Data taken by the Mars Science Laboratory's Radiation Assessment Detector, or RAD, during Curiosity's interplanetary journey to Mars and published in the May 31 issue of Science provides experimental confirmation for the radiation prediction models NASA already uses.
With current propulsion systems, the leisurely, 560-million-kilometer cruise to the red planet clocks in at 253 days, a length of time that based on the amount of radiation RAD registered from its shielded perch inside the spacecraft, would put astronauts above the threshold for career radiation exposure.
"In terms of accumulated dose, it's like getting a whole-body CT scan once every five or six days," lead author Cary Zeitlin said in a press statement.
Over the course of its journey, the Curiosity rover was exposed to 1.8 milliSieverts per day of radiation from galactic cosmic rays, particles that comes from outside the solar system and provide a chronic low-dose of radiation. Astronauts making interplanetary journeys would also be exposed to short bursts of low-energy solar energetic particles from solar flares and coronal mass ejections.
"We need to get there faster to reduce the impact of the galactic cosmic rays," Eddie Semones, a spaceflight radiation health officer with NASA, said in a press conference. Even if NASA cut the travel time to Mars down to 180 days each way, people on board would be exposed to an estimated total of 662 milliSieverts in transit, plus any radiation they might encounter on the surface.
Curiosity's journey also occurred during a weak solar maximum, and it's possible the solar energetic particle exposure could be greater at a different period in time, the researchers write.
Exposure to 1 Sievert of radiation over a lifetime has been associated with a 5 percent increase in a person's risk of developing fatal cancer. NASA's current career limit for astronauts is a 3 percent increase in fatal cancer risk.
RAD has continued to operate since Curiosity's August landing, and will provide data on the radiation levels on the surface of Mars in the future. In 2015, NASA will launch a modified version of RAD to study the radiation environment in the International Space Station.
Interesting information for all those volunteers of a oneway trip to Mars on a Previous PoPSCi article, sizzle!
NASA will eventually solve these problem and one day land on Mars, to only find a whole bunch of popcorn PoP humans from a previous private venture to Mars.
This article also does not include those pesky solar flares with all that extra HIGH radiation bursting!
Does that mean the SPF-50 won't be enough? ;)
Brush the dust off the nearly 50 year old NERVA NRX/XE engine that was designed for this very mission. Use it in a 'conveyor belt' orbit it could pick up manned and unmanned missions and reduce the need for the once every two years launch window.
These limits were formed using an antiquated understanding of chronic radiation exposure that assumed a burst of radiation in a short period of time was created the same cancer risk as the same amount of radiation spread over a longer time. This has been demonstrated to not be the case.
Areas with higher background radiation have lower levels of cancer and birth defects.
In taiwan radioactive cobalt 60 was recycled along with steel and was used to make rebar for 180 buildings.
"Approximately 10,000 people occupied these buildings and received an average radiation dose of 0.4 Sv, unknowingly, during a 9–20 year period. They did not suffer a higher incidence of cancer mortality, as the LNT theory would predict. On the contrary, the incidence of cancer deaths in this population was greatly reduced—to about 3 per cent of the incidence of spontaneous cancer death in the general Taiwan public. In addition, the incidence of congenital malformations was also reduced—to about 7 per cent of the incidence in the general public."
Just incase that was not clear to you that's a 97% reduction in cancer deaths and a 93% reduction in birth defects. The models predict an increase in cancer not a drastic decrease. Please read the article, I absolutly love figure one showing showing cancer morbidity over time.
There are also studies on mice showing a powerful protective effect chronic exposure has over the affects of acute exposure. Meaning if extremely high radiation is not as damaging to you if you were pre exposed to lower levels of radiation for a long period of time.
In closing, cosmic radiation was invented by the man to keep us down.
"...In closing, cosmic radiation was invented by the man to keep us down.", ~ author troll.
I think this is very good news. That's actually a sufficiently small dose, and it ignores several things.
First, as mentioned, this was during a solar maximum. Yes, it was weaker than normal, but it was still a time of highest radiation in the cycle. Solar minimums would be a very different story.
Also, there was essentially no shielding at all for the instrument, because it isn't needed for these things. In fact, Curiosity actually releases its own radiation as well thanks to its Radio-isotope Thermal Electric Generator. In the case of a human flight, we would have some basic current shielding, such as placing any water in the back, between the sun and the astronauts.
Finally, bringing back into what adaptation was going on about: Albert Stevens ( http://en.wikipedia.org/wiki/Albert_Stevens ) was injected with Plutonium. Over the course of 21 years, he received a total dose of 64 Sieverts. Not millisieverts, full Sieverts. This comes out to a dose of a little over 8mSv per day. More than 4 times higher, for a period more than 30 times longer, than what Curiosity received...at a time of solar maximum!
Albert died of natural causes, cancer free. ( They actually thought he had terminal cancer before the study, but later it was discovered it was just a rather massive benign ulcer. )
So, ignoring any potential health benefits of low level exposure ( which is still controversial ), it is quite clear that at the least these low level exposures do not add up like has previously been thought. Time and time again people and animals receive massive doses over time with no negative effects.
A great example of this is Chernobyl. The place has had low levels of radiation for decades. Life is flourishing in the area so much that it has been made into a national park and is now protected.
To put all of this into further context: 2 Sieverts over a short time leads to severe radiation poisoning and sometimes death. 8 Sieverts is considered fatal even with any treatment. Clearly, time has a substantial affect on the effects of the radiation, and these need to be re-evaluated.
I would still gladly sign up to go to Mars, even tomorrow while we are still relatively in solar maximum.
How is this news? We live 93 million miles from one helluva nuclear core. No atmosphere, no dice. Go underground or stay home.
@12 useless post with no content, mild personal attack, look within and find the true troll.
I firmly believe my beliefs, cosmic radiation is of very little concern.
The earths magnetic field flips periodically and during the flp its protection is nullified, yet no mass extinction event is associated with such occurrences.
isn't radiation the basis around the conspiracy theory that the moon landing was fake?
how do you get a 3 inch lead plated spaceship into orbit to get a crew safely through the radiation of space?
Yes I understand that some people in life speak and write with a style of conviction and they believe with the sound or writing style of their voice they are correct. It does work for some and many do follow this type of sound. You do write very well with a good style of conviction.
Very interesting contributions by both "zechio" and "adaptation". I have always wondered how people live, and even more so, what they die of, in areas with very high natural background radiation. There is a place in Iran with some way out figures.
I read once that water is a great block for interstellar radiation. The plan was to build the transportation module INSIDE the astronaut's drinking water tank. Theoretically, this would give the travelers adequate protection on the voyage to Mars. The question is: how much radiation does the surface of the planet receive? Would colonists be able to live there? Would they have to build their habitats under the martian surface to escape such radiation? I suppose it could be done, but how much fun would THAT be?
In reality, solving this problem is fairly easy compared to the others facing the engineers of a space vehicle system capable of a round-trip manned mission to the surface of Mars. Designing a vehicle that can land a crew and sufficient supplies safely on the surface of Mars, and then launch them back into space with enough velocity to return to earth, is an incredibly difficult task.
All we have to do is hollow out a passing asteroid and attach a propulsion system to it: 100% protection from radiation!
@Wonder show me a study of chronic radiation exposure anywhere near the duration or sample size as mine indicating results that support current models. I am willing to alter my views if presented with good data. Your faith in an disproven model are the ones based on unfounded beliefs.
@Newbeak5 that would work but it's tricky, you need orbit called an Aldrin cycler, every two years it makes a 146 day transit. But it requires more fuel to link up with and depart from the orbit than other more direct approaches, you need much more fuel than the mass of your cargo, this means reduced cargo and increased expenses. You would need a sizable asteroid in a nearly perfectly arranged orbit because modifying the orbit of a non synced asteroid would require huge amounts of fuel.
This approach is probably only practical for live cargo. Dead cargo could take a much longer much cheaper approach.
McCoy: I may throw up on you.
Kirk: I think these things are pretty safe.
McCoy: Don't pander to me, kid. One tiny crack in the hull, and our blood boils in thirteen seconds. Solar flare might crop up, cook us in our seats. And wait till you're sitting pretty with a case of Andorian shingles. See if you're still so relaxed when your eyeballs are bleeding! Space is disease and danger wrapped in darkness and silence.
Kirk: Well I hate to break this to you, but Starfleet operates in space..."
Yes, in fiction Captain Kirk has the last word.
Um, this is not fiction, but reality.
@Wonder I don't even know what you're trying to say. I guess you're just trying to get me to post again. Well then, well done.
I understand you keep making statements with conviction that space is a typical place to be as walking around on the ground of Earth via you opinion and in response you want to argue with stated facts.
Ok, stated facts, read the article, NASA says the fractionation in space is hazardous and this article does not even elaborate much on the sudden solar flares as well.
REALITY, NASA with SCIENCE SAYS THE RADIATION IS HAZARDOUS and a lot more defensive environmental development needs to be made for humans to settle on Mars.
health physics technician here. I deal with radiation and work in nuclear power plants on a daily basis.
Lets start with some conversions for those of us based in the united stats. Here, we commonly use milliRem/hr for dose rates. 1 Sievert is equivalent to 100 Rem (roentgen equivalent man). Therefore 1 millisievert is equivalent to one rem, which is of course equivalent to one thousand milliRem. Which leads us to understand that your exposure would be 1800 milliRem/day en route.
We can then derive an average exposure of 75 mRem per hour, which isnt terrible, but over a period of 180 inescapable days it gets fairly severe.
at 1800 mRem a day, we get 324,000 mRem for the one way trip. We'll say 324 Rem, because dealing with larger numbers means its easier to just use Rem.
To give you a baseline, you are likely to pick up 450-600 mRem in a given year on average in the United States from all the various sources of exposure (background radiation). This means in just 6 hours, you will have hit your yearly background exposure.
Now don't get worried. There are people who get as much as 12 Rem per year exposure JUST FROM BACKGROUND sources (andes mountains due to naturally occuring radioactive carbon in the mountains.) But 12 rem? Why, you reach 12 rem in just 6.67 days. WOW, that is a large number.
For further reference use, it is accepted that at around 450 REM ACUTE exposure (all at once), fifty percent of people are likely to perish within 30 days without medical attention.
OKAY. this exposure is chronic, however, its high enough and over a short enough period of time, its in a gray area.
I have another concern which has little merit. I highly doubt that exposure record is equivalent man, which means there is a necessary tissue quality factor. I'll just assume since were in space and there is some shielding, it's all gamma and the quality factor is 1, which puts it close enough to REM for our purposes with those exposure levels (very, very high.)
Another reference point. In commercial nuclear power, the federal exposure yearly limit is only 5 REM, and most plants limit that exposure to 1 or 2 REM (purely occupational). That means I would break my federal occupational exposure limit in just 2.7 days.
This draws me to my next question, and that is why have these spacefaring companies not employed any health physicists? I've been looking for job postings to no avail!
Now lets look at the moon. The only data I've EVER found is that if you live on the moon for one year, you will get 1 REM of exposure. That is fairly insignificant. Why? Because the moon is shielded by our magnetosphere (big part), and has some atmosphere.
In regards to the person above who spoke of the magnetosphere inverting, I may be wrong, but that doesnt remove its influence if the polarity changes. Even if it did, we still have our atmosphere to shield us (we have a fairly dense atmosphere here).
On a side note, if you got to Mars, it will have its own magnetosphere, and an atmosphere, and there are plenty of materials to erect shielding. The same can be said of the moon.
Furthermore, it would not be difficult to build a shielded ship. The difficulty would be in launching it, which means you only need to build it either A) in space or B) on the moon. Problem solved.
My opinion is that speed is not the answer (with our current technology), shielding is the answer. Water and lead being the most effective, or any high Z number material will suffice.
In summary: 324,000 Rem is a LOT of exposure, and aside from death there are many other health effects. Receiving a chronic exposure that high for 180 days will surely result in problems other than cancer and possibly cancer (higher probability). You could see reddening of the skin, naseua, vomiting, hair loss, and lots of other fun side effects. I dont know of any studies where anything was exposed to 1.8 REM/day for 180 days or anywhere close to that.
One last subject, there could be effects on the exposed individuals genetic offspring. This means trouble for any one-way trip colonists. We've seen such effects around the Chernobyl area.
It will be much easier to cut those dose rates with shielding than to cut the trip time to a few weeks.
oh and pardon me adaptation, but cancers appearance is not all encompassed in radiation exposure, nor is it an effect with a known threshhold.
Lots of things like genetics, diet, and physical activities play an effect. Trying to say higher exposure results in less cancer is silly. There is some evidence of hormesis (thats what youre talking about) being true, but not at these levels. I can assure you, these levels would be VERY hazardous.
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Answer: Go to Luna, pick up large block of HO, cut in sections to surround spacecraft living and plant growth areas, water/food suppliy, etc... It's shielding capability, low mass and it's usefulness at Mars make it a no-brainer.
It must be reiterated that the sensor collected data without significant shielding. Lightweight shielding material exists at 1/3 the mass of lead xenolite provides the same protection.
During a magnetic reversal there is no significant magnetic field, during a reversed polarity period I would expect there to be an equivalent level of protection. You make a very valid point about the protection of the atmosphere, if our atmosphere where liquified it would be about 10m deep, and slightly less than half of the radiation is blocked by the earth itself.
@quasi44 thats a good plan for colonisation but its not practical for near term missions.
Wow, i love articles where the comments are more interesting and elucidating than the article itself. Adaptation and czellingsworth, thanks! Although worth mentioning czellingsworth - it was 1.8 milliSieverts, not 1800.
But Popsci, can you put the bar up just a little bit? Why just peg the journey to Mars as 253 days, as though the two planets are always in the same place? That's an average, and in this case knowing that there are times when the orbits of the two planets makes the journey much shorter or much longer is highly relevant. I also think a brief discussion of shielding was called for.
Actually Space radiation environment is also known be critical for electronic devices boarded in spacecraft, inducing functional errors .
Particles, such as, neutrons, protons, or heavy ions, are known to induce these errors in electronics devices, so called SEE (Single Event Effects). These energetic particles can be induced by solar flares, comics rays, etc...
It’s critical for industrial and space agencies to evaluate this risk.
You could find more details in the blog of spacetravelfoundation below