"This site would have some use if they told you how they derive a No or Yes for the whole year. There is more than one bill per year and how much of any one bill do you have to disagree with to have it become a No? "

I imagine it is the appropriation bill for space budget each year, so as far as the final bill passing there would be only one per year. Of course it could be tack on to other things- I think NASA is part veterans and HUD, so Kerry could voting against for a number of reasons. Also, he would been in opposition party so probably would vote against a lot of bills which passed. Though must say that both California Dem Senators voted yes most of the time [aerospace is important in California].