The two-stage NEPTUNE rocket uses high-performance liquid oxygen and densified propane propellants. The first stage is powered by four stationary throttleable ablatively-cooled liquid rocket engines, each generating 10,000-lbf of thrust. Throttling of the engines generates the pitch, yaw, and roll control moments required for steering. The second stage is powered by a single stationary ablatively-cooled liquid rocket engine generating 3,000-lbf of thrust. Cold-gas thrusters provide pitch, yaw, and roll control during the second-stage engine burn and on orbit. By using throttleable stationary engines instead of gimballed engines, the heavy and complex gimbals, gimbal actuators, and the gimbal actuator drive hardware are eliminated, substantially reducing the weight and complexity of the propulsion system. All of Interorbital's ablatively-cooled rocket engines are rapidly manufactured using a filament-winding process. These state-of-the-art composite engines are manufactured with the most advanced high-temperature resistant composite materials allowing the engines to be safely operated for up to forty minutes. They are more reliable and much lighter than the typical regenerative-cooled engines that use primitive nineteenth-century steam-engine technology for cooling and they simplify the engine plumbing and the multiple engine start process while on orbit.
The propellants are fed into the NEPTUNE liquid rocket engines by a proprietary pressurant system that does not require dangerous and heavy high-pressure pressurant tanks. This system design results in a propellant tank/pressurant system that weighs the same as an equivalent propellant tank/pressurant system/pump-fed system. By eliminating the propellant pump and its heavy electric or gas-generator pump-drive system, we have substantially reduced both the overall rocket development cost and the manufacturing cost and manufacturing time.
IOS customers can choose from a variety of orbits, ranging from sun-synchronous to equatorial. Our mobile Ocean Launch Platform allows us to select the launch location for optimum performance. Circular, elliptical, and custom orbits are available
All IOS rockets are launched from an ocean-going barge with motion compensation. Equivalent to a private spaceport, barge-launch eliminates the enormous cost of liability insurance when launching from the existing land-based spaceports and allows IOS to schedule launches based only on the weather and sea conditions. Initially our orbital flights will take place from the Pacific Ocean southwest of Los Angeles.
An ongoing series of NEPTUNE Test Vehicle launches began in 2014. The first in the series of test launches was the successful launch (below) of the CPM-TV, which included a test of a stage-one prototype rocket engine. A flight test the NEPTUNE second-second stage rocket engine was carried out with the IOS Neutrino rocket launch in 2018.
Launch of NEPTUNE Prototype
At just $995,000 per dedicated launch, the NEPTUNE launch vehicle will be the smallest and lowest-cost rocket on the market. It is designed to launch multiple nanosatellites or single satellites with payloads up to 127-kg to low-Earth-orbit. For rideshare missions, we plan to charge a fraction of the price the current launch-booking agencies are charging. For example, we expect to charge less than $100,000 per 3U CubeSat (commercial rate).
A scaled-up version of the NEPTUNE rocket, the TRITON rocket, is currently in development. Its upper stage is powered by the same four engines that power the NEPTUNE first stage (with vacuum optimized expansion nozzles). The basic TRITON launch vehicle is expected to cost only $6 million per dedicated launch or $4,800 per kilogram. The TRITON Heavy rocket is assembled from a TRITON core-stage with two TRITON boosters strapped to each side. With a much higher payload capacity than the TRITON, we expect to charge only $2,600 per kilogram on dedicated launches of the TRITON Heavy, a price around half that of our current competitors.