except the reaction would be happening in the astronauts lungs. Maybe MSL can do more work on this, nature of dusts or oxidants in the soil?
Garrett - 4/4/2008 6:52 AMQuoteTyMoore - 2/4/2008 7:49 PMI think this illustrates not only the need for more research--but also a different philosophy regarding mission architectures: either we need to think of sending larger vessels that are better shielded to protect crews, or we need to send the crew on a faster vessel so that the total radiation 'integration time' will be less.Hmmm, I'm not an expert but I don't think it's really possible to send a faster vessel if we want to use a Hohmann transfer orbit to Mars, which is the only transfer orbit that we seem capable of performing with today's technology.