Future of Earth defense – ground-based planetary radars

(ORDO NEWS) — Powerful radar systems have played an important role in the study of planets, moons, asteroids and other objects in our solar system for several decades, and now they will play a “unique role” in planetary defense – “providing protection of the earth from the devastating impacts of asteroids and comets,” according to recently published by the Decennial Review of Planetary Sciences and Astrobiology 2023-2032.

The National Radio Astronomy Observatory (NRAO) and the Green Bank Observatory (GBO) are developing new capabilities for the Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA) that will make them key tools to meet this need.

A report on the results of a study published by the National Academy of Sciences, Engineering and Medicine, talks about the dangerous consequences of collisions with near-Earth objects (NEOs).

The key to mitigating such a hazard is tracking objects and measuring their size and other characteristics to determine the likelihood that they will hit the Earth and the effect they would have if they hit. According to the study, radar is the most important tool for this task.

“Ground-based radar observations of NEOs provide invaluable information for long-term tracking,” the review says.

“Because NEO impact energy depends on density, diameter and velocity, and radar can determine all of these parameters, radar observations of planets are an important method for characterizing after detection,” the authors of the review added.

Until its destruction in 2020, the Arecibo telescope had the most powerful radar capabilities for the global astronomical community, often operating with GBT and VLBA as receivers.

A next-generation radar system being developed for the GBT and VLBA, and later for the Next Generation Very Large Array (ngVLA), will help replace the capabilities lost on Arecibo.

The review recommends the development of “a plan for the development of ground-based planetary radars comparable or superior to the capabilities of the Arecibo observatory necessary to achieve planetary defense goals.”

Since its discovery in 2000, the GBT has been a fundamental tool for planetary science and planetary defense, observing NEOs and potentially hazardous asteroids. Thanks to new technology being developed for the GBT, it is the world’s largest fully steerable antenna capable of transmitting radar signals for research.

The 100m diameter of the GBT makes it an impressive radar tool. The location of the GBT and its maneuverability allow it to observe 85 percent of the celestial sphere, which makes it possible to quickly track objects in the field of view.

A recent article in the Microwave Journal reports on radar experiments conducted with GBT and VLBA that have successfully acquired high-resolution images of the Moon and detected a near-Earth asteroid more than 5 times farther away than the Moon, making a close flyby of the Earth using at the same time less power than a microwave oven.

During these tests, as a proof of concept, the GBT transmitted a 650-watt radar signal at 13.9 GHz, which was received by the VLBA antennas, creating radar images of the lunar surface in unprecedented detail.

The National Science Foundation has funded the conceptual development of a more powerful GBT radar system that will be nearly 1,000 times more powerful than the concept.

In addition to a stronger transmitter, NRAO and GBO, working with industry partners, will use new array amplifier and receiver system technologies to maximize the efficiency of the new system.

In parallel, as additional funding becomes available, the group plans to move on to final design and construction work, which will begin in 2023.

The new radar capabilities of the GBT will enable astronomy to have a tool that was not available before, collecting data at higher resolution and at previously unavailable wavelengths. NRAO and GBO are also developing cutting-edge data reduction and analysis tools that were not available before.

The flexibility and increased performance of this new system will address an important need for planetary defense, as well as allowing astronomers to observe asteroids, comets, planets and moons. The universality of this system will contribute to the development of many areas of science.”


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