CAT: A Thruster for Interplanetary CubeSats
CAT: A Thruster for Interplanetary CubeSats
The CAT plasma thruster will propel a 5kg satellite into deep space, far beyond Earth orbit, at 1/1000th the cost of previous missions.
The CAT plasma thruster will propel a 5kg satellite into deep space, far beyond Earth orbit, at 1/1000th the cost of previous missions. Read more
Send your name and message into interplanetary space engraved on gold panels!
Update 1: Lab CAT #1 needs a name, post your suggestions here
The Future of Space Exploration
We are currently developing the CubeSat Ambipolar Thruster (CAT), a new plasma propulsion system which will push small spacecraft like CubeSats around in orbit or far beyond the Earth.
This new thruster technology will enable us to send low-cost satellites from the Earth to distant destinations in the Solar System. You can be a part of space exploration history! By contributing to the CAT, you can help future spacecraft make amazing discoveries about extraterrestrial bodies and further our understanding of the near-Earth environment, the Solar System, and beyond. Who knows, maybe we’ll even be able to find life on those beckoning watery moons of Jupiter or Saturn!
Any amount of support is appreciated. Be a part of the mission and receive: patches, T-shirts, and even laser engraving of your name and message on gold plated spacecraft panels. Since the spacecraft will ultimately be ejected deep into space, think of it as an “interplanetary message in a bottle,” lasting for hundreds of millions of years in orbit around the Sun.
"In-space propulsion technologies employing water, like the CubeSat Ambipolar Thruster, will be of increasing importance as access to water from volatile-rich asteroids becomes reality." -- Hannah Goldberg, Senior Systems Engineer, Planetary Resources, University of Michigan Alumnus
The World is Not Enough
A flight-demonstrated CAT engine could be added to any future CubeSat mission, enabling a wide variety of exciting experiments that are not possible any other way. Future missions (and perhaps Kickstarter campaigns) that we envision with this technology:
- Search for Life: Simple diagnostic equipment could be flown on a CubeSat through the water plumes that are ejected into space from Enceladus, a moon of Saturn, or put into orbit around Europa, a moon of Jupiter that is thought to contain more water than all of Earth’s oceans and may contain life.
- Inexpensive Network Nodes: Ejected from a single rocket launch vehicle, a fleet of CubeSats with CAT engines could be quickly deployed into globe covering orbits around the Earth for cheap global internet access, more current satellite photos, better global weather observations, or the first interplanetary internet.
- Formation Flight: An array of CubeSats flying in formation, can easily gather spatially resolved data in Earth's magnetosphere to learn more about solar flares and the aurora, making space weather as predictable as Earth weather. Fleets of spacecraft can also make coordinated optical observations for specific ground or celestial items of interest.
- Asteroid Inspection: A CAT-propelled CubeSat could be sent to the asteroid belt with scanning equipment and a radio beacon payload to identify and mark an asteroid of interest for later retrieval, mining, or human exploration.
This is just the beginning of how these CAT-propelled CubeSats could be used to go to destinations that have never been visited, but we need your help to get things off the ground – literally.
A Big Idea for Small Satellites
The future of space exploration is not limited to the conventional approach of the past with large, expensive spacecraft! Most satellites and interplanetary spacecraft launched by NASA and private industry today are the size of a car and can cost up to one billion dollars or more. CAT is a plasma propulsion system designed to fit in 1U of a 3U (or larger) CubeSat. CubeSats are a type of nanosatellite made up of 10x10x10-cm units (1U) and cost 1,000 to 10,000 times less to develop and launch than conventional satellites.
Currently, these CubeSats piggyback a ride on larger rockets, and once in space, they drift around Earth, trapped in their original orbit until they eventually de-orbit and burn up in the Earth’s atmosphere. However, CAT will extend the potential destinations of these CubeSats to way beyond Earth orbit.
We are working to complete and vacuum test a flight-qualified satellite with an integrated CAT. Through our existing partnerships with three NASA centers, the spacecraft will be launched into low Earth orbit and start its climb into deep space. The CAT engine is being developed at the University of Michigan’s Plasmadynamics and Electric Propulsion Laboratory (PEPL). Our team also includes the state-of-the-art Michigan Exploration Laboratory (MXL), which has over six years of experience building and flying CubeSats.
Initial CAT engine testing will be performed in our lab on the ground and then in low Earth orbit (LEO) to validate the CAT engine's performance and physics models developed by our team. Once these tests are completed, we will perform a series of spiral-out flight maneuvers to climb to higher and higher altitudes in order to escape the Earth.
How does the CAT engine work?
Just like a normal rocket that produces thrust from the burning and expansion of hot gases, 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 (milli-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.
First, the propellant will be injected from its storage container into the plasma discharge chamber, a quartz bottle that distributes the gas and contains the plasma. The gas is turned into a plasma by a radio frequency antenna that surrounds the chamber and launches a plasma wave known as a “helicon.” The plasma is then launched out of the quartz bottle and guided by magnetic fields from extremely powerful permanent magnets. As the plasma escapes the CAT engine, this causes an equal and opposite thrust, pushing the satellite in the opposite direction. Unlike conventional rockets, almost any substance can be used as propellant for CAT – even liquid metals or water vapor!
Plasma thrusters have been used on satellites for decades but they have been large, bulky devices that weigh up to 10 kg (20 lbs) or more, suitable only for large satellites. Some examples include ion engines (Deep Space 1 and DAWN), Hall thrusters (SMART1, GEO-COMM sats), resistojets, and arcjets. The CAT design scales down previously demonstrated technology (see Hall Thrusters, VASIMR) to make it practical for CubeSats, with a thruster and power supply weight of less than 0.5 kg (1 lb). Most of the thruster components have been built and have been tested individually. With your help through Kickstarter, we will be assembling everything into one compact thruster unit for testing the integrated components in the lab, then in Earth orbit, and then interplanetary space far away from the gravitational pull of the Earth.
Flight qualified solar panels (panels that have proven their functionality on previous successful CubeSat missions) mounted on the outside of the CubeSat will power the CAT engine and other critical onboard systems like the radios and computers, and recharge the onboard batteries. The RF power for ionizing the propellant within CAT is supplied by a novel DC to RF Φ2 power amplifier with air-core inductors  that has performed with high efficiency in ground level tests. Permanent magnets generate a converging-diverging magnetic nozzle that keeps the plasma away from the plasma chamber walls and accelerates the plasma stream out the back.
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)
- >90% efficient solid-state DC to RF converter
- Expected engine lifetime, >20,000 hrs of operation
- Expected propellant: Iodine or Water
- Expected propellant mass: <2.5kg (for a 3U CubeSat)
- Permanent magnet converging-diverging nozzle
- 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
Laboratories on the Ground and in the Sky
The CAT engine is being developed at the University of Michigan’s Plasmadynamics and Electric Propulsion Laboratory (PEPL). Here, we will test the thruster in a vacuum and thermal environment as close to space as we can achieve on the ground. The thruster will be fine-tuned and a fully operational satellite loaded with a CAT engine will be tested in the vacuum chamber in preparations for later use and testing in space.
Our team also includes the Michigan Exploration Laboratory (MXL), which has over six years of experience building and flying CubeSats, which have only been in existence for 14 years. In fact, our team launched the first CubeSat in the world and the first CubeSats for NASA JPL and the NSF.We have designed, tested, and flown most types of CubeSat components including radios, power systems, computers, structures, solar panels, and more.This flight proven spacecraft technology provides a stable, proven platform for testing the CAT engine in space. The CubeSat for the CAT engine will be based off of existing and proven LEO and deep space flight technologies from the RAX-2 and INSPIRE CubeSats.
The dc-rf power stage is currently being developed in the power electronics group of the Michigan Power & Energy Laboratory (MPEL).
CAT, this is Echo Base. Do you copy?
While the satellite is in orbit we will communicate with it via the Peach Mountain Observatory and Dish, a University of Michigan ground station.
These missions will be operated from the Michigan Space and Atmospheric Research Control Center (M-SPARCC). M-SPARCC is student run, engaging the next generation of explorers in our labs. Also, with a dedicated facility, we will easily connect with you via our blog, website, Twitter, and apps to keep you updated as the mission progresses.
Total Funding Goals
CubeSat Ambipolar Thruster (CAT) engine development:
Funding from Kickstarter will be used to create a complete flight-qualified CubeSat with integrated CAT engine and tested as a final unit in the University of Michigan LVTF vacuum chamber.
- Development and testing of the CAT engine and propellant feed system, power processing unit, and control unit.
- Complete performance testing of the CAT engine and the final CubeSat in our 250 cubic meter vacuum chamber (the largest university operated vacuum chamber in the world)
- We are working closely with our NASA-Ames, NASA-JPL and NASA-GRC partners and are pursuing NASA’s CubeSat launch program in Fall 2013 (provides a free launch into space). We will complete a technology demonstration in low Earth Orbit (LEO) first, then start firing for Earth escape once testing is complete.
Stretch Goal Missions:
- $500,000: We will purchase a commercial CubeSat launch slot in order to launch even faster and test the CAT engine on a CubeSat in low Earth orbit (LEO). Earth escape attempt after initial testing.
- $900,000: Two CubeSat “space race” to escape the Earth first.
- $7,000,000:Ten CubeSats with networking capability placed into optimal orbits by CAT engine, establishing the first interplanetary internet and paving the way for total solar system domination. Prepare to be assimilated.
Once the CAT propulsion system has been tested in LEO, the next phase of the mission is to propel the CubeSat away from Earth, into interplanetary space. If enough funding is secured, two spacecraft will be launched and raced against each other. Each spacecraft will have slightly different and competing designs that will be tested and characterized on the ground and then put to the true test once in space! If the Kickstarter campaign is highly successful, a large number of network nodes will be launched into interplanetary space onboard our CubeSats and pushed out into position with the CAT engine, effectively forming a daisy chain of deep space communication satellites in order to form the first interplanetary internet. Better think of your .sol domain names now!
"To the makers of music – all worlds, all times"
Your name or message (Tweet, love note, message to ET) will be laser etched into a gold layer on the exterior spacecraft panels, exposed directly to the vacuum and radiation of space as homage to the Voyager Gold Record. Your hopes, dreams, and love messages will be cast away from the Earth as a permanent record in space, the ultimate interplanetary “message in a bottle.” We estimate that your name or message will last for hundreds of millions of years, drifting among the planets. We have partnered with a firm that uses the same micro laser etching process that is used to inscribe the backs of iPads and MacBooks.
"This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings. We are attempting to survive our time so we may live into yours" — U.S. President Jimmy Carter, quoted on Voyager record
We are working with a large list of media partners around the globe and anticipate a large exposure. Please contact us if you or your firm are interested in:
- Greater than $10,000 worth of room for a laser etched message or a custom etched image.
- Naming/branding rights to our spacecraft.
- Naming/branding rights to our mission control room.
- Your own commissioned interplanetary spacecraft.
Who Are We?
We are faculty, researchers, and students at the University of Michigan's Aerospace Engineering department working in collaboration with several NASA research centers and private industry. We believe that this CAT technology will eventually enable CubeSats to make amazing discoveries about extraterrestrial bodies, sparking an exciting new chapter in the exploration of our solar system.
The team that will make all this possible includes:
- Prof. Benjamin Longmier: Assistant Professor, Project and science lead
- Prof. James Cutler: Assistant Professor, Spacecraft lead
- Prof. Juan Manuel Rivas Davila: Assistant Professor, DC-RF power lead
- Dr. J. P. Sheehan: Research Fellow, Science co-lead
- Ingrid Reese, Ph.D. student
- Tim Collard, Ph.D. student
- Ethan Dale, Ph.D. student
- Frans Ebersohn, Ph.D. student
- Jungwon Choi, Ph.D. student
- A standing army of talented and dedicated undergraduate students
External Collaborators and Partners
- NASA Ames Research Center
- NASA Jet Propulsion Laboratory
- NASA Glenn Research Center
- Planetary Resources
- Deep Space Industries
- Analytical Graphics
- Aether Industries
 S. C. Spangelo, B. W. Longmier, BravoSat: Optimizing the Delta-V Capability of a CubeSat Mission with Novel Plasma Propulsion Technology, Interplanetary Small satellite Conference, Pasadena, CA, June 20-21, 2013
 B. W. Longmier, J.P. Sheehan, A Large Delta-V Plasma Thruster for Nanosatellites, Interplanetary Small satellite Conference, Pasadena, CA, June 20-21, 2013
 B. W. Longmier, E. A. Bering, M. D. Carter, L. D. Cassady, W. J. Chancery, F. R. C. Diaz, et al., "Ambipolar ion acceleration in an expanding magnetic nozzle," Plasma Sources Science and Technology, vol. 20, p. 015007, Feb 2011.
 B. W. Longmier, L. D. Cassady, M. G. Ballenger, M. D. Carter, F. R. Chang-Diaz, T. W. Glover, et al., "VX-200 Magnetoplasma Thruster Performance Results Exceeding Fifty-Percent Thruster Efficiency," Journal of Propulsion and Power, vol. 27, pp. 915-920, Jul-Aug 2011.
 B. W. Longmier and J. P. Sheehan, "Initial Experiments of a New Permanent Magnet Helicon Thruster," International Conference on Plasma Science, San Francisco, CA, June 2013.
 Rivas, J. M.; Han, Y.; Leitermann, O.; Sagneri, A. D.; Perreault, D. J. “A High-Frequency Resonant Inverter Topology With Low-Voltage Stress” IEEE Transactions on Power Electronics, Volume 23, Issue 4, July 2008, Pages: 1759-1771.
Risks and challenges
In the world of cutting edge research, sometimes there are delays. Technical difficulties, launch delays, and communication challenges are just some of the known risks that may lie ahead. Fortunately, our team is prepared to tackle these difficult issues! Our backers must understand, however, that the CAT Mission may become delayed, have technical difficulties in orbit, be assimilated, or blown up by a Death Star. In case of any of these events we will keep our backers updated regularly regarding our continued progress towards overcoming such difficult hurdles. We appreciate your patience in advance. We're just as excited as you are and know how hard it is to wait!Learn about accountability on Kickstarter
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