2024-06-13 19:21:56 +00:00
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<figure>
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<img src="_Sb7_peak.jpg" title="_Sb7_peak.jpg" width="800" />
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<figcaption>_Sb7_peak.jpg</figcaption>
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</figure>
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# Flight Summary
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<figure>
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<img src="_Sb7_flight_path.jpg" title="_Sb7_flight_path.jpg"
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width="750" />
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<figcaption>_Sb7_flight_path.jpg</figcaption>
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</figure>
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| Date of launch: | Saturday, April 14, 2018 |
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|------------------------------:|---------------------------------------------|
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| Time of launch: | 11:08 |
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| Time of landing: | 14:30 |
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| Time of recovery: | ~17:15 |
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| Flight duration: | 3:22:00 |
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| Peak recorded altitude: | TBD |
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| Location of launch: | Strasburg VA, (38 59'48.77"N 78 21'03.27"W) |
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| Location of landing: | Manchester MD, (39 40'33.6"N 76 44'03.9"W) |
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| Distance (launch to landing): | 98.3 mi, (158.2 km) |
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| Balloon type: | 1500 g Kaymont |
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| Payload weight: | TBD |
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| Balloon lift: | TBD |
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| Net lift: | TBD |
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------------------------------------------------------------------------
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# Project Description & Status
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SpaceBlimp 7 was designed as a community project driven by independent
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specialists from DC (Nancy C. Wolfson-Project Manager), Maryland, and
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members from HacDC (Enrique Cobas-Technical Manager), Rockville
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Makerspace (Samarth C. & David R. DeLalio- Technical Manager), and
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Unallocated Hackerspace. Spaceblimp 7 is an educational and exploratory
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stratospheric balloon project that lofts various payloads to near-space
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(about 100,000ft). The team is dedicated to experimenting with new
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technologies that will make near space activities less expensive and
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more broadly accessible. From electronics to mechanical design to
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physics, the interconnectedness of disciplines teaches a lesson in
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engineering teamwork and collaboration.
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The project has Technical, logistical and Educational goals which are
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described below. Spaceblimp 7 looks to add new components that weren???t
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part of HacDC???s previous six Spaceblimp launches. By forming a
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partnership with several other area makerspaces, volunteers, hackers and
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educators we are expanding our team and pooling resources. By expanding
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the project we aim to increase its visibility and benefit all the
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organizations involved as well as an increase fund-raising opportunities
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to help sustain all the partners/organizations and the project
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Spaceblimp in the long-term. This will also expose high school students
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to educational and technical resources outside of the school environment
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as well as giving all the participants the opportunity to share skills
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and interests to work together and learn from one another to achieve
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shared goals. Local area hackers and space enthusiasts will also benefit
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by being able to actively participate and develop skills in the design
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and launch of the payloads.
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Local area hackers, space enthusiasts, and community members have come
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together to share and learn new skills in the design, construction, and
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launch of the project.The sixth launch, Spaceblimp 6, reached 104,000ft.
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Spaceblimp 7 is being done in collaboration with Rockville Makerspace
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[1](http://rockvillesciencecenter.org/programs/studio-i-makerspace/) and
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Unallocated Space [2](https://www.unallocatedspace.org/).
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COMING SOON: -Technical, Logistical, Educational and Outreach Results.
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-The Story Behind the Spaceblimp 7 -Photo Galery
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# Project Goals
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Baseline **technical goals** are the safe and successful launch,
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tracking and recovery of a stratospheric balloon and its payloads. These
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goals involve exploration of concepts of buoyancy, basic electronics and
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energy storage, triangulation and timekeeping, radio propagation,
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weather prediction, FAA regulations and stratospheric environment
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conditions. In addition to these baseline goals, the project will
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welcome additional technical goals from volunteers and students
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primarily in the form of payload experiments suggested, designed and
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built by them. Spaceblimp will encourage use of CubeSat geometry
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payloads to give students experience with the CubeSat design constraints
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and to foster discussion with future other CubeSat missions.
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The **educational objective** is primarily to provide an engaging,
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multi-day hands-on educational experience for students and volunteers
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heavily focused on STEM. Students will be engaged in a hands-on lesson
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by disassembling, reassembling and testing the basic tracking module
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components (GPS, radios) and other payloads. The nature of the balloon
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flight will naturally lead to discussion of scientific subjects like
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buoyancy, atmospheric composition and density, radio propagation,
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weather prediction and technical topics like power consumption and
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energy storage. Students will have first-hand exposure to a team working
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environment with delegation of responsibilities and the necessary
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communication and coordination. Critically, students will be allowed to
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suggest, design and build their own balloon payloads to be launched into
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near-space. This kind of self-directed educational approach uses
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students own natural curiosity and motivation to increase engagement and
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their sense of ownership of the resulting project.
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# Flight Summary
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After two weather-related postponements, launch took place on Saturday
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April 14, 2018, at Strasburg VA. Spaceblimp 7 was launched from Shopping
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Center Drive in Strasburg, VA and was recovered just outside of Pretty
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Boy Reservoir in Manchester, MD, just south of the Pennsylvania border.
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As indicated by the recorded track above, GPS coodinates were lost near
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Harper's Ferry, WV at an altitude about 30,000ft and regained during the
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descent. At the moment the cause for both GPS receivers to lose their
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lock at roughly the same time is unexplained. Possibilities include
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interference from the Raspberry Pi Power Supply DC-DC Converter or jet
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stream turbulence rocking the payload, causing loss of line-of-sight to
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GPS satellites. However, the GPS lock was reliable at first, and was
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regained during the more turbulent descent phase.
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# Logistics
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Project logistics include those necessary to achieve the technical
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goals, but also networking of area makerspaces and volunteers, outreach
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to local governments, funding sources and potential sponsors,
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coordination of project documentation and public exhibition of the
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project. This may include informational booths at relevant area events,
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compilation of video and publication of a project wiki. All new partners
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(including students) will be able to add or edit our project plan and
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proposed new topics for the meeting???s agenda.
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Points of Contact: HacDC: Enrique C, Technical Manager and Funding POC,
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enrique@hacdc.org HacDC: Nancy W, Project, Logistics and Student
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Outreach Manager Rockville RSC: Sam C, Technical Manager Rockville RSC:
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David D, Logistics and Outreach Manager Unallocated Space: Buddy,
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Technical and Logistics Manager
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# Environmental Data
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A nearly-complete record of sensor measurements was obtained from the
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Raspberry Pi Pimoroni Enviro PHAT sensor board. These divided into two
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data logs, one for pressure, temperature, illumination, illumination
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color and one for 3-axis acceleration and compass heading. The former
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acquired data several times per minute while the latter was acquired at
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about 40Hz. These were acquired and analyzed using Python scripts and
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plotted in gnuplot.
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The pressure drops as expected from atmospheric (101kPa) to 1.68kPa. The
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minmium pressure recorded corresponds approximately to 94,000ft altitude
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according to some online calculators. Since we lack a GPS log of
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altitude at high altitudes, this is an important estimate. However, the
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sensor component on the Enviro PHAT is only rated down to 30kPa and
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readings far below this range may be untrustworthy. We may perform
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additional tests of the EnviroPHAT board in a vacuum chamber to
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establish a calibration. In addition the timestamp for the minimum
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pressure (171156 UTC) may be incorrect due to an unexplained glitch (see
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below).
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**For all plots below, Flight Time (sec) was obtained by dividing evenly
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among all timestamps between 15:00:00 and 18:00:00 UTC. However, 18:00
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UTC should actually read 18:30 UTC (see glitch below). In addition, this
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method hides the uneven distribution of data collection especially in
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accelerometer data. In reality this was acquired in bursts at 40Hz.**
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<figure>
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<img src="Sb7P_ftime.png" title="File:Sb7P_ftime.png" />
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<figcaption><a
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href="File:Sb7P_ftime.png">File:Sb7P_ftime.png</a></figcaption>
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</figure>
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**Glitch at 164737 UTC.**
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At 16:47:37.75 an unexplained glitch occurred: the timestamps in the
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environmental sensor log jump backwards almost 30 minutes to 161717. The
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pressure log drops suddenly from 8.388kPa to 7.042kPa, a drop of
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1.346kPa. Note the Pi Zero doesn???t have an onboard clock so timestamps
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represent the running time of the script rather than the real absolute
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time. Extrapolating from the rate of pressure drop just before and after
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that point, the drop should have taken about 6 minutes. This is a
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reasonable delay for the Raspberry Pi to shutdown, reboot and complete a
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file system check and resume the measurement script. The glitch matches
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an unusually turbulent segment in the accelerometer data but the
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readings don't seem harmful (+/-0.1g at 1Hz). Far more turbulence
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occurred several minutes later during the ascent (+/-0.2g 1Hz), during
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the descent (+/-0.5g \>2Hz) and during the landing (+/-2.0g) with no
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corresponding malfunctions.
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The most turbulent part of the ascent (+/-0.2g at 1 Hz) occurred several
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minutes later and during the decent
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<figure>
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<img src="Pglitch_ftime.png" title="File:Pglitch_ftime.png" />
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<figcaption><a
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href="File:Pglitch_ftime.png">File:Pglitch_ftime.png</a></figcaption>
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</figure>
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**Temperature**
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Temperature readings fall steadily from ambient ground temperature about
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29.7 C to -39.9C at 16:20:19 UTC when the pressure reading was 17,568 Pa
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or about 40,300 ft calculated altitude. It then rises again to 36.3 C at
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17:12:10 UTC\* (the payload is in the sun and there???s less convective
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cooling with less air). That???s roughly the peak altitude. Then the
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temperature falls more steeply as the payload descends into cold (-40C)
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air, and then warms near ground altitude where the air is warmer.
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<figure>
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<img src="Sb7T_ftime.png" title="File:Sb7T_ftime.png" />
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<figcaption><a
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href="File:Sb7T_ftime.png">File:Sb7T_ftime.png</a></figcaption>
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</figure>
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**Illumination**
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Direct sunlight maxes out the illumination sensor (at 65,535 bits) and
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most of the data is thus this value. But some data points are lower,
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possibly measurements taken randomly in the shade of the nylon strap as
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the payload rotated. These would be measurements of the sky brightness
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not including direct sunlight, and they show a trend. They begin hear
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60,000 and fall steadily to 15,000, i.e the sky transitions from bright
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to relatively dark. Illumination includes light scattered from the
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balloon and rigging. Large deviations from the max value (i.e. dark
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measurements) stop abruptly near the peak altitude. I???ll guess the
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payload was spinning too fast in descent to acquire a complete
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measurement in the shade.
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<figure>
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<img src="Sb7Lux_ftime.png" title="File:Sb7Lux_ftime.png" />
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<figcaption><a
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href="File:Sb7Lux_ftime.png">File:Sb7Lux_ftime.png</a></figcaption>
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</figure>
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**Blueishness**
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I calculated blue saturation by taking the Blue/RBG ratio in the RGB
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sensor data. Again, most of the time the sensor is maxed out by direct
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sunlight, setting the Blue/Red ratio to 1.0. However in the shade the
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measurement is meaningful. The sky illumination becomes more blue for
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about 2000 seconds (35-40 minutes) and then becomes less blue. At the
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highest altitudes the illumination is actually slightly reddish (the
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latex balloon color?).
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<figure>
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<img src="Sb7Blue_fltime.png" title="File:Sb7Blue_fltime.png" />
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<figcaption><a
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href="File:Sb7Blue_fltime.png">File:Sb7Blue_fltime.png</a></figcaption>
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</figure>
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**Delay between measurements**
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In principle all measurements should take the same amount of time,
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although some scatter is expected from the script swapping between fast
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accelerometer data (about 10 seconds worth) and environmental sensor
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data (measured every few seconds). The Raspberry Pi Zero was also tasked
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with photographing another payload every 60 seconds or so, an operation
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that could hog the CPU or the microSD card momentarily. These should be
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regular, consistent delays throughout the flight.
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The timestamp differential between measurements is largely binomial; the
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measurements are either 21 or 27ms apart although there's significant
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scatter even up to 55ms.
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The **glitch** is visible in this data as well, as a statistical change
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in the measurement delay times: the fastest measurements (20.1-20.5ms)
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became more common than they were before. This changed lasted the
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remaining duration of the flight. The increased measurement delays
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exactly at the glitch time (6336 flight seconds or 16:48:30.5 UTC) are
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consistent with the script running while boot processes are still
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momentarily running after a reboot.
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<figure>
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<img src="Sb7Delay_ftime.png" title="File:Sb7Delay_ftime.png" />
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<figcaption><a
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href="File:Sb7Delay_ftime.png">File:Sb7Delay_ftime.png</a></figcaption>
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</figure>
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# Accelerometer Data
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The ascent phase was gentle with excursions of +/- 0.2g. There's no
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indication of an acceleration anomaly just prior to the glitch. The
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balloon pop occurs near 17:12:19\* UTC where the total acceleration
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suddenly drops from 1.0g to below 0.1g for several seconds. Terminal
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velocity is approached very quickly as within 10 seconds the payload
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registers an average of about 1.0g again.
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<figure>
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<img src="Sb7Accelg_pop_ftime.png"
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title="File:Sb7Accelg_pop_ftime.png" />
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<figcaption><a
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href="File:Sb7Accelg_pop_ftime.png">File:Sb7Accelg_pop_ftime.png</a></figcaption>
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</figure>
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Minimum Pressure: 1685Pa at 17:11:56.1\* UTC.
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Peak Temperature: 36.25C at 17:12:10.7\* UTC.
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Last '~1G' Data: 1.07g at 17:12:18.5\* UTC.
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First 'Zero-G' Data: 0.1g at 17:12:19.1 UTC.\*\*
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- Timestamps after 164737 are slow by 30 minutes due to a glitch (see
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glitch discussion above). 171200 corresponds to 17:42 UTC.
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<!-- -->
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- - Note the the sequence is 1.07, 1.75, 1.70, -0.06, 0.10g in a span of
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0.6 seconds.
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# System Logs
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**Useful Links** Working documents on Google Drive:
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[3](https://drive.google.com/open?id=1Lw55HiaDk5GbLUFwuXcTWeM44eYJ7sq1)
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2024-06-13 01:48:44 +00:00
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<noinclude> </noinclude>
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