Orbital’s Antares: An eye on the present and the future

by Chris Bergin

Orbital are still hoping to launch their Antares rocket on its debut trip into space this coming week, despite an issue during its Wet Dress Rehearsal (WDR). Elsewhere, the Castor 30XL upper stage motor – that will fly with Antares on later flights of the Cygnus spacecraft to the ISS – enjoyed a successful static fire in Tennessee.

Antares A-One:

Orbital are just days away from the debut launch of their new medium class rocket, having successfully conducted Wet Dress Rehearsals (WDR) – known as cold flow testing – ahead of the recent 7K hot fire test, in preparation for the A-One mission’s pre-launch flow.

The 27 second hot fire test proved to be successful, with a review of the results providing a green light to proceed towards this upcoming debut launch – a validation flight that will be the last major milestone ahead of the first Cygnus spacecraft mission to the International Space Station (ISS).

With the Antares that will conduct the debut launch under the COTS (Commercial Orbital Transportation System) requirements – complete with its Cygnus mass simulator payload – rolled out to the pad, engineers conducted another WDR as part of their pre-launch flow on Saturday.

The test was halted at the T-16 minute mark due to an issue with a valve on one of Antares’ two AJ-26 first stage engines.

“On Saturday, Orbital conducted the wet dress rehearsal for the Antares rocket in preparation its Test Flight scheduled for later this week on April 17. Late in the countdown, at about T-16 minutes, the test was halted because the launch team had detected a technical anomaly in the process,” noted Orbital via a statement.

AJ-26 Engine, via L2“Orbital has determined that a secondary pyro valve aboard one of the two first-stage engines used in the propellant chilldown process was not functioning properly. A replacement unit will be installed within 24 hours with the goal of maintaining the April 17 launch date.”

The replacement valve was shipped from its vendor – Aerojet –  and was installed overnight on the vehicle sat on the pad at the Wallops launch site.

Orbital were expected to test the replacement valve via another WDR on Monday. ahead of the Launch Readiness Review (LRR). However, confidence in the replacement work means no additional WDR is required.

The flow will next move into the L-1 Ops on Tuesday.

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The A-One mission has its first launch opportunity on Wednesday, with a three hour launch window opening at 17:00 local time.

Another opportunity is available on Thursday, with both days deemed to have a 30 percent chance of acceptable conditions, per sources. A third opportunity on Friday is also an option.

Cygnus approaching the ISS, via L2Should the launch prove to be successful, Orbital will then prepare for a full-up launch – with a functioning Cygnus – as they set their sights on a debut mission to the International Space Station (ISS).

Similar to SpaceX’s COTS 2+ mission, the ORB-D flight will be the final major requirement of their COTS contract.

*Click here for the full ORB-D Mission Overview*

Once into their Commercial Resupply Services (CRS) missions, Antares will swap the Upper Stage from the Castor 30A to an upgraded version called the Castor 30B. This will be used for the CRS-1 (Orb-1) and CRS-2 (Orb-2) ISS runs.

CASTOR 30XL Milestone:

The final transition for the rocket will come via the use of the CASTOR 30XL, which will power the last six CRS flights scheduled for the Antares – allowing for the transition towards the launch of extra cargo on a larger Cygnus Spacecraft.

The “enhanced” Cygnus is scheduled to fly the last five CRS missions, boosting payload capacity to 2,700 kg.

The new Upper Stage motor was recently shipped from its manufacturer, ATK, to the Arnold Engineering Development Center in Tennessee for a static fire test.

Screenshot from L2 video of CASTOR 30XL static fireAs seen via a dual camera engineering video acquired by L2, the motor successfully fired for its full duration of 156 seconds, which included gimbal checks on the motor’s nozzle.

“I am very pleased with our successful CASTOR 30XL test,” said Scott Lehr, ATK vice president and general manager of Defense and Commercial Systems. “In less than two years, the ATK/Orbital team designed and built the motor that was fired.

“We look forward to seeing this stage become part of the Antares launch vehicle, supporting ISS cargo resupply missions for NASA.”

CASTOR 30XLThe CASTOR 30XL solid rocket motor is 92 inches in diameter, 236 inches in length and weighs approximately 58,000 pounds.

The nozzle is eight feet long with a submerged design with a high performance expansion ratio (56:1) and a dual density exit cone well suited for high altitude operation.

Orbital Sciences Corporation contracted ATK back in April, 2011 for the development and qualification of the motor, along with the six production units that will ride with Antares and Cygnus on their ISS missions.

(Images: via Orbital and L2’s Antares and Cygnus Section – containing presentations, videos, images, interactive high level updates and more).

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