Can anyone help with the name of this movie?

Back in I believe the late 1970's I saw a made for TV movie that had to do with this same subject, a large meteor was on a collision course with Earth, and I remember a scene where a large unmanned ship carrying several nuclear missles was launched to intercept it. When the ship arrived at it's intercept point, it fired it's missles at the Asteroid, hitting it, but to no effect. The effects were of course, substandard by today's technology, but I can't remember what the name of this movie was. Meteor launched missles from orbiting satallites, but this movie sent a ship far out to meet the meteor before launching it's missles. Does anyone remember this movie and it's name?