Orbital ATK’ Cygnus resupply spacecraft finally returned to flight on Sunday following weather scrubs over numerous recent attempts. Riding United Launch Alliance’s Atlas V rocket uphill a year on from the loss of its previous mission atop Orbital’s own Antares rocket, liftoff from Cape Canaveral finally occurred at 16:44 Eastern on Sunday.



Cygnus Return:

Bound for the International Space Station, the launch was the first Cygnus flight since last October’s failure, and the first mission for NASA’s Commercial Resupply Services program since the loss of a SpaceX Dragon resupply mission in June.

United Launch Alliance deployed the Cygnus into orbit, with the spacecraft’s usual mount – Orbital’s Antares rocket – grounded for a redesign following its failure.

The Antares, which consists of a first stage designed by Ukraine’s Yuzhnoye bureau based on the company’s Zenit rocket and a Castor upper stage built by Orbital, failed shortly after liftoff last year, falling back onto its launch pad at the Mid-Atlantic Regional Spaceport and exploding.

Reports into the anomaly have found the failure was caused by a turbopump malfunction in one of the rocket’s AJ-26 first stage engines.

Orbital’s investigation found a manufacturing fault to be the root cause, while NASA’s report has also indicated the presence of foreign object debris in the turbopump – although the report did not find sufficient evidence to suggest whether this may have had an effect upon the failure.

The AJ-26 turbopump had been an early suspect in the failure investigation and shortly after the unsuccessful launch Orbital announced plans to move away from the AJ-26 – which is an Aerojet-refurbished NK-33 engine, using up a stockpile that were originally built for the Soviet Union’s N-1 rocket in the early 1970s.

Antares launches are expected to resume next year with NPO Energomash’s RD-181 engine in place of the AJ-26.

In order to fulfil its commitments to NASA under the Commercial Resupply Services program, Orbital ATK contracted United Launch Alliance to provide launch services for one resupply mission, with an option – since exercised – for a second launch.

The launch also marked the debut of an enhanced Cygnus vehicle, using an enlarged pressurised module to accommodate a larger payload than on earlier missions.

Launching atop the Atlas V – a larger and more powerful vehicle than the Antares – the Cygnus is able to carry even more cargo than had been planned for this configuration atop the most powerful Antares, the Antares 130.

The Cygnus launched is the Orbital ATK 4 (OA-4) mission, with the spacecraft named the SS Deke Slayton II after astronaut Deke Slayton. Slayton, the only member of the original Mercury Seven not to fly during the Mercury program – having been grounded due to a heart defect, was the first Chief of NASA’s Astronaut Office.

Finally cleared to fly in 1972, Slayton was a member of the American crew for the Apollo-Soyuz mission in 1975, when the US Apollo spacecraft, making its final flight, docked in orbit with the Soviet Union’s Soyuz 19 mission.

The Apollo-Soyuz mission was Slayton’s only trip into space. He retired from NASA in 1982 and died in June 1993 having been diagnosed with a brain tumour. OA-4 is the second Cygnus to bear his name; the vehicle which was lost last October was also named the SS Deke Slayton.

Orbital is one of two companies – along with SpaceX – contracted by NASA to deliver cargo to the International Space Station under the Commercial Resupply Services (CRS) program. OA-4 is the fourth operational Cygnus mission under CRS – the spacecraft having also flown one mission under the precursor Commercial Orbital Transportation Services (COTS) demonstration program.

SpaceX has flown seven operational CRS missions using its Dragon spacecraft, plus two COTS missions although their first COTS demonstration did not attempt a docking with the station.

(Animation created by Artyom Zharov, via L2’s huge collection of Dragon arrival hi res images)

SpaceX’s last resupply mission also ended in failure, with its Falcon 9 rocket appearing to suffer a structural failure while carrying the CRS-7 mission into orbit in June.

SpaceX hopes to return the Falcon to flight later this month, with Dragon launches to resume early next year.

A Russian resupply mission to the station, using a Progress spacecraft, was also lost earlier this year.

(Animation created by Artyom Zharov, via L2’s dump of Progress M-27M images taken from the ISS)

This high failure rate is unusual – prior to these three failures only one resupply mission had been lost across all space station programs since 1971; that being the failure of a Soyuz-U rocket carrying Progress M-12M in August 2011.

The OA-4 mission is carrying 3,513 kilograms (7,745 lb) of cargo to the Space Station. This includes supplies and provisions for the crew – including food and clothing – station, computer and scientific hardware, cameras, and equipment for performing spacewalks.

Among the cargo items are two prototypes of Microsoft’s HoloLens augmented reality headset. Part of an outreach program, but also being tested by NASA for applications aboard the station, these are being reflown after two headsets were lost aboard the Dragon spacecraft in June.

As has become common for CRS missions, several small satellites are being carried aboard the Cygnus to be deployed from the space station. Japan’s Kibo module is equipped to release these satellites into orbit. The OA-4 mission carries eighteen small satellites.

Planet Labs have twelve Flock earth observation satellites aboard the Cygnus; Flock-2e. These will join the many Flock satellites that have already been deployed as part of Planet Labs’ large constellation of low-cost imaging spacecraft.

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Other spacecraft that are being carried for deployment from the space station include the CubeSat Investigating Atmospheric Density Response to Extreme Driving (CADRE) for the University of Michigan, a three-unit CubeSat which will demonstrate the Wind Ion Neutral Composition Suite (WINCS) sensor suite ahead of a proposed larger-scale mission.

The University of Colorado’s Miniature X-ray Solar Spectrometer (MinXSS-1) satellite is another three-unit spacecraft that will be engaged in solar research.

NASA’s Network and Operation Demonstration Satellites (NODES) are a pair of 1.5-unit CubeSats which will be used to test using multiple small satellites for co-ordinated research. The satellites will collect radiation data over a two-week mission, relaying data and commands through the two-satellite constellation.

The spacecraft automatically determine a master or “captain” satellite, designating the other a “lieutenant” that will be commanded by the “captain”. NODES was conceived as a follow-up to the EDSN mission launched as part of the ORS-4 payload on last month’s Super Strypi flight, however this failed to achieve orbit.

The Satlet Initial Mission Proofs and Lessons (SIMPL) is a commercial payload for NovaWurks Incorporated, in association with NanoRacks. A technology demonstrator, SIMPL also carries an amateur radio payload. The St Thomas More Satellite 1 (STMSat-1) is an educational outreach and earth observation payload built by students at St. Thomas More Cathedral School – an elementary school (ages up to 11) – in conjunction with NASA.

In all, the Cygnus has a mass of 7,492 kilograms (16,517 lb).

OA-4 rode to orbit atop an Atlas V rocket. Flying in the 401 configuration, the rocket had tail number AV-061 and was making the Atlas V’s sixtieth flight.

Exactly half of the Atlas V’s flights have used the 401 configuration – the smallest version of the rocket to be developed – which consists of a Common Core Booster (CCB) first stage, a single-engine Centaur upper stage and a payload fairing with a diameter of four meters (13 feet).

Three different lengths of four meter fairing are used on the Atlas V, with the 12.2-meter (40.0-foot) Large Payload Fairing (LPF) the smallest and the Extended Payload Fairing (EPF) and Extra-Extended Payload Fairing (XEPF) adding one and two 90-centimeter (3.0-foot) segments respectively. For the launch, the 14-meter-long (46-foot) XEPF was used.

AV-061 lifted off from Space Launch Complex 41 (SLC-41) at the Cape Canaveral Air Force Station.

Originally built for the Titan IIIC and subsequently used by the Titan IIIE and Titan IV before being rebuilt for the Atlas between 1999 and 2002, SLC-41 supports all of the Atlas V’s East Coast launches with West Coast launches making use of Space Launch Complex 3E at Vandenberg Air Force Base.

During the Titan era, Complex 41 was the point of departure for the Viking missions to Mars, the Helios probes to study the Sun and the Voyager missions that flew past the outer planets.

Atlas launches from SLC-41 have included the New Horizons mission that flew past Pluto earlier this year, the Mars Reconnaissance Orbiter, Curiosity and MAVEN missions to Mars, the Juno probe which will reach Jupiter next year and the dual-launch of the Lunar Reconnaissance Orbiter and LCROSS spacecraft to the Moon.

The launch is the first mission to the International Space Station to use the Atlas V rocket and to launch from SLC-41, however the pad has recently undergone modifications to support future launches of Boeing’s manned CST-100 Starliner spacecraft atop the Atlas.

A new crew access tower has been built at the pad, with the structure topped off in early November. Rockets will continue to be assembled in the nearby Vertical Integration Facility, atop a mobile platform, and rolled to the launch pad ahead of launch – as was done with AV-061 – however the new tower will allow future crews to board their capsules at the pad before liftoff.

For the Cygnus mission, AV-061 flew a twenty-one minute mission to Low Earth orbit. The launch began with ignition of the first stage’s RD-180 engine, 2.7 seconds before the countdown reached zero.

Liftoff occurred about 1.1 seconds after zero when the thrust generated by the RD-180 exceeded the vehicle’s weight.

The Russian-built RD-180 burns RP-1 propellant oxidised by liquid oxygen and is a derivative of the RD-170 that was developed for the Soviet Zenit and Energia vehicles, as is the RD-181 which Orbital intends to use for its re-engined Antares.

About 18.4 seconds after lifting off, the Atlas began a pitch and yaw manoeuvre to establish its trajectory for the journey into orbit. Flying along an azimuth of 44.4 degrees, northwest across the Atlantic Ocean, the rocket’s velocity reached Mach 1 – the speed of sound – 82.6 seconds after liftoff. AV-061 passed through the area of maximum dynamic pressure 9.2 seconds later.

The RD-180 powered AV-061 for the first four minutes and 15.6 seconds of flight. After this, having depleted its propellant supply, the engine cut off. This flight event, Booster Engine Cutoff (BECO) marked the end of first stage powered flight with the spent stage separating six seconds later. Following a ten-second prestart sequence, the Centaur second stage ignited its RL10C-1 engine.

The Cygnus – despite not being publicized in advance – was actually the heaviest payload launched by the Atlas V to date, although the rocket flew a single-burn flight profile injecting Cygnus directly into her deployment orbit with only one firing of the Centaur’s RL10 engine, which eliminated the need for a coast phase and subsequent restart as often seen on other Atlas missions.

The Centaur’s burn lasted thirteen minutes and 45.1 seconds, with the Atlas’ payload fairing separating from the nose of the vehicle eight seconds after ignition.

Spacecraft separation occurred two minutes and 49 seconds after the end of the Centaur’s burn; at 21 minutes and 5.7 seconds mission elapsed time. After spacecraft separation, the Centaur restarted for a disposal burn, deorbiting itself to a destructive reentry over the Indian Ocean.

Cygnus was left in a near-circular orbit measuring 229.8 by 230.0 kilometers (142.8 by 142.9 miles; 124.1 by 124.2 nautical miles), at an inclination of 51.6 degrees. Array deployment was successful.

The SS Deke Slayton II will spend two and a half days adjusting its orbit for rendezvous with the International Space Station. The spacecraft will be captured by the station’s Canadarm2 remote manipulator system and berthed to the nadir port of the outpost’s Unity module.

OA-4 is the first resupply flight to use the port on the Unity module, which was until May occupied by the station’s Leonardo module which has now been relocated to the Tranquillity module. Previous Cygnus spacecraft berthed at the nadir port of the Harmony module.

During the Space Shuttle program Unity’s nadir port was occasionally used to berth a Multi-Purpose Logistics Module (MPLM) to the station, carrying additional cargo items to the station.

Earlier in the station’s development the port housed the PMA-3 docking adaptor, which was used by Space Shuttle Atlantis for the STS-98 mission in 2001. STS-98 delivered the Destiny module to the station, with the module’s installation requiring the temporary removal of the forward-mounted PMA-2 adaptor used by all other Shuttle missions.

At the end of its mission, the Cygnus will be loaded with cargo for disposal from the Space Station. The vehicle will be unberthed using the Remote Manipulator System and released away from the station before performing a deorbit manoeuvre.

The spacecraft is not designed to be recovered, and so will burn up in the atmosphere.

The launch was the ninth of the year for the Atlas V and the twelfth for United Launch Alliance – who have also launched two Delta IVs and a Delta II. It is the nineteenth orbital launch of 2015 for the United States, which may be the country’s last launch of the year; SpaceX has two Falcon 9 launches scheduled for December; one on an undetermined date in the middle of the month with eleven Orbcomm communications satellites followed by a second launch at the end of the month with the SES-9 satellite.

The Orbcomm launch is the Falcon’s return to flight after its failure in June, and introduces a new, upgraded, configuration; additional complexity which could make delays more likely. It is unlikely that both Falcon launches would be attempted in the month.

The next scheduled mission for United Launch Alliance will be the deployment of a Global Positioning System (GPS) navigation satellite by means of an Atlas V in early February. Orbital’s next Cygnus launch is currently slated to be the OA-6 mission, atop an Atlas in March, with the OA-5 launch aboard the revised Antares expected to fly no earlier than May.

(Images: NASA, Orbital ATK, ULA and L2 – including Photos from Philip Sloss and renders from L2 artist Nathan Koga – The full gallery of Nathan’s (SpaceX Dragon to MCT, SLS, Commercial Crew and more) L2 images can be *found here*)

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