Four years after his untimely death in a boating accident, NASA astronaut Alan “Dex” Poindexter—veteran of two pivotal space shuttle missions to assemble and maintain the International Space Station (ISS), including the delivery of Europe’s Columbus research module—will be honored this weekend, when Orbital ATK launches a Cygnus cargo ship, bearing his name. “Spaceship Alan Poindexter” marks the first Cygnus launch atop Orbital ATK’s homegrown Antares booster since the catastrophic loss of the ORB-3 mission, seconds after liftoff, back in October 2014. Lifting off from Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Va., no sooner than 8:03 p.m. EDT Sunday, 16 October, the OA-5 mission will deliver 5,346 pounds (2,425 kg) of equipment and research materials to the incumbent Expedition 49 crew.
According to NASA, the OA-5 payload aboard Cygnus includes 184 pounds (83 kg) of NanoRacks CubeSats, as well as a range of pressurized payloads. This includes 123 pounds (56 kg) of computer resources—laptops, cables, and hard drives, cameras and camcorders, video cables, and power inverters—together with 1,290 pounds (585 kg) of crew supplies to be unpacked by Commander Anatoli Ivanishin of Russia and his crewmates Kate Rubins of NASA and Takuya Onishi of the Japan Aerospace Exploration Agency (JAXA). Additionally, 1,098 pounds (498 kg) of utilization hardware is manifested from NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA). This includes hardware for French astronaut Thomas Pesquet’s forthcoming long-duration Expedition 50/51 increment, as well as cables for the Microgravity Science Glovebox (MSG), hardware and gas bottles for the Combustion Integrated Rack (CIR), and components to support as many as 250 scientific investigations to be performed during Expeditions 49 and 50. Rounding out the OA-5 payload is EVA hardware, including Helmet Absorption Pads (HAPs), an Extravehicular Mobility Unit (EMU) repair kit, and ion filter and general vehicle hardware, as well as 92 pounds (43 kg) of supplies for the Russian Orbital Segment (ROS).
Although this will be the sixth overall Cygnus mission delivered to the space station, it will actually only be the fourth to have been successfully lofted atop an Antares. First flown in April 2013, the booster represented the first foray into large-scale cryogenic rocketry for Orbital Sciences Corp. In its first-generation “100-series” configuration, Antares’ first stage was propelled by a pair of Aerojet-furnished AJ-26 engines. This vehicle delivered the ORB-D (“demonstration”) mission of Cygnus to the ISS in September 2013, after which it smoothly executed the ORB-1 and ORB-2 missions in January and July of the following year, but failed in October 2014 whilst attempting to transport ORB-3 uphill.
By this stage, a merger between Orbital and elements of ATK Thiokol was already underway, concluded in spring 2015. As outlined by AmericaSpace’s Elliot Severn last fall, the ORB-3 investigation pointed the finger of blame squarely at a turbopump failure within one of the AJ-26 engines, which triggered a voracious liquid oxygen fire and destroyed the vehicle. Efforts to replace the aging, Soviet-heritage AJ-26 was ongoing at the time, and in December 2014 it was announced that the RD-181 would fly aboard successive Antares 230 first stages. In the meantime, Orbital ATK contracted with ULA to launch two Cygnus missions atop its Atlas V, thereby closing a gap in flight operations before an expected resumption of Antares missions by mid-2016. Two Cygnus flights—“OA-4” and “OA-6,” the new nomenclature reflecting the Orbital ATK merger—were successfully launched aboard Atlas Vs in December 2015 and March of this year.
As ISS resupply operations continued unabated, Antares pressed toward a return to flight. By the end of 2015, Pad 0A at the MARS site had undergone significant repair and reconstruction, allowing an Antares 230 first stage to conduct a static hot-fire test on 31 May 2016. The RD-181 engines performed flawlessly during the 30-second firing, and the first stage will see future use to deliver the OA-7 Cygnus to the ISS. In the meantime, OA-5 hardware was being processed, initially aiming for an early July launch, although this has met with delay through the summer. It slipped initially until the third week of August and, eventually, to a five-day “window” from 9-13 October.
The spacecraft assigned to OA-5 is the third mission of the “Enhanced Cygnus,” which benefits from a longer Pressurized Cargo Module (PCM) and can deliver an approximately 60-percent larger haul of payloads and supplies than its predecessor, the Standard Cygnus. Combined with its Service Module (SM), the upgraded spacecraft stands 15.9 feet (4.86 meters) tall, about 3.9 feet (1.2 meters) higher than the Standard Cygnus, and although their diameters are the same at 10.1 feet (3.07 meters), the Enhanced variant is 4,000 ponds (1,800 kg) more massive and can accommodate a larger payload volume, about 950 cubic feet (27 cubic meters). The Enhanced Cygnus is also fitted with low-mass Ultraflex solar arrays, whose characteristic fan-like shape makes the overall appearance of the vehicle distinct to the wing-like appendages of the Standard Cygnus.
The OA-5 spacecraft was transported from NASA’s Wallops Flight Facility main base to Wallops Island for fueling on 19 September. Following the satisfactory completion of the Flight Readiness Review (FRR) on 4 October, the Cygnus was encapsulated within its bulbous payload fairing and mounted atop the Antares 230. Notwithstanding the risk posed to the United States’ eastern seaboard by the ravages of Hurricane Matthew, NASA and Orbital ATK eventually opted to launch OA-5 on the 13th.
This date ultimately proved untenable, as Tropical Storm Nicole intensified into a Category 3 hurricane and posed an elevated threat to range tracking assets in Bermuda. On Tuesday, 11 October, Orbital ATK announced a No Earlier Than (NET) target of Sunday evening for OA-5. “The tracking station at Bermuda is required to conduct the Antares launch from Wallops,” said Steven Kremer, chief of the Wallops Range and Mission Management Office. “The ability to support a launch will depend on the impact the storm has on not only our systems, but also the overall Bermuda infrastructure.”
In readiness for launch, the 133-foot-tall (40.5-meter) Antares 230 booster was rolled out to Pad 0A on Thursday, 13 October. At the instant of T-0, the two RD-181 engines will deliver a propulsive yield of 937,000 pounds (425,000 kg), representing more than a 12.5-percent performance hike over the AJ-26s of their predecessors. The first stage will power Antares for 208 seconds, burning a total of 527,522 pounds (239,280 kg) of liquid oxygen and a highly refined form of rocket-grade kerosene, known as “RP-1.” Following the cutoff of the RD-181 engines, the 90.5-foot-long (27.6-meter) first stage will be jettisoned, leaving Cygnus and its attached CASTOR-30XL upper stage to continue the boost to orbital altitude and velocity. This will be the first outing for the CASTOR-30XL, a solid-fueled motor which measures 19.7 feet (6 meters) in length and 7.7 feet (2.3 meters) in diameter and weighs some 58,000 pounds (26,300 kg).
More than a month since the return of Soyuz TMA-20M and its crew of Russian cosmonauts Alexei Ovchinin and Oleg Skripochka and record-setting U.S. astronaut Jeff Williams, the ISS is currently operating with three on-board personnel. Original plans called for Soyuz MS-02 to launch on 23/24 September, carrying Russian cosmonauts Sergei Ryzhikov and Andrei Borisenko, together with NASA’s Shane Kimbrough, but their mission was postponed due to technical difficulties with their spacecraft. Those difficulties—associated with damaged cabling in the descent module—appear to have been resolved and Soyuz MS-02 is targeted to rise from Baikonur Cosmodrome in Kazakhstan at 2:05 p.m. local time (4:05 a.m. EDT) on 19 October. In the days after the decision to delay the mission, the Soyuz MS-02 prime and backup crews returned to the Star City cosmonauts’ training center, on the forested outskirts of Moscow. They returned to Baikonur on 7 October.
Assuming an on-time launch on Sunday, the OA-5 Cygnus should be executing its final rendezvous maneuvers towards the ISS in the hours before Soyuz MS-02 departs Baikonur. Current plans envisage that Expedition 49 astronauts Kate Rubins and Takuya Onishi will grapple the spacecraft with the 57.7-foot-long (17.6-meter) Canadarm2 robotic arm and berth it at the Earth-facing (or “nadir”) port of the station’s Unity node on 19 October. According to NASA, Orbital ATK has until 23 October to launch Antares, “if need be.” However, with Soyuz MS-02 following a longer-than-normal two-day rendezvous, before its own docking on 21 October, there exists a “cut-out” period during which the incoming crewed vehicle will receive priority. With this in mind, if the OA-5 launch slips beyond Sunday, Cygnus will exercise its “loiter” capability in low-Earth orbit for several additional days, before it is robotically captured and berthed at the station on the 23rd.
A successful launch of OA-5 on Sunday night will open the floodgates for a busy fall and winter of 2016. With the subsequent launch and arrival of Soyuz MS-02, a week-long handover of operations will occur with the resident Expedition 49 crew, before Ivanishin, Onishi, and Rubins board their Soyuz MS-01 spacecraft and depart the ISS on 30 October. They will wrap up a relatively short ISS increment of just under four months. Two weeks later, on 16 November, Soyuz MS-03 is scheduled to launch from Baikonur, carrying Russian cosmonaut Oleg Novitsky, Frenchman Thomas Pesquet, and former NASA Chief Astronaut Peggy Whitson. They will form the second half of Expedition 50, under Kimbrough’s command, which will run through late February 2017. Rounding out the year are Russia’s Progress MS-04, Japan’s H-II Transfer Vehicle (HTV)-6 and Orbital ATK’s OA-7 Cygnus, all provisionally targeted for the December timeframe.
Under its initial Commercial Resupply Services (CRS) contract with NASA, agreed in December 2008, Orbital ATK was tasked with staging eight dedicated Cygnus missions, ferrying a total of 44,000 pounds (20,000 kg) of payloads and supplies to successive ISS crews. However, with the increased uplift capability afforded by two Atlas V launches and the larger payload envelope of the Enhanced Cygnus, it is expected that this total will be covered by the OA-7 mission. In August 2015, Space News reported that a pair of additional Cygnus flights had been contracted. Together with the already-baselined eighth mission, these formed part of an “Extension” program, designated “OA-8E” through “OA-10E,” and would bridge the gap between the end of the original CRS contract and the follow-on CRS2. More recently, in January 2016, Orbital ATK won a share of the CRS2 contract, with six follow-on missions beyond OA-10E slated for the 2019-2024 timeframe.