What is the name of this old sci-fi movie?

I saw it back in the 1990s, I don't remember it much.... the gist is that these two little sisters accidentally communicate with an alien spaceship orbiting Earth through their PC....but there must've been a bad alien, because near the end they find a spacesuit figure in a marsh during the daytime I think, and it tries to hurt them... I'm really confused! What I'm confirmed about is that in the end the girls tell the grownups about it all, and the last scene is a laboratory, and the elder girl sends a message to the good alien: 'See you in the sky', and everyone claps. Does it ring any bells?