Expedition 54 crewmembers Scott Tingle and Mark Vande Hei will spend about 6.5 hours outside the ISS, working on the station’s robotic arm, Canadarm2. Tingle, who will be conducting the first spacewalk of his career, was expected to follow Vande Hei out of the station’s Quest airlock shortly after 7 a.m. EST (1200 GMT). NASA TV was not yet on the air as the spacewalk due to the now-resolved government shutdown, which ended overnight Monday. But about one hour into the spacewalk, the agency’s live webcast with commentary was back online.
“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 told Space.com in a live, in-flight interview last Thursday (Jan. 18).
The two spacewalkers will replace one of two “hands” on the end of Canadarm2 known as latching end effectors (LEEs). Canadarm2’s other “hand,” LEE-A, was replaced during another spacewalk on Oct. 5, 2017. That was Vande Hei’s first spacewalk, and Tuesday’s spacewalk will be his third.
LEE-A and LEE-B are identical grappling devices located at opposite ends of Canadarm2, each weighing about 440 lbs. (200 kilograms) and measuring about 3 feet (1 meter) long. They’re used to latch on to incoming cargo spacecraft, but they also allow Canadarm2 to move around the outside of the station in an inchworm-like motion.
Tingle and Vande Hei will replace LEE-B with a spare that has been stored outside the ISS since 2009, when it was delivered by the space shuttle, Tim Braithwaite, the ISS program liaison for the Canadian Space Agency, said Thursday at a news conference previewing the spacewalks. The former LEE-B will also be stored outside the ISS after it is replaced, Braithwaite said.
Both astronauts have trained extensively for this spacewalk, but Tingle said he still anticipates that some of the tasks will prove challenging. “There’s a point in the spacewalk where I have to get out of my boot restraint, and I have to go over to my partner’s boot restraint, and I have to move him while he’s holding a massive piece of equipment from the robotic arm, so there’s a lot of mass there,” he said. “I think that will be tricky. I’ll probably take that slow and be very cautious.”
Although NASA does not schedule in much spare time to kick back and enjoy the view during spacewalks, Tingle said the astronauts will have a few minutes of “adaptation time” at the beginning of the spacewalk. That time is intended to “make sure we get our bearings right, and we kind of get adjusted on what kind of forces we need to move our body around with the suit on,” Tingle said.
They’ll 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.”
This will be the 206th spacewalk conducted by astronauts at the International Space Station in support of the station’s assembly and maintenance. On Jan. 29, Vande Hei will conduct another spacewalk with astronaut Norishige Kanai of the Japan Aerospace Exploration Agency, during which the two crewmembers will store the degraded LEE-B outside the ISS as a spare.