Whoever has read the books knows that James got shot on his thruster pack while trying to do repairs on a space dock with the rest of the Spartans in "The fall of Reach". He was propelled into space and lost. Here's a picture of him that I found (I know IGN found it too, but I found everything out myself first):
Picture: http://i149.photobucket.com/albums/s52/hemblahem/jehmz.jpg?t= 1245950097

Halo Reach trailer here:
http://www.youtube.com/watch?v=Zj1bXFcuM38


Three more nice little pictures:
http://i149.photobucket.com/albums/s52/hemblahem/Dos.jpg
http://i149.photobucket.com/albums/s52/hemblahem/Tres.jpg
http://i149.photobucket.com/albums/s52/hemblahem/Uno.jpg