I remember back some 10-11 years ago I saw this awesome anime series on channel 13(Los Angeles) on Sunday morning. It was about this teenage guy who, along with his family, are on a science mission to Jupiter. Along the way they are intercepted by aliens who are planning on invading the earth. The entire family is given the ability to turn into a totally awesome battle robots and then brainwashed to obey the aliens. The only thing is with the guy(I wish I remembered his name) the brainwashing didn't work for some reason, but he still gets the power.
He escapes and eventually goes to earth were he becomes the only hope for defending the earth from the invasion.
He transforms by holding this crystal up and then he gets a awesome spear and hover craft thing he rides on.
I thought I remember it being called "Techno D" but I can't find it any were. The sad thing is channel 13 cancelled it after about 6 or 7 weeks, but I'm sure there's got to be a series out there. Please help! Thanks.

http://en.wikipedia.org/wiki/Gundam

Gundam is my best guess at what it could be. Check out that link and see if any of that looks right.

I know there are other robot series out there but Gundam was the one I thought of first.

Well....no. Unlike Gundam, in this animated series I remember you don't "jump" into a robot...you become one! Oh yea, and the aliens would send these crab looking robots to attack earth.
Another detail I remember is: the guy had a twin who was given the power and brainwashed also. The evil twin would taunt the good one...it made for some good drama.

Are you sure it was an anime? If it was Channel 13 it might well have been an American cartoon. But yeah, so far I am coming up empty as well. At first I thought it might be Guyver but the plot doesn't match what you described.