Former astronaut Mark Kelly said during a Senate committee hearing on Wednesday that he believes closing loopholes in the nation's background check system for firearms buyers is the number one item that should be on the gun control agenda.

"Rights demand responsibility," he said. "This right does not extend to terrorists, it does not extend to criminals and it does not extend to the mentally ill. When dangerous people get guns, we are all vulnerable."

Kelly's wife, former Rep. Gabby Giffords (D-AZ), made a surprise introductory statement at the hearing and urged lawmakers to be "bold" and "courageous" in issuing new rules on gun control. Her shooter, Jared Loughner, had a history of mental illness and outrageous public behavior, but still passed a background check before acquiring his semi-automatic pistol.

"We have some ideas on how we can take responsibility," Kelly said. "First, fix gun background checks. The holes in our laws make a mockery of our background check system. Congress should close the private sales loophole and get dangerous people entered into that system."

"Second, remove the limitations on collecting data and conducting scientific research on gun violence," he added. "Enact a tough federal gun trafficking statute -- this is really important. And finally, let's have a careful and civil conversation about the lethality of firearms we permit to be legally bought and sold in this country."

Implementing universal background checks would include closing the so-called gun show loophole, which permits unlicensed, private sellers at gun shows to offer firearms to buyers without performing background checks, a loophole intended to allow private transfers of guns that's often exploited to allow multiple sales by unlicensed sellers. The National Rifle Association is adamantly opposed to universal background checks.

This video is from Fox News, aired Wednesday, January 30, 2013.