Recently, a not-for-profit organization known as Mars One released the list of 1,058 applicants who could be selected for colonization on Mars. Over 200,000 applications were said to have been received by the organization, which aims to "establish human life on Martian soil."

"We're extremely appreciative and impressed with the sheer number of people who submitted their applications," Mars One co-founder Bas Lansdorp was quoted as saying in a press release.

But researchers in a new study said that human body is yet not ready for life in space. They are concerned about the long-term health effects space can have on astronauts.

A typical human being is about 60 percent water, and in the free fall of space, the body's fluids float upward, into the chest and the head. Legs atrophy, faces puff, and pressure inside the skull rises.

"Your head actually feels bloated," said Mark E. Kelly, a retired NASA astronaut who flew on four space shuttle missions. "It kind of feels like you would feel if you hung upside down for a couple of minutes."

The human body did not evolve to live in space. And how that alien environment changes the body is not a simple problem, nor is it easily solved.

Some problems, like the brittling of bone, may have been overcome already. Others have been identified - for example, astronauts have trouble eating and sleeping enough - and NASA is working to understand and solve them.

The lack of gravity is also said to negatively affect the body's neurovestibular system, leaving astronauts with a weakened ability to, literally, determine which way is up. Dizziness is also an issue, according to those who have endured it.

The biggest hurdle remains radiation. Without the protective cocoon of Earth's magnetic field and atmosphere, astronauts receive substantially higher doses of radiation, heightening the chances that they will die of cancer.

At the Johnson Space Center here, the home base for NASA's human spaceflight program, scientists probably have until the 2030s to dissect these problems before the agency sends astronauts to Mars - a mission that would take about 2.5 years, or nearly six times the current standard tour of duty on the space station.

Astronauts at present on the ISS have been performing human research experiments, like looking for osteoporosis in space, cardiovascular tests, heart rate, sleep patterns and blood pressure.

The longest any human has been off Earth is almost 438 days, by Dr. Valery Polyakov on the Russian space station Mir in 1994 and 1995.

Source: Voice of Russia