“Untethered” Spacewalk Flight

My next flight is planned for this coming Wednesday, 7th February, to commemorate the first untethered spacewalk by Bruce McCandless on the same day in 1984, by trying to recreate the classic image:

There will be a total of 3 Pi cameras with different viewpoints and different lenses, to best capture images of a Revell model astronaut and MMU (Manned Maneuvering Unit), sending live pictures down to the ground.

The flight will have 2 trackers, one a Pi with 434 and 868 LoRa modules and the other a simple AVR LoRa tracker with cutdown:

  • BRUCE: Pi, LoRa, 869.850MHz, Mode 3, SSDV and telemetry
  • MMU: Pi, LoRa: 434.225MHz, Mode 1, SSDV and telemetry
  • EVA: AVR, LoRa: 434.450MHz, Mode 2, telemetry only

The main tracker is a Pi 3 plus LoRa and UBlox boards.  The SSDV images will cycle between 3 cameras – one on the Pi 3 and 2 more on a pair of Pi ZeroW boards, all connected via wifi (the Pi 3 is an access point).  The cameras are (currently – may change): Pi V2 (Sony) camera, Pi V1 (Omnivision) camera, and a PiHut “fisheye” Omnivision camera.  The cameras are arranged on the payload to get different views, so you will see different views during the flight.  Same applies for both LoRa transmitters, with different images being sent to each.  If for any reason the wireless stops (though it’s been 100% reliable in testing), then the Pi3 will just send its own images.

Both include landing prediction fields, and those from MMU will be re-uploaded by a Python script to appear as “XX” on the map.

The LoRa signals will stop for a few seconds each minute, during which time one of my gateways will be sending a message up to the tracker to request a re-send of missing SSDV packets on the 869.85MHz link.

The Pi 3 also has a USB 3G modem on it, which will attempt to connect while below 2km.  When connected it will:

* Upload telemetry directly to habitat every 1 minute, as payload ID STS41B
* Stream video to YouTube
* Copy images to a web server

The video uses the Pi 3’s camera, so there will be no SSDV from this camera before launch or after landing – all SSDV will be from the other cameras.

The backup tracker will be attached just above the parachute, and will cut the balloon away if the flight gets south of 51.1 latitude (may ehcnage that depending on predictions), or on a specific upload from the ground, to prevent a watery death.

And just because the payload isn’t heavy enough already, and doesn’t have enough trackers on it, we are adding a couple of car GSM/GPRS trackers, both sending messages to Anthony’s traccar server from where a Python script will send them to SNUS, as:

  • HTGSM1 – Upu’s car tracker
  • HTGSM2 – My cheap car tracker

There will be 2 YouTube streams – one from the payload (launch and landing, hopefully) and one at launch only using a camcorder connected to a laptop.  Both streams will appear on a web dashboard – see links below:

 

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