(Visited 92 times, 1 visits today)FacebookTwitterPinterestSave分享0 Through the imagination, we can soar through distant galaxies. Sooner or later, physical reality hits home.Amazing, isn’t it, that space travelers in the movies can walk normally and breathe the air no matter what planet they land on. It may save money for Hollywood, but is it realistic? A couple of articles suggest otherwise. For better or worse, we humans are stuck here.Fried BrainsNew Scientist explores the topic that “Space travel’s mental health toll could endanger long missions.” Human beings have pretty good experience with low earth orbit. Peggy Whitson just broke the spacewalking record, exceeding a cumulative 50 hours in a spacesuit outside the space station. The longest continuous space flight so far is 437 days. But when it comes to living for years in a tin can aimed for Mars or other distant worlds in Star Trek mode, mission designers hit the wall of physical realism:“Two of the most critical issues are the radiation exposure beyond low Earth orbit and the psychosocial effects of confinement and isolation,” says Carol Scott-Conner at the University of Iowa, chair of the committee behind the report. She calls them “potential showstoppers” that could cause missions to fail.One rogue crew member losing his marbles could ruin the mission. Dead astronauts drifting forever in space doesn’t make for a good movie plot.Astronauts bound for distant destinations would share a small space with a few fellow crew members, and would be away from friends and family for years. They are also likely to be working hard, with their sleep patterns disrupted, and will lack real-time communication with Earth, all of which could affect mental and physical health.The human body is used to sunrises, sunsets, seasons, and other circadian rhythms. Humans can adapt for periods of time; astronauts do sleep in weightlessness apparently well. But would the body and brain adjust to years of absence from the familiar cues of light and temperature?Another problem is that nobody knows the cumulative effects when the risks are added together. “Isolation, radiation and other dangers could interact to pose a major risk to mental and physical health on long space missions, according to the US National Academies of Sciences, Engineering, and Medicine.” We must remember that Leonard Nimoy and William Shatner were always safe in a Hollywood studio on terra firma during their long treks of the imagination.Gravity of the matter On Space.com, UCLA bioengineering student Andy Tay raises another problem: “Life on Earth is Used to Gravity — So What Happens to Our Cells in Space?” We know from decades of astronautics that life of many kinds can operate in space fairly well. Astronauts like Sunita Williams in this tour of the space station seem fit and happy after months up there.The aftereffects on the human body, however, are not trivial; we’ve seen astronauts hardly able to stand up when emerging from a space capsule. Bodies become elongated and lose muscle mass. Tay says, “Our cells have evolved to deal with forces in a world characterized by gravity; if they’re suddenly liberated from gravity’s effects, things start getting strange.” Problems reach all the way down to the level of sub-cellular organelles and molecules:Without gravity, the forces acting on mechano-sensitive ion channels are imbalanced, causing abnormal movements of ions. Ions regulate many cellular activities; if they’re not going where they should when they should, the work of the cells goes haywire. Protein synthesis and cellular metabolism are disrupted.Tay lists several known problems with long absences from earth gravity: (1) blood pools in the brain, creating pressure that leads to cognitive problems; (2) bone and muscle atrophies, leading to a 1% loss per month even with strenuous exercise; (3) the immune system becomes compromised, leading to easier infections. Some of these can be mitigated by exercise, supplements and sterilization, but “So fare there’s no quick-fix substitute for gravity,” the article says.We know from the movies that rotating space stations can create artificial gravity, but the more mass you put on a spacecraft, the harder it is to build, launch, and accelerate. Earth’s gravity well is unforgiving. Governments paying to launch these human sardine cans with their citizens’ taxes will have to balance cost with benefits. Human longevity after the mission is unlikely to reach the highest priorities.Are you sad that after 50 years, man has never been back to the moon? Are you disappointed that humans may never get out of low-earth orbit to build colonies on Mars in your lifetime? Don’t be. You’re living on the best spaceship there is right now.Many have likened our planet to a kind of spacecraft. Here’s an early-bird announcement: your friendly editor is working with a renowned rocket scientist on a book that will investigate some of the many features of Spacecraft Earth that make it perfect for life. Watch for word about it later this year.Spacecraft Earth is the best environment we know for our journey through space. Live long and prosper, and may the force of gravity be with you.