INFRASOUND Infrasound Detection of Rocket Launches Gopalaswamy Bharath a , Smirnoff Alexandr b a Postdoctoral Associate, Peace Studies Program, Cornell University, Ithaca, USA b Institute of Geophysical Research, National Nuclear Center, Kazakhstan Event Identification Figure 1. Geographical location and configuration of I31KZ infrasound array I31KZ (50.41 N 58.03 E) is set up on the North-West of Kazakhstan. It is part of the International Monitoring System (IMS) composed of 60 infrasound stations for the enforcement of the Comprehensive Nuclear Test Ban Treaty (CTBT) (Figure 1A). Even not fully completed, this network already allows a global Earth coverage for infrasound monitoring. Figure 1B shows the detailed station map. The callout shows configuration of the group having a form of a triangle with a 2km side. The central point of this triangle is surrounded with another four elements located in a square with a 200m side. The triangle and the square have the same geometric center. The array is composed of eight MB2000 type microbarometers that can measure pressure fluctuations from 0.003 up to 27 Hz with an electronic noise level of 2 mPa/rms in 0.02-4 Hz band. I31 KZ (50.40 N, 58.3 E) Zenith Launch Azimuth =45 deg Land Time: 07:40 GMT Area : (50.73, 61.160) Dist : 692 Kms Date Time of Launch, UTC Launcher 23.8.2005 21:10:00 Dnepr 2.9.2005 09:50:00 Soyuz 1.10.2005 03:54:53 Soyuz 25.12.2005 05:07:10 Proton 29.12.2005 02:28:40 Proton 30.3.2006 02:30:20 Soyuz 24.4.2006 16:03:25 Soyuz 15.6.2006 08:00:00 Soyuz 17.6.2006 22:44:05 Proton 24.6.2006 15:08:18 Soyuz ~=581 Kms Conclusions Detections using infrasound sensors is possible only after a launch because of the time needed for the signal to reach the detector. However, confirming events post-launch can often be important. For example, agreements to constrain the testing of ballistic missiles can be a useful confidence-building measure, as in the case of the agreement signed by India and Pakistan in 2005 on pre-notification of missile tests. Infrasound sensors provide a cheap and easy way for states to verify such agreements. Infrasound sensors are also capable of detecting re-entry events such as the ones shown in this poster. This could be useful in providing a method to distinguish between testing of Satellite Launch Vehicles and ballistic missiles since reentry is a critical technology required for ballistic missiles. Finally, the ability of the IMS to routinely detect such events enhances the confidence in its ability-something key to the US ratification of the CTBT. The IS 31 routine observes rocket detections from Baikanour Cosmodrome (46.07°E, 62.97°E). The cosmodrome is situated approximately 600 kms South-East of the sensor in Aktuybinsk. Table 1 lists some of the detections observed at Aktuybinsk. Here we show the detection of a Zenith Rocket from the Baikanour Cosmodrome launched on 29 th June 2007. It is observed that the mean signal speed (0.30-037 km/s) is typical of a stratoshperic return. It can also be observed that the back azimuth of the arriving signals are 136.5± 0.6°, which are quite representative of the directions of the cosmodrome. I. Source Localization II. Rocket Launch Detection 1A 1B 1C 1D Table 1 Figure 2A: Zenith Launch Detected at I31 on 29 th June 2007 Figure 2B: The direction of the arrival of signal Figure 2C: Aktuybinsk in yellow, trajectory in red, and the intersection is Baikanour Figure 2B shows the directions of the arrival of the signal. Figure 2C shows the rocket trajectory simulation in red. The yellow marker represents Aktuybinsk. The distance between the source and the receiver is Approximately 600 kms. I 31 KZ I31KZ has been operating for 8 years. For the last 3 years, the station records are searched for coherent signals. This search is automatic and continuous. Progressive multi-channel correlation (PMCC) detector is used. The main advantage of the detector is its possibility to find coherent signals in the records calculating cross correlation between the different element records. This advantage allows us to discover permanent sources. The detector applies to all the data of I31KZ coming to KNDC in near real time mode. An analysis of long-term observation results allows to define directions to permanently detected sources. Azimuthal distribution of detections in the PMCC bulletins on the Figure 2 clearly shows such directions. Figure 3 shows the reentry event of the Soyuz TMA-11 capsule. The touchdown area is approximately 700 kilometers from the sensor. Detections are observed at Approximately 08:15 UTC with the reentry time being 07:40 UTC. III. Reentry Detection Figure 3A: Waveforms from Reentry