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In zero gravity conditions, it has been found that the bone density of humans deteriorates about 10 times faster than that of osteoporosis patients on Earth—even if they exercise for two hours each day.

As a result, astronauts are more likely to suffer from bone fractures.

For example, Wakata will monitor the development of cells that develop into kidneys of frogs. The cells will be frozen in the middle of the cultivation process and brought back to the Earth for genetic analysis.

He will conduct a similar study on cells that develop into livers.

Veteran astronaut Koichi Wakata is offering himself as a human guinea pig through a prolonged stay aboard the International Space Station.

Wakata, 45, will become the first Japanese to spend three months in space following his scheduled lift-off aboard the Space Shuttle Discovery from the Kennedy Space Center in Florida later this month. He was originally set to go in space on Feb. 12, but fuel tank valve problems caused a postponement.

His mission is to gauge the effects of weightlessness on the human body in zero gravity. To do this, he will conduct various experiments in the "Kibo," a laboratory module set up by Japan on the ISS.

The effort is aimed at advancing research that will prove useful for future explorations of the moon and Mars.

The ISS is in orbit around the Earth at an altitude of about 400 kilometers. The environment is harsh because the skeletal structure tends to deteriorate in zero gravity after a while. Being bombarded by cosmic radiation, which can affect the genes, is another worrisome factor.

Wakata will try to figure out if humans can adapt to such an environment without risking their health.

Key experiments will focus on ways to prevent bone fractures among future space travelers and prevent them from contracting cancer.

"They are valuable experiments that will allow us to see the process in which fertilized eggs make a variety of organs by repeating cell divisions," said Makoto Asashima, executive vice president of the University of Tokyo.

Asashima set up the experiments in the hope that he will be able to clarify the mechanism of creating kidneys and develop medicines for dialysis patients.

"(Through the experiments,) we will be able to obtain information that will be useful (for dialysis patients) on Earth as well as for reproduction in space," Asashima said.

Wakata's daily activities will be regimented. He will be in touch with mission control between 6 a.m. and 10 p.m. Greenwich (mean) time (between 3 p.m. and 7 a.m. Japan time) daily.

Soon after he awakes each day, he will contact JAXA staff back on Earth to confirm his work schedule for the day.

More than one hour will be devoted to each of the three meals he eats each day. There will be 28 Japanese dishes and about 330 types of meals provided by the United States and Russia. Those meals will include saba no misoni, or mackerel boiled with miso, and okowa, which is glutinous rice steamed with red beans.

After working, he will spend two hours in physical training to strengthen his bones and muscles in the zero-gravity environment.

Before going to sleep, he will have time to exchange e-mails with family and friends or call them.

The history of prolonged stay in space dates back to 1971 when the Cold War was raging. At that time, the former Soviet Union launched the world's first space station, named, Salyut 1. In 1973, the United States followed with the launch of Skylab 1. In the 1990s, a Russian astronaut set a space endurance record of 437 days aboard the Russian space station Mir.

These experiences led to the improvements in life support systems and space diet. All of the information gleaned from these expeditions has not been made public.

Because the journey to Mars would take eight months, Japanese researchers are keen to build upon the knowledge accumulated by the United States and Russia with regard to long-term stays in space.

There are still many technological problems to be solved.

As calcium dissolves from the bones, it inevitably builds up in the urinary tract to form excruciatingly painful stones.

"These are the most important issues for long-term stays in space," said Hiroshi Oshima of the Space Biomedical Research Office, which is part of the Japan Aerospace Exploration Agency (JAXA).

To cope with these problems, Wakata will consume a concoction once a week that is used to help cure osteoporosis, which causes bones to deteriorate. The condition is exacerbated by exposure to zero gravity.

"The experiment should help clarify the mechanism of bone density deterioration and also lead to measures to prevent osteoporosis," said Toshio Matsumoto, professor of medicine at the University of Tokushima.

Another major problem is cosmic radiation. The amount of cosmic radiation that an astronaut aboard the ISS is exposed to every day exceeds what an Earthling experiences in half a year.

At all times, Wakata will be equipped with a JAXA-developed mini-sized dosimeter to measure the exact amounts of cosmic radiation to which he is exposed.

Wakata will also test a palm-sized simplified electrocardiogram monitor, which operates around the clock to check his body functions. It will allow doctors to offer advice on medical treatment from the confines of Earth. He will be able to transmit images of electrode locations and rashes on his skin.

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