Tracking satellites and space debris using radio antennae

Every year, thousands of satellites are launched into orbit around our planet. The result is an increasingly congested “space” above Earth populated by equipment that provides services to the surface. At the same time, these satellites affect ground-based astronomy and create the potential for damage when they eventually fall through Earth’s atmosphere to the surface. In addition, near-Earth space hosts old rocket bodies and other materials (cameras, gloves, etc.) left in orbit by past missions.

Artificial objects in orbit aren’t the only things “out there.” Near-Earth asteroids—usually referred to as NEOs—can cross Earth’s orbit. We also contend with smaller bits of debris that form meteors. Eventually, all these things fall to Earth or, in the case of NEOs, their trajectories can bring them uncomfortably close to intersecting the planet. All of these objects need to be monitored, not only for their own safety and health, but for ours. Their orbits need to be tracked and characterized so that fair warning can be given if and when a piece of space “stuff” is coming to Earth.

Incoming!

That’s where a monitoring array called the Long Baseline Multistatic Radar (LMBR) will come in useful. A team of radio astronomers and radar experts found a way to use radio telescopes to track satellites and other objects in orbit and recently demonstrated it for partners in Australia, the United States and the United Kingdom.

In particular, they’ve linked the 76-meter Lovell Telescope at Jodrell Bank in England, along with other antennas in the e-MERLIN array, to track objects in space for what’s called Space Domain Awareness. A research team tested the concept in September 2025 by measuring and tracking 20 distinct rocket bodies, using the NASA Deep Space Network antenna in Canberra, Australia, the Australia Telescope Compact Array and other antennas in Australia, and installations in Tasmania.

They performed micro-Doppler analysis (essentially using the Doppler effect) to measure axial rotation signatures of the rocket bodies. That let them determine rotation periods, object dimensions, surface characteristics and mass-distribution parameters with enhanced accuracy in orbital refinement. The team then used advanced imaging reconstruction techniques to generate shapes of the targets.

They described their results in a paper, showing successful determination of debris rotation periods with second-level precision, dimensional estimates within 10% of known specifications, and improved orbital-parameter determination that reduced position uncertainties by up to 30%. That level of accuracy helps determine threats from incoming asteroids or satellites re-entering the atmosphere.

Radar signatures track objects in real time

Radar is a powerful tool for monitoring objects in orbit, and it is widely used on Earth to track aircraft. For example, radar facilities send signals that bounce off aircraft and return data to the radar system. Depending on the types of signals used and radar modes, tracking stations can get information about the type of aircraft, who is operating it and other properties such as size and shape.

Radar has also been used to study the surfaces of planets, asteroids, moons and other solar system objects. For example, scientists have mapped Venus’ surface features using radar, particularly with the Magellan spacecraft. As another example, the Jovian moon Europa was mapped using radar in the 1980s and 1990s.

There are some limitations to using conventional radar for monitoring space objects. Tracking a satellite in geostationary orbit, for example, requires higher-power, more sensitive antennas than those used to follow aircraft on Earth or spacecraft coming back from a mission. This is where radio telescopes like those at Jodrell Bank come in handy. They’re built to receive natural signals from very distant objects ranging from the solar system to other stars and galaxies. In addition, installations such as the Deep Space Network are built to relay information back and forth between spacecraft in the solar system.

According to Simon Garrington of Jodrell Bank Observatory, including the Lovell Telescope is a big step forward. “The 76-m Lovell Telescope at Jodrell Bank makes a superb radar receiver for this type of work,” he said. “We are very keen to realize its full potential in contributing to monitoring objects in orbit, protecting UK assets in space, and making space safer. Our e-MERLIN array is also being used in this work and is a unique UK capability for high-precision measurements of objects in orbit.”

These uses (and more) are a good reason to bring radio telescopes into the mix. Essentially, they’d be used as geographically distributed radar receivers, enabling the detection of objects of nearly all sizes at great distances. All the data from the radar echoes received by the radio telescopes would be collected and analyzed in real time.

The UK Space Agency recently demonstrated this live tracking capability for stakeholders such as the government, defense agencies and industrial partners. It’s the first time such tracking techniques performed by radio telescopes have been used. The UK, United States and Australia are expected to benefit from the additional “radar firepower.” Details of the radar-network studies can be found in the paper cited below.

Will Jodrell Bank be part of this moving forward?

Ironically, the successful use of Jodrell Bank as part of the LMBR tracking network could be in jeopardy if recently announced budget cuts to UK science occur. Media stories report that funding cuts will force the closure of parts of Jodrell Bank Observatory sometime in 2028. The United Kingdom Research and Innovation offices announced cuts that will force the shutdown of the e-MERLIN telescopes, including the Lovell radio antenna. The facility itself will remain open to host the Square Kilometer Array Observatory headquarters and other programs of higher importance to the UK science community. Of course, astronomers are looking for alternative funding sources in the meantime.

These cuts are part of a larger effort to reduce funding for science across UK science facilities. The UK science community is heavily involved in consortia and projects outside the country, providing instruments and research for facilities such as CERN, the upcoming Vera C. Rubin Observatory and others. In particular, the cuts will force the UK to reduce its participation in the Rubin Telescope by as much as 20%. If and when e-MERLIN is shut down, it will definitely affect the observatory’s participation in LMBR, although the extent of those effects is not yet clear.

Who’s behind this story?

Swati Mestri

Swati Mestri holds a bachelor’s degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space.

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Andrew Zinin

Master’s in physics with research experience. Long-time science news enthusiast. Plays key role in Science X’s editorial success.

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