NASA Photos: Images From 200th Spacewalk, Past Space Station Walks

iss space walk — Astronaut Piers J. Sellers exiting the airlock on the ISS to conduct a spacewalk. NASA

On Friday morning, when NASA astronauts Peggy Whitson and Jack Fischer stepped outside the International Space Station, they made history. Friday's spacewalk was the 200th spacewalk from the ISS.

Each astronaut made personal history as well. The walk was Fischer's first walk, an exciting milestone for an astronaut. It also marked Whitson's ninth walk, breaking her own record for most spacewalks conducted by United States female astronaut.

Read: Apollo 13 Story: Jim Lovell On How Mission Changed From Moon Landing To Survival

The two were conducting maintenance on the station. They were replacing the avionics box that supplies energy to experiments on board the ISS as well as replacing routine hardware, according to NASA. They were also replacing a protective shield, working on adding a new international docking port for crew and adding a new high definition camera. The walk began at 6:30 a.m. EDT and was scheduled to last six and a half hours, there is a live stream online.

The first spacewalk to build and maintain the station was conducted in 1998. That walk lasted more than seven hours and NASA astronauts Jerry Ross and James (Jim) Newman mated more than 40 cables and connectors from the U.S. Unity portion of the station to the Russian Zarya portion.

space walk 1 — Astronaut James H. Newman waving to Jerry L. Ross during the first space walk off of the ISS in 1998. Ross can be seen reflected in Newman's helmet. NASA

The two can be seen connecting the cables between the Unity in the foreground and the Zarya in the background.

space walk 1 (2) — Astronauts James Newman and Jerry Ross working on connecting the Unity and Zarya potions of the ISS. NASA

The first woman to ever conduct a spacewalk from the ISS for the U.S. was Susan Helms. She was the first female ISS crew member from the U.S. and in 2001 set a record for longest spacewalk.

helms space walk — Susan Helms conducting a spacewalk off of the ISS in 2001. NASA

Read: NASA Astronaut Peggy Whitson Breaks US Record For Most Number Of Days In Space

Astronaut Sunita Williams set the record for most walks done by a female U.S. astronaut that Peggy Whitson recently broke. Williams set the record of seven space walks, which Whitson broke in March, and set again Friday.

williams space walk — Sunita Williams appears to be touching the sun in this photo from one of her space walks. NASA

On March 30, 2017, Peggy Whitson, the first female commander of the ISS became the female astronaut with the record for most spacewalks for the U.S. She furthered that record Friday by completing her ninth walk.

whitson walk — This photo is from a 2008 walk Whitson did. Flying high above Earth she's smiling at the camera. NASA

Astronauts prepare for space walks by training in giant tanks of water at the Neutral Bouyancy Laboratory in Texas. They practice in the water because the water simulates the feeling of being in space. It's the best prep they can get for conducting work outside of the station in their bulky suits.