Open-Source Satellite Propulsion Hack Chat

Michael Bretti

Wednesday, December 11, 2019 12:00 pm PST Local time zone:
Hack Chat
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Michael Bretti joins us for the Hack Chat on Wednesday, December 11, 2019 at noon PST.

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Join Hack ChatWhen you look back on the development history of any technology, it's clear that the successful products eventually reach an inflection point, the boundary between when it was a niche product and when it seems everyone has one. Take 3D-printers, for instance; for years you needed to build one if you wanted one, but now you can buy them in the grocery store.

It seems like we might be getting closer to the day when satellites reach a similar inflection point. What was once the province of nations with deep pockets and military muscles to flex has become far more approachable to those of more modest means. While launching satellites is still prohibitive and probably will remain so for many years to come,  building them has come way, way down the curve lately, such that amateur radio operators have constellations of satellites at their disposal, small companies are looking seriously at what satellites can offer, and even STEM programs are starting to get students involved in satellite engineering. 

Michael Bretti is on the leading edge of the trend toward making satellites more DIY friendly. He formed Applied Ion Systems to address one of the main problems nano-satellites face: propulsion. He is currently working on a range of open-source plasma thrusters for PocketQube satellites, a format that's an eighth the size of the popular CubeSat format. His solid-fuel electric thrusters are intended to help these diminutive satellites keep station and stay in orbit longer than their propulsion-less cousins. And if all goes well, someday you'll be able to buy them off-the-shelf.

Join as for the Hack Chat as Michael discusses the design of plasma thrusters, the details of his latest testing, and the challenges of creating something that needs to work in space.

  • Hack Chat Transcript, Part 2

    Lutetium12/11/2019 at 21:19 0 comments

    Applied Ion Systems12:48 PM
    However, for plasma thruster testing, 10^-5 is more than fine, and where I start operating at. technically, 10^-4 is the bare recommended rule of thumb min for plasma thrusters, but you want at least a decade overhead in your pumping requirements

    Ethan Waldo12:48 PM
    If you can do local pickup, sometimes entire SEMs that include vacuum chamber, pumps, and controllers is cheaper than buying them seperately

    Applied Ion Systems12:48 PM
    Actually, my vacuum system is very simple compared to a lot of other enthusiasts out there

    Bob12:48 PM
    I assumed the vac test videos I saw were at a facility designed for that kind of thing. Very cool. Is your background specifically in astro thrusters?

    anfractuosity12:49 PM
    i just joined, sorry if this was covered, i heard for some very high vacuum stuff, you bake the chamber to remove gases that 'stick' to the sides iirc, do you do anything like that?

    Applied Ion Systems12:50 PM
    SEMs are great, however not really ideal for a thruster chamber. You could get a simple one much cheaper. Mine is based off of only 2 6" conflat tees. It shows that you can do this testing with an incredibly small system, as opposed to the often massive chambers you seen that you can walk into that most places have

    Applied Ion Systems12:51 PM
    @Bob nope, no formal background in any thruster stuff. However, I have come to study and specialize in areas such as plasma, pulsed power, high voltage, particle beams, and high vacuum on my own, which all comes together for this stuff

    Applied Ion Systems12:52 PM
    @anfractuosity actually, i don't need to bake for my system. Pumping speed is so high for the small chamber, and I don't need to reach UHV that it's not really necessary. Only really need to bake if trying to break past the 10^-7 and higher range

    Bob12:52 PM
    Encouraging stuff. I'm working my way towards an astronautical engineering path, kind of picking your experience for tips to get my feet wet before I reach that part of my education :)

    anfractuosity12:52 PM
    aha, gotcha, thanks!

    Applied Ion Systems12:53 PM
    But yes, baking is used to desorb the gasses, and is definitely needed for most UHV applications

    hornig joined  the room.12:53 PM

    yashelite12:53 PM
    Are vacuum chambers needed to test the thrusters? Because once you have launched the satellite into space there won't be any need of vacuum chambers.

    Applied Ion Systems12:54 PM
    @yashelite Yes, vacuum is needed for ground testing. You need to be able to generate high vacuum at the ground level. Once in space, it is already in vacuum. These thrusters just won't work at atmosphere

    Applied Ion Systems12:55 PM
    Actually, I precheck the PPTs in atmosphere by firing the igniter and listening for the spark "click" sound. Since it is not in vacuum, the main bank can't fire. It allows me to check HV and ignition circuitry, then I test ignition at high vacuum after everything is verified

    Applied Ion Systems12:55 PM
    for ILIS though everything must be tested at high vacuum.

    Jonny Wester12:55 PM
    Spark plug thrusters and EMC. How to be able to have circuitry next to it?

    hornig12:56 PM
    hi and thanks for the chat with us.

    how about power during the orbit cubesat mission. how much power does the system need and is it more like charging it for a long time and then bursting it out in a short period of thrust?

    Applied Ion Systems12:57 PM
    @Jonny Wester well, that can be a challenge. The PPT at least can crash the arduino which poses some testing issues for sure. For onboard testing, that is one thing that will be checked with qualifications with the GENESIS mission, to see if it interferes with the computer and if shielding is required. Usually for PPTs, some form of EMF shielding is needed

    RichardCollins12:58 PM
    @Applied Ion Systems I am checking on the current status of nuclear propulsion. I have been tracking develoments for nearly 50 years. Your immediate reaction reflects the poor state of developments and poor options currently available....

    Read more »

  • Hack Chat Transcript, Part 1

    Lutetium12/11/2019 at 21:18 0 comments

    Hi everyone, welcome to the Hack Chat. Today we're excited to welcome Michael Bretti of Applied Ion Systems to the Hack Chat. He's literally building the future - open-source thrusters for DIY satellites that you'll be able to buy off-the-shelf someday!

    Welcome Michael - can you tell us a little about how you got to this point?

    Applied Ion Systems12:03 PM
    Thanks Dan! Like Dan mentioned, I am currently leading development of open source propulsion for small satellites. As far as I am aware, this is really the first and only fully open source propulsion program out there. I have a small, modular high vacuum system for testing these systems. Details are archived on my website here:

    Applied Ion Systems12:03 PM
    Other media and references can be seen on twitter and Instagram as well:

    Applied Ion Systems12:03 PM


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    Applied Ion Systems12:04 PM
    Currently, I have 2 thrusters slated for space this upcoming year with AMSAT-Spain's GENESIS PocketQubes

    Applied Ion Systems12:04 PM
    Lot's of new and exciting collaborations to come with others in the community though!

    I was just going to ask when you expect to fly hardware. That's really exciting!

    Applied Ion Systems12:05 PM
    I have primarily been focusing on pulsed plasma thrusters, but have recently switched gears for more advanced systems such as ionic liquid ion source (ILIS) thrusters

    Applied Ion Systems12:05 PM
    Yeah, it should be sometime early 2020, assuming they pass integration and environmental testing

    RichardCollins12:06 PM
    What is the primary power source?

    Applied Ion Systems12:07 PM
    For the PPT that is being launched, the AIS-gPPT3-1C, it is designed to run from 3.3V to 4V power from the PQ battery bus

    Nicolas Tremblay joined  the room.12:07 PM

    Applied Ion Systems12:07 PM
    the circuit boosts this to about 1kV for the primary bank, and a pulse transformer provides a 10kv trigger pulse for ignition

    Applied Ion Systems12:07 PM
    Ill post the circuit here

    RichardCollins12:07 PM
    Solar panels feeding the batteries?

    Applied Ion Systems12:08 PM

    Applied Ion Systems12:08 PM

    Nardax joined  the room.12:08 PM

    RichardCollins12:08 PM
    Can private groups use radio-isotopes yet?

    Jake Moomaw joined  the room.12:09 PM

    Applied Ion Systems12:09 PM
    I highly doubt it, dealing with any radioactive sources would be a nightmare to deal with

    Applied Ion Systems12:10 PM
    No need though, the groups out there are using quite high efficiency cells, and lots of exciting development for deployable arrays to really boost power capabiities

    Jake Moomaw12:10 PM
    What type of fuel are you looking to use with the ILIS engine?

    Plus I think the government has a pretty tight lid on plutonium-238 supply. They've got pretty much the world supply sitting in the RTGs that will go to Mars with the Mars Rover mission.

    Applied Ion Systems12:11 PM
    I will be using standard EMI-BF4, a popular room temperature ionic molten salt. Very well studied and understood, and highly stable

    RichardCollins12:12 PM
    Pardon me for interrupting. What kinds of packages are people talking about sending?

    yashelite12:12 PM
    Weren't plasma thrusters first used in 1964? What kind of innovation or improvement has this now?

    Applied Ion Systems12:13 PM
    Electric propulsion (EP) in general dates back to the 60s. The thrusters built back then were monstrous though, huge beasts 10s to 100s of kW of power. The key difficulty in EP has been scaling down.

    Applied Ion Systems12:13 PM
    Curently, there is no EP solution on the market for PQs

    Applied Ion Systems12:14 PM
    there is a lot of competition at the cubesat level, but it is still very costly

    Applied Ion Systems12:15 PM
    My goal is to radically bring down price, and scale to...

    Read more »

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