HacDC Spaceblimp

A collection of stuff about HacDC's near space initiatives, including the Hackerspaces In Space Contest entry (2010).

Documentation

Spaceblimp-2

Flight date: 8/21/10

Time of liftoff: 10:47 (All times are GMT-5)

Time of touchdown: 11:49

Time of recovery: 12:20

Total flight time: 1:02 (62 minutes)

Liftoff to recovery time: 1:33 (93 minutes)

Touchdown to recovery time: 0:31 (31 minutes)

Weight of payload/chute: 1lb 13oz

Total cost of launch: $320

Airframe & Rigging:

Balloon: 800g Kaymont/Totex latex weather balloon cost: $69

Parachute Cord: 250-lb test Dacron line

Balloon Cord: 50-lb test Dacron line

Fill: 190 cubic-feet Helium - cost: $95 (~10# nozzle lift, gas @ $0.50/Cu-ft)

Chute: Rocketchutes flat 24" - cost: $9

Capsule: Insulated lunch pail (free, valued at ~$7)

Payload:

Canon model PowerShot SD300 running CHDK (Canon Hack Development Kit) intervalometer script - cost: $20

Canon Li battery cost: $3.25

Canon 2GB SD card: $6

Falcom (uBlox based) GPS receiver + Serantel Antenna module - cost $47

Radiometrix VHF Narrow Band 300mW transmitter - cost $38

Ultralife U9VL-X Lithium-Manganese Dioxide non-rechargable battery cost: $7

Flight computer/Terminal Node Controller (TNC) - cost $19

HacDC Spaceblimp Flickr Group Pool

/ aprs.fi Flight Map

Some details on the avionics:

Our balloon carried a minimalist avionics package consisting of a custom built APRS tracker and a Canon PowerShot SD300 digital camera.

The camera is configured to take pictures every 20 seconds using CHDK (http://chdk.wikia.com/wiki/CHDK) and one of the stock intervalometer scripts. It is powered by its own rechargeable lithium battery and operates independently of the tracker.

The tracker is based around an atmega328p AVR microcontroller, running code derived from an open source AVR based APRS tracker called the WhereAVR (http://garydion.com/projects/whereavr/). By updating the sine wave generation code to use filtered 7-bit pulse width modulation in place of the 4-bit resistor network, we were able to improve tone quality with a reduced part count. A few additional components were added, including an I2C eeprom for local backup of flight data, external and internal I2C temperature sensors, and a cutdown MOSFET for switching power to a short strip of nichrome wire coiled around the balloon line (the cutdown system was not used in our final flight because we were apprehensive about the complications it added to the balloon rigging).

To keep things light, compact, and simple, we designed a surface mount circuit board to integrate all of the trackers components with a Falcom FSA03 GPS module and a 300mW Radiometrix HX-1 144.39 MHz transmitter. The board was fabricated using the toner transfer method and hand soldered.

For an antenna we used the common 300 ohm twinlead j-pole design (http://www.qsl.net/wb3gck/jpole.htm), tuned as close as possible for use on our frequency (144.39 MHz) and fed with a short length of 50 ohm coax cable for routing/strain relief.

The tracker is powered by a single lithium 9v battery, and regulated down to 5v and 3.3v by linear regulators on the board. The typically undesirable loss of power to heat with these regulators is useful in this case for warming the electronics in the extreme cold temperatures encountered during the flight.

Each chase vehicle had a radio tuned to 146.415 for simplex communication between the vehicles, and another radio tuned to 144.390 for receiving packets from the balloon. For packet decoding we used radios with built in TNCs or laptops with external modems/soundcard modems and TNC software (Soundmodem and Xastir for Linux, AGWPE and UI-View for Windows).

Press

Email from Heather Goss (8/25/10)

(DCist, http://dcist.com/profile/dcist_heather/posts)

"I'll probably run most of this as a straight interview -- if it helps, answer lengths of a sentence or two, to a paragraph are usually good, unless it requires a more detailed answer. Can't wait to hear more!

• Can you tell me a little about HacDC? How did you get involved? What kinds of other big projects have you done?

The official description of what we are can be found at http://hacdc.org/about/. The shorter version is that HacDC is a member-supported space dedicated to making things by inventing, extending and repurposing new and junked stuff. We also research common interests by forming working groups and building projects, and building associations with like minded communities of interest, in DC and beyond. The general public is welcome to all events and is encouraged to join the hacker space.

I [Alberto] came to HacDC via DorkbotDC, the DC chapter of the international group of people to doing strange things with electricity. Two of our members, Nick Farr and Adam Koeppel were DorkbotDC regulars and they germinated the idea to form a hacker space on DC. Parallel to their efforts to raise enough charter members to rent a space, a joint DorkbotDC and HacDC build-a-thon event was planned at the Koshland Museum of Science, spearheaded by DorkbotDC regular Mark Adams. The first friends and members of HacDC came from that community.

HacDC is a relatively young organization but has organized several workshops aimed at teaching the basic skills necessary to be able to approach present and past technology with the creative mindset to mutate it in an innovative or idiosyncratic way. HacDC maintains a wiki with much of the organization's history (in progress) including ongoing and past projects: http://wiki.hacdc.org/

• Tell me about Hackerspaces in Space. What was the goal? How many groups were involved?

The Hackerspaces in space contest was initiated by Workshop 88 (http://www.workshop88.com/), a hackerspace in Chicago. According to their website, 19 groups are involved from as far away as Thailand. The contest officially ended on August 31st. The rules are here: http://www.workshop88.com/space/assets/download2.php and include rules on cost, launch and recovery team size. Scoring criteria include retrieval time, weight of package, and cost. Our working group was code named the Spaceblimp Project because Near-Space Balloon Project didn't have the same ring to it; besides, Spaceblimp has a certain 70s disaster movie feel to it and this whole thing could have turned out to be so much pie in the sky. The team included a small core group of very talented and motivated people who dedicated many, many hours of planning, design, experimentation/prototyping, fabrication, funding, and good ol'sweat. It was their commitment and dedication that made this happen.

• What was your experience building the spaceblimp? Did you have any interesting challenges to overcome? How long did it take to build the blimp?

The rules were pretty limiting and we're still not sure where we rank. We learned that it's quite difficult to get a balloon into near space cheaply. There are also regional differences in materials/supplies pricing that give a relative advantage to some groups. We lost one balloon the week before the successful launch and that was traumatic and demoralizing. We had to weigh the desire to add redundant systems and more sensors—both of which would have allowed us to account for more contingencies—against the need to keep the payload light. As with most projects, the highly motivated few who drove the process had the most to lose so they were more nervous than the bystanders on launch day.

• What was launch day like? (I'm curious more about everyone's feelings/reactions than a blow-by-blow of the day. Also can you give me the nitty gitty -- time, location, how long did it run.) Did anything surprising or crazy happen?

The final launch took place on August 21, at Camp Spring, MD. The jet stream was acting crazy so the balloon deviated from the original prediction. The team was divided into launch and recovery subgroups. They both became parts of the chase team once the balloon was aloft. The stats on the launch can be found on the wiki: http://wiki.hacdc.org/index.php/HacDC_Spaceblimp#Documentation

"My feeling, at least, was excitement mingled with extreme dread; we'd lost the last capsule pretty badly, and if this one didn't make it we would completely miss the competition deadline. I really wanted to see it all go well, and it's really thrilling to do that countdown and release it into the sky," recalls Tom Cohlmia.

The package descended a short distance from a private residence's pool, just beyond reach from outside the fence. Nobody was home and we were faced with a dilemma, jump the low fence and grab the package, or wait until the owners arrive? The decision was made for us as the owners' car pulled up. Our efforts turned to explaining to them why a group of people were congregated at the edge of their relatively rural property. They were amenable and allowed us to retrieve the package and go on our way. We gathered at a church up the road and converged there with the rest of the chasers. We cracked the "launch box" open and let it warm up a bit before pulling the SD card and transferring the images: without a photograph of the curvature of the planet, we would have nothing except a fun chase. As the images of blackness the of space appeared on the laptop, there was a great cheer.

• What were the results of HacDC's launch in particular? Was it successful? How high did it go? And were you able to recover your payload? Did any other blimps achieve something spectacular?

"Ours was a big success! The payload went to 60,000 feet, and then parachuted back to the ground. The payload was found in someone's backyard, a few feet from their swimming pool. Everything was intact, though, and the pictures turned out great. Total time from launch to recovery, 1 hr 33 mins, traveling 27 miles as the crow flies."

• What are the applications of the spaceblimp project? (What kinds of research can be done with blimps, and/or can even the process of developing new near-spacecraft like this help us in other ways?)

We look forward to launching another balloon without having to worry about meeting contest criteria. We're talking about adding an accelerometer, several cameras with faceted mirror array to get many angles at once, and perhaps including video.

There are a wide range of applications to this kind of technology, all of which have the potential of engaging communities at the grass roots level in the observation and analysis of the kind of scientific data collected from (near)space. Given the controversies over issues like global warming, land use, environmental disaster (yes, BP and Exxon, we are looking at you,) having a means for communities to monitor and record their own world and the changes in it is increasingly important. This technology greatly democratizes access to most of the value of a space program (satellites, etc.) without the cost. A relatively small group can monitor air quality, haze, temperature, radiation, and many other factors live and near-real time from 60,000 to 120,000 feet for very little money—without dependence on large government agencies or commercial organizations.

In addition, the project provides a really exciting platform for a range of educational opportunities- all of which include the excitement of seeing the student's own work go into (near)space! We have had both school-age kids and teachers participate in our activities, and everyone went away excited about participating, along with being very interested in perhaps doing their own near-space balloon launch in the future! One thing is for certain: kids really "get it" about the fun and potential of high-altitude balloon launches!

"If there's anything else you want to add, please let me know! Also, please send along any helpful links (I've got the ones to HacDC, Hackerspace, and the Flickr page), as well as a short bio describing you and anyone else who responds. Thanks!"

Some quotes from the number crunching

From an email dated 8/21/10:

Woot! And because I just can't look at the raw numbers without my

graphing fingers getting all itchy....

[1] is the rise/fall profile. Kinda boring. For more fun, have a look at [2], which is calculated by differencing altitude and time, and dividing. Nice freefall until the chute opens!

Many graphs just confirm stuff was working. gpsSatellites_time.pdf and gpsHeading_time.pdf, for instance.

The two temperature graphs, temp_time.pdf and temp_altitude.pdf give a good idea of how cold it is up there (-50C Brrr...) and an test of our improved insulation -- we bottomed out at a positively summery 6C.

The neatest (IMO) is [3] which shows the balloon's lateral travel as a function of its altitude, which is a good guess at windspeed. There's four points, one each for the GPS's speed variable and a calculated speed (from differencing location and time) and one each for rising and falling. Overall, a decent profile of winds aloft.

All files are hosted up on a bazaar repo at [4]. You can browse it directly. blimp2_eeprom_log.txt has a copy of the raw data (thanks Nick), and analyseBlimp.R has my R code for all the graphs. (apt-get install

r-base or just google "R"). — Elliot Williams

Related Links

HacDC Spaceblimp Flickr Group

GPS visualizations of balloon trajectory by Nick Beauregard (from the Flickr Group):

Google Earth GPS trajectory visualization and Google Maps GPS trajectory visualization

HacDC Spaceblimp Project:

Main Page	Press Page	First Launch (Found)	Second Launch (Successful)
Third Launch (Successful)	Fourth Launch (Successful)	Fifth Launch (3% short of goal)	Sixth Launch (Successful)	Seventh Launch (Successful)

HacDC Spaceblimp Team Contact Info:

[email protected]

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