3 mins read 10 Feb 2020

Outback radio telescope utilised for space situational awareness

Outback radio telescope detects International Space Station, Satellites through passive radar techniques – adding value to space situational awareness.

Australian researchers have showcased the capacity of the Murchison Widefield Array (MWA) telescope, located in the central outback region of Western Australia, to detect orbiting satellites as part of a demonstration of its space situational awareness (SSA) capability.

The Western Australian researchers, representing the International Centre for Radio Astronomy (ICRAR) and the Commonwealth’s science agency, the CSIRO – developed a new concept known as Dynamic Signal to Noise Radio Spectrum (DSNRS) and successfully detected five orbiting satellites, including the International Space Station (ISS).

The bright spot circled on the left image is the ISS in front of the Vela supernova remnant. The second image on the right showcases an object not on the TLE catalogue. The circled objects are known and catalogued. Credit: Prabu et al.

It was during the development of the imaging methodologies that scientists noticed that images could be affected by FM signals in two-ways, as detected by the MWA. The first was the FM signal being reflected off objects in orbit and the second the FM signals could enter the telescope’s field-of-view by direct reception from the transmitter, bent through Earth’s atmosphere.

In doing so, signals from the Alouette-2, ALOS, UKube-1, and Duchifat-1 satellites were observed, in addition to the ISS. Most of the observations occurred when the objects were at a distance range between 430 – 750km above the Earth, with the exception of the Alouette-2, whose range was approximately 2,180 – 2,290km above.

Space Situational Awareness is the term used to describe the monitoring and analysis of information regarding Earth’s local space environment, in particular for the purpose of hazards and risk mitigation (across a number of industries including military, commercial and scientific).

SSA can be split into three major segments:

  • Space weather monitoring – ongoing monitoring of solar activity and its impacts on orbiting space assets, and Earth’s magnetic field and upper atmosphere
  • Near-Earth object tracking – continual observation of natural objects such as asteroids and comets and their potential impact probabilities with the Earth
  • Space surveillance and tracking – tracking of active and inactive satellite and space debris management

The MWA telescope is a low-frequency radio array instrument, with an operating frequency range of 70 – 300 MHz. It is made up of spider-like antennae, each with 16 dipoles and arranged in a 4 x 4 configuration, sitting atop a 4m x 4m mesh ground plate.

It is generally used for astrophysical surveys, such as galactic and extra-galactic sciences, time-domain astrophysics, and detection of the epoch of re-ionisation – a key period in the Universe’s history when neutral hydrogen gas was re-ionised by the first sources of light, such as early stars and galaxies.

By showcasing the capability to utilise the MWA for SSA purposes, the telescope’s range of usage can be expanded from not only the ability to observe deep-space phenomena but also localised near-Earth events and objects.

The paper is available on arXiv