Status: Saturday’s launch scrubbed with just minutes remaining in the countdown due to a range violation caused by a wayward plane. The next attempt on Sunday morning was successful, although not without incident, as two boats were in the range requiring Antares to launch at the end of her window.
Cygnus, which was developed by Orbital ATK’s predecessor Orbital Sciences Corporation for NASA’s Commercial Orbital Transportation Services (COTS) and Commercial Resupply Services (CRS) programs, is one of two US cargo vehicles that form part of a fleet of international spacecraft used to support the International Space Station (ISS) in orbit.
The two spacecraft contracted for NASA’s CRS missions – Cygnus and SpaceX’s Dragon – carry the majority of US cargo to the station.
CRS-8, also known as OA-8, is the ninth mission of Cygnus and the fifth to use the “Enhanced Cygnus” configuration with an enlarged pressurized cargo module and redesigned solar arrays, which was introduced in 2015.
Cygnus spacecraft are named in honor of former astronauts who have passed away. The CRS-8 spacecraft is named the SS Gene Cernan, after Gemini and Apollo astronaut Eugene Cernan who died in January at the age of 82.
Cernan, who was the last man to walk on the Moon, served in the US Navy before joining NASA in 1963 as part of NASA’s third astronaut group.
The first of his three spaceflights – Gemini IX-A – came in June 1966, Cernan having been promoted from the mission’s backup crew alongside Thomas Stafford after the original prime crew were killed in a plane crash.
Cernan and Stafford spent three days in orbit aboard Gemini IX-A, although the primary mission objective of docking with the Augmented Target Docking Adaptor (ATDA) was unsuccessful as the ATDA’s payload fairing had failed to separate, obstructing its docking collar.
During the Apollo program, Cernan was one of three astronauts to visit the Moon twice. He was the Lunar Module Pilot of May 1969’s Apollo 10 mission, which tested the spacecraft in lunar orbit ahead of the Apollo 11 landing two months later.
Cernan’s second trip to the Moon was as the Commander of the final Apollo mission – Apollo 17 – in December 1972, during which he spent three days on the Moon and made three moonwalks. Climbing back into the Lunar Module after the mission’s Lunar Module Pilot, Harrison Schmitt, Cernan became the last astronaut to leave the surface.
Cygnus consists of a service module, which houses the spacecraft’s power-generation and propulsion systems and a Pressurised Cargo Module (PCM) which contains the cargo to be delivered to the space station.
The PCM is manufactured by Thales Alenia Space, based on the design of the Multi-Purpose Logistics Modules (MPLMs) that were carried on Space Shuttle resupply missions. The service module draws on Orbital’s experience with building satellites for low Earth orbit and geosynchronous missions, and incorporates an IHI Aerospace BT-4 engine.
The SS Gene Cernan is carrying 3,338 kilograms (7,359 lb) of cargo for the International Space Station.
This includes 1,240 kilograms (2,734 lb) of supplies and provisions for the space station crew, 851 kg (1,875 lb) of space station hardware, 34 kg (75 lb) of computer equipment and 132 kg (291 lb) of hardware for use in performing spacewalks.
Scientific equipment and experiments make up 740 kilograms (1,631 lb) of the cargo, while a 109-kilogram NanoRacks CubeSat deployer is mounted on the outside of the spacecraft and will be used to release fourteen CubeSats after Cygnus leaves the station.
Some of the experiments that are being carried aboard Cygnus to be performed aboard the ISS include studies into the life cycles of mealworms in space – investigating whether they could be a source of protein for astronauts on future long-duration missions – an investigation into the growth of a mustard plant, Arabidopsis thaliana, and a study of how microclover processes nitrogen in the microgravity environment.
Several small research satellites are also being carried – with satellite deployments expected to occur both from the NanoRacks deployer on Cygnus and at least one from the International Space Station itself.
NASA’s E. Coli Antimicrobial Satellite (EcAMSat) will be used to examine how cultures of E. coli bacteria respond to antibiotics in microgravity, as well as demonstrating for NASA a six-unit (6U) CubeSat platform.
The 10.4-kilogram (22.9 lb) satellite will be operated by NASA as part of a collaboration with Stanford University’s school of medicine, and is expected to operate for at least 45 days. The spacecraft carries 48 microfluidic wells that will be used to grow E. coli, thirty-six of which will then be treated with antibiotics while the remainder serve as a control. EcAMSat’s investigation will begin four days after it is deployed from the ISS.
The Integrated Solar Array and Reflectarray Antenna, or ISARA, is a three-unit CubeSat which will conduct a technology demonstration for NASA’s Jet Propulsion Laboratory (JPL).
After deployment from Cygnus, ISARA will deploy a folded panel reflectarray (FPR) which will serve as both a solar array and a communications antenna, providing the satellite with 56 watts of power and a 32 gigahertz Ka-band downlink with a bandwidth of up to 100 megabits per second – a significant improvement over data rates available to most current nanosatellite missions.
Two satellites for The Aerospace Corporation’s Optical Communications and Sensor Demonstration (OCSD) investigation are aboard the launch.
OCSD-B and OCSD-C, also known as AeroCube 7B and 7C, are a pair of 1.5-unit CubeSats which will be used to demonstrate optical communications – using lasers to transfer data to and back from a ground station at California’s Mount Wilson Observatory.
The two satellites follow on from the OCSD-A, or AeroCube 7A, satellite which launched in October 2015. OCSD-A was intended to demonstrate all of the satellites’ systems in space ahead of the launch of the next two satellites, however its attitude control system malfunctioned, preventing it conducting any laser communications tests – which require precision pointing of the satellite.
The Naval Postgraduate School’s single-unit PropCube-2, or Fauna, CubeSat will be used for ionospheric studies. Two previous satellites – PropCube-1 and PropCube-3 (also known as Flora and Merryweather) – were launched on the same October 2015 launch as OCSD-A, as secondary payloads to the National Reconnaissance Office’s NROL-55 mission which deployed a pair of Intruder ocean surveillance satellites.
Asgardia 1, which will be operated by Asgardia Space, will put a 512-gigabyte solid-state drive (SSD) into orbit in a demonstration of space-based data storage. The two-unit CubeSat is expected to operate for six months, with data being transferred to and from its hard drive via Globalstar communications satellites.
Asgardia, which has declared itself to be a country and claims over 110,000 “citizens”, describes itself as a “space nation” and “a global, unifying and humanitarian project”. Asgardia 1 is the first satellite to be launched for a self-declared micronation.
The Cost-Effective High E-Frequency Satellite (CHEFSat) is a Naval Research Laboratory (NRL) satellite, a three-unit CubeSat that will demonstrate an off-the-shelf radio system in space as a risk reduction experiment for future missions.
The NanoRacks deployer is also carrying eight Lemur-2 satellites for US firm Spire Global. Each of these three-unit CubeSats carries two instruments: SENSE, which relays Automatic Identification System (AIS) signals from ships, and STRATOS, which monitors the occultation of GPS satellites as they pass through the atmosphere.
Data collected by STRATOS allows the temperature, pressure and humidity within the atmosphere to be inferred.
Cygnus can launch either on Orbital ATK’s own Antares rocket, or aboard United Launch Alliance’s Atlas V.
The launch used Antares, which was last used for the CRS-5 launch in October 2016. Antares, which was developed primarily to launch Cygnus, first flew in April 2013 with a demonstration payload and four CubeSats aboard.
Its subsequent launches have all carried Cygnus missions bound for the International Space Station. This mission will be Antares’ seventh launch and the second for the Antares 230 configuration that will be used.
Antares is a two-stage rocket with a liquid-fuelled first stage – which burns RP-1 propellant oxidized by liquid oxygen – and a solid-fuelled second stage.
The first stage was developed and is produced by Ukraine’s Yuzhnoye design bureau and Yuzhmash machine plant, derived from the first stage of the former-Soviet Zenit rocket.
The stage was originally designed to be powered by a pair of Aerojet AJ-26 engines – refurbished from NK-33 engines originally built for the Soviet N1 rocket program in the early 1970s – however following an October 2014 launch failure the rocket was refitted with two RD-181 engines from Russia’s NPO Energomash.
Each of the three digits in Antares’ configuration number denotes what is being used as the first, second and optionally third stage of the vehicle. The first digit represents the first stage, with a one denoting the AJ-26-powered first stage and a two the RD-181 revision.
The second digit represents the second stage, with a three meaning that a Castor-30XL motor was used. Earlier flights have used the less powerful Castor 30A and 30B motors – indicated by a one or a two respectively.
The final digit will be used to differentiate a three-stage version of Antares, should one be ordered. A third stage is not required for Cygnus launches.
Antares launches are conducted from the Mid-Atlantic Regional Spaceport, a commercial spaceport facility located at Wallops Island, Virginia, alongside NASA’s Wallops Flight Facility.
Antares launches from Pad 0A, which was built for it on the site of an old launch complex that had been built for the short-lived Conestoga rocket in the 1990s.
Aside from the six previous Antares launches, the only other launch to have been made from LP-0A was the Conestoga 1620’s single, failed, launch in 1995.
When the countdown reached the zero mark, Antares’ two RD-181 first stage engines ignited.
Liftoff occurred at about T+3.7 seconds, with the rocket beginning her climb away from Wallops Island.
Antares’ first stage burned for about three minutes and 35 seconds, before main engine cutoff (MECO) took place with the rocket at an altitude of about 99 kilometers (62 miles, 53 nautical miles) on the edge of space.
Antares then began its unusual staging sequence be jettisoning the spent first stage six seconds after cutoff. The second stage, encapsulated within the payload fairing and still attached to an interstage adaptor, continued to coast.
Thirty seconds after first stage separation, with Antares now at an altitude of 127 kilometers (79 miles, 69 nautical miles), the payload fairing separated from around stage two and Cygnus. Five seconds later the second stage separated from the interstage, igniting eight seconds after separation to begin a two-minute, 42-second burn.
At nine minutes and five seconds mission elapsed time – about 119 seconds after second stage burnout – Cygnus separated from the second stage into a 189-by-296-kilometer (117-by-184-mile, 102-by-160-nautical-mile) orbit inclined at 51.63 degrees with respect to the equator.
Following separation, the SS Gene Cernan deployed its solar arrays and began a series of burns to set up a rendezvous with the International Space Station on Monday.
Upon arrival the spacecraft will be grappled by astronauts Paolo Nespoli and Randy Bresnik, using the station’s CanadArm2 robotic arm, and berthed at the nadir – Earth-facing – port of the Unity module via its Common Berthing Mechanism (CBM).
Cygnus is expected to remain at the International Space Station until early December.
After unberthing the spacecraft will temporarily be positioned, at the end of CanadArm2, close to the zenith-facing port of the station’s Harmony module to allow NASA to investigate the effect that a spacecraft in that position would have on the station’s communications. The following day Cygnus will depart from the space station.
Unlike SpaceX’s Dragon, Cygnus is not designed to be recovered at the end of its mission. Before leaving the station, OA-8 will be filled with trash and unwanted equipment. Following departure from the space station, the spacecraft will be deorbited and burn up during reentry over the Pacific Ocean.
CRS-8 is the second Cygnus mission of 2017, following on from the CRS-7, or OA-7, mission that was launched aboard an Atlas V in April.
The Antares launch was the third and final launch to be conducted by Orbital ATK this year – following the company’s first Minotaur launch from Cape Canaveral in August and a successful return to flight for the Taurus rocket – renamed Minotaur-C – at the end of October. An air-launched Pegasus-XL rocket had been expected to launch NASA’s ICON satellite in early December, but this launch has now slipped into 2018, per L2 information.
A new date for the ICON launch has not yet been announced, however this is likely to be Orbital ATK’s next launch. The next Cygnus mission is expected to fly aboard another Antares 230 at the start of May.
nasaspaceflight.com by William Graham