Ground-based radar systems can play a unique role in planetary defense; It could help humanity protect Earth by detecting asteroids and comets on potentially devastating collision courses with our planet.
This was the conclusion reached by the National Academies in their 2023-2032 Decadal Survey of Planetary Science and Astrobiology. Currently, only one radar system on Earth focuses on detecting threatening space rocks: NASA’s Goldstone Solar System Radar, which is part of the Deep Space Network (DSN).
On Saturday, February 17, at the American Association for the Advancement of Science’s annual conference in Denver, Colorado, scientists announced results that suggest ground-based radar could significantly impact asteroid detection and therefore planetary defense.
Future efforts in this direction include the National Radio Astronomy Observatory’s (NRAO) next-generation RADAR (ngRADAR) system, which uses the National Science Foundation’s Green Bank Telescope (GBT) and other facilities to expand humanity’s ability to detect asteroids and comets in the environment It is located. Earth using radar.
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Scientists are aware of more than 1.1 million asteroids in the solar system, of which more than 30,000 are called Near-Earth Objects (NEOs). NASA’s Center for Near-Earth Object Studies (CNEOS) estimates that about 90% of NEOs larger than about 0.62 miles (1 kilometer) have been discovered.
Additionally, CNEOS has determined that there are no NEO orbits that currently threaten Earth, at least within the next century. However, this does not mean that the remaining 10% of undiscovered NEOs do not contain objects that could threaten our planet.
Radar, a word from the acronym radio detection and range, uses radio waves to determine the distance and speed of targets. Radar systems consist of transmitting antennas that emit radio waves and receiving antennas that collect these waves while reflecting them back. Radio waves reflected back from space rocks could help reveal asteroids or comets, as well as study the nearby solar system in unprecedented detail.
“There are many applications for the future of radar, from significantly improving our knowledge of the solar system to informing future robotic and crewed spaceflights to characterizing hazardous objects that come too close to Earth,” NRAO director Tony Beasley said in a statement. said.
Radar can give early notice to DART
Earth’s geological history is full of examples of the devastating impact asteroids have had on our planet and its species. The most striking example of this is the 120-mile (200-kilometer) wide Chicxulub crater on Mexico’s Yucatán Peninsula. This crater was created by the impact of a 6.2-mile (10-kilometer) wide asteroid 66 million years ago.
This asteroid impact triggered the Cretaceous-Tertiary (TC) extinction event, which wiped out three-quarters of the planet’s plant and animal species, including non-avian dinosaurs.
So, to ensure humanity doesn’t go down the same path as the dinosaurs, space agencies are developing strategies to divert asteroids and comets in orbits that could one day impact Earth. Arguably the most striking example of this defense mechanism is NASA’s Double Asteroid Redirection Test (DART) mission. In September 2022, DART crashed into Didymos and Dimorphos, the smaller bodies of the double asteroid system. The purpose of this was to see if a kinetic impact could redirect an asteroid’s orbit enough to knock it off the collision course. In short, it worked.
Other asteroid deflection methods include the obvious – detonating a nuclear device on its surface – the sublime – pulling an asteroid away with a solar sail – and even the very strange – painting one side of the asteroid black to absorb more sunlight, thus changing its orientation. The center of mass and orbit are changing. While it may seem wildly exaggerated, there is some basic research behind the last one.
But all these potential diversion methods require is time.
The lead times required for asteroid deflection missions can vary from many years to decades. This means space agencies need lots of advance warning before implementing a method for adjusting an asteroid’s orbit.
As the GBT is the world’s largest fully steerable radio telescope, it is proposed as an important tool in the effort to detect asteroids hitting Earth orbit. This means it can observe about 85% of the sky on Earth and quickly track objects as they speed across its field of view. Such capability would allow space agencies to determine the location, size and speed of potentially hazardous NEOs on faster timelines, scientists say.
“Recently, GBT helped confirm the success of NASA’s DART mission, the first test to see whether humans could successfully change the orbit of an asteroid,” Patrick Taylor, an NRAO scientist and project director for ngRADAR, said in the statement.
Radar is already revealing the solar system
During initial testing, GBT’s ngRADAR system has already demonstrated its ability to reveal solar system inhabitants in incredible detail.
“With support from Raytheon Technologies, ngRADAR pilot tests on the GBT using a low-power transmitter with less output than a standard microwave oven produced the highest-resolution images of the Moon ever taken from Earth,” Taylor added. “Imagine what we could do with a more powerful transmitter.”
So, in addition to detecting and tracking asteroids and comets, radar can also help planetary scientists study the geology of relatively nearby planets and moons. This may give us a clue as to how these objects have evolved over the 4.6 billion year history of the solar system.
Not bad for a technology that has been around since 1935, when the first working radar system was built in the form of six wooden towers – two for the transmitting antenna, four for the antenna. This system was built at Orford Ness in Suffolk, England, and as scientists explain, NASA’s Goldstone facility didn’t actually develop much after that.
“The public may be surprised to learn that the technology we use in our current radar at Goldstone has not changed much since World War II. We send and receive 99% of our observations from a single antenna,” said NASA’s Marina Brozović. in the statement. “New radar transmitter designs, such as ngRADAR at GBT, have the potential to enable higher resolution imaging by significantly increasing output power and waveform bandwidth.
“It will also use telescope arrays to increase the collecting area, producing a scalable and more robust system.”
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“NRAO is the ideal organization to lead these efforts because of the tools we have at our disposal to receive radar signals like the Very Long Baseline Array did in our pilot ngRADAR project,” Brian Kent, NRAO director of science communications, said in a statement. said. “Future facilities such as the next-generation Very Large Array as receivers will create a powerful combination for planetary science.”