Interorbital Systems (IOS) is an American company based in Mojave, California that specializes in the manufacturing of rockets and satellites. It was established in 1996 by Roderick and Randa Milliron. As of October 2023, the company is in development stage for three low-cost orbital launch vehicles: NEPTUNE, TRITON, and TRITON HEAVY.
Interorbital Systems has participated in the development of a launch vehicle for the Google Lunar X Prize Team Synergy Moon and has provided suborbital commercial launch services, For Orbital launch they have used ISRO and Jaxa. Additionally, the company participated as a competitor in the Ansari X Prize and America's Space Prize competitions.
NEPTUNE Launch Vehicle: General
The NEPTUNE rocket, a two-stage vehicle developed by Interorbital Systems, uses high-performance liquid oxygen and densified propane propellants. The first stage is equipped with four stationary throttle-able ablatively-cooled liquid rocket engines, each capable of generating 4,500 pounds of thrust. Throttling of these engines allows for precise control of pitch, yaw, and roll during flight. Unlike gimballed engines, the stationary engines eliminate the need for heavy and complex gimbal mechanisms and actuators, resulting in a lighter and less complex propulsion system.
The second stage of the NEPTUNE rocket is powered by a single stationary ablatively-cooled liquid rocket engine that generates 3,000 pounds of thrust. During the second-stage engine burn and while in orbit, pitch, yaw, and roll control are provided by cold-gas thrusters.
Interorbital Systems manufactures their ablatively-cooled rocket engines using a filament-winding process, enabling rapid production. These engines are constructed with advanced high-temperature resistant composite materials, allowing for safe operation for extended periods of up to forty minutes. They offer reliability and reduced weight compared to regenerative-cooled engines that employ outdated steam-engine cooling technology. Additionally, the ablatively-cooled engines simplify engine plumbing and the multiple engine start process while in orbit.
NEPTUNE Launch Vehicle: Pressure-fed Propulsion System
The NEPTUNE liquid rocket engines of Interorbital Systems are fed propellants through a proprietary pressurant system. This innovative design eliminates the need for hazardous and heavy high-pressure pressurant tanks. As a result, the weight of the propellant tank/pressurant system is equivalent to a traditional propellant tank/pressurant system/pump-fed system.
By removing the propellant pump and the associated heavy electric or gas-generator pump-drive system, Interorbital Systems has significantly reduced both the overall rocket development cost and the manufacturing time. This streamlined approach to the propulsion system has led to cost savings and improved efficiency in the manufacturing process.
NEPTUNE Launch Vehicle: Exclusive Ocean-based Launch
All Interorbital Systems (IOS) rockets are launched from an ocean-going barge equipped with motion compensation technology. This unique approach, similar to a private spaceport, offers several advantages. Launching from a barge eliminates the need for costly liability insurance associated with land-based spaceports. It also provides flexibility in scheduling launches, as they are dependent only on weather and sea conditions. Initially, IOS plans to conduct orbital flights from the Pacific Ocean southwest of Los Angeles.
In 2006, IOS held an active launch license from the Office of Commercial Space Transportation for Tachyon, a sounding rocket designed for suborbital flights reaching an apogee of 120 miles.
Preliminary design concepts
Solaris was a suborbital rocket design developed by IOS in the early 2000s. The intention behind the Solaris project was to compete for the Ansari X Prize. However, the rocket was not completed in time, and it was surpassed by Scaled Composites' SpaceShipOne, which successfully claimed the prize.
Milestones
The main engine of the Common Propulsion Module (CPM) underwent its first successful static engine firing on October 28, 2012. This composite-chambered engine generated 7,500 lbs of thrust and used nitric acid and turpentine propellants.
The Common Propulsion Module Test Vehicle (CPM TV) completed its inaugural test flight on March 29, 2014, achieving a maximum altitude of 10,000 feet. The payloads on board included two CubeSats, a payload from Synergy Moon, and a music CD titled "ENCLOSURE" by John Frusciante, former guitarist of the Red Hot Chili Peppers. The CPM TV will be reused for future test flights, and all payloads were successfully recovered without damage.