It was serendipity that had already made scientists play with a demonstration of a new planetary radar system, just as the earth had lost its most powerful instrument.
Well, serendipity and a fervent desire for more radar observations of everything from asteroids hanging around near the earth to icy moons around the farthest planets. And the facility behind the experiment, the Green Bank Observatory in West Virginia, has enough history with planetary radar systems to take on a new role in the field. The result is a sparkling new image of a historic site on the most famous object of the solar system, the moon. Scientists hope the image is the reason for the permanent installation of a much more powerful radar transmitter at the observatory’s leading telescope, the Robert C. Byrd Green Bank Telescope.
“We have achieved absolutely fantastic results,” said Karen O’Neil, director of the Green Bank Observatory site, said about the demonstration project during a panel discussion that took place on January 21st. “Phase one was an absolute success and we were very pleased with everything that happened to it,” O’Neil told the panel, referring to the science of small objects of the solar system such as asteroids, which the committee of the National Academy will inform who compiles the document that will shape planetary science’s priorities for the next decade.
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The recent radar experiment was a decade in the making. And the facility’s flagship radio telescope, the 100-meter (100-foot) dish has worked with radar transmitters in Puerto Rico and California over the years. Then why not go a step further and create your own signals?
“It’s a part of radio science where we’re been involved for a long time, on a certain level,” Tony Beasley, director of the National Radio Astronomy Observatory, which built the telescope, told Space.com. “About ten years ago, there was interest in thinking about what other roles and other areas of radio science are that Green Bank could be involved in, and therefore radar was an obvious candidate.”
The case for radar
Radar astronomy occurs in two pieces: scientists must first create the radio beam to reflect the mystery object, and then study the relatively faint echo that returns and decipher the object’s surface, shape and location from it.
The steps can take place at the same radio dish, as it can quickly switch between send and receive modes, or two radio facilities can work together, with one producing the radar beam and the other ready to collect the return signal. When Green Bank began planning its demonstration project, it never sent radar signals itself, but also worked as a receiver for both of the largest U.S. planetary radar transmitters.
At that 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 scientific platform of the Arecibo radio telescope – including the transmitter – crashed after the cable failed at the plant, ending its tenure.
Planetary scientists will continue to feel the loss, even if the Green Bank project turns into a full-fledged transmitter. The provisional Green Bank system is not designed to do this replace Arecibo, as no one realizes that the Puerto Rican plant is nearing its end; Instead, it is designed to work with Arecibo and Goldstone.
“The program we developed was really built and designed in some way to complement the existing U.S. radar infrastructure,” Beasley said. “The thing we are talking about certainly has a relevance to a post-Arecibo world, but in no way will it be a substitute for Arecibo.”
And it is unclear whether the loss of Arecibo will affect the fate of the Green Bank project. The National Science Foundation (NSF), which owns the Green Bank and Arecibo sites, plans to evaluate the project, acknowledging the recent loss, but without stepping up radar capability.
“If some abilities are lost, there is always the question of where the abilities would otherwise come from? Is there anything else that could continue such a thing?” Harshal Gupta, NSF’s program director for the Green Bank Observatory, told Space.com. ‘It is independent of what’s going on at Arecibo. Given what has happened, it can, if fully developed, provide some of the capabilities that the planetary community can use. But again, these two are two separate things. ‘
Demo and design
The years of interest were there and the numbers looked promising. But before Green Bank committed to a full-fledged planetary radar project, astronomers wanted to test the waters. To do so, scientists built a miniature transmitter, powered by less than a kilowatt, and as large as a refrigerator, Beasley said. In November, he briefly put it on the main focal point of the Green Bank telescope. dish.
Thereafter, the team took advantage of the superlative of the telescope: it is the largest, fully controllable radio telescope in the world capable of studying objects in 85% of the air. The team showed the telescope and fired the radar system on the moon – more specifically on the Apollo 15 mission’s landing site in the Hadley-Apennine region. The team used antennas from the NRAO’s Very Long Baseline Array (VLBA) to pick up the bouncing signal.
The statue, with its sloping hills, sharp crater and winding ridges, gives a hint of what may come. But the moon is our old companion. Scientists would rather use a shiny new planetary radar system to study more mysterious objects, such as the asteroids zipping through our solar system environment, most of which are faded and spotted, or the strange moons of the outer planets that received little spacecraft. visitors.
“Now we’re just thinking about what the next step is,” Beasley said.
There are different options for deciding what a system would look like, Beasley and O’Neil both emphasized. The scientists suspect they will use a separate radio scheme to capture the return signal, rather than the housing that also works at Green Bank Observatory. For now it is the VLBA, but as a next generation Very large array become, antennas of the system will be even more promising receivers, O’Neil said.
Two key factors that influence what exactly a radar system can do are the power of the transmitter and the specific frequency of the radio wave it produces. Green Bank is looking at a transmitter that will use ten or hundreds of times more power than the demonstration tool and will operate on one of the two frequencies. It also wants to use a new transmitter technology, which would be more compact and, according to scientists, less operational to work with.
Given the design parameters currently being considered by scientists, the system could study objects in a much larger part of the solar system than existing systems, including strange, icy moons. “You increase the volume you’re looking for in the solar system by an order of magnitude,” Beasley said. “It’s a significant increase, so we’m very excited about the possibility there.”
Of course, there are logistical problems, and this could be a major problem for Green Bank, which is an extremely popular tool and already does not have time to do the scientific researchers. The telescope usually observed two or three objects a year through its radar partnerships with Arecibo and Goldstone; Beasley said that if the transmitter project becomes a reality, it is possible that the facility will spend about a third of its time on radar.
According to all scientists, a full-fledged project would reform the planetary radar, the scientists said.
“The capabilities we’re talking about are something that goes beyond anything we could have done in the past of planetary radar astronomy,” O’Neil said. “We’re talking about something that has a pretty amazing potential for planetary radar and a system that has the ability to take us a leap forward, I would say within the planetary radar capability of the United States. to think and pretty amazing to talk about. ‘
If the project continues and Green Bank installs a full-power radar transmitter, it is unlikely to go online until perhaps 2024, depending on how quickly funding – probably “in the tens of millions of dollars”, O’Neil said – comes together.
Gupta at the NSF said he was delighted with the success of the demonstration and looked forward to seeing what happens next at Green Bank.
“Everything indicates that there is a lot of promise. Initial tests are great and there is great potential,” he said. “The whole picture becomes clearer as science is done, as technology develops. So I will just say: there are unforeseen advances, unforeseen opportunities. Eventually it will be exciting and we will see how it unfolds.”
Email Meghan Bartels at [email protected] or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.