Mars Mission's Invisible Enemy: Radiation (space geeks ought to give up on an iminent Mars trip)

NY Times ^ | December 9, 2003 | MATTHEW L. WALD

[presidio9]

As the United States considers new goals for NASA after the loss of the Columbia, some space enthusiasts have renewed calls for a mission to Mars.

But a team of physicists and biologists here at a laboratory on Long Island is demonstrating that even if the nation wanted to commit to such a goal, it would be far more complex than the Moon mission that gripped the country in the 60's.

One reason is radiation, in the form of heavy ions from distant stars, zipping through everything in their path. Others include price, estimated at $30 billion to $60 billion, and launching enough food, supplies and fuel for a round trip. Any one of these could make the project impractical.

In a new $34 million NASA laboratory here, part of Brookhaven National Laboratory, scientists are using subatomic particles accelerated to nearly the speed of light to slam into materials that could be used in a spaceship, and tissue samples and small animals. Using tools like PET and M.R.I. scans and DNA sequencing, they hope to shed light on ways that radiation damages biological tissue, and what can be done about it.

On a trip to Mars and back, probably every cell in the body would be hit by an ionized particle or a proton, researchers say, and they have very little idea what that would do. "If every neuron in your brain gets hit, do you come back being a blithering idiot, or not?" asked Dr. Derek I. Lowenstein, the chairman of Brookhaven's collider accelerator department.

A trip to Mars means "trying to live in an environment that human beings were not built to live in," Dr. Lowenstein said. "Space is not `Star Trek,' but the public certainly doesn't understand that."

On earth, radiation shielding is easy; just add concrete or lead. That is not so easy on a spaceship, where weight is of the essence. Nor is there much prospect of significantly reducing the amount of time the astronauts would be exposed, unless NASA develops a much more effective propulsion system.

The NASA administrator, Sean O'Keefe, has identified radiation as one of three problems that will have to be solved before a Mars mission. The others are better propulsion and on-board power generation.

Brookhaven is studying the radiation in a a sprinkling of undistinguished-looking corrugated metal buildings, connected by low earthen berms. "That's where the action is," said Mona Rowe, a spokeswoman. The berms are shields for tracks underneath that carry the accelerated particles that slammed into targets or one another. Above the berms, wild turkeys amble through the woods.

The radiation environment that the accelerator is mimicking is vastly different from the terrestrial one.

The average American receives about 350 millirem of radiation a year: the fraction of solar and cosmic radiation that makes it through Earth's magnetic field and atmosphere; radiation from naturally radioactive rocks and minerals, some incorporated into building materials; higher doses from flying in airplanes; and sources like medical X-rays.

In contrast, the astronauts who went to the Moon on Apollo 14 accumulated about 1,140 millirem, equivalent of about three years on Earth in their nine-day mission. The astronauts on the Skylab 4, who spent 87 days in low Earth orbit, received a dose of about 17,800 millirem (equivalent to a 50-year background dose on Earth).

That dose was near the threshold of radiation exposure that produces clinically measurable symptoms. Longer-term effects like increases in cancer rates have not been observed in adults exposed to doses at that level, but experts presume the effects exist. By comparison, nuclear power plant workers are limited by law to exposures no greater than 5,000 millirem a year; in this country they are generally held below 2,000.

A round trip to Mars would be of a different order of magnitude. Brookhaven puts the exposure at 130,000 millirem over two and a half years. That is equivalent to almost 400 years of natural exposure.

But radiation in space is not like radiation on Earth.

[Tijeras_Slim]

The astronauts on the Skylab 4, who spent 87 days in low Earth orbit, received a dose of about 17,800 millirem

FYI total legal allowable dose for a radiation worker in the US is 5000 mr/year. This does not take into account the Q factor, which is a biological multiplier. X-rays have a Q factor of 1 where as neutrons (somewhat similar in damage effect to the particles discussed in the article) can go up to 20.

[KantianBurke]

Saw an interesting show on PBS regarding the earth's magnetic shield. It was theorized that Mars became lifeless due to the loss of their shield. Interesting stuff. The problem for our astronaunts can and will be solved.

[WinOne4TheGipper]

"If every neuron in your brain gets hit, do you come back being a blithering idiot, or not?"
Does already being a blithering idiot give you immunity? If so, I know some test people. cough-DU-cough

[rellimpank]

--sounds like Mars travel should be left to robots or the private sector--i.e., don't use my tax money for it---

[Constitution Day]

"If every neuron in your brain gets hit, do you come back being a blithering idiot, or not?"

I vote "Not"!!
See, I've already solved the problem.

[boris]

Am not an expert, but I had seen something about an emergency "closet" made of lead...where the astronauts would go during solar flares.

Off the top of my head, I wonder about magnetic fields to deflect the incoming particles...? Using superconducting coils?

And yeah; something like VASIMR or nuclear propulsion is key to reducing trip times...

--Boris

[Young Werther]

Water is the "moderator" in a nuclear reactor. It is a natural shield for the types of radiation which would bombard a Mars bound crew. This type of shielding has been suggested before and would work now.

Let's get on with the funding and planning. It is our species' imperative to move out into space as we did when we crawled out onto the land aeons ago!

Spock's waiting so lets get on with it.

[Yossarian]

Maybe this is a good reason for returning to the moon - perhaps we can obtain and apply sheilding materials there for any extended human spaceflight.

[eclectic]

On a trip to Mars and back, probably every cell in the body would be hit by an ionized particle or a proton, researchers say, and they have very little idea what that would do

Reminds me of the argument that ships made of iron cannot float

[smith288]

FYI total legal allowable dose for a radiation worker in the US is 5000 mr/year. This does not take into account the Q factor, which is a biological multiplier. X-rays have a Q factor of 1 where as neutrons (somewhat similar in damage effect to the particles discussed in the article) can go up to 20.

Total agreement...

Furthermore, Quantum juxtaposition is adherent to max-flux propulsion in a zero functional environment... Not only does it fluctuate from inversions, it aggrandizes based on static or inert regressions...

...

...

I'm a frickin' genius... ;)

[Tijeras_Slim]

Exactly... hydrogenous materials provide shielding for heavy particles, polyethylene is what I use when dealing with small neutron sources.

[dead]

LOL! An article in today’s Sydney Morning Herald reaches exactly the opposite conclusion:

'Man could survive on Mars'

Man could survive a mission to Mars according to NASA scientists, who say experiments on board the Mars Odyssey craft prove that humans could endure the planet's harsh conditions.

The results show that radiation around Mars might cause some health problems, but scientists told the BBC that humans could survive the conditions.

[Frank_Discussion]

The fuel source for VASIMR is a set of fairly large tanks of hydrogen, and most ship designs using VASIMR place the bulk of the hab and work areas inside the tank cluster for shielding. Between this and the shorter trip times using VASIMR, the whole radiation thing is a red herring.

[Frank_Discussion]

EXACTLY! Nail on the head!

[Tijeras_Slim]

Yes you are. :)

[upchuck]

scientists are using subatomic particles accelerated to nearly the speed of light to slam into materials that could be used in a spaceship, and tissue samples and small animals.

And PETA is outraged no doubt.

[Dead Dog]

One reason is radiation, in the form of heavy ions from distant stars, zipping through everything in their path.

Like this hasn't been a concern for quite awhile? NYT is about 30 years too late for this band wagon. One possible solution is to surround the crew with their water supply, or at least part of their shelter. Heavy, but deffinately doable.

Others include price, estimated at $30 billion to $60 billion, and launching enough food, supplies and fuel for a round trip

Once again, whoever wrote this has had no connection with the space program for the last 30 years. Fuel, water, and possibly some food (Grown in the base on the planet)for the return trip will produced on the planet. Most before human's arrive.

The fact that this article ignores proposed solutions to these problems, and the fact that it is the NYT, I'm guessing that this peace is a preemptive strike on what they fear will be a history making speech by GW next week. One that will eclipse that over rated tripe JFK spewed 30 years ago. "We will go to the moon and do the other things (Other Things? WTF? Marilyn Monroe?)..."

[KellyAdmirer]

Sounds like it could turn into a quagmire up there....

[justrepublican]

But radiation in space is not like radiation on Earth.

This looks like something I would write.Did I miss something in the article about two kinds of radiation?

[NotJustAnotherPrettyFace]

What about time travel? Weas-ley Clark thinks it's possible!

[Mr. Bird]

Space exploration comes with extraordinary risks, as well as the acceptance of several unknowns. No one will ever be forced to go, and I'm sure if the odds of a safe return from Mars were only 50-50, you'd still have thousands of takers.

The society that put a man on the moon didn't flinch when as a child I rode my bike down steep hills with no protection. Or when people smoked like chimneys. I'm not saying safety precautions are bad; but sometimes you gotta say "what the ----".

[Tijeras_Slim]

Did I miss something in the article about two kinds of radiation?

Not exactly. A space craft does not provide the type of protection from the space radiation environment like the Earth's atmosphere and magnetic fields.

[NotJustAnotherPrettyFace]

I think you're onto something there about the motive of NYT printing such a story at this particular time!

[Redcloak]

Hmmm... Better stock up on Trellium-D.

[William Terrell]

The average American receives about 350 millirem of radiation a year: the fraction of solar and cosmic radiation that makes it through Earth's magnetic field and atmosphere. . .

Surround the space vehicle with a magnetic field?

[NotJustAnotherPrettyFace]

"What the flux?" ;-)

[Hank Rearden]

Surround the space vehicle with a magnetic field?

But then their compass wouldn't work.

[cinFLA]

Exactly... hydrogenous materials provide shielding for heavy particles, polyethylene is what I use when dealing with small neutron sources.

Water is not the best shield for heavy materials. Polyethylene is NOT a shield for neutron sources; you need an absorber in addition to the poly which only slows the neutrons.

[js1138]

This was a key plot element in the SciFi book series, "Red Mars", "Blue Mars", "Green Mars".

[Egg]

The average American receives about 350 millirem of radiation a year: the fraction of solar and cosmic radiation that makes it through Earth's magnetic field and atmosphere...

Ain't God an awesome engineer?

He causes His sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous. [Matt 5:45b]

[presidio9]

This was a key plot element in the SciFi book series, "Red Mars", "Blue Mars", "Green Mars".

Yes, I read the first two books. I think this is where Boris is getting his "emergency" closet idea. The problem is that some levels of readiation are constant. In order to be protected, the astronauts would need to spend the entire trip in the compartments.

[AngryJawa]

Hmmm... Better stock up on Trellium-D.

No thanks. That crap makes me a little nutty...worse than tequila even. 8^)

[hattend]

Hmmm... Better stock up on Trellium-D.

Just don't let a Vulcan near it.
(Is Trellium-D a date rape drug?)

[JmyBryan]

Personally, I would rather see more money poured into undersea explaration and habitation. Limit space funding to earth orbit and possibly moon missions - until we have developed more exotic propulsion systems.

[bagman]

Nuclear reactors for space propulsion typically do not use water as the moderator. Too much mass, too many moving parts.

[Young Werther]

NASA is pursuing nuclear power plants for ion and other advanced propulsion systems. My point was that water, as a shield, could put this issue of space radiation to bed.

[Search4Truth]

We need to develop new propulsions systems first. Then we need to send robotic probes out everywhere. Think of them as scouts. In the coming decades those probes will reach other solar systems. When we find a place we would really like to go and settle, an Earth-like planet, we can then resolve the formidable problems of sending humans there.

First we have to find a place we really want to go then figure out how to get there. The initiative now should be on long range, high velocity propulsion systems.

The only reason to go to the Moon is to use it as a launch site for the interstellar probes and the subsequent human missions, national strategic security interests not withstanding.

Imagine how awestruck the world would be when seeing for the first time, video from another world. It would be the media event of all time. What a grand vision it would invoke for all mankind.

[Doctor Stochastic]

Shielding has its own problems (aside from the weight.) Secondary radiation given off by the shielding in response to energetic solar flare could be worse than the flare itself.

Let the robots do it.

[presidio9]

Imagine how awestruck the world would be when seeing for the first time, video from another world.

Barnacle Bill is going to be very depressed to hear that you think the Mars Pathfinder mission was a hoax.

[Looking for Diogenes]

Spock's waiting so lets get on with it.

Spock was a fictional TV character.

[Search4Truth]

I was thinking of something more like this. Someplace worth crossing time and space for.

[Young Werther]

..and Dr. Spock was a noted pediatrician. What's your point? Is there no room for alittle romance and frivolity? Lighten up its the holdiay season.

[Looking for Diogenes]

Is there no room for a little romance and frivolity?

I thought we were talking about Mr. Spock. Romance and frivolity? I must have missed that episode.

What's your point?

My real point is that we have to remember there is a big difference between science and science fiction.

[Young Werther]

My NSS club edited and updated the Boy Scout Space Exploration Handbook. I was credited with rewriting the History portion of the manual. The gulf between science fiction and science is alot narrower than you think, my opinion.

If you look at Tsiolokovski's drawings and models of rocket ships and Burt Rutan's SpaceShipOne you would be surprised at the similarities. Jules Verne's Around the Moon positions the "lunar gun" in Florida. The capsule with astronauts aboard swings around the moon, lands in the Pacific and the crew is picked up by a US Naval vessel. This was written 100 years before Apollo 8!

Read Asimov's robot series and then look at the coming robotic/nanotechnology revolution and maybe the Three(four)Robotic Laws will be implemented shortly.

Sorry for the rant but when I rewrote the history section I retitled it "The Dreamers and the Doers!" Boys Scouts loved it and my contribution is ....good, (pardon my bragging!)

[MediaMole]

Imagine how awestruck the world would be when seeing for the first time, video from another world. It would be the media event of all time. What a grand vision it would invoke for all mankind.

If the first image arrived at 9am on Monday, it would be old news by the 5pm network news. By Wednesday, it wouldn't make page 23 of the newspaper. By Friday, the Dems would be proclaiming planetary exploration a failure because we hadn't found life on Mars. By the following Monday, Moveon would be calling for the President's impeachment for lying about the existence of life on Mars.

[chimera]

The one proposed for the JIMO mission is a fast reactor. No moderator and control is effected via neutron reflectors. It's a very sweet design. I am working on the rad-hard electronic components for the PMAD systems. Silicon carbide is looking pretty good right now...

[Looking for Diogenes]

I haven't seen any 'lunar guns' yet. I guess that it's still in the future. (Some folks have suggested rail guns for launching very small satellites into orbit.) Nonetheless, Verne was remarkably prescient in many of his predictions.

The best science fiction writers have either based the technical aspects of their stories on good science or in a few cases have even looked forward to what might be possible.

So far as I have seen, Star Trek does neither. Its writers make up whatever mumbo-jumbo is needed to move their plot forward. Yeah, it's still fun, but is is not in the class of Asimov. It's more like Flash Gordon.

[chimera]

By comparison, nuclear power plant workers are limited by law to exposures no greater than 5,000 millirem a year; in this country they are generally held below 2,000.

That's the limit for any occupational exposure, not just nuclear plant workers. But I'm concerned the article is blurring the distinction between acute and chronic exposures. For a long-duration mission, I think chronic exposure is the mechanism we should look at, and there you're more concerned with cumulative, lifetime exposures, which have higher limits. Organic systems have repair mechanisms which tend to mitigate the effects of long-term exposures.

Wasn't there a Mir mission where a cosmonaut was up there for like 450 days? That might come close, at least within hailing distance, of the exposure duration for a Mars mission. If so, we should look at the exposure data for that mission to get a handle on what we're talking about here.

[dhs12345]

Good idea -- mag field. Will only affect charged particles though and is probably a power hog. Superconductors will improve efficiency.

The Earth's mag field helps protect from radiation.

Still a good idea.