Introducing The ConstantQ™ Thruster

The New Generation of Plasma Thrusters

Inexpensive. Powerful. Safe.

Water is an excellent source of power for the future

ConstantQ™ Water propulsion offers: 

  • High performance
  • Non-toxic (low safety risk)
  • Ease of transport / handle on ground
  • Ease of fueling / refueling
  • Low handling and
  • Manufacturing costs
  • Easily added to ride share 
  • Excellent fuel economy
  • Powerful thrust

Miles Space now offers low cost primary or secondary thrusters  to satisfy the pending FCC regulations on maneuverability.

Built for CubeSats

Our innovative hybrid electrostatic thruster is available in a 0.5U or a 1U form to provide the delta-V needed to meet your mission needs.

The World's Most Efficient Thruster

The ConstantQ's compact and power-efficient design provides fuel economy, low mass and volume and market leading low power essentials.

Rugged and Reliable

The M1.4 model was built to the rigorous safety standards of the NASA SLS EM-1 Mission (now Artemis)

The M1.4 ConstantQ Thruster has undergone successful testing campaigns at both Georgia Tech and NASA Glenn Research Center

The ConstantQ™ family of thrusters use a pulsed electrostatic cycle to enable a variety of Earth-orbiting and deep space missions using water propellant. Test results show water’s vapor pressure and its plasma speciation are especially useful to this operating cycle.

A ConstantQ™ thruster has:

  • a plasma formation region containing spark electrodes
  • two exhaust ports, each ringed by acceleration electrodes
  • a single power supply providing spark and acceleration power


Vapor enters the plasma formation region, expanding and changing pressure on its path towards the exhaust ports. Paschen’s law ensures a spark occurs within the vapor at the point where the supply voltage meets the pressure on the Paschen curve.

Each exhaust port is ringed with high voltage electrodes. One exhaust port’s voltages act to focus and extract positive ions from the plasma. The other affects electrons.

Electrons, being far less massive than ions, leave the plasma before ions, generating thrust from their interaction with the acceleration electrodes. Once outside the thruster, the electrons form a virtual cathode that pulls upon the ions remaining within the thruster.

As the ions leave, thrust is obtained from acceleration electrodes. However, the ions also derive kinetic energy from the virtual cathode, slowing the exhaust electrons and even causing electrons to flow back toward the thruster. This gives an increased acceleration voltage upon the ions, expanding the classic Child-Langmuir limits for space-charge flow rate and thrust density.

As the ions exit the thruster, they meet the returning electrons, neutralizing the plasma. With water vapor, the interface between exiting ions and returning electrons appears as a white-hot sphere 5-8mm outside the ion’s exhaust port. This phenomenon is believed to be due to the presence of multiple ion species with different velocity profiles. In the image below, the two exhaust ports are shown, with the electron port on the left and the ion port on the right. Note the distinctly different exhaust appearances of the two.

A resonance occurs between the incoming gas pressure, spark push back, and plasma drain rate through the exhaust ports (as driven by the supply’s high voltage which can be varied to align with mission Isp). The ConstantQ™ uses a very specific geometry to drive this resonance, minimize wear, reduce power supply complexity, and reduce flight computing demands.

ConstantQ™ thrusters have produced thrust using water vapor, Xenon, Argon, Krypton, Iodine, and air.

The Future has already begun

Our Philosophy And History Determine Our Future Trajectory.


From Earth to LEO and beyond, our team of stars really shine.


Our technologies make Miles Space a first-mover in the deep space SmallSat industry.


Our technology is inspired and enabled by the citizen science and maker movement.


We aren't just innovating the technology, we're also invigorating the entire business of space exploration.

First flight scheduled Q1, 2021

Yes. For deorbit, the Delta-v for 3U or 6U spacecraft is sufficient to reduce orbit and accelerate decay through drag. Delta-v is sufficient for several orbit maneuvers.

The M1.4 device uses ConstantQ™ propulsion technology, converting electricity and water

vapor into thrust. Thrust is derived from electrostatic acceleration of separated ions and

electrons using a combination of classic collisionless flow and electrohydrodynamic (EHD)

regimes, all working in a cycle determined by propellant temperature, input power, and device

geometry. The operating cycle is self stabilizing and does not require real time active control

once initiated, though altering temperature and/or power will alter delivered thrust. The process

is self neutralizing and does not require a neutralizer device. Pressures throughout the system

generate water vapor through sublimation, avoiding the need for water to boil and tolerating

frozen ice as the propellant.

Temperature management is achieved with a high-density flat heater on the tank, a valve

self-heating feature, and routing of electronics waste heat to minimize freezing of water vapor.

Thrust is attained with a wide range of temperatures, including a tank full of frozen water ice.

Water vapor is generated through sublimation that occurs when the system is run below the

vapor pressure – a process that does not require water to boil into steam. Water vapor, not liquid

water, reaches the thrust heads and is converted into plasma and thrust. Should liquid water get

near the thrust heads, it would rapidly sublimate into vapor due to vacuum exposure

11.5W is drawn by the heater when energized with 12V. The heater’s resistance is 12.5 Ohms, so it draws 0.96 Amps at 12 Volts. Thermal modeling of a 3U spacecraft shows this is 10%+ more power than required to compensate for a typical 10C change when a LEO satellite is eclipsed.

5V digital logic and valves are expected to draw 65mA, 0.33W, peak. At idle, 20mA, 0.1W, is expected.
12V heater power draws 11.5W.
At room temperature, 12V thruster operation draws 150mA, 1.8W, per thrust head. All four thrust heads running concurrently draw 600mA, 7.2W total.
The heater and thrust heads should not be run simultaneously.

No. The M1.4 naturally operates in pulses with a slight breathing mode around an unstable operating point. Internal capacitors essential to starting the process also prevent instant shutdown as their stored energy continues to feed pulses. As such, impulse bit timing, duration, and thrust are likely not regulated tightly enough for precision pointing of small craft.

Our established partnerships allow us to deliver commercially available LEO and GEO communication systems at a fraction of the cost of conventional dishes. Readily deployable worldwide at a fraction of the cost of fixed

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