Jay C. Buckey, associate professor of medicine at Dartmouth Medical School and a former Shuttle payload specialist, argues that advances in high temperature superconductors may allow creation of a protective magnetic field around a Mars mission spacecraft.
Just as a magnetic field protects Earth, it might be possible to put a magnetic field around a spacecraft. A coil of a superconducting material could produce a substantial magnetic field, which could, in turn, deflect the energetic galactic cosmic radiation. For a small-coil radius, the magnetic field would have to be quite strong (several Tesla) to be effective. A field of this size presents major structural and safety issues. The larger the coil, however, the weaker the magnetic field needs to be. A wire wrapped on a spool could be unwound in space into a large coil. As the radius of the coil approaches a kilometer or so, the field strength and current that is needed will drop to reasonable levels. This approach to shielding, called active shielding, potentially could keep radiation levels within the spacecraft at any desired level.
One of the big unsolved problems for a Mars mission is how to protect the astronauts from cosmic radiation while they are travelling between Earth and Mars and while on the surface of Mars. A physical shield around crew living quarters would require too much mass. Maybe an artificial magnetic field could solve the problem.
Buckey notes that the bone loss from zero gravity might be solved in time for a Mars mission by on-going biomedical research aimed at developing treatments for osteoporosis and other bone diseases. This fits a larger pattern: Most of the problems that make a Mars trip highly problematic will eventually be solved because of research and development advances that will come from industrial and academic labs motivated by profit and by the desire to solve problems we face down here on Earth.
A push for a Mars mission is unlikely to lead to funding of large numbers of areas of research well enough to appreciably accelerate the various fields of science and engineering that will produce those solutions. Why? The number of people wanting those advances for space exploration is far smaller than the numbers who want those advances for purposes on Earth. We will get better superconductors because the electric power industry and other industries on Earth see those superconductors as a way to lower costs by huge amounts. We will get better ways to control bone cells because of the desire for better ways to treat osteoporosis and bone injuries. We will eventually get better nuclear reactors and even fusion reactors which would be of considerable value for a Mars colony. But those reactors will come as a result of the widely recognized need for better replacements of costly fossil fuels down here on Earth.
Another big area of research is robotics. In two or three decades robotics should reach a point where robots could be sent ahead of a human mission to operate mining operations and construct habitats for humans on Mars. Will NASA and other space agencies get budgets large enough to appreciably accelerate the rate of advance of robotics? I'm guessing the answer is No.
I'm not arguing against funding specifically aimed at developing technologies in order to use them in space. In fact, if a larger fraction of NASA's budget was allocated to new technology development and less of NASA's budget was allocated to operating existing technologies ("existing technologies" examples include the expensive Space Shuttle and International Space Station) we'd be better off because technological advance would be accelerated. But a big push to put people on Mars in 20 years would mostly go to engineering development and manufacturing aimed at using existing proven lower risk technologies. Look at the International Space Station for an example of what big budget space hardware projects produce: Little new technology and lots of work for aerospace contractors.
My lack of enthusiasm for space exploration is in large part due to my perception that there are far better ways to spend money to accelerate the rate of scientific and technological advance than to do a new Moon mission or a Mars mission. Want advances in robotics? Fund robotics research. Want advances in energy? Fund energy research. Want advances in medicine that are useful for space trips? Fund osteoporosis research, stem cell research, tissue engineering, gene therapy, genome mapping, microfluidics, and many other areas of biomedical research.
Humans will go into space in larger numbers and travel greater distances once technologies developed for Earth-bound purposes mature to the point where future technologies provide solutions which lower the cost and increase the safety of space exploration by orders of magnitude. Changes in government policies that accelerate the general rate of advance of science and technology on Earth will do far more in the long run to bring about a new age of space exploration than would a push to start development of spacecraft and other equipment needed for a Mars mission.
By Randall Parker at 2005 April 07 05:55 PM Space Exploration | TrackBackIf we actually get something like room-temperature superconductors, I can immediately think of a far better use for them than that: building smaller fusion reactors.
Room tempereature Superconductors, if they can be made more flexible, would also be
used to store energy at high density, and this would also revolutinize energy.
But we are still a long way from fusion reactors, not just because we do not have
good enough superconductors, but because fusion is still a very complicated phenomenon
to control, even with good enough magnets. However, the brute force method (I mean slightly
bruter force method) of National Ignition Facility offers a ray of hope for fusion reactors,
because it bypasses the old and complicated designs like tokamaks, etc.
I've been considering this same thing, albeit for a slightly different purpose: self-tensioning a circular cable in zero G. On the other hand, it would deflect solar protons and other low-energy charged particles just fine.
i think unmanned missions are a lot more economical because you can tolerate a higher rate of failure when loss of life is not involved, thereby reducing the cost per mission by quite a bit.
There are non-economic reasons to pursue human space travel. Sometimes risk is good for the soul of the human species.
Jeff Gordon
Jeff,
Very few people will be put at risk by a Mars mission. The rest of us have to pay hundreds of billions of dollars so that we can watch only 8 or 10 people put at risk. I can put you at risk much more cheaply: Just ride in a car with my brother. He's a high speed maniac. I do not want to put myself at risk this way but he insists on picking me up at the airport when I come to visit. Is my soul being enriched by going at 90 mph in a pick-up in the rain in traffic?
That same hundreds of billions of dollars could put many more people at risk. It could pay for millions of white water raft rides or for horse rides up mountains or rides in fast cars.
We could even spend the hundreds of billions on medical research into aging cures and enroll hundreds of thousands of people in trials of risky gene therapies. Lots of people could be put at risk to produce much more useful and productive outcomes.
We can get all kinds of things from aging cures, but we can't capture the imagination of the nation that way. No matter how many people live to 200 through medical advances, the laboratory work is not going to focus the national attention like 8 people in a spacecraft going to Mars. They'll risk their lives doing it, but to see risk as the objective is to miss the point utterly.
Wasn't Mars Direct about a $40 billion program? Downright cheap.
Anyway, back to superconductors: IIRC, it's possible to cool things to near LN2 temperatures just by putting them in Dewar vessels behind IR transparent windows and letting them radiate to the sky (perhaps only from mountaintops, but even so... you can do it from the ground). It should be possible to cool a loop of high-temp superconductor just by putting it behind a few layers of sunshade (layers, so that the heat radiated by the sunlit one gets blocked). A slight static charge would separate the layers; this has the potential to be very easy to do and very reliable.
E-P,
The prospect of better treatments has caused NIH to get about 3 and a half times more budget money per year than NASA. Well, sure looks like a lot of imaginations are captured already. Lots more people are lobbying Congress as part of groups interested in specific diseases. Celebrities do it.
As for cost estimates of a Mars mission: I recall the cost estimates back in the 1980s for building the International Space Station. This huge station was going to get built for not too many billion dollars. It has been way scaled back and isn't its cost now north of $100 billion?
We went to the Moon. Some people were excited by it. But the public at large got really bored of it very fast. Since then the public has not been interested enough in L5 colonies or a return to the Moon or a trip to Mars to get any of this funded. Meanwhile, due to the aging of the population and advances in medical technology I see a growing interest in what biomedical research can accomplish and that interest is going to grow much larger. People see how they can benefit very personally from biomedical research.
So what point are we missing? That we can establish a Mars base so that some small number of people will survive when all life on Earth dies? Or are we supposed to be caught up in the excitement of the adventure?
I happen to agree that risk isn't the point and was perhaps a poor choice of words. I was just trying to note that not all things individuals or groups do are based solely on economic considerations. For example, I don't think most people have children based on cost/benefit analysis. They have children for deeper reasons. OK, some of them just forgot the birth control.
Space travel was what got me into engineering; I WAS caught up in the adventure. Of course once I really understood the physics of it (rocket equation is depressing) I know that we're going nowhere fast without vastly improved sources of energy (bare minimum = fusion) and propulsion systems. Thus, over time I've come to pretty much the same conclusion as Randall, basic aerospace / physics research is good. Stop wasting money sending seven humans to low earth orbit. Once good fusion engines are available (a space elevator wouldn't hurt either), then maybe we can get out there.
I also agree that money spent on basic biomedical research offers more bang for buck and improves life for more people. However, once we're immortal it would be nice to have some grand projects for the human race. I offer up human space colonization as one of those projects.
JM, what's your take on dissolved-salt nuclear rockets, pebble-bed fission rockets, and the like? Do you think they wouldn't work or that we just wouldn't be able to develop them?
We should be able to identify earth type planets by 2020. With a protective magnetic field it brings us the ability of reaching these new worlds a step closer.
What about claims by several astronauts and cosmonauts (such as the late Gordon Cooper) that NASA is actually a smoke screen concealing the truth about our contact and knowledge of Extra terrestrials and Advanced technologies?
Can we take such first hand testimonies by celebrated specialists so lightly?
And if this is true - should we waste any more tax payers money on NASA's disinformation?
It seems to me that we must have a publicly funded space program to put this issue to rest once and for all.
Respected Sir
I u publish a detail notes on Super conductors it Ill help more
More people who are proportionals in a perticular field they are eger to know
which metal is acting as a Superconducting in high temp
It also nice Sir
Thankyou For Giving Respect To our Comment
For a given magnetic field geometry, to deflect a particle of a given energy and charge/mass ratio, the magnetic field required scales as 1/r, r the radius of the system. The stored magnetic energy, and therefore (by the virial theorem) the mass of the coil and its mechanical structure, scales as volume x B^2, which is proportional to r. The mass per unit shielded volume gets better, though.
So, using a larger radius coil does not decrease the mass of the shielding system, it dramatically increases it. An exception would be if the coil can be anchored on a planet, moon, or asteroid, so the material of that body would take the J x B forces on the coil itself.