Two NASA astronauts will work in space today (May 16) outside the International Space Station (ISS), and you can watch their 6.5-hour spacewalk, or extra-vehicular activity (EVA), live online.

Expedition 55 flight engineers Drew Feustel and Ricky Arnold will exit the station through the Quest airlock at around 8:10 a.m. EDT (1210 GMT). NASA will provide live coverage starting at 6:30 a.m. EDT (1030 GMT), when the astronauts are getting ready for their work and putting on their spacesuits. You can watch it live here and on the Space.com homepage, courtesy of NASA TV.

The astronauts will upgrade the station's cooling system hardware and also install new communications equipment to help with future dockings of commercial crew spacecraft. [Space Station Photos: Expedition 55 Crew in Orbit]

First, they will move a component called the Pump Flow Control Subassembly (PFCS) from a spare-parts platform to an area within reach of the Special Purpose Dexterous Manipulator, or "Dextre," a two-armed robot outside the station. The astronauts will also remove a failed subassembly and move it to the spare-parts area. After the spacewalk is finished, flight controllers on Earth will use the Canadarm2 robotic arm and Dextre's robotic hand to install the new cooling system subassembly on the port-side truss of the space station for a checkout.

Time permitting, the spacewalkers' next task will be to replace a camera system on the Destiny Laboratory, as well as to upgrade the communications receiver for future commercial crew vehicles like SpaceX's Crew Dragon and Boeing's CST-100 Starliner. "We have a camera R&R [rest and recuperation] plan as well as a comm box … that will be part of the EVA as well," said Jordan Lindsay, the lead officer for today's spacewalk, in a briefing on May 8.

This spacewalk will be the eighth of Feustel's career and the fourth of Arnold's. It's the 210th spacewalk for ISS assembly, maintenance and upgrades since the orbiting complex was first put together in 1998. It will be the second spacewalk for Feustel and Arnold as a team; they completed another spacewalk together on March 29.

The duo is scheduled for another spacewalk on Thursday, June 14, to install brackets and cameras that will help guide commercial crew vehicles into their docking port on the Harmony module. The cameras will also be useful for transmitting and receiving wireless data from experiments and assemblies in Europe's Columbus laboratory and Japan's Kibo laboratory.

NASA initially planned to tackle the two EVAs this month (on May 16 and 30), but flight controllers elected to delay the second spacewalk into June. The decision was made to give more time for the Expedition 55 crew to focus on the May 24 arrival of a Cygnus cargo spacecraft at the ISS.

"As we started to get more and more of the science requirements defined for the Cygnus mission, and a better understanding of the timelines to get those activities — and work to start collecting the science data — it became clear that we were really quickly surpassing the amount of crew time available that we had at the end of an increment to do both an EVA and to get some of the critical science going," said Kenny Todd, NASA's ISS operations integration manager, in the same news briefing.

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