# Data Downloaded via Parachute from a NASA Super-Pressure Balloon
## 3 Descent and Recovery
### Reported Landing Sites  
Unfortunately, neither DRS reported or recorded its location during descent as they were supposed to (and as they did during the 2019 test flight). It is, therefore, impossible to reconstruct their true trajectories. DRS1 spontaneously started reporting back at 14:13:46 UT, after having reached the ground, and DRS2 started reporting back at 14:31:15 UT (intermittently at first and intermittently again overnight). Both DRS capsules reported lines of sight to many GNSS satellites. However, their initial reports included measurements of low battery voltages, and we later found that DRS2 was lying in a patch of snow. We infer that, although the temperature of the Raspberry Pis was successfully managed in space for 40 days (see Section 2.3), the adjacent batteries, which were used only after release, got very cold. We have previously used them in the stratosphere, but not for such extended periods.  
Self-reported GNSS coordinates after landing placed DRS1 at \(-47.88167^{\circ}\), \(-69.59300^{\circ}\) (altitude 786 m) and DRS2 at \(-47.86368^{\circ}\), \(-69.67452^{\circ}\) (altitude 806 m), after averaging over several readings to provide \(\sim\)2 m precision. These locations are 66.5 km and 58.3 km horizontally from their release points, respectively, 3.8 km and 1.6 km from the pre-release predicted locations or 2.4 km and 2.3 km from our best-estimate calculations that include weather data available afterwards. The true trajectories appear to have deviated approximately 950 m sideways from the predictions, with one landing 2.2 km earlier than expected and the other travelling 2.1 km farther, both within predicted precision.  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Event** & **Time (UT)** & **Latitude [deg]** & **Longitude [deg]** & **Altitude [m]** \\ \hline SPB log \#1 & 12:29:33 & \(-47.685\) & \(-70.518\) & 32,585 \\ SPB log \#2 & 12:30:37 & \(-47.692\) & \(-70.475\) & 32,488 \\ Release of DRS2 & 12:31:28 & \(-47.696\) & \(-70.444\) & 32,439 \\ SPB log \#3 & 12:31:40 & \(-47.697\) & \(-70.437\) & 32,428 \\ Release of DRS1 & 12:31:55 & \(-47.699\) & \(-70.421\) & 32,323 \\ SPB log \#4 & 12:32:44 & \(-47.707\) & \(-70.367\) & 31,981 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Contemporaneous logs from onboard superBIT around the time when two DRS capsules were released. Times are UT on 25 May 2023. SPB logs #1–4 recorded accurate GPS locations at known times, which we interpolated to the moments of release for DRS2 and DRS1.  
Our model for both the descent vector and its uncertainty thus appears accurate. The absolute uncertainty on our predictions is larger than previous drops because the high wind speed meant that capsules travelled farther downrange. Indeed, we had to extrapolate uncertainties from most of the test drops used to calibrate our model [6]. But, even in this regime, compared to our predicted landing sites, three of the four coordinate offsets are inside the predicted 68% confidence interval, with one just outside. Compared to our best-guess landing sites, all four offsets are _just_ inside. Furthermore, the two near-simultaneous trajectories neatly illustrate the irreducible component of uncertainty caused by small-scale spatial and temporal variations in wind velocity (gusts), as well as local topography, when the predicted trajectory at low altitude is only 21\({}^{\circ}\) below the horizontal. The two capsules started only 1.8 km (and 27 s) apart but ended up separated by 6.4 km.