# COSMIC-2 Mission Summary at Three Years in Orbit
## 3 Requirements, Products, and Performance  
### Key Requirements  
The program team conducted extensive pre- and post-launch requirement verification from levels 1-4. In Table 4 we summarize a few of the most important level 1 science threshold requirements and the system's performance to them.  
The selected TGRS neutral atmosphere science requirements relate to RO profile counts per day after quality control (QC) and retrieved bending angle and refractivity precision. Retrieved profile precision metrics are verified using early orbit data from 16 July-4 September 2019, when all satellites were still in the same orbit plane (REF). These data yield 270 inter-satellite retrieved profile pairs with separations \(\leq\)20 km. L2P signal rising occultation are excluded due to a tracking issue in early TGRS flight software (REF memo). This analysis verified bending angle, refractivity, dry temperature precision at various mean sea level (MLS) altitude levels from the surface to 60 km [27]. The 2 \(\upmu\)rad 30-60 km precision requirement is especially important as it measures bending angle precision with little contribution from the neutral atmosphere and therefore represents other system error sources including POD, residual ionosphere, and noise. Product latency is well below the 45 min median requirement (Section 3).  
Important TGRS ionosphere requirements are the TEC occultation and combined occultation and arc counts per day and absolute TEC uncertainty. GPS absolute total electron content is validated via comparisons to Swarm-B utilizing GPS data in certain regions with minimal ionospheric activity, and GLONASS absolute TEC is verified by comparing  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Description** & **Requirement** & **Verification Status** \\ \hline Neutral atmosphere profiles per day passing QC & \textgreater{}4000 & Met, typically \textgreater{}5000, ref. Section 3 \\ Neutral atmosphere profile median & \textless{}45 min & Met, typically \textgreater{}28 min, ref. Section 3 \\ product latency per day & \textless{}45 min & Met, typically \textgreater{}28 min, ref. Section 3 \\ Bending angle uncertainty, & 2 \(\upmu\)rad & Met, 1.6 \(\upmu\)rad [27]. \\ Referactivity uncertainty, 10–20 km & 0.1 N units & Met, 0.076 N units [27]. \\  & & Met 33\% of days January–May 2022, and 42\% of days in May 2022. Average \\ TEC occultations per day & \textgreater{}6000 & January–May 2022 is 5797 and May 2022 is 5870. Waiver issued. Waiver issued for 91.5\% compliance. \\  & & Met 31\% of days January–May 2022, and 65\% of days in May 2022. Average \\  & & 2022 is 11,948. Waiver issued for 91.5\% compliance. \\ Absolute TEC uncertainty & 3 TECU & Met, estimated 2.5 TECU for GPS and 2.6 TECU for GLONASS [15; 22] \\ TEC product median latency & \textless{}30 min & Met, typically \textgreater{}28 min, ref. Section 3 \\ per day & \textless{}30 min & Met, typically \textgreater{}28 min, ref. Section 3 \\ IVM in-situ plasma & 1\% & Met, ref. [25] \\ density precision & 1\% & Met, ref. [25] \\ \hline \hline \end{tabular}
\end{table}
Table 4: Selected level 1 science threshold requirement verification summary.  
COSMIC-2 GPS and GLONASS TEC observations with closely matching geometries [15; 22]. Both TEC products were shown to exceed the 3 TECU precision requirement following extensive calibration. TEC product latency is similar to the neutral atmosphere and has been below 30 min median for nearly all days in 2022 (see Section 3). IVM density data were validated by comparing with TGRS GNSS electron density and deemed to have a precision of 1% or better [25].