Project:HackSat One
HackSat1 is a sprite: a tiny independent satellite. It'll be due to launch some time in early 2013 as part of the KickSat swarm. The primary aim of the project is to receive simple signals from HackSat1 at a ground station at the London Hackspace in Hoxton. In the longer term we hope to design and launch our own hardware designs.
All the sprites in the KickSat swarm will have the same hardware design. So focus is on the software and ground station. The dev kit is due May 2012. Speak to Flux if you're interested in getting involved.
Current Activities
- Messing around with a TI LaunchPad and learning the basics of MSP430. See also MSP430 Mac Howto.
- Working out the payload
- Working out what's needed for Hoxton Space Centre (ground station)
Sprite Hardware
We don't get to design the hardware on this mission, just program it.
- controller: CC430F6137 (16-Bit Ultra-Low-Power MCU, 32KB Flash, 4KB RAM, CC1101 Radio, AES-128, 12Bit ADC, USCI, LCD driver)
- sensors: temperature + one other TBC (KickSat are taking suggestions)
- radio: we can transmit what and when we like (subject to solar power) but data rate is only a few bits per second
"For sensors, basically they have to be packaged in a tiny SMT chip and not use too much power (no more than a few mW). We don't have a list yet, but one example of something that would work is this magnetometer: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Sensors/Magneto/HMC5883L-FDS.pdf"
The Orbit
"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 height - 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. "Criteria and Trade-offs for LEO Orbit Design" in IEEE Xplore has a pretty good overview.