[amsat-bb] Tracking Non Earth Orbit Spacecraft......how?
tosca005 at umn.edu
Tue Oct 18 16:16:07 UTC 2016
I have wondered about Zach's question about tracking of bodies in other
than simple Earth orbit, particularly in Trans-Lunar Trajectory or Lunar
Orbit (as in the Cube Quest Challenge). I would be particularly interested
in a solution that could run on a PC without concurrent internet
connectivity. Are there any programs like that out there?
On Tue, Oct 18, 2016 at 8:45 AM, Nico Janssen <hamsat at xs4all.nl> wrote:
> Don't worry too much about frequent updates of ephemerides. Deep
> space spacecraft don't experience as many perturbations as satellites
> in low Earth orbit, like (variable) atmospheric drag.
> If you really want to dive into serious orbit modeling and tracking,
> also for deep space, you should have a look at the General Mission
> Analysis Tool (GMAT):
> Nico PA0DLO
> On 18-10-16 00:24, Zach Leffke wrote:
>> Thanks for the response Nico. Pete, WA6WOA, also recommend I take a look
>> at the Horizons system as well. I gave it a quick once over, and actually
>> logged into the telnet interface and played around a bit. It definitely
>> looks like the type of thing I'm looking for. Next step for me is to learn
>> the API and figure out how to integrate with my existing Python tools.
>> Also, changing how I think about satellite orbits and tracking algorithms
>> is also probably a requirement for me (I'm an EE type, not an AOE type, so
>> probably time to learn a little more about how these tracking algorithms
>> actually work).
>> Not being familiar with the system yet (or deep space tracking in
>> general), my only concern at the moment is the frequency with which they
>> update the system. TLEs get updated pretty regularly and need to be
>> refreshed by the client software. My cursory examination of the HORIZONS
>> system seems to indicate that they give ephemerides that cover much longer
>> windows, possibly indicating that they don't update the data as frequently?
>> Hopefully there is something about Deep Space tracking that is different,
>> not requiring such frequent updates. I have a sense that I'm not thinking
>> about 'scale' correctly yet. Like maybe these objects are so far out, that
>> errors that might creep into the SGP4+TLE algorithms relatively quickly
>> (requiring the weekly or bi-weekly updates) take a lot longer to creep up
>> and matter with the deep space trajectories.
>> My concern here is primarily related to the Cube Quest Challenge stuff.
>> I think this is being launched as part of the Orion mission to the Moon in
>> the next couple years. Can we expect ephemeris data to be quickly added to
>> the HORIZONS system soon after launch and after the TLI burn for the Orion
>> mission? Maybe I'm just wrong about how frequently they update the info.
>> Since this system is being run by JPL, I'm assuming (maybe hoping?) that
>> the datasets on HORIZONS get updated every time they conduct ranging
>> operations on active missions with the DSN (kind of like TLEs get updated
>> every time NORAD does RADAR tracking for things closer in)? Hopefully,
>> this will then include the Orion Mission relatively quickly so that the
>> community can quickly pull the tracking data required to compute pointing
>> angles for their ground stations to monitor the CQC bird.
>> Thanks for the pointers folks. In only a few emails, I've got some great
>> stuff to look into, and a whole new area to look into and learn about! Fun
>> stuff! Keep them coming!
>> Zach, KJ4QLP
>> Research Associate
>> Ted & Karyn Hume Center for National Security & Technology
>> Virginia Polytechnic Institute & State University
>> Work Phone: 540-231-4174
>> Cell Phone: 540-808-6305
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