[Ground-station] Satellite program

Mon May 28 08:14:12 PDT 2018

I have been following this project, as best as was possible, since it's inception. It appears to be a very good design but not having a pathway to a rad hard product makes it  only usable to a maximum of a MEO altitude. If we are talking about HEO/LEO and beyond, a level of radiation hardness is a must have.

  *   Howie AB2S

________________________________
From: Ground-Station <ground-station-bounces at lists.openresearch.institute> on behalf of Jonathan Brandenburg via Ground-Station <ground-station at lists.openresearch.institute>
Sent: Monday, May 28, 2018 10:14 AM
To: ground-station at lists.openresearch.institute; Zach Metzinger
Subject: Re: [Ground-station] Satellite program

[I'm speaking a bit for Zach Metzinger, so I've copied him on this email. I'm not sure if he's on this mailing list or not and want him to be in a position to expand or correct my statements, or even disavow anything I'm saying, if he desires.]

A small team, primarily Zach Metzinger with the assistance of others (Bill Reed, Jordan Trewitt, me), is designing an IHU based on the TI Hercules safety-critical processor. While the Hercules is not necessarily radiation-hardened, the processor is designed for operation in very noisy environments. It's also designed to detect faults, by executing instructions on two cores in lockstep, detect when the result differs, and signal a failure. (I imagine there are other features, but this is a high point.)

So, we've been designing an IHU with two Hercules processors and two digital transceivers configured in a fail-over configuration along with redundant power circuits. There's still work to be done, but Zach has begun laying out this board in a 1U footprint.

[This is the part where I'm speaking for Zach...] I believe Zach is committed to ensuring this design is open and available. As a result, I expect we'll be quickly publishing this work (by ITAR/EAR definitions) as we achieve milestones. This IHU work was begun before the AMSAT Golf program was kicked off and is now being integrated into Golf. I don't know of any reason this work couldn't be leveraged and used in other satellites.

Thus, I submit this IHU-in-progress for our consideration...

Jonathan Brandenburg

On 5/16/2018 1:54 PM, Bruce Perens via Ground-Station wrote:

Legal stuff first: Image credit: XKCD #1992: "SafetySat" at http://xkcd.com/1992/<https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fxkcd.com%2F1992%2F&data=02%7C01%7C%7C862c446dbca646a1e15008d5c4a57ac7%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636631137360432495&sdata=For1mSb5cEctXX3Up7zid4n5gKrnUF%2BDKEC6O9G%2FdB0%3D&reserved=0> Creative Commons Attr-NC 2.5 license.

Yes, we should have a satellite program and do what AMSAT is not. Everyone I have heard from so far is asking for a "DX Satellite", "like AO-13" and not LEO.

Mission should include digital communications using Michelle's design. I also have some blue-sky ideas that we can discuss at Hamvention, some of them might be good grant candidates. Think grant. Money is out there, we will start soliciting as soon as we have a mission plan.

Build the satellite (and maybe P-pods) first, approach launch providers with flight hardware in hand and ready to go. Satellites are cheap, launches are not. Be prepared to take advantage of opportunities on very short schedules.

I think we should fabricate extras of parts we design, and sell them as TAPR does to supplement their budget, but right off of Amazon Prime. Make them really easy and fast to buy, and someone else does the shipping. Aim at flight-quality but mostly going to classroom use rather than flight, to start. Nicer for the class than the PLA 3-D printer stuff that is so obviously non-flight that they are using now.

Aim for 100% to 200% markup over cost, Amazon gets around 18% of the order and a warehouse fee and fulfills from their warehouse. Most of the commercial cubesat companies, like Pumpkin, are running 500% to 1000% markup in order to amortize R&D and operational costs and still make a profit, but most of them have flight heritage that we would not start out with. We use slave labor :-) and can mostly base our final cost on fabrication and sales costs.

I have been looking at cubesat structures (because I feel competent enough to make one, at least with your help) and I really like Pumpkin's design. Almost all laser-cut 5000-class sheet aluminum, bent on a brake, anodized corners on the sheet, only the 8 corner pieces are machined, and that only simple shaping and drilling of bar stock into a simple rectilinear shape with specified-radius corners and edges and a place to put the springs and cutoff switch pins. Most other designers seemed to be more interested in showing their skill in CNC machining than making a practical structure. If you look at Pumpkin's stuff, it is clear that they put a lot of thought into mechanical engineering. And they actually engineered for cost and mass-production, while few others bothered. We will not ever directly copy anything (I am an intellectual property specialist, and will keep us legal), but we can and should learn from their work.

Besides the structure, other non-mission-specific stuff we should be building would include an IHU (computer) and the other general bus components: lithium battery pack with heaters and per-cell management, magnetorquer, solar panels (what cells, from where?), maybe some heat distribution components like adiabatic heat pipes?

Can we hear from volunteers for any of this?

LIME mini might be a good flight candidate, besides Ettus and Rincon. Their CEO and Open Source guy are very friendly and their PCB design may already be licensed appropriately. No idea how the chip would take radiation.

We should look into the Open Source finite element analysis and CFD programs. We should simulate as much as possible before going to thermal vacuum, vibration and shock, etc. And publish all input data so that it can be reused along with our part designs.

I saw a really nice indium electronic thruster at Cal Poly. All proprietary, of course. Goes up with the fuel solid, gets heated in flight. No moving parts, works by wicking through a sintered tip. Probably very patented. But a source of ideas.

    Thanks

    Bruce

On Wed, May 16, 2018, 09:23 Michelle Thompson <mountain.michelle at gmail.com<mailto:mountain.michelle at gmail.com>> wrote:
Heh! The SDR really ties it all together in your sketch there.

Yes, there's interest in building an open source satellite. The time is right and we have the best chance of making it happen that I've seen in a long time. There's a variety of forces at work in the industry, in academia, and in open source culture and achievement that help make a modern, innovative, amateur, open source payload possible.

I don't know enough about MEO but I'm game for supporting any payload that enables an enduring amateur community through reliable communications in space. I'm very happy we get the chance to dig into this and I want to enable and support it as much as possible.

The Careful COTS of an Ettus USRP effort is one way to get a capable SDR for space. This is a joint project between Phase 4 Space and GOLF to get the E310 in play soon/now for GOLF and the E320 later for Phase 4 Space. Business unit at Ettus is reviewing it. Systems engineering lead for GOLF endorsed it as an open source effort. Meeting minutes were posted to the list. Next steps depend on what IP from Ettus. We'll proceed with the E320 as far as it takes us regardless. I expect to make a lot more progress here in late summer/early fall, especially at GNU Radio Conference 2018.

The Rincon AstroSDR is another option, and Rincon has reached out with questions and clarifications in response to the Kittens Weekly Report. There will be more talks after Hamvention. Rincon will be a significant presence at GNU Radio Conference 2018.

Propulsion, attitude control, solar power, and a variety of antennas all have open source flight-tested options at LEO. I don't know much about navigation.

I do know that we have a lot of support out there from like-minded organizations and projects.

I do know that a payload design is within the capabilities of people on this list and within our extended Slack/GitHub/phone/email/club/conference network. That does not mean it's easy by any stretch, and it means that our economic development team will be tested. I think we are up to the challenge.

What's the first thing that you think we need to do?

-Michelle W5NYV

---------- Forwarded message ----------
From: Howie DeFelice <howied231 at hotmail.com<mailto:howied231 at hotmail.com>>
To: "ground-station at lists.openresearch.institute"<mailto:ground-station at lists.openresearch.institute> <ground-station at lists.openresearch.institute><mailto:ground-station at lists.openresearch.institute>
Cc:
Bcc:
Date: Wed, 16 May 2018 04:16:15 +0000
Subject: Satellite Building
Just wondering if there is interest in putting together a project to build a satellite. There is no particular launch in mind and no particular mission at this pint other than the generic Amateur Radio goal of furthering the art of communication. I think most will agree that the LAST thing we need another LEO. To simply exploit the microwave bands I think we want to consider orbits that allow hours of coverage at a time. A GEO would be great, a HEO would be really good. An overlooked orbit, at least in ham radio, is MEO. An orbit between 8000 and 10,000 Km would provide about 2 hours of coverage and orbit the earth about twice a day. The problem is that not too many people fly there so we need another  strategy. If we aren't in a big hurry, maybe we can get there from LEO. This means we need propulsion, attitude control, navigation, lots of solar power and a really cool radio. Does this sound reasonable? How  long would this actually take with a milli-Newton thruster ? I have attached a sketch of my first ideas.

- Howie AB2S

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Jonathan Brandenburg
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