[Ground-station] Satellite program

Wed May 16 19:08:13 PDT 2018

OK, I'm *sure *I'm going to get something wrong, so please, list folks,
feel free to jump in and correct me when I do. I still don't know much
about satellites.

Keith,

While silicon-on-insulator parts are a great way to go, there is at least a
$1000 cost differential for CPUs and then you get to memory... So, cubesat
folks have been creative in finding radiation-tolerant parts in consumer or
industrial grades. The main problem we're trying to avoid is latch-up that
actually damages the part. The second problem is bit errors. I have heard
that some FLASH gate-array-based CPUs do not suffer *damage *from radiation
induced latch-up and there are viable recovery mechanisms, and their
FLASH-based gate-array does not require configuration memory and is
resistant to single-element errors. I googled this:
https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=3399&context=smallsat
which discusses the Microsemi SmartFusion2 (which we used for our abortive
Whitebox SDR, so Chris Testa knows it well). No doubt you can find more.

Others in the group have experience with other radiation-tolerant consumer
or industrial grade parts.

The Cortex M0 is more than enough for housekeeping and might be enough for
some signal and image processing tasks. But the housekeeping CPU need not
be the signal-processing CPU as well.

AMSAT has had some interesting strategies. First, they had a cache of SoS
1802s which they used for 30 years or so. They used a lot of components
that were given to them from cancelled space projects. They didn't always
use rad-hard memory, just because they could not afford it, but used
error-correcting memory architectures and scrubbed the memory constantly so
that single-bit errors were corrected before they became large enough to be
uncorrectible. There was *no* ROM onboard, a hardware modem loaded memory
from the radio and then reset the CPU and set it running. Nobody's told me,
but if there was any cryptography on that it wasn't much more than
exclusive-OR of a secret word. They have their own FORTH-like language,
first written in the '70's, which does concurrent but not parallel threads.
Most housekeeping is written in this language.

So, you can expect that some of an IHU project might be prospecting for
radiation-tolerant parts that don't cost so much. Others have left
breadcrumbs to follow.

Even when you do have rad-hard parts, generally they have a consumer or
industrial grade pin-equivalent so that non-flight and LEO units don't have
to be made with the most expensive parts.

    Thanks

    Bruce

On Wed, May 16, 2018 at 1:37 PM, Keith Wheeler <keith.m.wheeler at gmail.com>
wrote:

> Bruce,
>
> I'm not familiar with the requirements for an IHU, but I've done a lot of
> embedded firmware/hardware design.  With the desire for DX (above LEO), I'm
> assuming rad-hard will be a requirement.  I was looking at a rad-hard ARM
> Cortex M0.  What kind of horsepower would the IHU require?
>
> -Keith Wheeler
>
> On Wed, May 16, 2018 at 11:54 AM, Bruce Perens via Ground-Station <
> ground-station at lists.openresearch.institute> wrote:
>
>>
>> Legal stuff first: Image credit: XKCD #1992: "SafetySat" at
>> http://xkcd.com/1992/ 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> 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>
>>>> To: "ground-station at lists.openresearch.institute"
>>>> <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
>>>>
>>>>
>>>> ---------- Forwarded message ----------
>>>> From: ground-station-request at lists.openresearch.institute
>>>> To:
>>>> Cc:
>>>> Bcc:
>>>> Date: Wed, 16 May 2018 00:16:18 -0400
>>>> Subject: confirm db1d86455ef4eb7857a41676b75024137549ff1d
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>>>
>>>
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>

-- 
Bruce Perens K6BP - CEO, Legal Engineering
Standards committee chair, license review committee member, co-founder,
Open Source Initiative
President, Open Research Institute; Board Member, Fashion Freedom
Initiative.
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