Xenon ion and water cubesat engines for interplanetary cubesats with costs ten thousand times less

Benjamin Longmier, Michigan University, is developing the CubeSat Ambipolar Thruster (CAT), a new rocket propulsion system powered by the Sun and propelled by water, which will push small spacecraft like CubeSats around and far beyond the Earth.

They received a $200,000 private donation and have raised over $96,000 on Kickstarter.

What can be enabled with successful cubesat ion drive

* interplanetary missions to Mars and Europa for about $1 million
* Ten interplanetary cubsats for a solar system wide internet
* Cheaper satellite wi-fi around the earth
* Future combination with Spacex reusable rockets, Planetary resources cheap space telescopes, Googlex low cost space robotics for radical lowcost space exploration

A private donor will pay for the Xenon ion technology and a launch in 2014 aboard a NASA rocket. They hope their propelled CubeSats will one day fly to Saturn’s moon Enceladus and Jupiter’s moon Europa, both of which hold water – and perhaps life. A fleet of CubeSats with propulsion in orbit around a planet or moon can do a lot of things that big expensive satellites cannot, such as monitoring several locations in the atmosphere at once.

Propelled CubeSats could even be useful back here on Earth. Creating a universal “satellite Wi-Fi”, like existing satellite phone coverage, would require thousands of big satellites, which is prohibitively expensive. But you could dump a thousand CubeSats in one place then spread them out to the right points, for a fraction of the price.

CAT produces thrust from the expansion of a super-heated 350,000 °C plasma stream. Plasma is an ionized gas that can be accelerated to produce thrust (F=ma). The force generated by this thruster will be very low (micro-newtons) but very efficient. The engine will be turned on for long durations, accelerating the spacecraft to much higher velocities than a typical chemical rocket. Our first test will use xenon, a safe, non-toxic gas typically used in large-scale plasma thrusters. With support from you, we can begin work on our long-term goal of designing a water-based propellant system to make the first truly sustainable plasma propulsion device for CubeSats.

The CubeSat Ambipolar Thruster is a new design for a permanent magnet helicon generated plasma thruster. Its small plasma volume (~10 cm3) and low power requirements (less than 100 W) make it ideal for propelling nanosatellites (less than 10 kg). The source is powered by a novel DC to RF oscillator with air-core inductors suitable to be flown on small spacecraft. Specifically, the CAT is being made to fit the CubeSat form factor, a design of nanosatellites made up of 10x10x10-cm units (1U). Permanent magnets generate a converging-diverging magnetic nozzle with a magnetic field that decreased to the strength of earth’s magnetic field within 50 cm allowing the entire exhaust plume to develop in the vacuum chamber. Low gas flow rates (~4 sccm) and high pumping speeds (~10,000 l/s) are used to more closely approximate the conditions of space.

One of the patents is here

The base funding goal of $50,000 [already reached] is enough to add specialized equipment to the satellite to observe the plasma plume ejected by the CAT engine. Integrating a high-resolution camera and associated subsystems is critical to validate our theories on plasma flow along a magnetic nozzle and complete our test matrix when CAT is on-orbit. Because this is an entirely new type of engine, we need a camera in order to directly observe how the super heated plasma follows the magnetic nozzle and then detaches to create thrust. Without a camera we can’t know precisely when the plasma is being created. Basically, we need to see the engine actually creating plasma to verify our assumptions.

CAT Engine Specs
Up to 2 mN thrust for 10W (20mN for 100W pulsed)
Up to 20,000 m/s plasma exhaust velocity
Up to 10 Watts continuous (or higher power when pulsed)
over 90% efficient solid-state DC to RF converter
Expected engine lifetime, over 20,000 hrs of operation
Expected propellant: Iodine or Water
Expected propellant mass: less than 2.5kg (for a 3U CubeSat)
Permanent magnet converging-diverging nozzle

Spacecraft Specs:
3U CubeSat (30 cm x 10 cm x 10 cm)
2.5 kg dry mass (5 kg total mass)
20 W of power produced from deployable solar panels
Passive magnetic attitude stabilization from nozzle magnets interacting with Earth’s magnetic field
Anticipated lifetime in LEO: 5 yrs (radiation limit for onboard chips)
Anticipated lifetime beyond Earth: 10 yrs (battery lifetime)
Anticipated lifetime before micrometeorite impacts degrade spacecraft beyond recognition: 100,000,000 years

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