Featured Image Source: NASA

The United States reemerged as a space power when SpaceX returned human spaceflight capabilities on May 30^th. A Falcon 9 rocket propelled the Crew Dragon spacecraft to the International Space Station (ISS) with NASA Astronauts Robert ‘Bob’ Behnken and Douglas ‘Doug’ Hurley aboard. SpaceX made history; it was the first crewed flight launched from American soil in nearly ten years. The brave duo joined the Expedition 63 crew at the orbiting laboratory. The demonstration mission, known as Demo-2, is meant to certify that the Crew Dragon spacecraft is safe to transport and return humans onboard. According to ISS Deputy Program Manager Kenneth Todd, Behnken and Hurley will return aboard the spacecraft on August 2^nd, before then the astronauts will conduct two final spacewalks.

Last month, ISS NASA Commander Astronaut Chris Cassidy and Behnken conducted a pair of spacewalks to upgrade a module of the space stations power system. Today, July 16, Cassidy and Behnken will conduct another Extravehicular Activity (EVA) task – “NASA astronauts Chris Cassidy and Robert Behnken will conduct a pair of spacewalks Thursday, July 16, and Tuesday, July 21, to finish a 3.5-year effort to upgrade the International Space Station’s power system,” the agency wrote in a press release today.

Live coverage will begin at 6:00 a.m. EDT. The spacewalks will initiate at around 7:35 a.m. EDT. The spacewalks could last around 7-hours. You can watch the spacewalk live in the video linked below, courtesy of NASA TV.

During the spacewalk, astronauts Cassidy and Behnken are tasked with continuing to upgrade the ISS laboratory’s power system. Hurley will assist the pair by helping them suit-up and overseeing all tasks. The agency detailed that each astronaut will be wearing an indicator – “Behnken will be designated extravehicular crewmember 1 for both spacewalks and wear a spacesuit bearing red stripes. Cassidy will be extravehicular crewmember 2 for both spacewalks, wearing a suit with no stripes.”

They will remove old nickel-hydrogen batteries and replace them with new lithium-ion, “the replacements will be on the starboard 6 truss’ 3B power channel,” the agency details. A total of 5 out of 6 nickel-hydrogen batteries are expected to be removed on Thursday, and 3 lithium batteries will be installed. “The last nickel-hydrogen battery will be removed from the truss and stowed on July 21,” NASA stated. These batteries are used to store solar energy from the station’s solar arrays. ISS orbits Earth very fast at approximately 4.76 miles per second; It completes a full orbit around the entire planet every 90 minutes – which means the space station remains in daylight for 45 minutes and darkness for 45 minutes, so, every 24 hours the space station remains in darkness 16 times per orbit. The batteries store energy to power the laboratory when there is no sunlight during orbital night periods. “We are going with newer technology with the lithium-ion battery. Basically, a newer technology with a smaller footprint. You can get way more [energy] storage capacity on orbit, which is the reason that we made the leap of technology several years ago. […] For the past four years now, over four years, we have been slowly swapping out from the nickel-hydrogen to the lithium-ion,” ISS Deputy Manager Todd explained last month.

Since January 2017, astronauts have been working to replace the batteries for the station’s eight power channels. As of today, 12 spacewalks have been performed with that purpose. “When the power upgrades are complete, the astronauts will shift gears and remove two lifting fixtures used for ground processing of the station’s solar arrays prior to their launch,” NASA detailed. “They’ll also begin preparing the Tranquility module for the installation of a commercial airlock provided by NanoRacks and scheduled to arrive on a SpaceX cargo flight later this year. The airlock will be used to deploy commercial and government-sponsored experiments into space.”