Callisto II

Estimated Completion:June 2022


The purpose of Callisto II is to serve as an intermediate testing platform between Callisto I, our first flight, and Callisto III, our projected attempt at a suborbital flight. The possibilities of multi-engine stages, solid strap-on boosters, and a high altitude optimized upper stage are still on the table. Perhaps the greatest innovation in this iteration of the Callisto family is the implementation of a helium dynamic pressure regulation system (DPR) to ensure constant and controlled chamber pressures throughout the entirety of the flight. In addition, due to the projected top speed and high altitudes, the recovery and communication systems may need to be redesigned entirely.




Aphlex 30A


~40 kN (9000 lbs.)


Liquid methane, liquid oxygen

Specific impulse

280 sec

Burn time

~70 sec

Feed system

Helium DPR

Cooling system

Regenerative & film cooling

Ignition source

Pyrotechnic charge


48 km (30 miles)

Max speed

1300 m/s (2910 mph)

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