Things to know: Atlas V ready for launch from Cape Canaveral
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An Atlas V rocket stands ready at Cape Canaveral Air Force Station for a Tuesday morning blastoff of a Cygnus spacecraft destined for the International Space Station.
The 194-foot United Launch Alliance rocket, which rolled to the pad at Launch Complex 41 early Monday morning, is scheduled for liftoff at 11:11 a.m. Weather is 90 percent "go" for the window that closes at 11:41 a.m.
What's on board?
Orbital ATK's Cygnus spacecraft is packed with more than 7,600 pounds of science experiments, supplies and cargo for the crew of the ISS.
"We have a wide range of support equipment that's going to be headed to station to support the science that's up there already, but also to introduce brand new capabilities," said Tara Ruttley, associate scientist for the ISS program, during a prelaunch news conference at Kennedy Space Center.
The Advanced Plant Habitat, a new KSC experiment, is a minifridge-sized plant chamber that will be able to grow larger, more nutritionally dense plants that could one day be consumed by astronauts on deep-space missions. Also on board are experiments that could improve chemotherapy treatments for cancer and magnetized tools for easier reproduction of Earth-like experiments.
Cygnus will also take 38 CubeSats, which are miniaturized satellites designed for research purposes, to the station for deployment at a later time.
[How to watch world's first 360-degree live stream of a rocket launch]
Remembering John Glenn
Orbital ATK named the Cygnus the S.S. John Glenn in honor of the first American astronaut to orbit Earth, who died last December.
"I feel like we're bridging history," said Vern Thorp, program manager for commercial missions at United Launch Alliance. "John Glenn flew on an Atlas rocket in 1962 when he became the first American to orbit the Earth and right now we're preparing Atlas to begin flying astronauts again in the near future as part of NASA's Commercial Crew Program."
Weather status: excellent
Atlas V is expected to vault off the pad into clear skies thanks to a 90 percent chance of favorable weather.
"This time of year is generally very favorable for launch operations," said David Craft, a weather officer with the Air Force's 45th Weather Squadron, during the news conference. "It's no exception for this week."
A slight chance of cumulus clouds is the only potential concern. Conditions are just as favorable for the backup launch time of 10:48 a.m. Wednesday.
[Space salad? Plant growth experiment hitching a ride on Atlas V to ISS]
Third launch of Cygnus from Florida
Tuesday's launch will be Cygnus' third flight from Florida on ULA's "workhorse" Atlas V rocket.
The spacecraft, previously launched from the Space Coast in 2015 and 2016, transitioned to launching on Atlas V rockets after the 2014 explosion of an Orbital ATK Antares rocket at Wallops Island, Virginia.
ULA is now on its 71st overall launch of Atlas V and the 36th in the 401 configuration that is launching Tuesday.
"That 401 configuration has really become the Atlas V workhorse," Thorp said. "That particular configuration has launched about half of our Atlas V missions over the years."
The launch was delayed from March due to hydraulics leaks on the booster and ground support equipment.
George Diller's swansong
One of NASA’s most recognized voices will call “Liftoff!” for the final time on NASA TV when the Atlas V and Cygnus set sail.
George Diller, a public affairs representative at Kennedy Space Center for 37 years and longtime countdown commentator on NASA TV, plans to retire at the end of May.
A 68-year-old Titusville resident whose credits include calling the final space shuttle launch in July 2011, Diller has not wanted to draw attention to his departure.
But during the press conference, Frank Culbertson, a former NASA astronaut who is now president of Orbital ATK's Space Systems Group, publicly thanked Diller for his service.
“A real, true fan of the space program, but also a real contributor,” Culbertson said. “So George, thank you for everything.”
Contact Emre Kelly at aekelly@floridatoday.com or 321-242-3715. Follow him on Twitter and Facebook at @EmreKelly.
Contact James Dean at jdean@floridatoday.com or 321-242-3668. Follow him on Twitter at @flatoday_jdean.
Launch Tuesday
Rocket: United Launch Alliance Atlas V
Mission: Orbital ATK Cygnus spacecraft for ISS resupply
Launch Time: 11:11 a.m.
Launch Window: 11:41 a.m.
Launch Complex: 41 at Cape Canaveral Air Force Station
Weather: 90 percent "go"
Watch 360-degree video: YouTube.com/NASAtelevision (10 minutes before launch)
Join floridatoday.com starting at 10 a.m. for countdown chat and updates, including streaming of NASA's webcast.