Two NASA astronauts on Tuesday conducted the first spacewalk of the year while working on a robotic arm.Astronauts Scott Tingle and Mark Vande Hei, crewmembers of the Expedition 54 aboard the International Space Station (ISS), spent about 6.5 hours outside the space station."This is going to be a lifetime memory for sure, and I'm looking forward to getting out there and fixing up the systems that we'll be working on," Tingle who conducted the first spacewalk of his career, was quoted as telling Space.com.The two astronauts were tasked with replacing one of the two "hands" on the end of Canadarm2 known as latching end effectors (LEEs), because the old one (LEE-A) had suffered from wear and tear.The LEEs are identical grappling devices which are used to latch on to incoming cargo spacecraft, located at opposite ends of Canadarm2, each weighing about 440 lbs (200 kilograms) and measuring about 3 feet (1 meter) long. They also allow Canadarm2 to move around outside of the station in an inchworm-like motion, the report said. The two astronauts replaced LEE-B with a spare that has been stored outside the ISS since 2009. They will likely have a few minutes of downtime in between tasks, Tingle said. "I do expect a little bit of time to kind of look down at the Earth and look up at the stars and the moon and whatever else we can see there," he noted.This will be the 206th spacewalk conducted by astronauts at the ISS.