Mars is a close neighbor of Earth, with a closest distance of about 55 million kilometers to Earth. With current technology, launching a spacecraft from Earth to Mars can only be maneuvered using inertial kinetic orbits, which takes about 6-8 months.
If the astronauts can be in a "dormant" state after the spacecraft is launched, it will undoubtedly greatly improve the comfort of astronauts in deep space exploration, which is equivalent to "one sleep to the destination", and this technology has also become a topic that scientists have been competing to study for many years.
The "dormant" mechanism of some animals
Previous studies have shown that when ultrasonic signals are sent to the brains of some rodents, they will be in a dull state, equivalent to being "hypnotized", so whether this mechanism of action applies to humans will directly determine whether it can be applied to astronauts in deep space exploration.
In fact, not only mice, when food is scarce or the weather is too cold, some mammals, birds, insects, amphibians and fish involuntarily enter a state called "numbness", a mysterious and temporary state characterized by a sharp decrease in metabolism.
When at rest, the animal's body temperature and heart rate drop sharply and blood flow slows down. During hibernation, animals string together multiple dormant states, slowing their heart rate from hundreds of times per minute to just a few times; Breathe every ten minutes or more; and weaken their brain activity until it becomes undetectable.
These physiological changes greatly reduce the amount of energy needed for animals to survive. As a result, scientists have long been keen to see if these benefits could reach humans in severely injured states, or those who fly alone to distant planets for extended periods of time.
Perform ultrasonic "bombardment" experiments on mice
In fact, records of potential medical uses for hypothermia date back to ancient Egypt. Napoleon's chief surgeon, Baron Larry, also observed this phenomenon in 1812. Before amputating the injured soldier's limb, Larry applied ice to the injured soldier's limb and observed that the injured person died faster in the warm flames than in the cold. In modern times, surgeons use hypothermia during heart and brain surgery to improve patient survival.
However, for those who will not naturally enter the "dull" state, whether it can be artificially and safely pushed into the sluggish state remains an open question.
To investigate this possibility, the scientists who supported the new study created a wearable ultrasound hat that they initially glued to the heads of mice. When powered on, the device emits ultrasound into a part of the rodent's brain, the preoptic area of the hypothalamus, a key brain region for many animals to control body temperature and sleep, and an activation area for hibernation and paralysis in hibernating animals.
After receiving the ultrasound impact, the mice immediately entered a sleep-like state, with a sharp drop in body temperature, heart rate and oxygen uptake. The mice became sluggish and ate significantly less food.
By repeating the ultrasound burst each time the mice's body temperature rose above the target level, the scientists were able to keep the mice in this sleep-like state for up to 24 hours without observing any signs of injury or discomfort. When the ultrasound cap was turned off, the rat's normal body temperature and activity levels were restored in less than 90 minutes.
Is this experiment applicable to humans?
After repeating the experiment on 12 rats, the scientists found that the device also caused a drop in body temperature in the rats, albeit by a smaller amount, up to 2 degrees Celsius. This means that the hat can still be used on mammals, including humans, that go into dormancy unnaturally.
"Further research is needed to determine the safety and feasibility of this approach in humans," the researchers said. ”。“ We can imagine astronauts wearing a helmet-like device designed to target the hypothalamus region to induce a state of retardation. ”
However, there are still many hurdles before using ultrasound devices induced by dullness to buy time for doctors to operate, or to put astronauts in a state of suspended animation.
The researchers found that their ultrasound cap appeared to cause a sleep-like state by stimulating specific ion channels within rodent brain cells, but the natural dormancy observed in the wild was also accompanied by other changes at the hormonal and molecular levels that were unclear. The effects of prolonged hibernation on the brain are similarly unclear, but some studies have suggested the possibility that "memory" is lost in hibernating animals.
As a result, some scientists believe that we know very little about the effects of hibernation, especially prolonged hibernation, on brain function, synaptic connections, or memory, and that before we try to induce human hibernation, we must first make sure that we know how to "bring them back" intact.
The implication can be seen that many scientists are still cautious about the technology, after all, with the current science and technology, this state of change does have a lot of unknown and uncontrollable, so the use of ultrasonic bombardment of the brain, so that the brain in a "suspended animation" technology, whether it is not suitable for humans, whether it can be absolutely safe, but also have to carry out in-depth research.