Can anyone explain the intuition and perhaps health of twins? Perhaps not, but NASA is about to embark on an ambitious study that involves twin astronauts that could answer some health questions by having one twin on the International Space Station (ISS) and the other twin Earth bound.

Twin astronauts, Scott and Mark Kelly, will take part in a year long study next spring. In the study, conducted by the Kellys and NASA, they will be reviewing and hoping to understand prolonged weightlessness and its effects on the body, and they will do so by comparing the twins, The Washington Post reported.  

The 50-year-old twins are both excited about the experiment. This study will not only be a first for NASA. This will be, however the longest ISS stay (one year) that any American astronaut has undertaken. Russian cosmonauts clocked in at 14-and-a-half months in space in 1994-1995. Scott, along with Russian cosmonaut Mikhail Kornienko, 54, a former paratrooper, will be part of a six member crew on the ISS, CBS News reported.

The Kellys will undergo medical testing before, during and after the American-record-setting flight. Seven months is the maximum for NASA's single human mission.

Although the space mission is a year away, Scott said in a recent interview with The Associated Press that he is excited as the study draws near.  

Deputy chief scientist for the human research program Craig Kundrot, at NASA's Johnson Space Center in Houston, said not only are the Kelly's the same genetically, but both are astronauts, Scott Kelly currently and Mark Kelly now retired.

NASA has already selected 10 proposals for the twin study, some involving tests on the immune system, reaction time, fluid shifting in space and its potential connection to visual impairment, and DNA and RNA molecular science, among others, CBS News reported. 

One Stanford University sleep specialist and immunologist Dr. Emmanuel Mignot wishes to give the twins a standard flu shot before, during and after the one-year mission. Blood will perhaps highlight any differences between the space twin and the twin on Earth.

The Kelly twins are both retired Navy captains. Scott is divorced, and he has two daughters ages 19 and 10; and he lives in Houston.

Mark also has two daughters, and he is married to former Congresswoman Gabrielle Giffords, who survived a 2011 assassination attempt. Scott was on the space station when his sister-in-law Giffords was shot. Back then, Mark commanded NASA's next-to-last shuttle flight for four months after the shooting. He then left NASA. The couple live in Tucson, Arizona.