The International Space Station (ISS) is primed to receive its sixth visiting vehicle of 2020 in the coming days, although of a kind unseen in almost a decade and of a nature never seen before. Retired Marine Corps Col. Doug Hurley, who piloted the final voyage of the Space Shuttle, and former chief astronaut and Air Force Col. Bob Behnken, a former NASA chief astronaut, will launch from historic Pad 39A at the Kennedy Space Center (KSC) in Florida at 4:33 p.m. EDT Wednesday, 27 May.
Flying atop a Falcon 9 booster, theirs will be the first mission by U.S. astronauts, aboard a U.S. spacecraft and from U.S. soil since the end of the shuttle program in July 2011, as well as being the first-ever time that humans will have traveled into low-Earth orbit in a wholly commercial vehicle.
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So far this year, we have seen the arrival of three uncrewed cargo ships—Northrop Grumman’s NG-13 Cygnus in February, SpaceX’s CRS-20 Dragon in March and last month’s flight of Russia’s Progress MS-14—as well as the launch of Soyuz MS-16 crewmen Chris Cassidy, Anatoli Ivanishin and Ivan Vagner on 9 April to kick off Expedition 63. Yesterday, Japan’s H-II Transfer Vehicle (HTV-9) arrived at the space station and was robotically captured and berthed onto the Earth-facing (or “nadir”) port of the Harmony node. But the launch and arrival of Hurley and Behnken will be arguably the most important U.S. mission of 2020, as the long-delayed Commercial Crew comes of age, the scope to expand future ISS expeditions to seven members becomes a reality and a whole new era of human space exploration begins to dawn.
As outlined previously by AmericaSpace, the Demo-2 mission was not originally intended for a multi-month ISS residency, but rather as a short visiting flight of one or two weeks. However, the lengthy and politically frustrating delays to which Commercial Crew has fallen prey in recent years prompted NASA and SpaceX to reconsider the mission last year. It was recognized that after the return of Expedition 62 crew members Oleg Skripochka, Drew Morgan and Jessica Meir in mid-April, a period of some months threatened to elapse with only one American crewman—Cassidy—to oversee the entire U.S. Operational Segment (USOS). The undesirability of this situation led to plans to extend Demo-2 to bridge this gulf in reduced ISS staffing.
Surprisingly, a Crew Dragon failure came indirectly to the aid of this plan. When the capsule used for the unpiloted Demo-1 mission in March 2019 was accidentally lost on the test stand a few weeks later, Hurley and Behnken’s original spacecraft for Demo-2 was shuffled forward along the line to execute the dramatic In-Flight Abort Test last January. And the capsule originally earmarked for SpaceX’s first Post-Certification Mission (PCM-1)—informally known as “Crew One”, the first operational long-duration flight—was correspondingly assigned to Hurley and Behnken. This proved to be one of the enabling factors in allowing them to fly a longer mission.
How long Demo-2 will be is dependent upon spacecraft consumables and particularly the lifetime of Crew Dragon’s body-mounted solar arrays, which are predicted to support a mission of up to 119 days. In recent remarks at last week’s socially-distanced crew arrival ceremony at the Cape, Hurley explained that he and Behnken were preparing themselves to spend between one and four months aboard the ISS, potentially returning to Earth as late as the middle of September.
And as to the specifics of what they will do whilst there, the astronauts felt that they will be able to add a couple of extra pairs of hands to Cassidy to support ongoing maintenance and the conduct of an estimated 164 experiments on Expedition 63. They have been in regular email correspondence with Cassidy, who jokingly told the pair that he was looking forward to having their “ugly mugs” aboard the space station soon, but it was not difficult to discern that even the veteran Navy SEAL is looking forward to having some U.S. company. “He likes solitude,” said Hurley, “but it was very obvious that he is ready for some human interaction from us.”
Assuming Demo-2 launches on time tomorrow afternoon, rendezvous and docking onto International Docking Adapter (IDA)-2 at the forward end of the station’s Harmony node is anticipated about 19 hours later. After pressurization and leak checks have been conducted, hatches into the ISS will be opened and doubtless Hurley and Behnken will be greeted warmly by Cassidy, Ivanishin and Vagner, who have lived and worked together as a three-man crew for over five weeks. One of the earliest exchanges may well be a U.S. flag which was carried aboard both the first and last voyages of the Space Shuttle and which has, since July 2011, been kept in pride of place aboard the station. Hurley and Behnken plan to grab the flag from Cassidy, put it somewhere safe and bring it home with them at the end of their mission, whenever that may be.
As the likelihood of a long mission became a reality, the Demo-2 crew ramped up their preparedness with additional ISS training. This included Extravehicular Activity (EVA) refresher training for Behnken, who already has six spacewalks totaling 37.5 hours under his belt, but has not flown in over a decade. Hurley, too, received additional training time as an Intravehicular (IV) crewman and practice with the station’s 57.7-foot-long (17.6-meter) Canadarm2 robotic arm.
Those skills may be needed this summer as NASA completes the replacement of aging nickel-hydrogen batteries aboard the four power-producing truss segments of the station’s Integrated Truss Structure (ITS) with upgraded lithium-ion units. The “inboard” S-4 and P-4 truss segments had their batteries replaced in January 2017 and March 2019, respectively, and required two sessions of EVA apiece to complete the task. However, the S-6 and P-6 truss segments are further “outboard” and less readily accessible to Canadarm2. The greater distances the arm and the spacewalkers needed to travel to transport hardware and tools out to the S-6 and P-6 work sites produced a correspondingly larger workload. Between October 2019 and January of this year, a series of four EVAs were performed to successfully changeout the P-6 truss batteries.
As of now, the S-6 truss—which arrived at the station during shuttle Discovery’s STS-119 mission, way back in March 2009—is the only component of the ITS which still requires a battery upgrade. Additionally, Europe’s Barolomeo payloads-hosting platform and the Columbus Ka-band Antenna Terminal (COL-Ka) are expected to be activated during another EVA at some point this year. But although AmericaSpace understands that Behnken is fully EVA-qualified and Hurley is trained “to support suit-up and robotics”, it remains to be seen if either man will participate in any upcoming spacewalks. “No decision has been made on conducting EVAs whilst [Demo-2] is docked to the station,” NASA’s Rob Navias explained, “or if EVAs are approved by the ISS Program, what EVAs they would be.”
Certainly, the Demo-2 astronauts will assist Cassidy with the station’s continuing maintenance and research workload. Some 164 experiments are planned or currently ongoing during Expedition 63, including 87 provided by NASA or U.S. investigators and 77 furnished by its international partners. These include human research, biology and biotechnology, physical science, Earth and space science, technology development and demonstrations and a wide variety of commercial, cultural and educational activities.
They will also participate in a number of Crew Dragon-related activities, overseen by Behnken as the mission’s joint operations commander. According to NASA, the work encompasses six key strands. Emergency Safe Haven Configuration will require the astronauts to reawaken Crew Dragon from a quiescent mode and execute procedures to establish an emergency safe haven. Emergency Hardware Stowage Evaluation will see them configure and evaluate all emergency hardware in the spacecraft Dragon to prepare for a fast-response emergency safe haven. Docked Audio Evaluations will require them to verify audio communications to the USOS, the Russian Segment and Soyuz which would be necessary in an emergency. Hurley and Behnken will also characterize the wifi strength from ISS routers to determine if NASA and SpaceX devices can access wireless networks aboard the Crew Dragon. They will participate in donning/doffing evaluations of their SpaceX launch and entry suits in microgravity and transition from the SpaceX emergency mask to the suit. And they will evaluate the habitability and crew preferences for future missions with larger crews of four.
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