A Closer Look at Orbital Sciences’ Stable of Launch Vehicles

Continuing our look at U.S. launch vehicles, we turn our spotlight onto Orbital Sciences Corporation.  Although the Virginia company is traditionally a supplier of small launch vehicles, it recently made the leap to medium-lift rockets.

Orbital currently operates four launch vehicles:

• Pegasus, an air-launched solid-fuel vehicle for small satellites;
• Taurus, a land-based variant of the Pegasus booster with a decommissioned Peacekeeper ballistic missile used as the first stage;
• Minotaur, a family of small solid-fuel launchers that uses a mixture of decommissioned Peacekeeper and Minuteman II ballistic missile stages and Pegasus and Taurus technology; and,
• Antares, a new medium-class, liquid-fuel booster developed under NASA’s Commercial Orbital Transportation Services (COTS) program that will launch Cygnus freighters to the International Space Station.

The company also is developing a new air-launched rocket nicknamed Pegasus II for Paul Allen’s Stratolaunch Systems company. This new medium launch vehicle is set to make its debut flight in 2016.

Let’s now take a closer look at Orbital’s programs. The launch history tables below are adapted from Wikipedia.

Pegasus

Named for the mythical winged horse, Pegasus is an air-launched booster carried aloft by a L-1011 jetliner named Stargazer after a ship that fictional Star Fleet Capt. Jean-Luc Picard once served on. The rocket has three solid-fuel stages with an optional liquid fourth stage that is capable of delivering payloads weighing 443 kg (980 lbs) into low Earth orbit.

Pegasus has flown 42 missions between 1990 and 2013, with 37 successes, two partial successes, and three failures. The last Pegasus failure was 17 years ago in 1996.

Despite its reliability, demand for Pegasus launches has declined in recent years as the price of launches has risen.  Pegasus launches were priced at $11 million in 1990. NASA paid Orbital about $36 million to launch its NuSTAR satellite in 2012, and about $40 million for the IRIS spacecraft launched earlier this year.

In June 2012, Orbital officials said they might end production of Pegasus boosters after NASA canceled its Gravity and Extreme Magnetism Small Explorer (GEMS) X-ray telescope due to cost overruns. However, Orbital has continued the program.

Taurus

The Taurus rocket is a ground-based, four-stage variant of Orbital’s Pegasus air-launched vehicle. The ATK-supplied Castor 120 first stage is based on the decommissioned Peacekeeper missile. The other stages are adapted from the Pegasus launch vehicle. The all-solid fuel vehicle can launch 1,458-kg (3,214-lb) satellites into low-Earth orbit.

Taurus has been launched nine times over the past 19 years, with six successes and three failures. The rocket suffered back-to-back failures in 2009 and 2011, sending NASA’s Orbiting Carbon Observatory and Glory environmental satellites to the bottom of the Pacific near Antarctica. The cause of both failures was the inability of the payload shrouds to separate from the launch vehicle. The failures cost NASA $700 million, not including the cost of the rockets.

Although the launch vehicle’s nine flights have all been from Vandenberg Air Force Base in California, Taurus is approved for launch for launch from Cape Canaveral Air Station (CCAS) in Florida, Wallops Flight Facility (WFF) in Virginia, and Kodiak Launch Complex, Alaska.

Minotaur

The Minotaur family of rockets is Orbital’s most reliable launch vehicle, with a perfect operational record of 23 successes and no failures.

The launch vehicles use solid-fuel stages from decommissioned Minuteman II and Peacekeeper intercontinental ballistic missiles combined with stages and systems from Orbital’s Pegasus and Taurus rockets. The Minotaur comes in four main variants:

Minotaur I: This launch vehicle uses Minuteman II motors for the first and second stages, and Pegasus XL technology for the third and fourth stages. The Minotaur II can launch payloads weighing 580 kg (1,278 lbs) into low Earth orbit.

Minotaur II: The suborbital rocket uses first and second stages from Minuteman missiles with various third stages: M57A1 (Minuteman II), SR-73-AJ (Minotaur II+), and Orion 50XL (Minuteman II Heavy). The Minotaur II Lite variant has no third stage.

The Minotaur II baseline configuration can launch 400 kg (880 lbs) payload to 4,000 kilometers (2,500 miles) downrange. The Minotaur II Heavy can launch a 1,400-kg (3,100-lb) payload to a distance of 8,000 kilometers (5,000 miles)  downrange.

Minotaur IV: This variant uses three Peacekeeper solid rocket stages, a commercial Orion 38 fourth-stage motor, and Pegasus and Taurus subsystems. It can launch 1,730 kg (3,814 lbs) to low Earth orbit.

Minotaur V: Adaptation of Minotaur IV with a fifth stage motor for small GTO, lunar, and interplanetary missions.

Minotaur V is scheduled to make its inaugural flight next month, launching NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) mission from Wallops Island, Virginia.

Antares

Antares is Orbital’s newest rocket, a medium-lift launch vehicle developed under NASA’s Commercial Orbital Transportation Services (COTS) program to send Cygnus cargo freighters to the International Space Station. It is capable of sending payloads weighing up to 6,120 kg (13,492 lbs) to low Earth orbit.

The Antares is a multinational rocket. Yuzhnoye SDO of Ukraine builds the first stage, which is similar to the company’s Zenit launch vehicle. The stage is powered by two Aerojet AJ26 engines, which are reconditioned Soviet-era NK-33 engines. ATK supplies the rocket’s Castor 30 third stage. Orbital has added systems used in its Pegasus, Taurus and Minotaur rockets.

Antares made a successful inaugural flight on April 21, 2013, carrying a mass simulator for the Cygnus freighter. In September, it will launch Cygnus on a demonstration mission to the International Space Station. If that flight is success, Orbital will launch a series of eight Commercial Resupply Services (CRS) flights to the orbiting facilities, with the first flight scheduled for December.

In addition to Cygnus missions, Orbital is promoting Antares for the type of medium-class missions that are typically launched by United Launch Alliance’s Delta II rocket, which is being retired.

Stratolaunch Systems

Orbital is also developing the multi-stage, air-launch vehicle (ALV) for Microsoft billionaire Paul Allen’s latest space project, Stratolaunch Systems.  The launch vehicle, nicknamed Pegasus II, will be taken aloft by a giant carrier aircraft with a wingspan of 385 feet.

Last week, Orbital announced that it had awarded a contract to develop the first two stages of the booster to ATK, with which it has worked since the Pegasus program.

“Our design solution for the ALV will take full advantage of ATK’s experience with large diameter solid rocket motors, like those built for the Space Shuttle and for the Titan IVB launch vehicle. The stages for ALV will also use high-strength, low-weight graphite composite cases, advanced propellants, and heritage materials from ATK’s extensive line of commercial solid rocket motors,” said Scott Lehr, vice president and general manager of ATK’s Defense and Commercial Division.

The rocket will have a restartable, cryogenic third stage and an optional fourth stage. The launch vehicle is being designed to place payloads weighing 6,123.5 kg (13,500 lbs) into low Earth orbit. The payload is nearly identical to that of the Antares rocket.

The carrier aircraft is set to make its first test flight in 2015, with the inaugural launch of the booster scheduled for the following year.