What movie is this?

When I was very young (almost 20 years ago) my father was really big into sci-fi movies. I recall one that I watched, forgive me if the details are off but:

The movie centered on a plot of people going to another planet (totally original idea right? :D ).... And, much shock to the viewer of the movie, the locals of this planet weren't exactly all that friendly. I recall some kind of ray gun that would shoot a person and turn them into a monster (in a very pod people-esqe sort of way) of some sort, or if you shot them with it a second time it would kill them.

The other thing I recall about the movie, was that it had an inconclusive ending. It ends with the survivors leaving the planet and the main character realizes that the other survivors have been changed into "pod people" (doing the bidding of the hostile aliens) and heading to Earth.

The main character is last seen attempting to destroy some sort of device on the ship from my memory the action was with the intent to crash the ship and prevent them from spreading whatever malicious design on Earth.

I cannot remember if this movie was black and white or color unfortunately. But I am leaning towards it being black and white or very early on in the color era.

Any help identifying this movie would be appreciated. Thanks!
It very well could have been a TV show of some sort, but for some reason I think it was longer than that. The Angry Red Planet is ALMOST like it, but I don't think it was. I want to say the movie it was themed on was Mars.... (A place that seems to get a pretty bad rep) I seem to remember the Angry Red Planet being watched the same night. (like I said, when I was a kid my dad was a big time sci-fi nut) I remember the "we can and will destroy you" line from that movie. I wish I could ask my father what it was, hes still alive but we aren't on speaking terms and havent been for several years.

Maybe it is just a creation of my own imagination.. in that case.. I claim Copyright!!! lol