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It’s a coincidence that scientists have already played with a demonstration of a new planetary radar system when Earth lost its most powerful instrument.
Well, a coincidence and a burning desire for more radar sightings of everything from asteroids hang out near Earth to the icy moons around the most distant planets. And the facility behind the experiment, the Green Bank Observatory in West Virginia, has enough history with planetary radar systems to want to take on a new role in the field. The result is a tantalizing new image of a historic location on the most familiar solar system object of all, the moon. Scientists hope the image justifies the permanent installation of a much more powerful radar transmitter on the observatory’s main telescope, the Robert C. Byrd Green Bank Telescope.
“We have had absolutely fantastic results,” Karen O’Neil, Director of Green Bank Observatory site, said of the demonstration project at a panel discussion on Jan.21. “The first phase was an absolute success and we were very happy with everything that happened with it,” O’Neil told the panel, which focuses on the science of small solar system objects like asteroids and which will inform the National Academies Committee which is preparing the document that will shape planetary scientific priorities for the next decade.
Related: Loss of giant Arecibo dish makes humans more vulnerable to space rocks, scientists say
The recent radar experiment lasted a decade. And the installation is lighthouse radio telescope, the 100-meter (300-foot) antenna has partnered with radar transmitters in Puerto Rico and California over the years. So why not go further and create the signals themselves?
“It’s kind of a part of radio science that we’ve been involved with at some level for a very, very long time,” Tony Beasley, director of the National Radio Astronomical Observatory, told Space.com, who has built the telescope. “About 10 years ago, there was growing interest in thinking about what other roles and certain other areas of radio science were Green Bank could get involved in, and so radar was an obvious candidate.”
The case of radar
Radar astronomy takes place in two parts: scientists must first create the radio beam to bounce off the mysterious object, then study the relatively weak echo that returns, deciphering the surface, shape and location of the object. the object.
Stages can occur on the same radio dish as it quickly converts between transmit and receive modes, or two radio installations can team up, one producing the radar beam and the other ready to collect the feedback signal. When Green Bank began planning its demonstration project, it had never sent radar signals itself, but had worked as a receiver for America’s two major planetary radar transmitters.
At the time, there were two such transmitters: one at the Arecibo Observatory in Puerto Rico and one at NASA’s Goldstone Deep Space Communications Complex in California. But in December, the Arecibo radio telescope’s science platform – including its transmitter – collapsed after cable failures at the facility, ending its tenure.
Planets will continue to feel this loss, even if the Green Bank project turns into a full-fledged issuer. The interim Green Bank system is not designed to replace Arecibo, since no one realized that the Puerto Rican installation was coming to an end; instead, it was designed to collaborate with Arecibo and Goldstone.
“The program that we developed was really built and designed in one way or another to complement the existing US radar infrastructure,” Beasley said. “Certainly what we are talking about producing has some relevance in a post-Arecibo world, but by no means will it replace Arecibo.”
And it is not known whether the loss of Arecibo will influence the fate of the Green Bank project. The National Science Foundation (NSF), which owns both the Green Bank and Arecibo sites, plans to assess the project, acknowledging the recent loss, but not scrambling to bolster its radar capability.
“If some abilities are lost, there is always the question of where those abilities would come from? Is there anything else that can continue something like this?” Harshal Gupta, NSF’s program director for the Green Bank Observatory, told Space.com. “It is independent of what was happening in Arecibo. Now, given what has happened, when it’s fully developed, it might offer some of the abilities that the planetary community might be able to use. But again, these two things are two separate things. ”
Demo and design
The years of interest were here and the numbers looked promising. But before Green Bank embarked on a full-fledged planetary radar project, astronomers wanted to test the waters. To do this, scientists built a miniature transmitter, powered by less than a kilowatt and about the size of a refrigerator, Beasley said, and transported it in November for a brief stint at the main center of the Green Bank telescope, suspended above the large dish.
Then, the team took advantage of the telescope’s superlative: it is the largest fully steerable radio telescope in the world, capable of studying objects over 85% of the sky. So the team pointed the telescope and shot the radar system at the moon – more specifically, at the Apollo 15 mission landing site in the Hadley-Apennine region. The team used antennas from NRAO’s Very Long Baseline Array (VLBA) to pick up the bounced signal.
The image, with its sloping hills, austere crater, and oblique groove, offers a glimpse of what could happen. But the moon is our old companion. Scientists far prefer to use a shiny new planetary radar system to study more mysterious objects, like the asteroids that roam our Solar System neighborhood, most of which are blurs and specks, or the strange moons of the outer planets that have received few spaceships. visitors.
“Now we’re just thinking about the next step,” Beasley said.
There are several options to weigh in deciding what a system would look like, Beasley and O’Neil pointed out. Scientists suspect they will continue to use a separate radio network to pick up the return signal, rather than housing what is also working at the Green Bank Observatory. For now it would be the VLBA, but if a new generation Very large painting comes to be, the antennas for this system would be even more promising receivers, O’Neil said.
Two key factors that influence precisely what a radar system can do are the power of the transmitter and the specific frequency of the radio waves that produces. Green Bank is studying a transmitter that would use tens or hundreds of times more energy than the demonstration instrument and operate at one of two frequencies. He’s also looking to use new transmitter technology, which would be more compact and, scientists hope, less oppressive.
Given the design parameters scientists are currently considering, the system would be able to study objects in a much wider swath of the solar system than existing systems, including to strange icy moons. “You’re increasing the volume you’re looking for in the solar system by an order of magnitude,” Beasley said. “It’s a substantial increase, so we’re very excited about this possibility.”
There are logistical issues, of course, and these could be a key issue for Green Bank, which is an extremely popular instrument and already doesn’t have the time to do whatever scientific researchers would like. Typically, the telescope has observed two or three objects per year through its radar partnerships with Arecibo and Goldstone; Beasley said if the transmitter project becomes a reality, the facility could look to spend about a third of its time on radar.
In all, a full-fledged project would reshape planetary radar, the scientists said.
“The capabilities we are talking about go beyond anything we have been able to do in the past with planetary radar astronomy,” said O’Neil. “We’re talking about something that has pretty amazing potential for planetary radar and really a system that has the ability to leap us forward, I would say, as part of the planetary radar capability of the United States. It’s fun to think about and pretty amazing to talk about. “
If the project continues and Green Bank installs a full-power radar transmitter, it will likely come online no earlier than maybe 2024, depending on how quickly the funding – likely “in the tens of millions of dollars” , O’Neil said. .
Gupta of the NSF said he is happy to see the success of the protest and looks forward to seeing what happens next at Green Bank.
“Everything indicates that there are great promises. The first tests are excellent and there is great potential,” he said. “The big picture becomes clearer as science advances, as technology develops. So I’ll just say that: there are unforeseen advancements, unforeseen opportunities. Ultimately, that would be exciting. and we’ll see how it plays out. “
Email Meghan Bartels at [email protected] or follow her on Twitter @meghanbartels. follow us on Twitter @Spacedotcom and on Facebook.
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