[quote=Voltaire]
Does anyone happen to know how to keep Mordin alive during the attack on the collector base? I keep losing him for some reason and there aren't any clues as to why. The entire crew is alive when I go to fight the human reaper, and then when I come back he's dead for some reason.
[/quote]

How upgraded is his equipment that he uses? 

I mean if I want him to survive I usually send him as an escort or use him as an additional squadmate.