cnn's john zarrella joins us with this exclusive report. john?e a game changer for nasa, and not in a good way. we had an opportunity to sit in exclusively on an eye exam glifg to a nasa astronaut. with changes to his vision, not for the good. astronaut mike barrett undergoes an eye exam. no big deal, right? >> i would say this is a top priority in establishing counter-measures. this has all of our attention. >> you see barrett is one of the ten astronauts who have returned from long space station missions with changes to their eyesight, sometimes permanent and not at all good. the cause -- a mystery. >> we're seeing structural changes to the retina, wrinkles or folds to these areas. >> reporter: and as this image shows, the back of mike's eye has flattened out. >> again, the car for the far-sighted shifts appearing to be the globe flattening. >> reporter: sometimes they correct themselves, but not barrett's. >> i'm dependent on -- >> doctors say it's only occurred in male astronauts. it's a possible pressure inside the cranium. doctors don't kno

cnn's very own john zarrella got this exclusive opportunity to sit in on an eye exam given to one nasaastronaut, who like many has come back from long endurance flight missions and had changes to his vision. take a look. >> reporter: astronaut mike barrett undergoes an eye exam, no big deal, right? >> ekeag. >> reporter: unlike your eyes or mine, the future of deep space flight could be riding, literally, on astronaut eye sight. >> i would say this is our top priority at the moment in terms of establishing countermeasures for long duration space flight. this has all of our attention. >> reporter: why? you see barrett is one of ten astronauts who have returned from long space station missions with changes to hr eyesight, sometimes permanent and not at all good. the cause, a mystery. >> what we're seeing is structural changes to the ret a retina. we're seeing wrinkles or folds on a microscopic level to these areas. >> reporter: as this image shows, the back of mike's eye has flattened out. >> you see the farsighted shift. the cause appears to be the globe flattening. >> reporter: in some

john zarrella, cnn, ft. lauderdale. >> so is the u.s. headed towards world war three? iran's nuclear warning today could make keeping the peace even more difficult. time magazine's foreign policy correspondent joins me live in just a few minutes and she says iran may be itching for war. in america, we believe in a future that is better than today. since 1894, ameriprise financial has been working hard for their clients' futures. never taking a bailout. helping generations achieve dreams. buy homes. put their kids through college. retire how they want to. ameriprise. the strength of america's largest financial planning company. the heart of 10,000 advisors working with you, one-to-one. together, for your future. ♪ golly, that is deep snow! yeah, can you get me out of it? of course. travelocity? that's how i got here! that's amazing! but i'm still stuck. come on man, dig it! [ female announcer ] travelocity. get great deals on all kinds of beach vacations. at meineke i have options... like oil changes starting at $19.95. my money. my choice. my meineke. >>> it is 31 minu

john zarrella is live from miami, the state where they do not want to hear this kind of thing, especiallyg about a colony on the moon. how do we go from colony on the moon to no more mars. >> this is one of those good news/bad news stories. the good news is nasa's budget is about flat this coming year, the proposed budget, about just under $18 billion. before you say wow, that's a lot of money, it's actually half of 1% of the federal budget. but the big loser in all of this is planetary exploration. losing about 20% is what we're hearing about $300 million, and the two big missions that are going to be cut are going to be the 2016 mission and maybe the 2018 mission, both joint projects with the european space agency, and this all comes as you're looking at this video of the curiosity rover, which is on its way right now, speeding to the red planet, and if all goes well lands in august and could find the first signs of organic material. that's what it's looking for. the building blocks of life. so all these cuts coming at a time when some fascinating science may be on the horizon for nasa.