The International Space Station is a technological marvel that has expanded mankind's understanding of the universe. Despite the space station's cutting edge technology, one famous astronaut says Internet service on board is decidedly low tech.

"It's kind of like a cross between old dial-up and what you might have now with very high speed Internet," astronaut Captain Scott Kelly told CNBC in an interview this week. "It's not ideal, and it varies from time to time in how well it works."

Kelly, 51, is currently in the midst of a mission to spend nearly a full year in space—the longest ever stay for an American. He will return to earth, along with Russian cosmonaut Mikhail Kornienko, in March of 2016.

During his 342 days in orbit, Kelly, whose twin brother is also a decorated NASA astronaut, will engage in research on behavioral health, visual impairment, and physical performance, among other things. Unfortunately, one thing that he won't engage in is fast and reliable web service. 

"You have to be patient sometimes and be flexible and access it when we have the comm coverage, because we don't always have it," he said. "Probably about 45 to 50 minutes an hour…we have the capability to get on the Internet on the ground."

NASA says the spotty internet service is the result of the space station's proximity to certain ground-based sites.

"The ISS requires certain communications with the ground to allow for internet access, and there are breaks in that communication depending on where the ISS is over our ground sites," said a NASA spokesperson. 

CNBC's interview with the crew was "specifically planned to be carried during a period of solid communications, and not during one of those small breaks," the spokesperson added. "The ISS onboard internet also applies to that, and that link is not always solid for the crew."

NASA also addressed the dial-up era speeds when the Internet is working in space. The agency said it's "somewhat slower because there are additional security measures in place to ensure the safety and integrity of the internet data that is viewable aboard ISS."

While the Internet may be spotty and slow, Kelly said the introduction of newer technologies like Apple's iPad onto the International Space Station has greatly increased efficiency and portability.

"The last time I was up here, about four-and-a-half years ago, we didn't have iPads, we did most of our work off of these laptops," he said. "The iPad's great, you can look at a procedure while you're floating behind one of these large science racks or something and it just makes us more efficient."

When he does have service, Kelly said he uses the internet much like the rest of the 7 billion or so earth-bound humans. "I use it for a bunch of things," he said. "Certainly e-mail, social media type stuff with Twitter, Instagram, that kind of stuff. I actually do some banking. I access my online bank accounts."

Apart from posting pictures to Twitter and Instagram, Kelly also said he spends some of his limited downtime watching television. 

What exactly does a highly trained astronaut watch while orbiting the planet and contemplating the mysteries of life? Kelly said his two indulgences are "Game of Thrones" and "Better Call Saul." 

—CNBC's Stephanie Landsman contributed research to this report