The Cygnus spacecraft is back in rotation for cargo runs to the International Space Station for the first time since the previous spacecraft was destroyed during the Antares rocket explosion in October 2014. The cargo craft will launch on an Atlas V rocket in December, resuming flights while the Antares rocket continues safety upgrades.

Resuming Cargo Runs

Cygnus loaded with cargo prior to the doomed launch in October 2014. Image credit: NASA/Patrick Black

The spacecraft will haul approximately 3,600 kilograms (4 tons) of material in a pressurized cargo module to the International Space Station in December 2015. This is the fourth Commercial Resupply Services cargo run by Orbital Sciences (OA-4).

The Cygnus spacecraft is developed and produced by Orbital Sciences. Historically, it has always launched on an Orbital Antares rocket, but that rocket is still grounded for safety upgrades following the unscheduled rapid disassembly last fall. Instead, the Cygnus will be launched by a United Launch Alliance Atlas V rocket. It will also be launching from a new pad — Cape Canaveral instead of the still-being-repaired pad at Wallops Flight Facility.

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Cygnus service module with Ultraflex solar arrays. Image credit: NASA

The uncrewed, unpiloted spacecraft will be the fourth operational mission for Cygnus. This will also be the first launch of the Enhanced Cygnus, a modification of the cargo tug with a larger cargo module and a more mass-efficient service module. It will carry 1,300 kg (3,00 pounds) more than the original model of the spacecraft for a total of 3,600 kilograms (8,000 pounds) of experiments, equipment, and supplies to the space station. The service module that provides power, guidance, and control will have a new lightweight power system and Ultraflex solar arrays.

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The pressurized segment of the spacecraft is currently at Kennedy Launch Center, and is being inspected to insure it is ready for cargo installation and flight. It will be connected to the service module in October, undergoing final integration and testing before launching in early December. Three-quarters of the cargo will be packed into Cygnus by October, with the remaining material loaded just two weeks before launch to allow for a bit of flexibility.

Cargo container holding the Cygnus pressurized cargo module at the Space Station Processing Facility at Kennedy. Image credit: NASA/Kim Shiflett

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After launch, the craft will direct itself within reach of the Canadarm on the space station. The robotic arm will grasp the craft, pulling it into the station and safely docking it. After astronauts unload the cargo, they will refill Cygnus over several weeks with garbage and other disposable items. When the spacecraft is full of junk, it will be released from the space station and sent on course to burn up during reentry as a fiery garbage day.

This will be the second attempt at the fourth cargo run by the Cygnus spacecraft after the previous spacecraft was destroyed in a rocket explosion. Three additional missions are tentatively scheduled for 2016: one using an ULA Atlas V rocket, and the other two using the upgraded Antares rocket.

Upgrading the Rocket

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A pair of R-181 engines being integrated with the Antares rocket first stage. Image credit: NASA

In the aftermath of understanding what happened during the unscheduled rapid disassembly of the Antares Rocket during the October launch, Orbital decided to upgrade the rocket with new engines and modifying the first stage core. The modified rocket is still undergoing testing and certification, but is expected to start flight operations in spring 2016.

New RD-181 engines are replacing the AJ-26 engines suspected of being the cause of the launch mishap and subsequent explosion. The new engines produce higher specific impulse and extra thrust than the previous engines, which will increase the payload capacity of the rocket. The engines have passed individual tests, and are being integrated into the rocket along with new propellant feed lines and first stage avionics systems for hot fire testing this winter.

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The RD-181 engine is the next generation of the RD-191 engine, which is currently used on the Russian Angara rocket. Both are based on the RD-171 and RD-180 engines used on the Zenit and Atlas V rockets.

The Commercial Resupply Services contract between Orbital Sciences and NASA requires that Orbital carries a specific weight of cargo to the space station, not complete a fixed number of flights. Increasing the payload of each launch will enable Orbital to make up for the cargo lost during the October explosion.

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New RD-181 main engines are replacing the old AJ-26 engines suspected of causing the launch explosion in October 2014. Image credit: NASA/Joel Kowsky

Repairing the Launch Pad

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The explosion damaged Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) at Wallops Island. The explosion damaged the transporter erector launcher and lightning suppression rods, broke windows and imploded doors in support buildings, and destroyed a nearby sounding rocket launcher. Debris from the rocket and its payload also required extensive cleanup.

The pad is being repaired and upgraded with a new hydraulic system to erect rockets on the pad. The pad should be ready by the end of September, and will be the site of hot fire testing of the Antares rocket in late 2015 or early 2016.

[NASA, Orbital ATK]

Top image: Cygnus Pressurized Cargo Modules at the production facility in Italy. Credit: NASA

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