 With the launch of Sputnik in 1957, the world was witnessed to human beings venturing into outer space, an event that catalyzed decades of space exploration and technological innovation for countries all over the world. Shortly after Sputnik's launch, NASA was created in a revolutionary move. Just as John F. Kennedy stated, the 60s saw men landing on the moon with Apollo 11. As more and more manned space operations started succeeding, space agencies started daring to venture further and further into outer space. Humans started leaving for space for longer and longer periods of time. During the 1960s, NASA broke through with the projects Gemini and Apollo, testing astronauts' ability to endure long periods of spaceflight. Consequently, scientists began to see the effects that space was having on the human body. First, we touch upon the effects of changing gravitational states on the body. Astronauts often find themselves encountering different levels of forces based on where they are in space. Due to changing gravity, astronauts experience changes in spatial orientation, hand-eye and head-eye coordination, balance, and locomotion. Reportedly, motion sickness is quite the common ailment in space. NASA has also learned that moving between different gravitational states results in bones losing vital minerals, with bone density dropping one percent a month. On Earth, this rate is usually around one-tenth of that. The changing gravity also results in fluid shifting toward the head, causing vision problems and kidney stones as a result of dehydration and increased excretion of calcium from the bones. Cosmic radiation is just as detrimental to the human body as changing gravity states in space. At the ISS, astronauts are faced with 10 times the radiation levels that humans experience on Earth's surface. Though Earth's magnetic field and atmosphere protect us from this radiation on land, space is no man's land for these killer waves. Radiation exposure at the levels experienced in outer space causes cancer, damage to the central nervous system, reduced motor functions, and drastic behavior changes. You could develop degenerative tissue diseases such as cataracts, cardiac and circulatory diseases in space due to this radiation as well. And on top of this, the food and medicine astronauts need to survive in space are also subject to this radiation. Scientists have to engineer special solutions to protect astronauts as well as their vital resources against gravitational force changes and cosmic radiation in space. After many years of space exploration, NASA established the Human Research Program in 2004 to formally study in great detail, space's effects on the human body. Many of you have heard of their famous experiment term, the Twin Study. Astronauts Mark and Scott Kelly were separated, one remaining on Earth while the other lived aboard the ISS for a year. Because identical twins share the same genetic makeup, the study provided a way for scientists to explore how our health is impacted by the environment around us, independent of the physical variations that naturally occur between most of us as individuals. Based on the results of studies like this one, the HRP has been able to develop and iteratively improve devices and methods that protect astronauts and their resources from the bad parts of space we talked about. These include better spacesuits, synthesize foods and medicines, high-tech onboard systems to remove carbon dioxide and provide oxygen for astronauts aboard the ISS, and special heat shielding panels and tech for spacesuits and spacecraft. If the human race ever follows a storyline like interstellars and decides to colonize another planet, we're going to need significant protection against the many dangerous forces in space. And even if we don't go down that route, to ensure the safety of our brave astronauts as they explore the cosmos and send important knowledge back down to Earth, we must keep supporting the innovation that makes space travel possible. Many scientific questions we never dreamed of answering 40 to 50 years ago have been solved by human space exploration. With companies such as SpaceX and Virgin Galactic among others, people will increasingly start traveling into space, and knowing how space travel affects the body is of utmost importance if we want to limit casualties and maximize opportunity. Well, that wraps up our two cents about space travel's effects on the human body. Stay tuned for more science videos.