>Update: The Antares rocket exploded shortly after liftoff on Tuesday. Follow breaking news on Twitter.
The countdown has already begun for the launch of the Antares rocket scheduled to carry the Cygnus cargo spacecraft, and 5,000 pounds of supplies and experiments, to the International Space Station this evening (you can watch the launch here). The rocket is scheduled to lift off from NASA’s Wallops Flight Facility at 6:22 p.m. EDT, barring an interruption like the one that scuttled the Antares’ planned launch last night, when a stray 26-foot sailboat was spotted within the launch’s 1,400-square-mile “danger zone” off of Virginia’s eastern shore, and all attempts to contact its operator prior to launch were unsuccessful.
NASA spokesperson Allard Beutel said it was the first time NASA has aborted a commercial launch for this reason, though stray watercraft infrequently delayed Space Shuttle launches in the past.
“Boats out that far in the ocean are supposed to be monitoring marine band channel 16,” Beutel says. The effort to warn away at-risk boasts is robust: Nine hours prior to launch time, Wallops begins broadcasting a warning on channel 16. Four hours before, a complement of “seven or eight” boats from the U.S. Coast Guard, Coast Guard Auxiliary, and Virginia Marine Police begins patrolling and clearing the launch area. An hour after that, they’re joined by three aircraft—a radar airplane, a spotter airplane, and a helicopter—all on the lookout for stray boats.
The leisure boat that scuttled last night’s planned launch was spotted early in the launch count, but it did not respond to numerous attempts at radio contact. The spotter plane’s subsequent attempt to signal to the boat by circling it and dipping one wing, as is standard practice when radio contact fails, also went unanswered. The boat was traveling at only about four knots. “There was no way it was going to be able to clear the hazard zone in time for the launch,” Beutel says. Last night’s launch was scheduled for 6:45 p.m. EDT. Beutel says the launch window was 10 minutes, and NASA usually tries to aim for the middle of it to maximize the rocket’s fuel efficiency.
NASA posted a “Notice to Mariners” about the launch on its website on Oct. 16. Today is one of four backup launch days listed in the notice after the Primary Launch Day of Oct. 27.
The unmanned Cygnus capsule will remain with the space station for approximately one month before being filled with refuse and incinerated in Earth’s atmosphere.