Their mission is unlike any before.
The launch is scheduled for 3:42 pm ET out of the world's largest space launch facility, located in Kazakhstan, and will then dock with the International Space Station several hours later, at 9:36 pm ET.
When the group climbs, or rather floats, aboard the ISS, it will mark the beginning of a historic one-year-long mission in space for Kelly and Kornienko. That'll be the longest anyone has spent on the ISS and the longest any American has ever spent in space at one time.
The experiment will explore the long-term effects of space on the human body, something that must be well-understood before we can safely send astronauts on deep-space missions to Mars and back.
NASA will broadcast the launch live. Coverage begins at 2:30 pm ET, about one hour before lift off. You can watch the live feed below: