Orbital Sciences Prepares Antares Rocket For Afternoon Launch
April 20, 2013

Orbital Sciences’ Antares Rocket Postponed Until Sunday 5 PM

Lee Rannals for redOrbit.com — Your Universe Online

Update 4 (April 20, 4:00 p.m.)

Excessive wind levels have forced NASA and Orbital to once again delay the launch of the Antares Rocket. Today´s 5:00 p.m. EDT launch has been scrubbed and the team will try again for a Sunday afternoon launch at 5:00 p.m.

Mission managers decided to pull the plug on today´s launch after high-altitude wind speeds were found to exceed range safety restrictions. NASA TV coverage will begin at 4:30 p.m. EDT on Sunday afternoon.

Stay tuned for further updates.

Update 3 (April 20, 2:05 p.m.)

Everything is a go for a launch today at 5:00 p.m. EDT for Orbital´s Antares rocket. The Range countdown began on time at 9:00 a.m. EDT in preparation for the launch, which has been postponed twice due to unfavorable weather conditions.

Antares will launch in less than a few hours from Launch Pad-0A at NASA´s Wallops Flight Facility on Wallops Island, Virginia. The launch will be broadcast live on NASA TV beginning at 4:30 p.m. EDT today (Apr 20).

Update 2 (April 19, 6:55 a.m.)

Orbital has scrubbed a Friday launch after a review of the weather forecast called for unfavorable weather conditions. The next launch window will now open on Saturday April 20 for a 5 p.m. EDT launch attempt. Reports show an 85 percent of favorable conditions for Saturday, but NASA and Orbital are keeping an eye on Sunday if weather conditions deteriorate.

NASA TV will begin coverage of the event beginning at 4:30 p.m. EDT. For more information and updated briefing on the coverage schedule, visit NASA´s Orbital site.

Update 1 (April 18, 6:55 a.m.)

Orbital´s Antares rocket launch has been delayed most likely due to unfavorable weather conditions. According to NASA, the next available launch window will open no earlier than Friday, April 19, with a possible launch time around 5 p.m. EDT.

NASA will have live coverage of the launch on NASA TV. Coverage will begin at around 4:30 p.m. EDT.

Main Story (April 17, 12:23 p.m.)

Orbital Sciences Corporation will be launching its Antares rocket from NASA's Wallops Flight Facility in Virginia this afternoon.

The goal of today's launch is to boost a simulated payload to a target orbit of 155 miles. This will demonstrate Antares' capabilities of delivering payload into orbit. The test launch is the final development operation leading to Orbital's demonstration of cargo delivery to the International Space Station (ISS).

In a statement by NASA, it was acknowledged that there remained a 45 percent chance of having favorable weather for today's launch. If weather does not allow for the opportunity of a launch today, then more windows will be available April 18 through 21.

Orbital conducted a wet dress rehearsal for its Antares rocket on Saturday in preparation for today's flight. During this dress rehearsal, the test was halted because the team detected a technical anomaly in the process. Orbital determined that a secondary pyro valve aboard one of the two first-stage engines used in the propellant chill down process was not functioning. Engineers installed a replacement within 24 hours so it could keep its April 17 launch window open.

Antares is a two-stage rocket designed to help provide NASA with low-cost, reliable access to space. Orbital holds a 10-mission contract with NASA, including eight resupply missions to the space station.

After lift-off, Antares' first stage will fire for approximately four minutes, helping to place the launch vehicle to an altitude of 70 miles. Once the launch vehicle reaches this altitude, Stage 2 will kick in and continue to boost the simulated payload to its proper orbit. NASA says the simulated payload will be reaching its orbit in less than ten minutes from lift off.

The Antares rocket will be carrying the Cygnus advanced maneuvering spacecraft along with it. This space vessel is what will eventually be holding the payload for future ISS resupply missions. The Cygnus spacecraft consists of a Service Module, power and navigation systems, and a Pressurized Cargo Module (PCM).

SpaceX became the first company to dock with the space station last year. Its reusable Dragon capsule has been working hard since then to provide astronauts aboard the orbiting laboratory with more supplies. Although it has been working almost perfect as a resupply vehicle since its first launch, the spacecraft will eventually be transformed for use as a way to carry astronauts into space instead of cargo.