Third time’s the charm for Antares?

Antares on pad

The Antares launch vehicle on the pad at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Virginia, earlier this week. (credit: NASA/Bill Ingalls)

The launch of any rocket requires a large number of things to fall into place: all the various components and subsystems of the rocket itself, the weather, and the range. Getting all of that together is a challenge for a veteran rocket, but more so for a vehicle making its first flight. That’s why it shouldn’t be surprising that Orbital Sciences Corporation’s Antares rocket is still standing on its launch pad at Virginia’s Mid-Atlantic Regional Spaceport (MARS) this morning, after two very different issues postponed its first two launch attempts.

On Wednesday, it was the case of an unforeseen technical issue. About 12 minutes before the planned liftoff time, an umbilical between the rocket’s second stage and its Transporter Erector Launcher (TEL), which serves as the gantry for the rocket, disconnected from the rocket. The umbilical was an Ethernet data cable providing information on the state of the rocket’s upper stage. The disconnected cable meant that Orbital had to, figuratively and literally, pull the plug on Wednesday’s launch.

The problem, Orbital executive vice president and mission director Frank Culbertson said, was a combination of a “slight hydraulic movement” in the TEL and insufficient slack in the umbilical. When the TEL shifted slightly, the cable came loose. “The good news is that this is a simple adjustment to the external support systems,” Culbertson said at the time, and the launch was rescheduled for Saturday, since weather conditions on Friday were not promising.

Saturday dawned with a 90-percent chance of acceptable weather at launch time. A cold front passed through the night before and, while there were still some high clouds, conditions initially looked good for the launch. However, as the day wore on and the clouds gradually moved off to the east, powerful upper-level winds posed an issue for the launch. The concern was not with the vehicle itself, but worries that any debris from an accident would be blown beyond a designated limit. Ultimately, Orbital decided not to fuel the vehicle—thus preserving the option of a Sunday launch—and scrubbed the attempt at 4:30 pm EDT (2030 GMT) Saturday.

“We had the rare case of the wind coming from the southwest at a very high velocity,” Culbertson told reporters after the scrub Saturday. Orbital postponed the launch by over an hour, to 6:10 pm EDT (2210 GMT) to wait for more weather balloon data to come in on the state of the upper level winds, but saw no hope for a Saturday launch when the new data came in. “It was still red, and the trend towards green was not nearly strong enough, so we made the decision to go and scrub at this point.”

Other than the winds, though, the vehicle was in good condition, Culbertson added. Those upper level winds are forecast to diminish to acceptable levels on Sunday, with a 75-percent chance of acceptable weather at launch time: gusty ground level winds are the main issue, but Culbertson said that concern is “marginal” at best. So, perhaps Sunday conditions will align to permit a launch, or, perhaps, they’ll find another little unforeseen issue that forces them to try again another day.

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