Hack Chat Transcript

A event log for Modeling Space Hack Chat

Bringing space down to Earth

tom-nardiTom Nardi 10/04/2023 at 20:170 Comments
Dan Maloney  3:00 PM
OK, here we go! I'm Dan, I'll be modding today along with Dusan as we welcome Bryan Murphy and Sam Treadgold to the Hack Chat. I've seen Bryan, is Sam there too? Also maybe someone else?
Dusan Petrovic  3:00 PM
Welcome to the Modeling Space Hack Chat! We are thrilled to have you all here for this exciting event.
Bryan  3:00 PM
Yes! Sam is right here with me. We'll both be responding. Assume all good responses come from Bryan.
Dusan Petrovic  3:01 PM
Let's get started!
Bryan  3:01 PM
We are very excited to be here!! [joy emoji here]
Dan Maloney  3:01 PM
So maybe kick us off with a little about yourselves and how you came to build that sweet ISS model?
Bryan  3:02 PM
Sam here - I work on the ISS Meteoroid / Orbital Debris team and have been with the ISS mimic team since 2014 .
Pete Willard  3:03 PM
Nice Credentials!
Bryan  3:03 PM
Bryan - I really need to stop letting Sam go first since his job is so cool. I also support ISS - dynamics and control systems - robotics-ish.
Bryan  3:04 PM
B: we both supported ISS for a while, and got to see behind the curtain at all the cool data coming down. NASA released some of that streaming data publicly, and we knew we had to do something with it.
Bryan  3:04 PM
We wanted something that *everyone* could access - something tangible responding to all that yummy data. We wanted it to work for space nerds, students, and teachers.
Bryan  3:05 PM
So, "mimic-ing" the ISS seemed like a good way to go.
Dan Maloney  3:06 PM
Data wants to be visualized...
Bryan  3:06 PM
For those who haven't already read the HAD post (shame), here's a vid from Joel Telling interviewing us in July:
Bryan  3:09 PM
Bryan  3:09 PM
S: here is one of our telemetry visualization screens
Boian Mitov  3:09 PM
Cool! :-)
Bryan  3:09 PM
featuring the infamous urine tank quantity that has recently gotten a lot of attention
charlotte  3:10 PM
What are each of your favorite parts of the project?
Dan Maloney  3:10 PM
Our coverage, ICYMI:
Dan Maloney  3:10 PM
Dan Maloney  3:11 PM
Urine tank? Interesting -- I was working on a "recycling water in space" article, maybe I should dust that off and start working on it again
Bryan  3:11 PM
B: My fav is supporting teachers by giving them something interesting to work with. I love that schools can build these and have them tangibly-connected to ISS. And love all the skill-building along the way.
Tom Nardi  3:11 PM
I remember years ago looking through some of the telemetry data in a mobile app that NASA had released, love this evolution of the concept.
Bryan  3:12 PM
Our github hosts two pages that show all of the public telemetry coming down from the ISS: and the cooler:
Pete Willard  3:13 PM
The fact that they still remember to *share* with us is great!
Dan Maloney  3:16 PM
Just wondering -- does ISS telemetry come down through the DSN? Or is the station close enough that they don't need the really big ears?
SimonAllen  3:16 PM
Any ideas how to build a visual tracker for the ISS so that a video can be taken. I've tried this with a Canon handheld, but I cannot keep the ISS in view.
Bryan  3:17 PM
Great question - ISS transmits all the data through the Tracking and Data Relay System Satellites (TDRSS) in Geostationary Orbit which then forward the data to ground sites around the world (Guam, White Sands, Maryland) and then to JSC
Dan Maloney  3:18 PM
TDRSS -- there's another article I've been meaning to write
Bryan  3:18 PM
There was a great visual ISS tracking project using a raspberry pi to point a finger at wherever the ISS currently was which could be adapted to a camera setup perhaps
Pete Willard  3:19 PM
Bryan  3:20 PM
Not that but that is very cool and we need to look at the code
charlotte  3:22 PM
if you had endless time and endless money, what features would you develop for mimic?
SimonAllen  3:22 PM
Great ideas, but I am doubtful this will give accurate enough tracking.
Bryan  3:23 PM
B: Want: 3 degree-of-freedom rotation of MImic -- in a hamster ball so we can reflect the attitude in real-time (we DO have the data).
Pete Willard  3:23 PM
Cool idea
Bryan  3:23 PM
Simon - agreed. Would need to have some visual tracking as well to refine the target lock
Pete Willard  3:25 PM
Cmon... invent that anti-gravity device so you can just float it with no armature... :-P
Bryan  3:25 PM
Pete: Make it so
Mark J Hughes  3:25 PM
@SimonAllen Check out GPredict -- it's for tracking satellites. And the ISS qualifies. It seems like there is an output module meant for controlling antenna's with azi-ele mounts. And if you figure out the rest of the mechanicals, lemme know, yeah?
Tom Nardi  3:26 PM
Even for NASA, seems pretty wild that so many of these values are being reported out to 10+ decimal places. Is that because of some kind of unified sensor/reporting platform, or are they really interested in cooling water temps down to the billionths of degrees?
Bryan  3:26 PM
Back to pointing at ISS, we gave a little virtual presentation to "Raspberry Pint" in the UK. The topic after us was a really cool Pi-based tracking system, which you may be able to adopt. It's intended to be precise but likely could not move quickly.
Bryan  3:27 PM
We see that @Tristan Moody has joined -- T: do you want to take that data question? (surprise: Tristan is also a Mimic'er)
Tristan Moody  3:27 PM
dang I was gonna start planting questions in here lol
Tristan Moody  3:27 PM
on the number of digits: for the most part, the data is not that fine grained
Tristan Moody  3:28 PM
maybe 10-16 bits resolution full scale, for example
Tristan Moody  3:28 PM
There just ends up being a lot of digits when you do the math to put it back in engineering units, and the data stream reports it out that way
Tristan Moody  3:29 PM
if you watch a lot of the data, you'll see it twiddle between two nearby numbers, that's most likely a toggle on the least significant bit for that channel
Bryan  3:31 PM
Long-shot: has anyone on here seen us out in the wild? We've mostly been around Houston but finally got to San Francisco and Seattle this summer. Heading back to San Fran in a few weeks for Maker Faire Bay Area.
Dan Maloney  3:32 PM
What's traveling with the Mimic like? Doesn't seem very "TSA friendly"
charlotte  3:33 PM
how can people get involved developing the hamster wheel and other new features?
Bryan  3:33 PM
We did receive several "inspected by TSA" mementos in our luggage.
Pete Willard  3:34 PM
Neat. I'd be having nightmares about "fragile handling" or lack of...
Bryan  3:34 PM
haha, charlotte! Discord is by far the best way to engage. It's become more lively in there after some recent highlights. Jump in.
Bryan  3:34 PM
Bryan  3:35 PM
@Pete Willard , yep, we were worried. Especially Sam's needlessly-refined-and-therefore-fragile truss components. But all made it safely.
charlotte  3:35 PM
clarify that *needlessly* part?? ;)
Tristan Moody  3:36 PM
@charlotte A workable attitude indicator is a puzzle we've been pondering for a while tbh
Pete Willard  3:36 PM
I would imagine refined = Accurate
Tristan Moody  3:37 PM
even for a small scale one, mechanically spinning a ball around with precision can get tricky, especially if you are trying to avoid a gimbal lock problem
Bryan  3:37 PM
B: There are about 8 of us actively developing the project, and about half are laser-focussed on a *very* representative model...
Bryan  3:38 PM
B: To the question that wasn't asked... Why yes, we *do* have a photo with RasPi co-founder Liz Upton. They have already donated many RasPi's for teachers building the mini version of Mimic.
Bryan  3:38 PM
Pete Willard  3:39 PM
Bryan  3:39 PM
They also donated one (signed by both Liz and Ebon at our request) for this local-library pilot build.
Bryan  3:39 PM
Bryan  3:41 PM
The students and their parents worked with library staff and Mimic'ers to learn the coding, soldering, wiring, 3D printing, and plenty of debugging. Also, vinyl cutting and 3D print support removal.
Dan Maloney  3:41 PM
How long does a full build typically take?
Bryan  3:42 PM
B: It takes a while. Was 12 2-hr sessions with the students, with us prepping some materials in between. S: 3 Weeks
Dan Maloney  3:43 PM
In this case, a long build is probably desirable -- bite-sized chunks of work, learning as you go
Bryan  3:43 PM
Yes. And in response to feedback from educators we recently created a "Mini Mimic" build. It's still in work, but much, much simpler. Half the scale of the big one, with simpler motors, motor control, and prints. Uses the same RasPi code.
Tristan Moody  3:44 PM
Bryan/Sam: how about a discussion on what potential updates to the project are in the works?
Bryan  3:44 PM
We did a teacher pilot "ISS Mimic Summer Institute" in July with teachers from Mexico, Puerto Rico, and Houston area. They built the Mini Mimics over a 3-day workshop.
Bryan  3:45 PM
S: Updates - we want to finish upgrading the ISS CAD model to the full high fidelity version and add the robotic mobile transporter "railroad car
Bryan  3:46 PM
to the ISS model to also move when the real one moves
Bryan  3:49 PM
B: I'm hoping to overhaul our motor scheme for the big Mimic. There are some nice continuous rotation servos with precise position feedback available, but they are a bit too big. Our current solution of geared DC motors with Hall-effect-sensors works fine, but they are a bit pricey, require zeroing, and require multiple motor drivers (and interrupt monitoring complexity). I'm hoping for a smaller package of the motors from Robotis or similar.
Dan Maloney  3:49 PM
Does the ISS reconfigure the solar arrays if there's a risk of incoming space debris? If so, does the Mimic reflect that?
Boian Mitov  3:51 PM
I doubt the ISS dates to get so close to a debris as to have to worry about the solar arrays... :-D
Bryan  3:51 PM
S: No not explicitly for a space debris event - they will maneuver the ISS out of the way if given enough advanced notice of a potential collision however. But whatever the arrays do - our model will reflect their live state - like over the summer after the Soyuz coolant leak, they positioned the port solar arrays to shadow the Soyuz and help keep the temps down and we could see that on the model
Boian Mitov  3:51 PM
I mean dares to get so close
Bryan  3:52 PM
S: Boian yes the ISS orbit is low enough altitude to have a fairly benign debris environment but there are times when they must conduct avoidance maneuvers
Boian Mitov  3:53 PM
My point was that they will maneuver far enough not to have to worry about the solar arrays
Bryan  3:53 PM
S: True
Dan Maloney  3:54 PM
Kinda figured the imperative would be electrical production and they'd just move the whole thing out of the way
Boian Mitov  3:54 PM
Do you show somehow the activity of the thrusters?
Tristan Moody  3:54 PM
@Boian Mitov For the most part, debris strikes to the solar arrays are accepted as a cost of being in orbit
Tristan Moody  3:55 PM
in general, individual strikes only cause very small differences in power production, so what we see is a slow degradation in power production over time
Bryan  3:55 PM
S: Thruster activity is not yet really shown on the model - but we do plan to add lights to indicate when they are boosting the station orbit
Boian Mitov  3:55 PM
COOL! :-)
fid  3:55 PM
Not like we have the spare time, but we could form a team of people going to Supercon and get assigned a section to 3D print, build, or buy motors, etc. Bring the parts to Supercon and put a Mimic together in the Alley or at Supplyframe. If too much of a time crunch, next year.
Tom Nardi  3:56 PM
That would be awesome, ISS mimic at Supercon definitely has my vote.
Bryan  3:56 PM
@fid , where/when is Supercon? Google says the one in Florida was in July.
Dan Maloney  3:57 PM
First weekend in November in Pasadena
fid  3:57 PM
Pasadena, November 3-5.
Tom Nardi  3:57 PM
As I recall, the Florida one is an anime convention that unfortunately has the same name as our event
Tom Nardi  3:57 PM
Not sure which one came first though, to be fair.
Bryan  3:58 PM
OOOH... HAD's Supercon. Cool.
fid  3:59 PM
Just went to this link it is awesome. Lots of information
Bryan  3:59 PM
Wow, that would be simply fantastic. I don't think we Houstonians could make it for that one. But we'd LOVE for the HAD community to build one there!! We can prob get a signed RasPi donated.
fid  4:01 PM
That would be great! If not I have some Pis collecting dust. One is still a camera with a Lego case.
fid  4:03 PM
I have to drop off. Farm work to get done.
Bryan  4:03 PM
The printing and post-print clean-up takes a while, so we'd recommend most of the printing prior to the even.
Bryan  4:03 PM
Thanks, @fid! Reach out on Discord if you decide to build one!
fid  4:04 PM
I was thinking about folks bringing printed stuff and hardware and put it together at Supercon.
fid  4:04 PM
@Bryan I sure will. Thanks for the informative chat.
Bryan  4:05 PM
@fid that would be awesome -- reminds me of when Adam Savage did the recreation of the Apollo hatch with 3D printed parts from several ppl
Dan Maloney  4:05 PM
Sounds like a cool idea, short notice but probably still have enough time. But we're out of time for the chat, time to let the Houston crew get back to work. Thanks so much for coming along today Bryan, Sam and Tristan! This was great!
Bryan  4:06 PM
Thanks, all! We really appreciate the invite and enjoyed chatting with you all!
charlotte  4:06 PM
thank you!
Tom Nardi  4:06 PM
Right. I've seen similar things at different 3D printing conventions, assign "chunks" of the final build to various individuals/groups, and then assemble it all on the day. The ISS model seems particularly suited for such a project.
Dan Maloney  4:06 PM
And thanks to everyone for the great discussion, as always
Boian Mitov  4:09 PM
Thank you @Bryan and Sam! This is super cool stuff!
Boian Mitov  4:09 PM
Can't wait to see a version with blinking thrusters!
Boian Mitov  4:09 PM
And as always, thank you @Dan Maloney for organizing the chat! :-)