03/08/2006
On to Mars?
No more morning walks on the Marco Island beach. It was back to New Jersey last week with freezing weather and an icy mixture of sleet, snow and rain that left a half-inch coating of ice on our driveway. My wife and I also simultaneously developed horrific colds. Back to reality! I left Marco realizing that this year I did not see a single dolphin, starfish, sand dollar or conch egg packet. I did not see the large heron standing at water’s edge that I’ve seen the past few years. I fantasized that the heron, standing in the water facing the western sky, shared my appreciation of the beauty of the setting full moon.
I also did not see an eagle this year. In my last column, I mentioned the controversy about the plethora of eagles in Homer, Alaska. Well, a front-page article by Aisling Swift in the Naples Daily News showed that eagles and the environment are a serious matter in Florida as well. A construction worker was on trial in Federal Court for cutting down a tree that housed an eagle’s nest. The fellow claimed that his employer, a development company, told him to cut down the tree and that he didn’t know the nest belonged to an eagle. The first-degree federal misdemeanor charge was brought under a provision of the Bald and Golden Eagle Protection Act and is punishable by a one-year sentence in federal prison and a fine of $5,000! The jury found the employee not guilty. However, the development company agreed to pay over $350,000 in fines and restitution. It doesn’t pay to mess around with eagles.
It’s been many years since Neil Armstrong said “Houston. Tranquility Base here. The Eagle has landed.” Just as John F. Kennedy is remembered for initiating the venture to land on the moon, George W. Bush would like to be remembered for his initiation of a program to land on Mars. It’s probably a sign of my age, but I never expected to read or find anything of interest in Rolling Stone. Therefore, I was shocked to receive from Brian Trumbore an article from the February 23 issue. The article by Benjamin Wallace-Wells titled “Mars or Bust” was a surprisingly good description of the proposed Mars mission and the challenges that it poses.
I’ve written before about some of these challenges and, while I endorse the concept of going to Mars, I’m of the opinion that it highly unlikely man will ever land on Mars and return safely back to Earth. Obstacles include the obvious ones of providing sufficient food, air and water for the proposed six-man crew on a trip lasting over two years. There are the huge psychological problems associated with a crew being cooped up together for that period of time, the problem of powering a spaceship big enough to house the crew, the hostile environment once the crew lands on Mars, the possibility of one or more of the astronauts coming down with a serious medical problem, etc.
Initially, it was claimed that the Mars program would not take money away from other space projects that were on NASA’s docket. However, in the last week or so, there have been reports of NASA canceling or delaying programs because of the shift to emphasis on Mars. Among those mentioned are programs aimed at finding earth-like planets outside our solar system, to my mind an objective that should take precedence over any Mars mission.
While none of the above challenges are obvious show-stoppers, there is a problem that must be addressed before a Mars mission gets off the ground. The problem is cosmic rays, which aren’t rays but are ions (mostly protons) hurtling through space at nearly the speed of light. We’re fortunate in that we’re surrounded by enough air that these cosmic bullets and the debris that results when they strike the atmosphere get absorbed or downgraded before reaching us on the ground. Eugene Parker, in an article “Shielding Space Travelers” in the March Scientific American makes the case that, unless there’s a breakthrough in protecting astronauts from these cosmic rays, this could be a show-stopper. Parker knows whereof he speaks. An emeritus professor at the University of Chicago, he’s a leading expert on interplanetary gas and is credited with first proposing the solar wind and explaining how it works.
There are three approaches to shielding against the cosmic rays. One is to surround the spacecraft with enough of some material to mimic what happens in our atmosphere. Water is one proposed material and is something the astronauts would need anyway. However, for a relatively compact space capsule, the water would have to be between 15 and 20 feet deep and would weigh about 500 tons! That’s a lot of water to carry around. For comparison, the Space Shuttle only carries a payload of some 30 tons. Instead of water, another suggested material is solid polyethylene but the weight would still be exorbitant, about 400 tons!
Another approach is to use a magnetic field to deflect the cosmic rays. Earth’s magnetic field helps in this regard for those living near our equator but does little or nothing to deflect cosmic rays at higher latitudes especially near the poles, where the field provides little or no deflecting of the cosmic rays. The magnetic field for our Mars spacecraft would have to be about 600,000 times larger than Earth’s magnetic field. However, Parker cites the case of a colleague who once stuck his head between the poles of an old particle accelerator magnet. When the fellow moved his head, flashes of light appeared in his eyes and he had an acidy taste in his mouth. The latter is thought to result from electrolysis of his saliva! Not a good thing. And this was in a magnetic field much weaker than that needed to shield the space travelers.
While one proposed design of equipment to generate a large enough magnetic field would “only” weigh 9 tons, that’s still a lot of extra weight to carry to Mars and back. Furthermore, if moving around in such a large field electrolyzes saliva and causes flashes in the eyes, who knows what other effects it might have on the body. It might be necessary to “neutralize” the large field in the living quarters of the spacecraft but that would add another degree of complexity and weight.
Another proposed approach to shielding the cosmic rays is to charge the outside surface of the space capsule. The cosmic rays are protons and other heavier nuclei with positive charges and should be repelled by a positively charged spacecraft. Parker points out that the charge would not only have to be huge to deflect the positive cosmic bullets but, in addition, the solar wind fills space with electrons, which are negatively charged. These electrons would be strongly attracted and accelerated by a positively charged capsule and generate gamma rays when they hit the capsule. These gamma rays would create as much of a health problem as the cosmic rays. So much for that idea.
Let’s assume that a crew does make it to Mars. With precious little atmosphere, there will be cosmic rays galore and the astronauts will have to quickly construct a shelter covered by tons of Martian dirt. This is something that they aren’t likely to be able to do with just a pick and shovel, especially if they haven’t solved how to avoid the loss of bone mass during space travel! It would seem that robots and heavy equipment capable of building a shelter would have to be sent to Mars prior to the astronauts’ landing.
Should a crew actually make it to Mars and back, Parker cites a NASA estimate that a third of the astronaut’s DNA will be cut by cosmic rays each year. Another estimate from the Federal Aviation Administration is that 1 in 10 male astronauts and 1 in 6 female astronauts will die of cancer caused by cosmic rays on a Mars trip. These figures are speculative because there just aren’t enough data to make firm conclusions. On the biomedical front, there is the chance that some people will be found to be genetically more resistant to radiation and/or that some sort of drug can be found to prevent or minimize radiation damage to DNA. I’d like to thank my brother, an expert in the field of radiation damage in DNA, for a tutorial in this field. He agrees with Parker that so far the only compounds known to provide some degree of resistance to radiation damage are themselves toxic.
In spite of the odds cited above, I have no doubt that there will be many brave men and women who will consider such odds to be quite acceptable just so they can be a part of such a monumental adventure. While a manned Mars landing won’t happen in my lifetime and I am highly skeptical of the wisdom of spending enormous sums of money on the project, I certainly wish any astronauts that do embark for Mars a safe and successful journey.
Allen F. Bortrum
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