Remember all those science fiction movies that showed space travelers encased in sleep chambers? The premise was that humans could be put into a deep sleep, thus making it possible for manned missions to reach far away planets and galaxies without the necessity of keeping crew members awake the entire time. Perhaps it's not just science fiction any more.
A NASA funded study on the feasibility of placing astronauts in a prolonged state of sleep-known as torpor---has recently shown that the idea may not be as farfetched as Hollywood makes it seem. NASA has contracted with SpaceWorks Enterprises in Atlanta, GA to look into the technology of long-term human stasis. The study, Torpor Inducing Transfer Habitat for Human Stasis to Mars, is showing early signs of successfully putting crewmembers into a kind of hibernation.
With current spacecraft technology, a flight to Mars would take about 180 days. In order to keep astronauts busy, healthy and fed on a journey that long, the baseline weight of the spacecraft would be around 400 tons. That includes food, galley space, exercise equipment, clothing and other crew equipment. The astronauts would be "fed" via an intravenous administration of nutrients, reducing the need for six months worth of food and water to be on board. If astronauts spent their transit time asleep, in a specific stasis habitat built into the spacecraft, the weight could be reduced to about 220 tons. In addition, the energy needs of a lighter craft would be significantly reduced.
How can this state of torpor be induced though? One method that is already used in medical science is known as "therapeutic hypothermia" where a patient's body temperature is deliberately lowered in an attempt to prevent brain damage and tissue injury following cardiac arrest, spinal cord injury or stroke. The preferred method of cooling the body is an intranasal system RhinoChill. An inhaled gas cools the body by about 1-degree Fahrenheit per hour and a torpor state can be fully achieved in about six hours. Stopping the gas will allow the body temperature to begin to rise, however warming pads are also planned so that a crewmember could be awakened faster in the event of an emergency.
So far, scientists have only been able to keep a person in this state for about a week. Research is ongoing into how to safely extend this time as well as how to wake crewmembers remotely if there were medical complications or a change in the mission. In addition, vital signs and health status of astronauts in stasis would need to be monitored in real-time. One option being considered is to rotate crew member sleep shifts, keeping one astronaut awake for a few says doing scientific research and other chores required while the rest of the crew is in kept in stasis for two weeks. By staggering stasis and awake times, the potential for complications from long-term damage would be greatly reduced and there would always be one crewmember awake to handle any unforeseen events.
While it seems an impossible task, the concept of a successful mission to Mars by astronauts who have been kept in a prolonged stasis could soon be a reality. NASA has made it a priority in backing this study and the knowledge gained could be a game changer in the race to send a manned spacecraft to Mars.
