Are humans doomed to remain marooned on a world orbiting a third-generation star while all the universe tantalizingly beckons just out of grasp?
A new study seems to suggest that depressing scenario. While it's true much of the human race would prefer to stay rooted to terra firma, the future—and future survival—of Mankind lies outward with the stars.
What irony it would be—now that astronomers have confirmed that the Milky Way galaxy has about 100 billion planets—if humans were condemned to remain on a little world whirling away in the Sagittarius arm of a spiral galaxy, one of a galactic clusters of galaxies flung into the midst of an infinite reality.
According to the study, even travel to Mars may be a venture fraught with danger to the brain. The environment of space may be more unfavorable to humans that previously believed.
What may keep humans from inheriting the stars? It's not space monsters, evil aliens, or insurmountable interstellar distances, but killer cosmic rays.
Space is an inherently dangerous place. Thoughtlessness can quickly lead to death. Extreme cold, irradiation from solar flares, malfunctions with environmental systems, or lack of pressure or oxygen are just some of the many hazards. Now a major new hazard has been discovered that overshadows all the others. Cosmic rays are difficult to shield against and the longer the human brain is exposed to them the more neural damage can occur. Eventually, the cognitive functions can deteriorate to the level of people suffering from Alzheimer's disease. In fact, those that have a high risk of the disease will accelerate its onslaught.
Cosmic rays encompass a category of particles known as high-mass, high-charged heavy ions (the so-called HZE particles). Researchers have discovered, writes physorg.com, that, "These particles—which are propelled through space at very high speeds by the force of exploding stars – come in many different forms. For this study the researcher chose iron particles. Unlikely hydrogen protons, which are produced by solar flares, the mass of HZE particles like iron, combined with their speed, enable them to penetrate solid objects such as the wall and protective shielding of a spacecraft."
The challnge that HZE particles present was first researched by the 1994 study, "HZE particle effects in space." That was followed by a study investigating possible ways to accomplish "Repair of HZE-particle-induced DNA double-strand breaks in normal human fibroblasts."
The new study, published in the journal PLOS ONE, "Galactic Cosmic Radiation Leads to Cognitive Impairment and Increased Aβ Plaque Accumulation in a Mouse Model of Alzheimer’s Disease," was led by Dr. M. Kerry O’Banion, a professor at the University of Rochester Medical Center (URMC) Department of Neurobiology and Anatomy.
“Galactic cosmic radiation poses a significant threat to future astronauts,” O’Banion explained, “The possibility that radiation exposure in space may give rise to health problems such as cancer has long been recognized. However, this study shows for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer’s disease.”
The study has dire implications to long range manned space missions planned by the American and Russian space agencies. NASA has missions to an asteroid and Mars scheduled in the decades ahead.
Colonies on the Moon or Mars may be able to protect against cosmic ray exposure by utilizing partial underground facilities and erecting heavy shielding. Spacecraft, however, cannot be built with walls of heavy material to block the constant bombardment. Therefore, HZE particles may doom Mankind's dream of ongoing interplanetary, and perhaps interstellar travel, unless a solution to the problem is found.