If we can solve the difficulty(cost) of getting things into orbit. Then radiation won’t be that great of a hurdle.
Or we can just send out robots. Which is what we’re going to do anyways.
Solar radiation can be reduced using magnetic shielding. Cosmic rays, however, can only be blocked using sheer mass. Earth’s atmosphere provides about one ton of mass per square foot. It would be difficult to duplicate this for a space ship unless it’s a real big space ship, or a large space station. Neither of these are impossible, however.
One advantage to remaining in LEO for these past 40+ years has been remaining under the relative protection of the Van Allen belts. Going through those on the way to and from the Moon wasn’t much of a challenge, because the transits only took a few minutes.
Prussian Blue is ferric cyanide! Ya gotta wonder about the long-term effects of consuming it!
Clearly in all the universe (no way we can know) there is one place amazingly created for man - the earth.
The complexity of the environment that protects us is almost beyond imagination - and yet - prideful man cannot see that such and environment HAD to be created. And only God could have created such an environment.
It’s fine to adventure out of our safe zone. USA would not exist if Columbus, the Puritans, and many others had not left the safety of their places of comfort. But there are limits to how far we can adventure.
Will we ever figure out how to safely travel great distances without earth’s protection? I doubt it. Not only is the hostility of space a major factor - the greatest one is time. One cannot break the laws of physics.
I know, some will say my view is similar to those hundreds of years ago who said we would never fly. But flying does not break the laws of physics - it uses them.
I doubt that we will ever be able to do that with time - in spite of all the science fiction we’ve become familiar with in the last 100 years...
Four centimeters of titanium does provide sufficient protection from almost all solar particle events or "SPE's." Counter to intuition, when the Sun is at it's most active its swelling of the interplanetary magnetic field refracts as much as 50 percent of the GCR's showering into the inner Solar System from outside. But those "GCR's" are often the very energetic stripped nuclei of iron and more exotic metals barrelling into our star system from every direction, and at near light speed. A ship-borne artificial magnetic field designed to refract such inbound GCR's would have to be initially effective beginning at 2000 kilometers distance away from a spacecraft. There is no advanced warning of their impending arrival from which one might gain shelter, unlike the risks posed by coronal mass ejections or other solar particle events.
The writers correctly admit that a four-centimeter thick titanium hull actually results in the spallation of a single heavy metal GCR nuclei from a single bullet into a shower of an only relatively less energetic shotgun shower of fragments that then pass dangerously through passengers. In other words, when it comes to GCRs, hulls that protect the crew from the dangers posed by the Sun, in the case of much more energetic and heavy GCRs, make a very bad encounter worse.
It's calculated in terms of risk, not mitigation.
Low Earth Orbit is somewhat shielded not just by our planet's relatively strong magnetic field, apparently unusual among the rocky planets of the inner Solar System, but also from proximity to the Earth itself. Like being on or near the Moon, Mars or Earth, the planet at our feet, so to speak, always provides shelter from half of the incoming GCR's. But unlike Earth, the sky above is wide open to at least half of these incoming interstellar bullets when standing on the Moon or on Mars, where an equivalent shelter might only be found 30 meters underground. It was hoped at one time that the strong highly local magnetic fields now mapped on the Moon, for example, such as the one near the landing site of Apollo 16, could provide sufficient shelter, but even though it might add to calculations reducing the cumulative risks to astronaut health, those fields don't stand off from the planetary surface the 2000 kilometers needed to begin bending away energetic GCR's in time.
For NASA's astronauts (not for its dependent industrial lobbyists and bureaucrats) the risk to health is coldly calculated in an individual passenger's lifetime risk of radiation-induced death. Flights across the poles, chest and head xrays, even exposure to radon over a person's life all go into their calculations, along with the altitude and length of earlier spaceflights. Once their periodic estimations and tables conclude that an individual astronaut's lifetime risk of eventual radiation-induced death reaches five percent, that astronaut is grounded. The simple fact of the matter is simple and stark when it comes to proposed roundtrip voyages to Mars, using present velocities and standard Holman-transfer orbit schematics. Such a trip would cross that threshold, as acknowledged by the National Research Council in 2003. It would be no more of a death sentence than a smoking habit or from being on the Fukushima clean-up crew, but enough risk for NASA to ground every crew member upon their return to Earth and in some cases prevent their being on such a crew at all.
Again, perhaps counterintuitively, older proposed crew members would have at least one advantage over youth. They are more likely to eventually die of other causes, over the shorter period of their estimated remaining lifetime. Just one more thing added to the cold actuarial calculations used to choose crew members. Nonetheless, even taking mitigating factors into account, like estimated solar activity during the time of the mission or the proposed time spent on the surface of Mars as well as life history into account, if NASA estimate's that an astronaut's ride along a planned mission into deep space will result in reaching beyond a five-percent risk of an eventual "radiation-induced death," that member won't be allowed to fly under their present guidelines and policy.
There are mitigation strategies designed to reduce if not entirely eliminate the real risks of travel to Mars, but nearly all of these involve innovation, new technologies that will need to be tested and coldly evaluated, including hull designs. It seems many of the stories appearing in industry and national press dismissing the challenge presented by GCR's is designed to address the low-information federal budget staffer and lawmaker.
Many in the space industry are hoping Congress never bothered to actually read the National Research Council's pre-Obama era studies on the subject more than a decade ago.