Next U.S. Cargo Spacecraft Ready to Launch to ISS – UPDATE 2

UPDATE, December 4, 2015:   Ground winds prevented the launch today (three attempts were made). Another attempt will be made tomorrow, December 5, at 5:10 pm ET.

UPDATE, December 3, 2015:  The launch was scrubbed today due to weather.   ULA and Orbital ATK will try again tomorrow, December 4.  The 30-minute launch window opens at 5:33:11 pm ET.  The weather forecast is 30 percent “go.”

ORIGINAL STORY, December 2, 2015: Orbital ATK’s Cygnus spacecraft is ready to launch to the International Space Station (ISS) aboard a United Launch Alliance (ULA) Atlas V rocket tomorrow (Thursday) at 5:55 pm ET.  The weather forecast is 60 percent “go.”  The launch is the return-to-flight of the Cygnus spacecraft following a launch failure of Orbital’s Antares rocket in October 2014.

The launch is the fourth operational cargo resupply mission under Orbital ATK’s Commercial Resupply Services (CRS) contract with NASA and is designated Orbital ATK CRS-4 or OA-4.   Orbital ATK names its Cygnus spacecraft after prominent individuals. This one is named the S.S. Deke Slayton II (S.S. for spaceship).  The Cygnus destroyed in the October 2014 launch failure was the original S.S. Deke Slayton.  Slayton was one of the original Mercury 7 astronauts chosen in 1959, although he did
not get his chance to fly until 1975 because of a health issue.  After leaving NASA, he became one of the first space launch entrepreneurs, founding Space Services Inc., which built the Conestoga rocket. 

Tomorrow’s OA-4 mission marks several firsts.

It is the first launch of the enhanced version of the Cygnus capsule, which can accommodate more cargo than the earlier version. Tomorrow’s launch will deliver more than 3,500 kilograms (7,000 pounds) of supplies, scientific experiments, and equipment.  The earlier version could carry only about 2,000 kilograms (4,400 pounds) of cargo.

It is the first use of a new type of solar array, which is circular rather than the typical rectangular shape.   The deployment process takes longer — as much as an hour after the spacecraft separates from the rocket.

Illustration of Orbital ATK’s Enhanced Cygnus spacecraft.  Image credit:  Orbital ATK.

It is the first launch of a Cygnus on a ULA rocket.  Cygnus was built to ride aboard Orbital Science Corporation’s (now Orbital ATK) Antares rocket.  Flights aboard Antares are expected to resume around May 2016, but in order to meet its contractual requirement to deliver 20 tons of cargo to the ISS by the end of 2016, the company will first launch two Cygnus capsules on ULA Atlas V rockets.  The second Cygnus/Atlas V launch is scheduled for March. 

At a press conference today, NASA, Orbital ATK and ULA officials lauded each other’s ability to work together to get ready to launch so quickly on a different rocket.   Several technical changes were needed, especially to the launch vehicle, but it has all been accomplished in just less than a year.   NASA ISS Program Manager Kirk Shireman said it was amazing that “Orbital and ULA have been able to create this marriage and be in this position just literally a year from when it started.  These are complicated vehicles.  Flying in space is difficult. …. I am very impressed.”

Tomorrow’s launch window is open for 30 minutes, beginning at 5:55:44 pm ET.  NASA TV coverage begins at 4:30 pm ET.  A post-launch press conference is scheduled for approximately two hours after launch and will be broadcast on NASA TV..

SpaceX also launches cargo missions to the ISS, but it suffered a failure in June 2015.  Two other non-U.S. cargo spacecraft can resupply the ISS — Russia’s Progress and Japan’s HTV.  

There were two successful SpaceX launches to ISS in 2015 prior to the failure.  SpaceX has not announced a date for its next attempt to launch to ISS, but Shireman said today it would be no earlier than January 8, 2016.  Russia’s Progress had its own failure in April 2015, but three other Progress spacecraft have successfully reached ISS this year; the next is scheduled for launch on December 21.  Japan’s HTV-5, which is significantly larger than the other cargo spacecraft, successfully resupplied the ISS in August.

Despite all of those successful missions, though, Shireman said that the supply of food and other necessities aboard the ISS is sufficient only through February, so NASA clearly is hoping that tomorrow’s launch is a success and OA-4 reaches the ISS as planned on December 6. 

If weather delays the launch tomorrow, another attempt can be made on December 4, although the weather forecast is only 40 percent “go” that day.