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?