Product review (5 stars): THESE WILL PROBABLY MAKE THE TRIP TO MARS
I wouldn't be surprised if NASA has considered using these (or maybe they already do).  The food goes in, along with an oxy-absorber and the bag gets a final seal.  I understand you can seal these with an iron, though I got a professional bag sealer since it looked so much easier (and it was easy, even working by myself).  I let the bags sit in open cans for a couple of days just to observe them and all of them got really tight, just like a vacumn seal bag.  I'm guessing the food is good to go for quite a few years.  Taking the advice of another reviewer, I put most of my bags in new steel trash cans with lids rather than 5 gallon buckets.  The 30 gallon cans hold a huge number of bags and it is just a matter of tossing them in the large can.  I'm guessing the steel lid will keep any critters out as well.