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CAPE CANAVERAL — Carrying more science research gear to the International Space Station than ever launched before by U.S. commercial logistics vehicles, the next Orbital ATK Cygnus freighter takes flight Tuesday.

The cargo ship, ceremonially dubbed the S.S. John Glenn, will be boosted into orbit atop a United Launch Alliance Atlas 5 rocket from Cape Canaveral at 11:11 a.m. EDT (1511 GMT).

A 30-minute launch window, spanning 15 minutes before and 15 minutes after the exact moment the station’s orbital plane passes over the Complex 41 launch pad, allows flexibility for the Atlas 5 to wait out unfavorable weather or seek resolution to a technical issue that could crop up in the countdown.

Liftoff will be possible during any of five specific opportunities — at every 7-minute 30-second interval — that simplified the analytical work for mission control. The rocket’s in-flight steering capabilities will be employed during ascent to guide Cygnus into the station’s orbital plane:

Opportunity 1: 11:11:23 a.m. EDT

Opportunity 2: 11:18:53 a.m. EDT

Opportunity 3: 11:26:23 a.m. EDT

Opportunity 4: 11:33:53 a.m. EDT

Opportunity 5: 11:41:23 a.m. EDT

(* exact times will be tweaked by a few seconds based on final radar tracking of the station’s orbit on launch day.)

The System Certification Review was completed Friday and the Launch Readiness Review was successfully passed on Saturday morning.

Weather forecasters, as of Saturday, predict an 80 percent chance of favorable liftoff conditions, with partly cloudy skies, light winds and a temperature of 75 degrees F..

An optimal spot for the general public to view the late-morning launch will be Playalinda Beach, located just north of Complex 41 along the Canaveral National Seashore and accessed from Titusville via State Highway 402.

Walking down the beach to the barrier fence line will put you just 4.8 miles away from the rocket at takeoff.

The park charges $5 per car to enter.

The Kennedy Space Center Visitor Complex also offers viewing options, but those require the standard admission fee plus a launch access pass, per person.

It will be the 71st Atlas 5 launch and the third to deploy a Cygnus for the space station.

NASA pushed for Orbital ATK to buy an Atlas for the OA-7 launch vehicle because the powerful rocket enables the Cygnus to carry more cargo than the company’s own Antares rocket.

“These missions are very special to us at Orbital ATK. To us, it is all about the crew, giving them the supplies they need to live and work in low-Earth orbit, but also to deliver the scientific experiments so they can perform that valuable experimentation while while in low-Earth orbit,” said Frank DeMauro, vice president and general manager of Orbital ATK’s Advanced Programs Division in its Space Systems Group.

The spacecraft weighs 15,928 pounds, and it is loaded with 7,443 pounds of internal cargo and an 183-pound external deployer for cubesats.

But, notably, it is carrying 2,072 pounds of science equipment, more than any of the 16 previous commercial resupply vehicles launched by Orbital ATK or SpaceX for NASA’s privatized station cargo-delivery service.

“The Cygnus spacecraft is a very robust and reliable vehicle. It is crucial to meeting our resupply needs. This mission, specifically, will showcase the Cygnus’ ability to accommodate science,” said Holly Vavrin from the International Space Station program office in Houston.

“There are four refrigerator-freezers onboard that contain biological samples for several investigations and there’s over 1,000 kg of other science that spans all fields from astronomy to meteorology to biology/medical research and technological demonstrations. There’s also a lot of hardware onboard needed to maintain operations and keep the crew healthy and happy during their six-month expedition.”

Cygnus will take a four-day trek to the orbiting laboratory for rendezvous on Saturday. Grapple of the vessel by the station’s robotic arm is planned for 6:05 a.m. EDT (1005 GMT).

Approaching the station from behind and below, it will use Global Positioning navigation and rendezvous laser sensors to arrive at a point within 40 feet of the lab complex.

The astronauts are responsible for monitoring the Cygnus vehicle’s approach, able to abort the rendezvous with the push of a button to make the craft retreat away if they spot something amiss. Expedition 51 flight engineer Thomas Pesquet, a Frenchman from the European Space Agency, will be prime from working the Canadarm2 to capture the ship, while commander Peggy Whitson of NASA serves as backup arm operator.

Ground controllers will remotely-operate the arm to maneuver and then seat the Cygnus into the berthing mechanism on the underside of the station’s Unity module. Sixteen electrically-driven bolts will be engage to firmly attach the two craft together, allowing the hatchway to be opened to begin a three-month stay.

“Cygnus can accommodate a truly impressive amount of cargo of all shapes and all sizes, and this vehicle can remain attached to station for up to three months, providing us the flexibility we need in planning the complicated dance of vehicle traffic,” Vavrin said.

Vehicle hardware: 2,677 pounds

* Express Carrier Avionics (ExPCA) box and jumper cable, lab external handrail wireless communication antennas, improved Payload Ethernet Hub Gateway (iPEHG) hardware, external high definition camera and enhanced MDM hardware

* Student-built spacewalk tools

* Food warmer, medical accessory kits and sleeping bag and liners

* Microbial sampling hardware, filter and batteries for smoke detectors, acoustic dosimeter and data receiver, cabin air assembly heat exchanger

* Exercise harnesses for treadmill to be used by Paolo Nespoli and Randy Bresnik

* Cabling for Waste and Hygiene Compartment, Nitrogen/Oxygen Recharge System tanks and ventilation monitor and air filters

* New distillation and fluid and pressure control pump assemblies for the urine-to-water recycler

* Solid-state lights, multipurpose glue, standard socket, L-wrench

* Waste water bags

* Urine and solid waste disposal containers

* Toilet paper package

Crew supplies: 2,103 pounds

* Crew suitcases and provisions

* 92 Bulk Overwrap Bags of food

* Public affairs items for European Space Agency astronaut Paolo Nespoli launching to the station in July

* Personal items for Mark Vande Hei launching in September

* NASA items for Russian crew

* Procedure manuals

Science utilization: 2,072 pounds

* European Space Agency: Extremophiles kit and the Portable PFS facility for human research in respiratory, cardiovascular and metabolic physiology

* JAXA: Group Combustion hardware, ELF hardware, Probiotics

* NASA: Alpha Magnetic Spectrometer 1553 terminator connector, Antibody Drug Conjugates in Microgravity, Magnetic 3D Cell Culturing, Genes in Space 2 and 3, Osteo-omics, Nanoracks equipment and deployers, Plant Habitat, Rodent Research 5 Animal Access Unit, VEGGIE, SAFFIRE-3

EVA gear: 161 pounds

* Hard upper torso, arms, legs, boots, checkout fixture for spacesuit

* Spacewalk tool kit, tethers, tape, scissors

Russian hardware: 40 pounds

* Bulk Overwrap Bags of food for cosmonauts Fyodor Yurchikhin, launching April 20, and Sergey Ryazanskiy launching in July

Computer resources: 4 pounds

* Plant Habitat software

* System upgrade CD and DVD for the Columbus module

* M12 to RJ45 adapters

With packing material included, the total “up-mass” on this Cygnus in the pressurized cargo module is 7,443 pounds.

The ExPCA avionics box and the 1553 cable for AMS will be dug out of the Cygnus quickly because both items are part of the spacewalk planned for early May.

That EVA, the 200th for the space station program, will replace the box to upgrade the capabilities of the ExPRESS Logistics Carrier pallet to hold external payloads on the starboard truss and the AMS cable will guide future upgrade planning for replacing cooling pumps on the particle physics experiment.

For the upcoming launch, Cygnus was partially loaded with its payload at Kennedy Space Center’s Space Station Processing Facility, the same building where much of the outpost had been readied for space shuttle launches from the late 1990s through 2011.

After the pressurized cargo module and the propulsion tug of Cygnus were mated together, the spacecraft was relocated to KSC’s Payload Hazardous Servicing Facility to be loaded with 1,825 pounds of maneuvering propellant, the final stowage of cargo, closure of the hatch and encapsulation within the Atlas 5 rocket’s 45-foot-long, 14-foot-diameter aluminum nose cone, the longest available in that diameter.

The shrouded freighter then moved to United Launch Alliance’s rocket assembly building at Complex 41, where the two-stage Atlas 5 had been stacked aboard a mobile launch platform, and hoisted atop the rocket.

The 194-foot-tall Atlas/Cygnus vehicle will be rolled out to the launch pad at 8 a.m. EDT on Monday and the seven-hour countdown begins early Tuesday morning.

This is the fourth flight of the Enhanced Cygnus, which features a lengthened pressurized section, produced in Italy by Thales Alenia Space, to increase the interior volume capacity by 25 percent, circular UltraFlex solar arrays, manufactured in Goleta, California, that are lighter and more compact, and updated fuel tanks made with new diaphragm technology for better control of propellant.

The changes to Cygnus enable the vessel to launch 2,600 pounds more cargo than the previous spacecraft version.

The cargo container is a smaller diameter version of the Italian-made Multi-Purpose Logistics Modules that flew up and down on space shuttles to outfit the station.

Cygnus stands 21 feet tall and 10 feet in diameter, clad in its silver-metallic shielding. It has one 100-pound-thrust main engine and 32 small thrusters for 7-pound-thrust.

Continuing Orbital ATK’s tradition of naming its Cygnus ships for late astronauts, this freighter was christened after the first American to orbit the Earth.

“It is my humble duty and with great pride to announce this mission, this spacecraft is named the S.S. John Glenn,” DeMauro said.

“He was my hero as a young boy. I was 9 years old when in February of ’62 he became the first American to orbit the Earth. There wasn’t a single youngster within 10 years of my age that didn’t know who John Glenn was,” said Brian Duffy, a Hall of Fame astronaut who flew on four space shuttle missions and now serves as Orbital ATK’s vice president of Exploration Systems.

“He was the epitome of a public servant, someone who was always looking out for the best for his country. He entered into the Marine Corps. shortly after Pearl Harbor and served as a fighter pilot in World War II as well as the Korean War. He was selected in the first group of astronauts and became very famous for that. But he was a humble man throughout. After becoming an astronaut, he opened up the space frontier for all of us.”

There is a poster of Glenn directly behind the hatch that the station crew will see immediately after opening the hatch. Otherwise, there are no commemorative items being carried aboard the spacecraft.

“We felt this mission, Sen. Glenn would want to be all about cargo, he would want us to focus on getting that to the space station. So we’ve not allocated any mementoes,” DeMauro said.

Orbital ATK is under contract to perform four additional resupply missions through the end of 2018. NASA bought 11 flights in all under its Commercial Resupply Services 1 contract.

The company is guaranteed to get six additional missions under the CRS 2 contract. NASA has authorized the schedule for the first, slated for late 2019.

“Back in the fall, this mission was originally slated for Antares. One of the things we do on a regular basis is we’re always talking about the manifest and cargo and when NASA needs the missions to fly. After the SpaceX mishap on the pad, as part of that, we entered into discussions about if we could fly a little bit more cargo for NASA. In those conversations, the topic came up if there was a way to convert this mission to an Atlas 5. Orbital ATK is about the mission, we’re about supporting our customers,” DeMauro said.

“We are looking at getting back on Antares this summer with OA-8, but this mission it was in NASA’s best interests, collectively as a mission’s best interests, to convert the mission to an Atlas.”

** CYGNUS FLIGHT HISTORY **

Name….Rocket…..Cargo up-mass…Launch date

Demo — Antares — 1,299 pounds — Launched Sept. 18, 2013

Orb 1 — Antares — 2,780 pounds — Launched Jan. 9, 2014

Orb 2 — Antares — 3,293 pounds — Launched July 13, 2014

Orb 3 — Antares — 4,883 pounds — Launched Oct. 28, 2014 *Failure

OA-4 — Atlas 5 — 7,746 pounds — Launched Dec. 6, 2015

OA-6 — Atlas 5 — 7,758 pounds — Launched March 22, 2016

OA-5 — Antares — 5,163 pounds — Launched Oct. 17, 2016

OA-7 — Atlas 5 — 7,626 pounds — …

** DRAGON FLIGHT HISTORY **

Name….Cargo up-mass…Launch date

Demo — 1,014 pounds — Launched May 22, 2012

CRS-1 — 1,001 pounds — Launched Oct. 8, 2012

CRS-2 — 1,493 pounds — Launched March 1, 2013

CRS-3 — 4,608 pounds — Launched April 18, 2014

CRS-4 — 4,885 pounds — Launched Sept. 21, 2014

CRS-5 — 5,108 pounds — Launched Jan. 10, 2015

CRS-6 — 4,387 pounds — Launched April 14, 2015

CRS-7 — 5,275 pounds — Launched June 28, 2015 *Failure

CRS-8 — 6,914 pounds — Launched April 8, 2016

CRS-9 — 4,976 pounds — Launched July 18, 2016

CRS-10 — 5,490 pounds — Launched Feb. 19, 2017

See earlier OA-7 Cygnus coverage.

Our Atlas archive.