Executive summary
- Target launch window is May 2nd, with immediate focus on board bring-up, battery enclosure design, sensor integration, and launch logistics.
- The team discussed a near-term hardware path: complete one board by Saturday, complete the other five next week, and use one of the six Argus boards for initial F prime work.
- Main open items are battery packaging, viewport/fogging strategy, spectrometer footprint, suspension layout, and legal/radio/logistics preparation.
Meeting Notes:
Overall planning and logistics
- The team wants to establish a timeline and work through logistical details.
- A BOM was reviewed, and materials were discussed, including:
- Sat tracker
- Sensors to integrate with the OBC and mainboard
- Argus boards
Argus boards, software, and team training
- The team has 6 Argus boards to experiment on.
- The plan is for 1 out of the 6 boards to be used to try F prime.
- The other boards will support:
- Board familiarization
- Soldering practice
- Additional testing
- LoRa packets
- STK testing
- Sensor testing
- This was discussed as a strong learning opportunity for the team.
Power system and battery enclosure
- The battery concept discussed was:
- 4 lithium AA batteries
- Batteries rated for the expected temperatures
- Batteries arranged in series
- Additional batteries arranged in parallel to increase capacity
- The system would also use 2 buck converters.
- The team wants a spring enclosure designed to connect the wiring and hold the battery configuration in its intended parallel and series arrangement.
- This was identified as something the team wants done soon.
Frost, moisture, and enclosure sealing
- Frost was raised as a concern and needs further investigation.
- The main concern is whether frost or moisture will affect the enclosure and internal hardware.
- Waterproofing was discussed, but the conclusion was that the enclosure does not need to be fully waterproof.
- The current view was that epoxy and rubber seals should be enough.
- Niclas said he can look into the frost question.
Battery mounting and chassis integration
- Joseph was asked to look into a preliminary design for storing the batteries in the chassis.
- He was also asked to look for:
- Sketches
- Existing printable designs
- Other references that could be used directly or iterated on for inspiration
Camera, tracker, and payload layout
- The payload layout discussed includes:
- A GoPro on the outside with its own case
- A sat tracker on the outside
- A camera inside the enclosure with its own Raspberry Pi
- The current concept includes an acrylic viewport at the bottom of the chassis so the internal camera sensor can look through it.
- A spectrometer may also be included inside.
Fogging and optical access
- The biggest concern with the acrylic viewport is fogging.
- Possible mitigations discussed:
- Silica packets
- Anti-fog coating on the acrylic
Spectrometer integration
- The team discussed specific spectrometer items that are needed.
- The current view is that only basic hardware and an acrylic viewport are needed.
- It would be ideal if the spectrometer fits on board.
- The team needs the following as soon as possible:
- Spectrometer footprint
- Required materials
Multiple viewports
- Because the payload may include:
- Light sensors such as UV and near-IR
- A spectrometer
- A camera
- The team discussed whether 2 separate viewports may be better than a single one.
- The team said they do know how big the sensors are.
Near-term hardware targets
- By this Saturday, the team wants:
- The first board fully complete
- An idea of the actual battery enclosure
- Preliminary sketches
- The spectrometer footprint
- As soon as the other boards are ready for F prime work, the team can begin that effort.
- The current board schedule discussed was:
- One board done by end of week
- Other 5 boards done by next week
Detector sizing and suspension system
- The detector from J Lab is quite large.
- The team needs to make sure it meets:
- Sizing requirements
- Power draw limits
- A Y-harness was discussed to prevent the payload from tangling.
- The team wants to design something similar.
Chassis support and mounting approach
- The team wants to rely on the chassis itself.
- Both 3-point and 4-point support approaches were discussed as workable.
- The GoPro would be separate from the styrofoam box, so its placement still needs to be brainstormed.
- The team’s view was that this should not be too difficult.
- They also want to look at other projects to see what has been done.
- The 3-point Y-harness was mentioned as the most common approach, but the team wants to stay flexible.
Mass and battery weight
- Some masses are already listed on the sheet and that sheet will continue to be filled out.
- Some sensors are only 2 to 3 grams.
- A battery configuration of 4 batteries, 5 in parallel, for a total of 20 batteries, was discussed.
- That battery configuration was estimated at 320 grams and was described as the heaviest part of the payload.
- The team is targeting a 2 to 4 lb payload.
Tracking, recovery, legal, and radio operations
- The team identified several logistics items that need to be handled:
- Tracking predictors
- Cars
- Launch site
- Legal considerations
- ATC
- Landing expectations
- The team emphasized that they do not want legal issues.
- Other operational items discussed:
- Battery life testing
- Antenna pointing to the balloon
- A mobile station that can be driven around
- The team also noted that licensed people need to be involved on all relevant radio sides of the operation.
Ham radio licensing and network support
- The April 22 ham radio exam day was mentioned.
- The radio team hosts one exam every month.
- Team members who want to can get licensed.
- The team is also reaching out to TinyGS so the mission can potentially be listed there automatically.
Manufacturing and sourcing
- There was discussion that the team might be able to get a professional fab run of around 100 boards made.
- LoRa parts were discussed as relatively easy to get.
- It was noted that they are not stocked on DigiKey, but are available from other vendors.
Procurement follow-up
- The team wants to find the original email thread to see if orders can be placed through Douglas Purdy.
Alternate viewport concept
- An alternate idea discussed was to poke a hole and seal around it instead of using a full acrylic viewport.
Software fallback option
- The team discussed that they could run Arduino on these boards and use the existing library.
- If the goal is just a simple beep-sat style payload with a few things running in a loop for a couple of hours, then simple Arduino code flashed onto a board would be the easiest route.
- By contrast, getting Zephyr fully up and running on the board was described as likely to be a boondoggle.
F prime follow-up
- Zac said he will reach out to the F prime team at JPL and close the loop to try to make that happen.
Action items
Hardware and payload
- Joseph
- Look into a preliminary battery storage design for the chassis
- Find sketches, printable designs, or references that can be reused or iterated on
- Niclas
- Look into frost risk and whether frost or moisture could affect the enclosure and payload
- Team
- Complete the first board by Saturday
- Complete the remaining five boards by next week
- Define the battery enclosure concept
- Produce preliminary sketches
- Confirm spectrometer footprint and required materials
- Check detector sizing and power draw from particle detector
- Review 3-point versus 4-point suspension options
- Brainstorm GoPro placement
Software
- Team
- Use 1 of the 6 Argus boards for initial F prime work
- Get Zephyr working on this chip
- Continue board familiarization, soldering, LoRa, and sensor testing
- Keep Arduino as the simple fallback path for a short-duration test payload
Logistics and operations
- Team
- Establish a timeline toward the first weekend of May launch target
- Work through tracking, landing prediction, legal, ATC, and site planning
- Plan car support and mobile station support
- Test battery life
- Test antenna pointing
- Make sure we have licensed operators
Procurement
- Team
- Continue updating the mass sheet
- Investigate remaining parts for spectrometer and balloon layout
Questions
- Should the optical system use an acrylic viewport or a sealed opening instead?
- Is one viewport enough, or are separate viewports needed?
- Does the J Lab muon-detector fit within size and power constraints?
- What is the final battery configuration? (# of batteries)
- What is the best GoPro placement if it is mounted separately from the styrofoam box?
- Is the team going forward with a 3-point or 4-point suspension layout?