Tuesday, April 17, 2007

SDG-4 final update

Our best guess is that SDG-4 is down. There was one final report from Tennessee at around 00:00 UTC, but the signal was weak and fading rapidly. No further reports have been received.

I have contacted some hams in North Carolina via Echolink - none could hear the beacon.

Two possible scenarios come to mind... First, the balloon simply may not have withstood the peak solar flux (around 5pm local time) and popped. This is entirely possible. Second, the balloon may have encountered terrain over the mountains - i.e., it might have crashed into a tree! I think this is less likely - HYSPLIT showed altitude above ground level dropping to 1000 meters, but never lower. On the other hand, the Google Earth output from HYSPLIT did, in fact, show the trajectory going right through the side of a mountain (and emerging on the other side!).

For now, we are calling the search off... No more blind emails sent off to hams-unknown in the southeast, no more Echolink calls.

If anyone has any further news on SDG-4 beyond what has been posted here already, please let us know!

SDG-4 update 3:20PM EDT

More data from Jeff near Columbus, Ohio:

Here is another set. The signal popped back up to S6 when I rotated the KT34XAdown to~139 degrees from here in NW suburbs of Columbus. [This is consistent with our projections - the balloon should have been around Middleport, Ohio at the time.]


1815Z UP5H 58M A177 T07C L242 B2.7V
1818Z UP6H 00M A179 T09C L242 B2.7V
1820Z UP6H 02M A179 T09C L242 B2.7V
1821Z UP6H 04M A180 T07C L241 B2.7V
1823Z UP6H 06M A179 T08C L241 B2.7V
1825Z UP6H 08M A179 T07C L243 B2.7V
1827Z UP6H 10M A180 T09C L246 B2.7V
1829Z UP6H 12M A179 T09C L241 B2.7V
1831Z UP6H 14M A179 T07C L241 B2.7V
1838Z UP6H 20M A178 T08C L241 B2.7V
1840Z UP6H 22M A177 T0?C L244 B2.7V
1842Z UP6H 24M A180 T07C L241 B2.7V

SDG-4 update 2:33PM EDT

Jeff, K8ND near Columbus, Ohio copied the beacon and sent Pierre the following telemetry:

UP5H 08M A179 T07C L241 B2.7V
1728Z UP5H 10M A179 T07C L241 B2.7V
1730Z UP5H 12M A179 T08C L242 B2.7V
1732Z UP5H 14M A179 T07C L242 B2.7V
1734Z UP5H 16M A179 T07C L241 B2.7V
1737Z UP5H 20M A179 T07C L243 B2.7V
1739Z UP5H 22M A179 T08C L246 B2.7V
1741Z UP5H 24M A179 T09C L244 B2.7V
1743Z UP5H 26M A180 T09C L244 B2.7V
QSB, No Copy
1751Z UP5H 34M A179 T07C L245 B2.7V
Missed one - phone call!
1754Z UP5H 36M A180 T08C L246 B2.7V
1756Z UP5H 38M A179 T06C L24? B2.7V
1758Z UP5H 40M A179 T05C L243 B2.7V
1759Z UP5H 42M A179 T08C L246 B2.7V
1801Z UP5H 44M A179 T07C L242 B2.7V

SDG-4 update 2:11PM EDT

Here's some of the telemetry recorded by KA8VIT and decoded by Pierre Thomson (father of the beacon):

UP 2H 28M A 181 T 08C L 246 B 2.7V

UP 2H 38M A 180 T 07C L 245 B2.7V

UP 3H 32M A 180 T 08C L 244 B 2.7V

UP 3H 52M A 179 T 08C L 243 B 2.7V

UP 4H 08M A 180 T 08C L 244 B 2.7V

UP 4H 46M A 180 T 08C L 242 B 2.?


This is great news - it means that the pressure is, in fact, stable after four hours of flight!

SDG-4 update 1:36 PM EDT

Bill, KA8VIT, in Cleveland was continuing to copy the beacon at 17:07 UTC, but just barely.

Based on the scant data that we have available right now, my prediction for the flight (based on a READY HYSPLIT trajectory) goes like this:

Time in UTC Location
1700 New Straitsville, OH
1800 South of Middleport, OH
1900 Alum Creek, WV
2000 Wolf Pen, WV
2100 SE of Marion, VA
2200 SE of Wilkesboro, NC
2300 Huntersville, NC
0000 Between Monroe, NC and Lancaster, SC
0100 NE of Bishopville, SC

If you are near any of these areas (or even if you're not particularly close), please listen to 28.636 and try to copy some of the telemetry. We desperately need your help!

And by the way, the balloon should be clearly visible in the sky when it passes over - it's flying at about 6000 feet and the balloon is a bright white cylinder 20 feet long. It will look like a small, bright line in the sky. If you see it, let us know - and a picture would be awesome!


Update on SDG-4 at 12:33 EDT

More reception reports received - SDG-4 is still flying! Phil Manor reported that he continued to receive signals from the balloon until 11:27 EDT. The data showed fairly consistent pressure readings and good temperature and voltage data. From his beam heading and a BALLTRAK prediction, Phil estimates that the balloon may have been over Plymouth, Ohio at the time that he lost the signal.

The pressure seems to be a tiny bit lower than earlier (it ranged from 180-182 during the first hour or so, then slowly crept to 179-180) - this could be noise in the data, or it could indicate an actual increase in altitude. Altitude increase could result from the balloon stretching a bit (and thus slightly reducing its overall density - this is expected) or from a gas leak (in a superpressure balloon, the balloon will rise in response to a gas leak until ambient pressure is reached - then the balloon will descend).

We also received a reception report from Tim, K8NWD in Waterford, Michigan at 14:27 UTC and from Bill Chaikin, KA8VIT in Cleveland, Ohio (who continues to record the signal at this moment). Scott, N8VCL in Maple Heights, Ohio let us know that he was listening as it flew past the Cleveland area as well.

If you're hearing the balloon, please let us know! Any telemetry that you might copy is very valuable to us and a beam heading (and your location) would help, too!

I've copied some information about the beacon itself from Pierre Thomson's web site - this should help to decode what you're hearing:

The payload package includes:

* An 8-bit microcontroller (PIC 16C715)
* A barometric altimeter (MPX100A/LM358M)
* An outside temperature sensor (DS1721S)
* An insolation sensor (CdS cell in a ping-pong ball diffuser)
* Battery voltage monitor
* CW Beacon on 28.636 MHz (crystal oscillator)
* Vertically polarized 10m dipole antenna
* Eight AA Li-Fe batteries for 12V @ 2500 mAh

Telemetry format (sent every 2 minutes) :

DE KA2QPG BLN GPA/SD2 UP 14H34M A 033 T NEG 55C L 204 B 8.7V


UP = flight time in hours and minutes
A = altimeter (absolute pressure, 0 - 255)
T = outside temperature (-99 - 99 degrees C)
L = light level (0 - 255, uncalibrated)
B = battery voltage (0.0 - 9.9 volts)

The remaining time in the 2-minute cycle will have a Morse "dit" and a beep of the piezo sounder every 4 seconds.

SDG-4 superpressure balloon flight today

Our fourth superpressure attempt - dubbed Soli Deo Gloria 4 - was launched this morning from the grounds of the Grosse Pointe Academy at 8:52 AM EDT (12:52 UTC).

SDG-4 is a small, cylindrical superpressure balloon made from Mylar film. It is carrying a high-frequency radio beacon transmitting CW on 28.636 megahertz. The balloon is expected to continue flying throughout the day and into the evening, following a south-southeast track across central Ohio and points southward.

Initial data received by Phil Manor, an amateur radio operator in Warren, Michigan, indicate that the balloon achieved a stable float not long after launch. Phil continued receiving data from the balloon until approximately 10:30 AM EDT (14:30 UTC), when the balloon most likely dropped below the radio horizon at his location.

We are hoping to receive further reception reports from interested hams throughout the day - if you can monitor 28.636, please do so!