Operations are progressing smoothly at Launch Complex-41 on Cape Canaveral Air Force Station, Fla., where a 196-foot-tall United Launch Alliance (ULA) Atlas-V booster is standing by to launch Orbital ATK’s first Cygnus cargo ship (named S.S. Deke Slayton II) since the loss of the ORB-3 mission last year at Wallops Island, Va. Cygnus is now bigger and better than ever, and it’s packed with over 7,380 pounds of supplies, equipment, and experiments for the incumbent Expedition 45 crew of the International Space Station (total weight with packaging is over 7,700 lbs).
The mission is set to lift off at the opening of a 30-minute launch window, which opens at 5:55 p.m. EST. Current weather forecasts still show a 60 percent chance of favorable conditions for launch.
The spacecraft as a whole is an enhanced version of the original, featuring an extended Pressurized Cargo Module (PCM), a lighter Service Module (SM), and new lightweight Ultraflex solar arrays—upgrades which will enable the Deke Slayton II to fly nearly as much weight as the last three Cygnus missions combined.
The spacecraft, encapsulated in its 13-foot-diameter (4-meter) bullet-like payload fairing, weighs in at over 16,500 pounds, making it the heaviest Atlas-V payload ULA will have ever flown, surpassing the 7.5-ton weight of the NAVY’s four Mobile User Objective System (MUOS) satellites launched over the last several years from the same pad.
Cygnus was transported from nearby Kennedy Space Center’s Payload Hazardous Servicing Facility clean room to pad 41’s beachside Atlas Vertical Integration Facility (VIF) to meets its rocket on Friday, Nov. 20. Following final integrated testing and closeout preparations for launch, Cygnus and its Atlas booster rolled to their nearby launch pad mid-morning on Dec. 2.
As reported in an in-depth article earlier this month by AmericaSpace Senior Writer Ben Evans, Deke Slayton II carries the heaviest payload ever delivered into space aboard a Cygnus, some 40 percent greater than any of its predecessors—to support ongoing scientific research, maintenance, crew needs, and preparations for future spacewalks. AmericaSpace understands from NASA that 500 pounds (227 kg) of this heavyweight payload will be EVA equipment, which comprises generic hardware and tools for the U.S.-built Extravehicular Mobility Units (EMUs), including a new Simplified Aid for EVA Rescue (SAFER) backpack unit, space suit gloves and batteries, a Liquid Cooling and Ventilation Garment (LCVG), and tool bags/caddies.
In addition to the EVA equipment, the spacecraft has onboard 1,867 pounds (847 kg) of science investigations for the ISS, most notably the Space Automated Bioproduct Lab (SABL), which will support a wide range of fundamental, applied, and commercial life sciences experimentation, as well as education-based investigations for students from kindergarten through the university level. Research in SABL will focus on micro-organisms, such as bacteria, yeast, algae, fungi, and viruses to animals cells and tissues and even small plant and animal organisms.
Another significant payload is the first NanoRacks microsatellite ever to be deployed from the ISS. Known as the NanoRacks-Microsat-SIMPL, it consists of a modular, Hyper-Integrated Satellite (HiSat) and is reportedly capable of providing complete satellite functionality on a nanosatellite scale. When released into space, it will become the first propulsion-capable satellite ever deployed from the NanoRacks-MicroSat-Deployer (Kaber).
In addition to the science and EVA payloads, Deke Slayton II will also transport 2,603 pounds (1,181 kg) of crew supplies, 2,220 pounds (1,007 kg) of vehicle hardware, and 191 pounds (87 kg) of computer resources to the ISS.
Given the performance and capability of ULA’s workhorse Atlas-V rocket, the launch window is unusually long for an ISS chase (30 minutes). ULA spokesperson Lyn Chassagne provided us the following explanation, courtesy of Jim Sponnick, ULA’s vice president for Atlas and Delta programs:
“Instantaneous launch windows are the standard way to accomplish a rendezvous mission with a low-earth object like the ISS, and this approach can significantly limit the probability of an on-time launch. We always strive to implement longer launch windows in our mission designs, to maximize the probability of a first-day launch for our customers. We have been enhancing our mission design capabilities and operational processes for years in order to make good use of the launch vehicle performance to provide the flexibility to accomplish launch window objectives.”
“For the OA-4 mission, the ULA mission design team has worked very closely with the Orbital ATK team to provide a design approach that enables a longer launch window. The OA-4 launch design approach accounts for the fact that the ISS orbit can change shortly before the launch, if either an overall orbit adjustment or evasive debris mitigation maneuver is required.”
“Considering the capabilities inherent in the Atlas design, the late changes that can occur in the ISS orbit, and the close coordination with the Orbital ATK Cygnus rendezvous design, we have implemented a 30-minute long window, which will occur within a bounding 50-minute-long window that accounts for the potential late orbital changes for the ISS.”
The OA-4 resupply mission will come over a year after Orbital ATK’s 133-foot-tall Antares rocket exploded spectacularly just six seconds after liftoff on Oct. 28, 2014, carrying the company’s Cygnus on its third ISS resupply mission under a $1.9 billion Commercial Resupply Services (CRS) contract with NASA. Signed in December 2008, the agreement requires the Dulles, Va.-based company to fly eight dedicated Cygnus missions to the ISS by 2016 to deliver a total of 44,000 pounds of payloads and other items for NASA.
The contract has since since been extended, for obvious reasons, and NASA has already given Orbital ATK two additional missions under that same contract as well, missions OA-9e and OA-10e, giving Cygnus 10 flights under the CRS-1 contract instead of the original eight.
However, the increased capability of the ULA Atlas-V compared to the Orbital ATK Antares means ULA can haul 35 percent more cargo to orbit with Cygnus, which would have allowed Orbital ATK to fulfill their original CRS-1 contract in seven flights instead of eight. Now, with the contract extended to 10 flights, it is expected that Orbital ATK will only really need nine, with the 10th Cygnus CRS-1 contract flight optional depending on the needs of the ISS.
“With OA-4 set to launch, and at least three additional missions to the ISS planned in 2016, we remain solidly on schedule to meet our CRS cargo requirements for NASA,” said Frank Culbertson, president of Orbital ATK’s Space Systems Group and former NASA space shuttle/ISS astronaut. “Our team’s performance in meeting milestones on an accelerated timeline demonstrates the company’s flexibility and responsiveness to customer needs. If all goes as planned, on Dec. 3, space watchers new and seasoned can thrill to seeing a unique, ‘two-of-its-kind’ launch, as an Atlas-V rocket lofts a Cygnus cargo ship to orbit.”
If the launch does not occur on Dec. 3, the next launch opportunity would be at 5:33 p.m. on Friday, Dec. 4, with a worse weather outlook of only 40 percent GO, with Cumulus Clouds, Disturbed Weather, Thick Cloud Layer, and Ground Winds all as potential violations of launch commit criteria.
.Missions » ISS » COTS » CYGNUS » ORB-4 »