What types of programs will you be running as part of an aeronautical sciences major? If it's heavy CAD, etc. you might consider the 15" Pro because of the GPU. Otherwise, as far as the CPU is concerned, it should be capable of handling software that comes out over the next 4 years. Remember, the Sandy Bridge chip just came out earlier this year.
The main reason the Mac Mini 1,1 was dropped this year is that Apple completed the transition to 64-bit with Lion and the early Mac Minis had 32-bit Core Duo chips (essentially spruced up Pentium M chips). These CPUs are nearly as powerful as the ones in the 2010 MacBook Pros, though the 2011 15" MacBook Pros with their quad-core Sandy Bridge chips blow them out of the water.
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If upgradeability is your concern, you are most definitely a MBP candidate The MBA is great for what it is - an ultra portable laptop. Another route is to use the MBA now and sell it in a year or two instead of upgrading it. Good luck with your decision!
If you go this route, I'd suggest getting the 13" Base model (128GB SSD, Core i5), since it will be cheaper and you'll lose less dollar value in 2 years. Figure a $1300 base will probably go for about $700 in 2013 when the Haswell MacBook Airs are out, while a $1700 i7/256 model will probably fetch $900. The i5 vs i7 probably won't make much of any difference in resale value (certainly not $100 worth), so the primary driver will be the storage space.
