It seemed like Sen. Bill Nelson was everywhere on Monday.

The third-term Democratic senator from Florida will forever be best known for, during his time in the House, orbiting Earth aboard the space shuttle Columbia.

But on Monday, Nelson’s politics and policy took center stage. He got a high-profile Republican challenger for his re-election bid and he was face-to-face with the Silicon Valley executive at the center of what was one of the biggest stories of the day.

As the ranking Democrat on the Senate Commerce, Science and Transportation Committee, he met with Facebook CEO for Mark Zuckerberg for roughly an hour on the seventh floor of the Hart Office Building.

Nelson said that among the topics that he brought up during his meeting with Zuckerberg was the investigation led by Special Counsel Robert S. Mueller III into Russia’s efforts to interfere in the 2016 election. Nelson made that revelation after being asked about what he would like to see done regarding regulation of Facebook and other social media platforms by the Trump administration.