INFRASOUND

Infrasound Detection of Rocket Launches

Gopalaswamy Bharatha, Smirnoff Alexandrb

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 29th 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 29th June 2007

Figure 2B: The direction of the arrival of signalFigure 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