Cygnus sets date for next ISS mission – Castor XL ready for debut

by Chris Bergin

Orbital’s Cygnus spacecraft will begin her latest trip to the International Space Station (ISS) on October 24, atop of the Antares carrier rocket – the rocket’s fifth launch in 18 months of operation. The ORB-3/CRS-3 mission will also debut the use of the more powerful Castor XL second stage motor, supplied by ATK.


Amid fanfares and fan frenzies over new spacecraft and rockets with legs, Antares – formerly known as Taurus II – has been calmly and methodically getting on with her job of flawlessly conducting her opening salvo of missions.

Although one of her future AJ-26 engines blew up on the Stennis test stand, the rocket’s career during the ride uphill has been conducted without issue.

She began her career with the A-ONE test launch in 2013. Just a few months after this successfully debut, Antares launched again, this time with the first operational Cygnus spacecraft as its passenger.

Z77The ORB-D1 mission saw Cygnus make her first journey to the International Space Station, achieving top marks on the Commercial Orbital Transportation Services (COTS) program scorecard.

This allowed the Orbital duo to begin Commercial Resupply Services (CRS) operations, with the CRS-1/ORB-1 Cygnus berthing with the ISS, following its successful ride atop of the third Antares rocket.

ORB-1 delivered 1,466 kilograms (3,232 lb) of upmass, out of a maximum of 2,000 kg (4,400 lb), before being unberthed and released by the Space Station Remote Manipulator System (SSRMS).

The next mission, CRS-2/ORB-2 was also conducted without issue.

Z5At the completion of berthing during the ORB-2 mission, Orbital’s system had delivered approximately 3,800 kilos (about 8,400 lbs) of cargo to support the Expedition crews conducting research and living aboard the ISS.

As with all Cygnus missions, the spacecraft – full of Station trash – completed her service with a fiery re-entry.

Now Orbital is preparing for Cygnus’ next mission, with CRS-3/ORB-3 tasked with her largest load of cargo to date, carrying approximately 5,050 pounds (2,290 kilograms) of upmass to the orbital outpost.

The extra mass is, in part, allowed by the increased performance of the second stage that will debut with what is now set to be an October 24 mission, targeting a 7:52 p.m. (EDT) T-0 from the Mid-Atlantic Regional Spaceport (MARS) at NASA’s Wallops Flight Facility in Virginia.

The increase of performance has been an incremental goal for Antares, with her ORB-2 mission utilizing the Castor 30B upper stage, replacing the less powerful Castor 30A used for the previous two Antares missions.

CASTOR 30XLNow the 30B will be replaced for the upcoming launch with an even more capable Castor 30XL.

During development of Antares and Cygnus, the initial plan for CRS-3 onwards was to switch to a liquid upper stage called the HESS, utilizing the Russian RD-0124.

However, the company later decided to go with a stretched version of the original solid-based Upper Stage, the Castor 30XL.

This rocket stage will allow 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.

2014-10-08 15_42_22-IMG_0358.JPG - PaintThe 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.

ATK Team for Castor 30XL, from ATKThe entire program took less than two years for ATK to design and build the static test article.

ATK note the CASTOR 30XL team maintained “an aggressive schedule” that included development and design release, qualification of the case including superproof testing, casting of an inert motor and completing production of the static fire unit.

Work was spread over several facilities, including the Aerospace Structures Division in Clearfield, who manufactured the case, while nozzle manufacturing was performed at the Promontory facility. The motor was cast and finished at the Bacchus facility.

Screenshot from L2 video of CASTOR 30XL static fire

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

As 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.

According to L2 information, ATK has wasted little time since test firing the motor, with at least three CASTOR 30XLs already constructed and ready to be used by Orbital.

The first of these motors has since arrived at Wallops for mating with the CRS-3/ORB-3 Antares.

Z3AUnder a $1.9 billion CRS contract with NASA, Orbital will use Antares and Cygnus to deliver up to 44,000 pounds (20,000 kilograms) of cargo to the ISS over eight missions, including the mission currently underway, through late 2016.

Antares and Cygnus are likely to be one of the favorites to win future missions past the current CRS agreement, with NASA recently releasing a request for proposals (RFP) for the next round of contracts for private-sector companies to deliver experiments and supplies to the orbiting laboratory.

Under the Commercial Resupply Services 2 (CRS2) RFP, NASA intends to award contracts with one or more companies for six or more flights per contract.

As with current resupply flights, these missions would launch from US spaceports, and the contracted services would include logistical and research cargo delivery and return to and from the space station through fiscal year 2020, with the option to purchase additional launches through 2024.

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

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