U.S.-Japanese Spacewalking Team Wraps Up Replacement of Canadarm2 'Hands'

The spectacular sight of the Sun rising from behind the limb of the Home Planet was closely mirrored by the “circle of the Sun” on the sleeve of an astronaut’s space suit earlier today (Friday, 16 February), when Japan’s fourth spacewalker ventured outside the International Space Station (ISS). Astronaut Norishige Kanai—who launched to the orbiting outpost for his first mission, last December—spent five hours and 57 minutes stowing and repositioning a pair of Latching End Effectors (LEEs) for the 57.7-foot-long (17.6-meter) Canadarm2 robotic arm. Norishige’s spacewalk with seasoned NASA veteran Mark Vande Hei comes a little over two decades since Takao Doi became Japan’s first spacewalker and the first to wear the white flag, emblazoned with the blood-red rising Sun on his sleeve. Today’s excursion was the third EVA of 2018, following one U.S. spacewalk last month and a record-breaking Russian spacewalk, earlier this month, involving Expedition 54 cosmonauts Aleksandr Misurkin and Anton Shkaplerov.

Designated “U.S. EVA-48”, today’s outing by Vande Hei and Kanai (referred to by their nicknames of “Sabot” and “Nemo”) was the 48th spacewalk to be conducted outside the ISS, in U.S.-built Extravehicular Mobility Units (EMUs), and in the absence of the Space Shuttle, in almost 16 years. Ever since U.S. EVA-1, performed by NASA astronauts Carl Walz and Dan Bursch on 20 February 2002, these so-called “stage” spacewalks have played a critical role in preparing the ISS for future expansion, as well as removing and replacing hardware and tending to unexpected contingencies. EVA-48 follows on the heels of EVA-47, performed by Vande Hei and Scott Tingle on 23 January, which saw the removal and replacement of LEE-B, one of two identical “ends” of Canadarm2’s grappling mechanism. Wear-and-tear degradation in both end effectors had prompted a decision to replace them, with the LEE-A “end” of the arm successfully changed out last October. The degraded LEE-A was placed onto the Payload Orbital Replacement Unit (ORU) Accommodation (POA) on the station’s Mobile Base System (MBS) for temporary storage, pending return to Earth for repair and refurbishment.

Following the removal and replacement of the LEE-B “end”, last month, its degraded end effector was placed onto a “temp-stow” ring on the Flight Support Equipment (FSE) on External Stowage Platform (ESP)-2, a large storage pallet attached to the port side of the Quest airlock. Original plans called for Vande Hei and Kanai to venture outside for U.S. EVA-48 on 29 January, tasked with removing the degraded LEE-A from the MBS POA and bringing it back to the airlock, for return to Earth aboard a SpaceX Dragon cargo ship, later in 2018. It will then be refurbished and launched at a later date to provide a long-term “spare” capability. Meanwhile, the degraded LEE-B—aging, but still functional—would be removed by Vande Hei and Kanai from the FSE temp-stow ring and moved over to its new home on the MBS POA, where it will pull duty as an on-orbit spare.

Problems arose during U.S. EVA-47, when the replacement LEE-B did not communicate properly on its primary “string”, but functioned perfectly on its backup. “An issue preventing the LEE from transitioning to an operational state on one of two redundant sets of communications strings was detected,” NASA explained on 26 January. “The spacewalking crew demated and remated the connectors and ground teams were able to power-up the arm to an operational state on its secondary communications string, leaving the arm operational, but without a redundant communications string.” Following troubleshooting by the Canadian Space Agency (CSA), it was initially decided to have Vande Hei and Kanai reinstall the degraded LEE-B, thus re-establishing fully redundant capability to Canadarm2.

In the meantime, CSA robotics specialists worked to develop a diagnostics “patch”, which verified that the problem was not, in fact, a hardware issue pertaining to the new LEE-B, but could be worked around through the implementation of software. Overnight on 27 January, a confidence test to validate the software was successfully conducted and it was decided that the urgency for Vande Hei and Kanai to go outside was removed and U.S. EVA-48 could comfortably be postponed until the mid-February timeframe, by which time the uplink of a software update was expected to be completed by CSA and Canadarm2 contractor MacDonald Dettwiler and Associates (MDA). “Eureka!” tweeted EVA flight controller and astronaut instructor Scott Wray. “After a busy weekend, @csa_asc & @MDA_Robotics have found a software fix for the spare LEE we installed last week! That means no spacewalk tomorrow to swap back to the degraded LEE.”

Initially targeted for Thursday, 15 February, preparations ran smoothly. “Had a video conference with crew on-board the International Space Station this morning,” tweeted Mr. Wray on 10 February. “@Astro_Sabot, @Astro_Kanai & @Astro­_Maker are well on their way in preparations for Thursday’s spacewalk.” However, a decision was made to push the U.S. EVA-48 back by an additional 24 hours, due to this week’s postponed launch and docking of Russia’s Progress MS-08 cargo ship.

Norishige Kanai found time to tweet an image of himself, working with his space suit in the airlock, during familiarization training and tool setups. Vande Hei would wear EMU #3003, which he previously wore during last month’s U.S. EVA-47. This particular suit has a chequered history, first flown on shuttle mission STS-77 in May 1996 and first used for an actual spacewalk on the STS-82 Hubble Space Telescope (HST) upgrade in February 1997. It was later worn by Susan Helms in March 2001 on what still stands as the longest single EVA ever performed. Meanwhile, Kanai wore EMU #3008, which played an integral role in the “internationalization” of the U.S. space suits, worn by Russian cosmonaut Vladimir Titov during STS-86 in October 1997. This marked the first occasion that a shuttle-based spacewalk featured a non-U.S. crew member.

Early Friday, the crew took a quick breakfast, before pressing directly into EVA preparations. Assisting Vande Hei and Kanai in the Quest airlock were Expedition 54 crewmates Joe Acaba and Scott “Maker” Tingle, who would oversee Canadarm2 robotics operations. The spacewalkers spent about 60 minutes “pre-breathing” on masks and Quest’s inner “equipment lock” was depressed from its ambient 14.7 psi to 10.2 psi, allowing for suit checks and purging. It was then repressed back up to 14.7 psi, enabling the astronauts to undertake a nominal pre-breathing regimen and 50 minutes of in-suit light exercise.

Shortly after 6 a.m. EST, Acaba and Tingle transferred the fully suited duo from the equipment lock into the outer “crew lock” and closed the connecting hatches. Depressurization of the crew lock commenced shortly afterwards and reached a condition of near-vacuum at 0.5 psi. Vande Hei and Kanai transferred their suits’ life-support utilities onto battery power and U.S. EVA-48 formally got underway at 7 a.m. As they opened Quest’s outer hatch, the astronauts were greeted by the glorious view of the Pacific Ocean, west of Peru, as the station approached orbital sunrise.

Vande Hei, of course, had three previous EVAs to his credit, totaling 20 hours and 45 minutes, but Kanai was embarking on his first excursion and became the 223rd human since Alexei Leonov to perform a spacewalk. Although 12 Japanese citizens have now traveled into orbit—the first being television journalist Toyohiro Akiyama, way back in December 1990—only four, including Kanai, have ventured outside their spacecraft in orbit. Takao Doi made two spacewalks during the STS-87 shuttle mission in the fall of 1997, helping to retrieve the Spartan-201 solar physics satellite and participate in ISS maintenance tasks. Then, in the summer of 2005, Soichi Noguchi made three EVAs on the first post-Columbia shuttle flight, after which Aki Hoshide did another three outside the ISS in the summer and fall of 2012.

Interestingly, Hoshide holds the record for the greatest number of spacewalking hours for a Japanese astronaut (a little over 21 hours) and was on duty as today’s EVA Capcom in the Mission Control Center (MCC) in Houston, Texas. Seated alongside him was ISS Capcom Doug Wheelock, together with Flight Director Zeb Scoville and his team.

And Mr. Scoville (callsign “Explorer Flight”) was clearly pumped and ready for a challenge. “Today, in this room, humans from planet Earth will do great things,” he tweeted, as he came on console in the early hours of Friday morning. “International Collaboration at its best with @csa_asc and @JAXA_jp. There is nothing not cool about a spacewalk.”

With Vande Hei designated “EV1”, with red stripes on the legs of his suit for identification, and Kanai as “EV2”, in a pure-white EMU, the spacewalkers got quickly to work, performing “buddy checks” of tethers and tools, gloves and Helmet Absorption Pads (HAPs). They then parted ways for their initial tasks, with Vande Hei moving to ESP-2 to retrieve an Articulating Portable Foot Restraint (APFR) and attaching it to Canadarm2, for a quickfire journey over to the MBS POA. (Interestingly, his foot restraint was mounted onto the new LEE-B, which he had helped to install, a few weeks ago.)

As he moved, Vande Hei took a few moments to admire the view, as the station passed over Turkmenistan and headed towards Afghanistan. At the MBS POA, he met Kanai, who had labored, hand-over-hand, up the airlock “spur” and across the station’s truss to the worksite. Their initial task was to remove a Camera and Light Assembly (CLA) from the degraded LEE-A and stow it in a Crew Lock Bag (CLB).

Next, they worked together to detach the degraded LEE-A from its perch on the MBS POA, removing a set of six Expandable Diameter Fasteners (EDFs). This task was completed by 8 a.m., barely an hour into the spacewalk. Once the cylindrical unit, which measures about 3.5 feet (1.1 meters) long and weighs around 415 pounds (188.2 kg), was freed, the spacewalkers took it back to the airlock. Vande Hei was then flown by Acaba and Tingle back to ESP-2, where their attention turned to the degraded LEE-B, sitting on its temp-stow ring. Working briskly, they detached it and transferred it over to its new home on the MBS POA, where Kanai installed the CLA which had been removed earlier from the degraded LEE-A.

In response to an AmericaSpace query on Thursday, NASA explained that no “get-ahead” tasks were planned for the end of U.S. EVA-48. However, by 9:30 a.m., the spacewalkers were working well over an hour ahead of schedule and Hoshide came on the loop to advise them that a couple of get-aheads would be attempted. Specifically, Vande Hei was asked to doff his APFR from the new LEE-B end of the arm and set to work applying lubricant from a hand-held grease gun. It was not an unfamiliar task, for he had performed an almost identical procedure during U.S. EVA-45, last October. Lubrication of the LEEs was never intended to be done by spacewalkers and a specialized Ballscrew Lubrication Tool (BLT)—consisting of a probe, wire-ties and tape—was developed by NASA, several years ago, to apply the lubricant. From inside the ISS, Acaba and Tingle positioned Canadarm2 next to Vande Hei’s line of sight, enabling him to access the rigidized central ballscrew, which runs directly through the core of the new LEE-B.

Meanwhile, Kanai worked to install the Robot Micro Conial Tool (RMCT) onto the station’s Dextre robot, which is presently berthed at a Power and Data Grapple Fixture (PDGF) on the U.S. Destiny lab. He then worked to add a “grounding strap” around the new LEE-A, which will permit the robotic replacement of its CLA group, should it malfunction or fail at some point in the future.

Returning to the airlock at 12:57 p.m. EST, Kanai concluded the first spacewalk of his career, totaling five hours and 57 minutes in vacuum. Meanwhile, Vande Hei—who returns to Earth, together with Joe Acaba and Aleksandr Misurkin, at month’s end—wrapped up his fourth EVA in a single expedition. His total now stands at 26 hours and 42 minutes, which places him within the Top 60 on the list of the world’s most experienced spacewalkers. The degraded LEE-A will likely be stowed inside the Bigelow Expandable Activity Module (BEAM), ahead of its return to Earth aboard SpaceX’s CRS-15 Dragon in the June-July timeframe.

Meanwhile, Vande Hei, Acaba and Misurkin will board their Soyuz MS-06 spacecraft on 27 February and return to Earth, touching down in Kazakhstan, after 168 days in orbit. With two long-duration ISS expeditions and a shuttle mission under his belt, Acaba will position himself as the eighth most flight-experienced U.S. astronaut of all time. Their departure will mark the beginning of Expedition 55, commanded by Russian cosmonaut Anton Shkaplerov. Together with Tingle and Kanai, they will run the ISS for three weeks, until Soyuz MS-08 arrives on 23 March, carrying U.S. astronauts Drew Feustel and Ricky Arnold, together with Russia’s Oleg Artemyev.

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