Changes

| launch site = Brigantino Park, Hollister, CA

| launch site = Brigantino Park, Hollister, CA

| launch coordinates = 36.849, -121.433

| launch coordinates = 36.849, -121.433

| flight duration = 5h:12m (first) <br/>

| flight duration = 5h:12m (first) <br/> 5h:40m (second)

| flight length = 195 km (first) <br/>

| flight length = 195 km (first) <br/> 236 km (second)

| flight profile = Ballast control (first) <br/> Standard latex (second)

| flight profile = Ballast control (first) <br/> Standard latex (second)

| landing time = May 18, 2019, 14:47 PDT (first) <br/> May 19, 2019, 21:10 PDT (second)

| landing time = May 18, 2019, 14:47 PDT (first) <br/> May 19, 2019, 21:10 PDT (second)

==Flight synopsis==

==Flight synopsis==

[[File:Ssi86traj.png|thumb|Mission trajectory (first segment)]]

[[File:Ssi86traj.png|400px|thumb|Mission trajectory]]

'''May 18 0935 PDT:''' Balloon released after being adjusted to a barely perceptible ascent rate. The mass of some 5m of tether was sufficient to cancel net lift, and an upward thrust was necessary at release time. Initial motion was very slowly to the southeast.

'''May 18 0935 PDT:''' Balloon released after being adjusted to a barely perceptible ascent rate. The mass of some 5m of tether was sufficient to cancel net lift, and an upward thrust was necessary at release time. Initial motion was very slowly to the southeast.

'''May 18 1143 PDT:''' After slowing ascent, balloon reached maximum altitude at 4430m over (37.3780, -121.0420). Balloon then began to descend. While it was not clear at the time why ascent stopped, it is apparent in retrospect that the trajectory had entered areas of inclement weather, and downdrafts and/or rain were pushing the balloon downward.

'''May 18 1143 PDT:''' After slowing ascent, balloon reached maximum altitude at 4430m over (37.3780, -121.0420). Balloon then began to descend. While it was not clear at the time why ascent stopped, it is apparent in retrospect that the trajectory had entered areas of inclement weather, and downdrafts and/or rain were pushing the balloon downward.

'''May 18 1153 PDT:''' Descent rate accelerated to an alarming 2.0 m/s over (37.462, -120.970). Although it was believed that the equilibrium ascent rate was already too high, ballasting was seriously considered in light of this rapid descent.

'''May 18 1153 PDT:''' Descent rate accelerated to an alarming 2.0 m/s over (37.462, -120.970), prompting immediate ballasting.

'''May 18 1220 PDT:''' After two ballast events, the trajectory leveled off over (37.713, -120.908), reaching a minimum altitude of 1220 m, and then resumed ascent just above 0.5 m/s. This was viewed as having effectively delayed launch by 2 hours and therefore a net benefit for mission endurance.

'''May 18 1220 PDT:''' After two ballast events, the trajectory leveled off over (37.713, -120.908), reaching a minimum altitude of 1220 m, and then resumed ascent just above 0.5 m/s. This was viewed as having effectively delayed launch by 2 hours and therefore a net benefit for mission endurance.

'''May 18 1331 PDT:''' Balloon equilibrates at 3431m, a second altitude maximum, over (38.082, -120.868).

'''May 18 1331 PDT:''' Balloon equilibrated at 3431m, a second altitude maximum, over (38.082, -120.868).

'''May 18 1341 PDT:''' Balloon descends at over 2 m/s less than 2km above the ground, again likely due to downdrafts and/or rain, prompting a series of frantic ballast events. Due to the low altitude and rising ground elevation, the trajectory was within two communications intervals of flight termination. All hopes of a long-endurance flight had been abandoned; survival was the only priority.

'''May 18 1341 PDT:''' Balloon descended at over 2 m/s less than 2km above the ground, again likely due to downdrafts and/or rain, prompting a series of frantic ballast events. Due to the low altitude and rising ground elevation, the trajectory was within two communications intervals of flight termination. All hopes of a long-endurance flight had been abandoned; survival was the only priority.

'''May 18 1416 PDT:''' Descent slows and balloon reaches a minimum altitude of 351m, less than 80m above the ground elevation of 285m at (38.277, -120.799) just east of Pardee Reservoir in Calaveras County (due to hilly terrain, it is possible the balloon was even closer to the ground and maybe even made contact). Nevertheless, the trajectory was recovered and ascent resumed.

'''May 18 1416 PDT:''' Descent slowed and balloon reached a minimum altitude of 351m, less than 80m above the ground elevation of 285m at (38.277, -120.799) just east of Pardee Reservoir in Calaveras County (due to hilly terrain, it is possible the balloon was even closer to the ground and maybe even made contact). Nevertheless, the trajectory was recovered and ascent resumed. A ballast command was sent to make sure ascent was steady enough to clear the rising Sierra Nevada foothills.

'''May 18 1446 PDT:''' After several consecutive intervals of ascent, sudden descent was observed at a rapid enough speed to terminate flight by the next communication. A ballast interval was sent --- too little, too late in retrospect.

'''May 18 1446 PDT:''' After several consecutive intervals of ascent, sudden descent was observed at a rapid enough speed to terminate flight by the next communication. A ballast interval was sent --- too little, too late in retrospect.

'''May 18 1451 PDT:''' Balloon reported its final resting coordinates and elevation. After the next communication, flight termination was confirmed.

'''May 18 1451 PDT:''' Balloon reported its final resting coordinates and elevation. After the next communication, flight termination was confirmed.

'''May 19 1608 PDT:''' Communications ceased, presumably due to rain. By now it had become clear that at least the last two hours of the flight had been in the midst of inclement weather.

'''May 18 1608 PDT:''' Communications ceased, presumably due to rain. By now it had become clear that at least the last two hours of the flight had been in the midst of inclement weather.

 

 

 

 

'''May 20 1952 PDT:''' Last RockBlock message received. It was not until the evening of May 23 that efforts were made to contact local individuals for recovery and the second flight was discovered.

[[File:Ssi86profile.png|frameless|800px|center]]

[[File:Ssi86profile.png|frameless|800px|center]]