Indian anti-satellite debris measured with the EISCAT Tromsø Radar

During the last few days, we've been scrambling to make a beam park measurement of the debris produced by the Indian anti-satellite experiment conducted on March 27th 2019. A beam park measurement is a type of a radar measurement, which points into a fixed direction (in our case East, 70 degrees above the horizon) for a 24 hour period of time, and records every detection of a space object that crosses the radar beam. This type of an experiment cannot provide precise information about the orbital elements of objects, but can provide a statistical sample of debris in orbit at the time of the experiment. Some information about orbital parameters and object size can be inferred from the recorded signal power, Doppler shift, and time of day. Such information is invaluable for modeling of the space debris population, assessing the the probability of collisions between space objects, and determining the evolution of the space object population.

Right after we heard the news about the anti-satellite experiment, we made an urgent scheduling request to EISCAT to conduct a measurement with the Tromsø UHF radar (shown in Figure 4), so that we could determine the amount of debris produced. Today we concluded a 24 hour statistical survey measurement of the debris in orbit now. Figures 2-4 show preliminary results analyzed by Jussi Markkanen from EISCAT. The experiment was carried out jointly by University of Tromsø (Norway), Institute of Space Physics, Kiruna (Sweden), and the EISCAT Scientific Association.

There is a large increase of debris produced by the Indian anti-satellite experiment, which is evident when comparing the post anti-satellite experiment beam park measurement with a similar measurement that we made one year earlier (Figures 1 and 2). The debris count doubles at the time when the debris cloud passes the EISCAT Tromsø site. You can see this in the time-range detections (Figure 2), time of day histogram (Figure 3), and time - Doppler velocity (Figure 4) plots very clearly between 21 and 0 UTC and 7 to 11 UTC. The cloud seems to extend up to ranges of 1500 km, which shows that also debris with relatively large eccentricities are produced by the explosion. The measurement also indicates that the target of the anti-satellite experiment was Microsat-R. These measurements will be important for determining the amount of and the orbital distribution of space debris produced by the anti-satellite experiment. 

The results are still preliminary. We are investigating the possibility for making more experiments in the near future to obtain better statistics. An effort is also underway to determine if the measurements fit with a model of an explosion of Microsat-R. 

Thanks to EISCAT for conducting this experiment on such a short notice and such a fast turn around time!

Contact information:

Associate Professor Juha Vierinen (juha-pekka.vierinen@uit.no)

University of Tromsø, The Arctic University of Norway

Figure 1. Beam park measurements of space debris objects BEFORE the anti-satellite experiment on January 4th, 2018. Detections as a function of time and range (Analysis: Jussi Markkanen, EISCAT)

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Figure 2. Space object detections as a function of time and range after the antisatellite experiment measured 2-3 April 2019. (Analysis: Jussi Markkanen, EISCAT)

Figure 3. Histogram of space object detections as a function of time (Analysis: Jussi Markkanen, EISCAT)

Figure 4. Space object detections as a function of time and Doppler velocity (Analysis: Jussi Markkanen, EISCAT)

Figure 5. EISCAT Tromsø UHF radar, operating at 930 MHz with 2 MW of peak power. (Photo: Derek McKay).