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Spaceflight may be associated with a process of accelerated aging of the immune system, researchers have claimed.

Long-term space flight is known to have detrimental effects on the human body, including muscle and bone loss.

But now it seems human missions to Mars will also need to develop ways to counteract the negative effects on the immune system in order to keep the crew fit and healthy.

French scientists have been testing the effects of microgravity on Earth. They found that long-duration missions, such as to Mars (illustration shown), could affect the immune system. Superficially, prolonged microgravity caused mice to experience changes also observed in elderly mice

The research, published in the journal Federation of American Societies for Experimental Biology (Faseb), was conducted by several French institutions including Lorraine University in Vandoeuvre-lès-Nancy.

The team used a ground-based model called hindlimb unloading (HU), which simulates some of the effects of spaceflight on mice.

It involves suspending the back legs of the mice in the air, while their front legs stay on the ground.

MARS-INSPIRED SHOWER LETS YOU KEEP CLEAN LIKE AN ASTRONAUT

A shower that recycles water just like that on a spacecraft has been unveiled.

Inventor Mehrdad Mahdjoubi, CEO and co-founder of the company behind the product - Orbital Systems - also worked on Nasa's Mars mission project.

Known as the Shower of the Future (concept above), it collects water instead of letting it run down the drain, and purifies it until it's drinkable, reducing consumption by 90 per cent.

On the ISS, almost all waste water is recycled to provide the astronauts with a nearly self-sustainable environment.

The shower starts at a rather daunting £2,405 ($3,629), but the company claims it will save an average of £212 ($320) per year in waste water. 

In the study groups of three mice were suspended for three, six, 13 and 21 days - and killed after each test - to test the effects of microgravity. 

The scientists analysed bone parameters and the frequency of cells that will give birth to B lymphocytes in the bone marrow of young mice, old mice and mice subjected to three weeks of HU.

B lymphocytes - also called B cells - are known to be one of major parts of the human immune system.

They found that mice in low gravity conditions experience changes in B lymphocyte production in their bone marrow similar to those observed in elderly mice living in Earth conditions.

The same effects could be present in humans.

While the effects of spaceflight on the human immune system have been known before, this study is the first to suggest that such a ground-based method - namely HU - could be helpful in understanding it further.

The researchers also say that their model could be used to test or develop molecules and compounds that could improve immune responses in astronauts.

'This study shows that a model of spaceflight conditions could not only be used to test the efficacy of molecules to improve immune responses following spaceflight in astronauts, but also in the elderly and bed-ridden populations on Earth,' said Dr Jean-Pol Frippiat, a researcher involved in the work from the Stress, Immunity and Pathogens Laboratory at Lorraine University in Vandoeuvre-lès-Nancy, France.

Dr Gerald Weissmann, Editor-in-Chief of The Faseb Journal, added: 'Getting to Mars and beyond promises to be a huge task, requiring contributions from almost every scientific discipline.

'For biologists and medical researchers, knowing how altered gravity affect our immune system from challenges aloft can be already be studied on Earth.

'Fortunately for biologists, it's not rocket science.'

Currently, astronauts must keep their bodies in shape on the ISS by performing regular exercise. Pictured is Nasa astronaut Sunita Williams, Expedition 32 flight engineer, exercising on the Cycle Ergometer with Vibration Isolation System (Cevis) in the Destiny laboratory of the ISS on 20 July 2012

While the effects on the immune system were known before, the study says its methods could be used to develop a solution for missions to Mars to help astronauts who have to operate in microgravity for a long time. Pictured is Bruce McCandless II performing a free-flying spacewalk in 1984

In March of this year, Nasa astronaut Scott Kelly and Roscosmos cosmonaut Mikhail Kornienko will undertake the first year-long stay aboard the International Space Station.

The mission is designed to see how astronauts cope with such a prolonged stay in space - previously, crews only spent a maximum of six months aboard the station before returning to Earth.

During the mission, experiments will study the effects of long-duration spaceflight on the immune system, in addition to other aspects of human biology such as body chemistry and the heart.

They will not break the record for the longest continuous time spent in space - that was 437 days, set by Russian Valeri Polyakov aboard the Mir space station from 1994 to 1995 - but nonetheless, the mission will provide invaluable data for the planned mission to Mars, which could take place in the 2030s.

In tandem with this one-year stay, though, experiments on Earth will also prove useful in preparing a crew for the journey to Mars - which could take a total of nearly three years, including nine months travelling there and nine months back.

Performing HU studies on mice could be one of the latest ways to gather data for the mission.

In March of this year, Nasa astronaut Scott Kelly (left) and Roscosmos cosmonaut Mikhail Kornienko (right) will undertake the first year-long stay aboard the ISS. The mission is designed to see how astronauts cope with such a prolonged stay in space  previously, crews only spent a maximum of six months on the ISS