Tim Peake boldly takes the Union Jack where no Briton has ever gone before

Britain’s first official astronaut, former helicopter pilot Timothy Peake, embarked on his first spacewalk Friday morning, alongside American astronaut Timothy Kopra.

The two ventured outside of the International Space Station to repair a broken electronic box called a voltage regulator. The regulator’s failure reduced power on the ISS by one eighth when it occurred two months ago.

Mr. Peake, whose compatriots back home in Britain have been closely following his historic journey, took to Twitter on Thursday ahead of the spacewalk to share his excitement for the day ahead.

Peake and Mr. Kopra were tasked with replacing the broken regulator with a spare (named Dusty) under strict time constraints. They are only able to work on the regulator in the dark due to the potential for electric shock, and due to the space station's rapid orbit around Earth, darkness only lasts for 31 minutes.

All told, the astronauts only have six and a half hours to complete their tasks. Peake and Kopra must be precise and methodical as they work. There is no room for error.

Because of the precision necessary, NASA has been planning this mission for a long time. According to Peake’s blog, “to undertake an EVA (Extravehicular Activity) actually takes several years of training. We have spent many hours working in our spacesuits, ‘floating’ in the largest swimming pool on Earth with a Space Station mockup.”

Peake and Kopra also practiced their tasks with a virtual reality simulator. More recently, the two read and reviewed their nearly forty page long mission timeline. It was imperative that they complete their missions correctly and within the time constraints. If either man forgets to clip in to the Space Station as they move about, they could float away into the vacuum of space.

The two astronauts will depend on each other during the six and a half hour space walk. As Peake said in his blog post on Thursday, “Tim and I will constantly be checking each other and relying on each other for assistance if something should go wrong.”

The spacewalkers can also count on support from back on Earth. US astronaut Reid Wiseman completed two spacewalks himself, including one very similar mission to replace a Sequential Shut Unit and will guide the astronauts as part of the ground operations team.

This mission is especially exciting for England, because no other British astronaut has ever been in space. A chemist named Helen Sharman visited the Russian space station Mir as part of a contest in 1991, but she was not trained as an astronaut. There have been other astronauts with dual citizenship, but all have worn the American flag on their spacesuits. Peake is the first to float in space bearing Britain's Union Jack.

As Peake left the space station, station commander Scott Kelly said, "Hey Tim, it's really cool seeing that Union Jack go outside. It's explored all over the world. Now it's explored space."

Peake responded, "It's great to be wearing it, a huge privilege, a proud moment."

This report contains material from the Associated Press.