Status: Recovered
Introduction
Pepto Gizmo is the name of a capsule that was designed and built by Austin Howard and the VAST structures team as a engineering project during the spring of 2005. The capsule was launched in October of 2005 and was lost 30 min into the flight. Nearly 3 years since the original construction of the capsule, Pepto was returned to the University of Idaho. This site is dedicated to the documentation of the design, failures and lessons learned from VAST's experiences with the Pepto capsule in an effort to prevent future failures, whether they be programmatic, technical, or otherwise.
The Design
The inspiration for the structural design of the Pepto capsule came from server rack design. An aluminum frame would support horizontal circuit board trays. Each tray would contain independently operating electronics or electronics connected through a backbone wiring system that ran vertically from bottom to top. A central power supply could provide power to all science and data collection electronics while independent power is supplied for radio and tracking electronics. Surrounding the aluminum frame was a 1 inch foam insulation that was wrapped in a thin layer of fiberglass for additional strength. The capsule was disassembled by removing the side walls exposing the internal electronics. This system was designed to allow easy access to all electronics without the necessity of removing any electronics to access switches, battery terminals or lights, etc.
Although the design included many attractive feature (most of which are listed above) in application it proved to be massive and quickly became the rats nest of wires that the we were trying to avoid. The structure was ahead of its time, most of our electronics were independently packaged and powered and the Pepto server trays were geared for unpackaged custom designed circuit boards operating on a centeralized power distribution system. Because the electronics that were placed inside Pepto had their own power and packaging, space was exhausted quickly during assembly. In order to fit everything that needed to be flown, circuit boards (including GPS units) were placed on their side and stacked underneath other electronics. See the pictures below for the flight configuration of the Pepto capsule.
First Flight of Pepto
Pepto was launched and successfully recovered during the spring of 2005. However the design showed signs of weakness. The telemetry system failed to function properly which raised questions of the thermal integrity of the design. Also, upon impact with the ground, the tray fixtures broke allowing the internal electronics to tumble freely inside the capsule as it came to rest. This failure mechanism was of specific concern because if switches or terminals were disengaged, the tracking system would fail and prevent location of the capsule on the ground.
Based on the lessons learned from the first flight, the design was modified for the fall flight. The tray fixtures were reinforced and gaps in the insulation were taped to prevent cold air from entering the capsule.
Second Flight of Pepto
The second (and final flight) of Pepto resulted in a complete loss of most of the VAST tracking electronics and science equipment. Loss of infrastructure took nearly two years to build and test as some of the technologies used were no longer available on the free market (Pocket Trackers - manufactured by Bynoics).
The team took 1.5 hours to assemble the capsule on launch day. The balloon was full and ready to be released for an hour of this time. The first launch attempt failed due to tangled ropes. During the second launch attempt no ropes were used and the capsules were launched directly. This resulted in a successful launch. A total of 4 radio tracking radio systems were used including one that was a custom designed science telemetry system. One of the radio links was lost during the first launch attempt the second was lost 4 min into the flight, another radio reported the launch site as the location only for the entire flight. Thirty minutes into the flight the telemetry system failed and all 4 tracking systems had failed except for the one radio that simply reported the location of the launch site consistently for 2 days.
The team split up into 3 groups but the groups had no way of communicating with one another. Two groups tried to track the radio signal of the single radio still transmitting but they did not have a tuned directional antenna. One group explored the area that the package was projected to land but they did not have maps or knowledge of the burst altitude which is critical information needed to accurately estimate the landing zone. The recovery effort lasted until after 5pm which means the students were working for over 12 hours strait (including drivers).
Detailed notes were taken the day of the launch, a manuscript of these notes follows:
Notes Taken by Shingis on Oct. 30, 2005
6:20 am – arrived at a launch place (Starbuck). Started unloading and taking pictures Sci/Engr, Structures team – setting up the capsule, 1st HOBO connections were checked.
6:27 am - Launch team – prepared helium tanks to fill the balloon.
6:30 am - HOBO was setup to start at 7:30 am.
6:32 am – Comm team has successfully setup the tracker.
6:32 am – Launch team has started filling the balloons.
6:38 am – Comm team is setting up two laptops to receive telemetry and radio signal.
6:43 am – Launch team has filled the balloon, capacity of 12lb 6oz.
6:46 am – a cushion was placed on the bottom of the capsule to reduce the impact when landing.
6:48 am – Comm team – one of the radios is transmitting (W7UQ2)
6:53 am – Comm capsule is loaded, the total weight of 2lb 4oz
7:04 am – Structures team - parachute is ready
7:07 am – Sci/Eng team is testing telemetry, success.
7:22 am – Comm team – Rise 2 is go, W7UQ2 is go!
7:23 am – Structures, Sci/Eng – capsule is good to go
7:26 am – Comm team – Rise 1 is go!
7:29 am – Main capsule weight is 7lb 14oz
7:32 am – launch team – balloon capacity remeasured – 12lb 6oz.
7:37 am – assumed parachute ~ 1lb, balloon is filled to ~ 14lb.
7:40 am – balloon with capsule is ready to launch, lifted up to the air with ropes still holding.
7:41 am – LAUNCH! BAD! Ropes caught up and didn’t let go of the capsule.
7:43 am – alternate launch – SUCCESS! WRAP UP AND LEAVE!
9:26 am – direct data packet received from Rise 2. We went to the approximate landing zone, however exact position is unknown. Divided into 3 groups for the search:
9:54 am – Greg and Jeff received a direct data packet when they were in Pullman
9:55 am – trying to establish communication with one of the units (van) Being separate isn’t working out well - communication is lost. Plan is to regroup somewhere in Viola. Plan for regroup in Viola is changed to regrouping in Moscow. One of the units searched for a little while around Viola, no success.
10:10 am – last data packer received
11:18 am – taking off from Moscow to Viola, direct data packer received. We went to Rocky, talked to people who own the property (Lewis – Clark amateur radio shack). Had permission to stay and do whatever we want, however we could not receive it on simplex. Could not pick up the signal directly from Rocky and decided to go back to Lewiston and tried to pick it up from Alpowa Summin, on H-12, whose altitude is 2700 ft. When going to Rocky, we have received data packets twice from Moscow.
2:50 pm – Arrived at Alpowa Summit, we tried to block Rocky and receive signal – NEGATIVE.
3:08 pm – Driving back to Moscow, looked if we would receive signal on the way.
4:54 pm – Arrived at Pullman, started receiving packets from Moscow digipeter for Rise 2.
Rocky doesn’t pick up signal anymore.
Rescue teams were deployed during the months following the launch with no success. Detailed assessment was performed of the launch and design and a list of likely failure modes was created.
Failure Theories
Communications losses:
- Set to transmit too frequently-drained battery in first few minutes due to high current draw.
- Set to transmit too slowly (that’s why the battery lasted so long) also programmed to only report location where it was turned on.
- GPS got unplugged from pocket tracker during launch.
- Batteries not charged.
- Thermal insulation not sufficient to maintain minimum battery temperatures.
- Serial connection got unplugged during first launch attempt.
- GPS upside down/on its side/aluminum tape blocked radio signal from GPS.)
- Batteries not charged.
- Radio interfered with basic stamp program.
Lessons Learned
Pepto was a victim of programmatic and technical oversights. Inadequate testing was performed the weeks prior to launch and known failure modes were not addressed because the quadruple redundancy in radios made the students feel comfortable with one or two failures during launch. After the launch, each team listed their theories and brainstormed a list of preventative steps for future launches.
Preventative Steps For the Future
- Check programming of pocket trackers morning of launch (or during pre-flight test.)
- Put entire capsule together before morning of launch to practice assembly.
- Cancel launch due to readiness of comm. team and glitch in sci-eng test on wed 26th .
- Check batteries and or label batteries that are conditioned.
- Stronger development of leadership in comm. Team.
- Turn pocket trackers on during trip to launch site the morning of launch.
- Bring directional antenna and other supplies needed for emergency tracking effort.
- Morning of launch go/no go check off.
- Recovery team stationed at landing site watching for capsule.
- Radio Moscow to check of other hams can get fix on balloon before lift off.
Improvement Areas:
- Make greater effort toward conducting all tests and checking off all items on preflight checklist.
- Plan assembly of capsule.
- Plan launch kit organization and packing of vehicles. Organize parts and tools (better than grocery bags.)
- Better switch cover/protection for Rise 2 connection with GPS.
- Assemble capsule before morning of launch to check for lengths of straps, clearance issues, etc…
- Have more fun with walkie talkies, don’t let the grown-ups hog them.
General Insights for Future Missions:
- Identify roles for members during the morning of the launch, including: assembler, recorder, etc… for each team. Also identify back-ups in case someone sleeps in. (to prevent Hobo incidents-hobo operator not present morning of launch, no one knew how to program it.)
- Develop emergency rescue plans for capsule if communication fails. Include things like where to look first, antenna strategies etc…
- Back-up drivers to prevent people from driving too long.
The Recovery
In spring of 2008, more than 2 years after the capsule was launched, Pepto was returned to VAST. A hunter had found the capsule in a tree during the fall of 2007 and kept it in his house not knowing what to do with it. Matthew Vavrosky (my hero), one of the members of VAST took a car battery into a tire shop to get it charged for an upcoming launch as part of a VAST project. After telling an employee at the shop what the battery project was for, he told Matt that he had found something like what Matt had described while hunting and told him that he could come take a look at it to see if it was ours. We called the employee up on a weekend and went to his house. Sure enough, it was Pepto and it had not even been disassembled. The tape that sealed the gaps was still in place and all the electronics remained in their flight configurations.
Jasper Nance photographed the disassembly of the capsule, pictures can be found here.
One of the radios was housed in a separate capsule. This radio failed during the first launch attempt and it was confirmed that the serial connectors were unplugged. Other theories remain unconfirmed however upon inspection of the capsule it is likely that all theories may have contributed to the failure.
