Satellite Hunting Hack Chat

What's really going on up there?

Wednesday, October 18, 2023 12:00 pm PDT Local time zone:
Hack Chat
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Rescheduled -- note new date

Scott Tilley will host the Hack Chat on Wednesday, October 18 at noon Pacific.

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From the very first beeps of Sputnik, space has primarily been the domain of nations. It makes sense -- for the most part, it takes the resources of a nation to get anything of appreciable size up out of the gravity well we all live in, but more importantly, space is the highest of high ground, and the high ground has always been a place of advantage to occupy. And so a lot of the hardware we've sent upstairs in the last 70 years has been in the national interest of this or that country.

A lot of these satellites are -- or were, at least -- top secret stuff, with classified payloads, poorly characterized orbits, and unknown communications protocols. This can make tracking them from the ground a challenge, but one that's worth undertaking. Scott Tilley has been hunting for satellites for years, writing about his exploits on the Riddles in the Sky blog and sometimes being featured on Hackaday. After recently putting his skills to work listening in on a solar observation satellite as its orbit takes it close to Earth again, we asked him to stop by the Hack Chat to share what he's learned about hunting for satellites, both long-lost and intentionally hidden. Join us as we take a virtual trip into orbit to find out just what's going on up there.

  • Hack Chat Transcript, Page 2

    Tom Nardi10/18/2023 at 20:11 0 comments

    Scott Tilley  3:47 PM
    The above image proves that a satellite's orbit is fixed to the stars.
    n1sat  3:48 PM
    What's the X axis? MJD??
    Matthew Phelps  3:48 PM
    What is your preferred pointing angle calibration method? Point at a good reference sat and and find point of max gain as it passes over the main lobe? Also, whats the beamwidth of your MLD?
    Scott Tilley  3:48 PM
    It's a full lunar day of NASA's LRO orbiting the moon. The sine shaped curve over the full lunar day shows us the change in the our perspective of the plan of the orbit as the moon orbits Earth.
    Scott Tilley  3:49 PM
    The best reference are GEO satellites, the Sun or distant space probes in orbit of say Mars.
    Scott Tilley  3:49 PM
    MJD = Modified Julian Date
    Scott Tilley  3:50 PM
    Julian dates are much better for calculation than Gregorian styles.
    Scott Tilley  3:51 PM
    MJD is somewhat of a standard when you refer to time for satellite tracking.
    n1sat  3:52 PM
    got it. Looks like it's easy to acquire with the astropy python lib
    ka9cql  3:53 PM
    @Scott Tilley Thank you for that - Exceptionally informative!
    JoseSanxez  3:53 PM
    Thanks for the GPS plot Scott. Would you please point to some literature on the pol method to derive sat attitude? If it is already in your blog is just ok;)
    Scott Tilley  3:54 PM
    Here's a summary of what I think are necessary skills for satellite tracking. Knowledge of the night sky and basic astronomy. Analytical skills to perform calculations and reduction of data. Good experimental skills to collect reliable data and understand error management. Research skills to find useful information to develop your work. The tech side of things will come. But one needs to understand the general concepts and have a good grasp of the scientific method and be willing to be beat up by it for a long time :-)
    Scott Tilley  3:56 PM
    The polarization method is just being developed live and in real-time on my micro blog here, its all new work.
    in3dye  3:56 PM
    Are all (or usually) satellite transmitting all the time on same frequency? I mean, is the a of doppler
    in3dye  3:57 PM
    Is the method of doppler analysis Always applicable?
    Scott Tilley  3:57 PM
    No satellites use all kinds of different frequencies. That's part of the fun. Some can be found in government databases, others you need to search for and find.
    Nate  3:58 PM
    some dont transmit over certain locations too, the fengyun's mentioned before shut off over most of NA
    Scott Tilley  3:58 PM
    Doppler works if you know that the spacecraft carrier is free running and not unstable. It can also be used for two-way and three-way analysis by including the ground station location in the analysis. There are some cases where Doppler doesn't work well like GEO satellites.
    Ian  3:59 PM
    sorry, I don't know much about satellites. Can someone please give ma an insight?
    Scott Tilley  3:59 PM
    One can also use radio positional measurements to develop orbits.
    in3dye  4:00 PM
    I mean, the same satellite uses Always the same frequency and is transmitting control data all the time? I assume the general answer is no, but maybe in most of the cases is yes?
    Dan Maloney  4:00 PM
    @Ian, we're just about to wrap up here, sorry. I'll post a transcript in a few minutes so you can review
    Scott Tilley  4:00 PM
    Ian  4:01 PM
    Ok, no problem. Thank you!
    n1sat  4:02 PM
    Which python libraries do you find yourself using most frequently?
    Scott Tilley  4:02 PM
    Most satellites use the same frequency...
    Read more »

  • Hack Chat Transcript, Page 1

    Tom Nardi10/18/2023 at 20:10 0 comments

    Dan Maloney  2:51 PM
    Gonna get started in about 10 minutes, folks
    Athsara Fernando  2:52 PM
    Mark J Hughes  2:53 PM
    Woohoo! Remind me Dan -- what comes after Part-D, but before Part-F?
    Eugene  2:55 PM
    Do we just join here and enjoy the ride? Sorry I'm new too this
    Mark J Hughes  2:56 PM
    @Eugene Yeah -- hang out -- ask questions once the presenter gets here.
    Mark J Hughes  2:56 PM
    You can just start asking now too if you want. Maybe a lurker knows the answer.
    Eugene  2:57 PM
    Ok. I'm on my phone, so will the media just play...I guess let me wait, feeling stupid haha
    Mark J Hughes  2:58 PM
    Oh - yeah, no, there's no media. It's all text based
    Mark J Hughes  2:58 PM
    It's an actual Chat.
    Eugene  2:58 PM
    AAA..okay cool
    Mark J Hughes  2:58 PM
    Not a webinar they're calling a chat
    Richard Stanley  2:58 PM
    Hi folks. I'm curious about what sats are transmitting in k-band. I think ESA Euclid is doing so, but I'm wonder about others.
    Mark J Hughes  2:58 PM
    Think of it as an AMA
    Mark J Hughes  2:59 PM
    @Richard Stanley Did you go to CSUF?
    Eugene  2:59 PM
    Richard Stanley  2:59 PM
    @Mark J Hughes Nope. Don't know what that stands for :)
    Mark J Hughes  2:59 PM
    California State University -- at Fullerton.
    Mark J Hughes  3:00 PM
    'twas a different Richard Stanley then :)
    Dan Maloney  3:00 PM
    OK folks, here we go. I'm Dan and I'm the mod today along with Dusan as we welcome Scott Tilley to the Hack Chat. Today we're going to be turning our eyes and ears upward in the search for satellites
    Dusan Petrovic  3:00 PM
    Hello and welcome!
    Scott Tilley  3:01 PM
    Thanks for the invitation Dan.
    Dan Maloney  3:01 PM
    Hi Scott! Welcome to the Hack Chat! Care to kick us off with a little about how you got into satellite hunting?
    Scott Tilley  3:01 PM
    Here's some boiler plate on my general background.
    Scott Tilley  3:01 PM
    Scott Tilley, AScT – Is an amateur radio astronomer with an interest in tracking spacecraft in low Earth orbit (LEO) into deep space. He has over 10 years of experience tracking various objects in space using optical, radio position and Doppler techniques on various radio bands from VHF to X-Band. Scott has built and maintains the S-band sensors to be used to support this RFI at his residence on the Sunshine Coast of British Columbia, Canada. NASA may recall that Scott re-acquired the lost IMAGE mission in Early 2018 and has also contributed time to present how amateurs track space missions to NASA-JPL in 2021. Professionally he holds the title Applied Science Technologist (AScT) and practices independently as a consultant in marine electrical and electronics systems.
    Scott Tilley  3:02 PM
    I became interested in tracking satellites as a kid. I saw a 60 Minutes piece on the kettering group in the UK and it wasn't long after I was sneaking into my dad's radio shack and hunting for COSMOS satellites on HF.
    Scott Tilley  3:03 PM
    Later in life I coupled my interest in astronomy with the search and tracking of satellites optically. During the process we began using radio to add more data and married the two methods together.
    Scott Tilley  3:04 PM
    As it rains a lot here I primarily focus on the radio side of things presently. As my skills grew I starting building more focused instruments to learn more from the distant weak signals satellites present.
    Scott Tilley  3:05 PM
    Dan Maloney  3:05 PM
    What's the furthest satellite that you've bagged so far?
    Scott Tilley  3:06 PM
    Here's some of my latest work. The measurement of the polarization of a satellite is allowing us to see their movements in attitude in space....
    Read more »

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