The massif of the Arecibo Observatory the radio telescope has collapsed; with it has become a crucial tool for understanding the risks of asteroids on Earth – and it would take serious government initiative to replace it.
Before the installation suffered irreversible damage in a series of cable failures this year, Arecibo Observatory was the most powerful planetary radar system on Earth. Astronomers can’t use radar to discover new asteroids, but the data these systems provide can give scientists the details about the size, shape, and location of an object they need to better assess and more. quickly the threat that individual asteroids could pose to Earth.
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But that’s easier said than done. There are two key complications involved when it comes to investing in planetary radar capability.
One is bureaucratic: planetary radar has to be done from the surface of the Earth. And while NASA is leading the asteroid-focused work in the country, the United States’ National Science Foundation (NSF) is leading the federal government’s ground observations, like the Arecibo Observatory; NASA simply paid for the observation time on the radar system. With the sole exception of the NASA infrared telescope facility in Hawaii, all of the agency’s observation facilities are in space.
(It’s also complicated. Technically, the other planetary radar installation in the world, at Gold stone in California, is run by NASA, but that’s because its primary duty is to communicate with spacecraft passing through the solar system. The radar installation recently completed an upgrade and returned to normal observations, although it has a less flexible schedule than Arecibo and cannot see objects as far from Earth.)
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“How our agencies are charged, ground observations are the responsibility of NSF,” Lori Glaze, who heads NASA’s Planetary Sciences Division, said at the same meeting. “It is not for NASA. ”
A second complication is the cost. A radar beam as powerful as Arecibo’s requires both a powerful transmitter and a huge radio dish, neither of which are cheap.
Taken together, the challenges mean that NASA would likely need to strike deals with one or more government counterparts before a new planetary radar system goes live.
“This sort of thing really requires an agency partnership,” Johnson said, adding that Arecibo itself had its roots in a Department of Defense-led partnership. Something similar could revive planetary radar, he said. “We certainly have an opportunity and an interest to collaborate with the US space force on a more efficient radar system. “The military branch is interested in technology as a way to track satellites between the Earth and the Moon,” he added.
Related: Arecibo is not the first radio telescope to fail unexpectedly. Here’s what we can learn from the Green Bank collapse.
A reduction in planetary radar does not strike at the core of NASA’s planetary defense system, which focuses on finding and tracking relatively large asteroids that come relatively close to Earth. Detection of such objects relies on installations that detect optical and infrared light and scan large parts of the sky regularly enough to notice when a new fast moving point appears against a background of stars.
Radar can’t do that; this requires scientists to have a good idea of exactly where the object they want to study is located, so that they can point the narrow radar beam precisely enough to bounce off the object. Instead, planetary defense experts are using radar to more quickly plot an object’s orbit further into the future and to determine the object’s characteristics like shape and density that could affect attempts to deflect an asteroid if it appears to be on track to impact Earth.
“Regarding planetary defense and the NEO [near-Earth object] sightings are concerned, it’s only a slight negative impact, “Johnson said of the loss of the Arecibo radar system.” This does not affect our rate of discovery of objects near the sea at all Earth, this only has an impact on the opportunities we have to characterize these objects. ”
Still, radar data is nice to have – and certainly the sort of thing Johnson would want for the planetary defense community.
Green Bank Observatory in West Virginia was already planning to add radar capability to its main radio antenna before Arecibo’s loss, scientists say, although the system, like Goldstone’s, does not replicate Arecibo’s specific skills. And even this new capability would build on an existing facility, rather than starting from scratch, which has both benefits and risks.
“In a perfect world, I would be looking for a new planetary radar capability,” Johnson said, even before Arecibo’s final collapse. “Trying to keep these old facilities running – they require a lot of maintenance.”
But a new ability wouldn’t mean a copy of Arecibo’s iconic dish, he stressed. “It is really time to look at the next generation of planetary radar capabilities,” he said, including hypothesizing that an array of parabolas might be a more attractive approach now than the massive parabola alone. from Arecibo.
“The technology has evolved since the 30, 40 years that radar capability was installed at Arecibo,” Johnson said. “We must take advantage of it. ”
Email Meghan Bartels at [email protected] or follow her on Twitter @meghanbartels. follow us on Twitter @Spacedotcom and on Facebook.