Difference between revisions of "Project:HackSat One"
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''"While we don't know the orbit, we're aiming for a circular low altitude LEO - around 300 km. altitude. That would mean a roughly 90 minute orbit with several daylight passes per day (usually 3 or 4 over any given location). Each pass would be somewhere around 5 minutes long."'' | ''"While we don't know the orbit, we're aiming for a circular low altitude LEO - around 300 km. altitude. That would mean a roughly 90 minute orbit with several daylight passes per day (usually 3 or 4 over any given location). Each pass would be somewhere around 5 minutes long."'' | ||
| − | At that (low) a hight - the orbit repeat cycle would really matter quite a bit; i.e. how many days before it passes within line of sight of a given ground station; and is there enough power to survive across such cycles; or if not - is there enough to be 'on' when doing an overpass (in daylight). | + | At that (low) a hight - the orbit repeat cycle would really matter quite a bit; i.e. how many days before it passes within line of sight of a given ground station; and is there enough power to survive across such cycles; or if not - is there enough to be 'on' when doing an overpass (in daylight). The basic concept that as it circles earth in a bit over 90 minutes; each pass is a couple of degrees westward (on the illuminated side of earth usually) - returning to roughly the same orbit after a couple of days/weeks. Key is then having (had) enough power to charge any batteries to be able to power up the transmitter (and generally not having enough time/power to establish position - so you need to do this a lot - in a hit and run mode looking for the elusive ground station and then offload your wares quickly -- within the 10's of seconds you have (left). |
B.t.w. http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4526281 has a pretty good overview. | B.t.w. http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4526281 has a pretty good overview. | ||