DSLR and night photography, or can we cut the noise?

Back in the High School and College I did a not of night photography.  Love it. Loved star trails and moonlit landscapes.  Armed with a tripod I was all over the Ozarks and Southern Illinois at night taking pictures.

Not so much since I got the DSLR. Dabbled in it, but got turned off by the noise that long exposures bring to the table. Add in a high ISO and the noise takes over and it begins to look like a pointillists painting, not a photograph.  Not that I find it objectionable, but sometimes I want a crisp clean black and no noise.

Now the current dilemma.  In a scant 6 weeks Comet Ison which I've been geeking out over since early this year is going to be at peak viewing.  Yes, I can capture an awesome sunrise, sunset and even a moon rise.  Capturing a comet, even one as "bright as the moon" will have challenges at dawn as I don't want a lot of noise.

Google will help. Any other ideas on where to go for help on this one?  I figure I have a month to get the info, practice and nail it for a pre-dawn road trip and excursion out to Joshua Tree or similar for best comet viewing and photo-ing.

This image is one I captured of a moon rise from the San Gabriel River near Azusa several summers ago.  It was just at dusk and didn't need a tripod or having to worry about excessive noise.