# Development of the Romanian Radar Sensor for Space Surveillance and Tracking Activities +
## 5 Predicted Performances
### Mean Duration of the Observed Track  
The simulation comprised a 24 h interval starting at 30 March 2018 09:00 UTC and took into consideration space targets passing above the lowest clear elevation angle of the radar, which was 20\({}^{\circ}\), in ranges between 200 km and 5900 km at the Cheia location.  
Regarding the number of passing objects possible to be tracked with actual antenna speed parameters, the results were the following [19]:  
* The total daily number of trackable targets was 47,068, which signified more than 98.16% of the number of passing space objects.
* For orbital altitudes between 750 and 900 km, the number of passes was 14,836, which was equivalent to 30.94% of the total number of passing space targets. From this  
Figure 6: Minimum size of detectable targets according to the orbital altitude in CW mode [19].  
Figure 7: Estimated number of targets trackable in CW mode at varying elevation angles [19].  
number, 4394 were detectable distinct satellites, which represented 32% of the total number of detectable satellites.
* For orbital altitudes above 2000 km, the number of passes was 1747, which was approximately 3.65% of the total number of passing space targets.
* The highest density of trackable objects occurred at three adjacent orbital altitudes: 750 to 800 km, 800 to 850 km, and 850 to 900 km altitudes above Earth.  
Other values of interest were the number of space objects that had several passes in the observed sky sector for 24 h and the average duration of one pass. To this purpose, the mean, the standard deviation, and the median for angular arc tracking and track-time were computed:  
* For orbital altitudes from 750 to 800 km, 1471 objects had more than one passing, and only three satellites have one passing. The average and median times per passing were 1.95 min and 1.86 min.
* For orbital altitudes from 800 to 850 km, 1561 objects had more than one passing, and only one satellite had one passing. The total number of objects with two or more passings in the 800 to 850 km orbital regime was 1561, and only one satellite had one passing. The average and median times per passing were 2.25 min and 2.08 min.
* For orbital altitudes from 850 to 900 km, 1355 objects had more than one passing, and only three satellites had one passing. The average and median times per passing were 2.59 min and 2.32 min.  
The estimations shows that the minimum mean tracking period of a space object that could be repeatedly discovered by the radar was at least 1.86 min with an average delay between tracks of at least 360 min for the same object.  
The average antenna repositioning time from the end of a track to the expected start position of the next scheduled track was 4 to 6 min at the actual moving speed of the antenna.  
The total average duration required to track one space object was a 6 to 8 min value resulting from the tracking duration of the present target added to the duration for calculating if the next target could be tracked, as well as repositioning time to the start of the following track. For orbital altitudes between 750 and 900 km, the estimated number of daily trackable targets was 180 to 240, out of which the largest number of distinct targets tracked in two passes was between 90 and 120. Should the antenna positioning speed be doubled, the number of tracked targets could be increased by 25% to 40%.