According to the scientists, neutron imaging is ideal for searching for water and other hydrogen-bearing compounds because neutrons readily ricochet off hydrogen. In contrast, X-ray imaging is best for finding deposits of heavy elements, such as iron and nickel, because X-rays are primarily scattered by the large number of electrons in heavy-weight atoms.
Neither imaging technique significantly harms or alters meteorites, unlike other methods of analyzing the chemical composition of the rocks, which require cutting thin slices of the meteorites. Although each imaging method has been used separately in the past, the team is among the first to use the two techniques simultaneously to create X-ray and neutron-beam snapshots.
In the pilot study, the group examined two meteorites whose mineral and water contents were already well known so that they could assess the accuracy of the combined imaging methods. One of the rocks, dubbed EET 87503, is a fragment from the surface of the large asteroid Vesta but also contains material from a different, water-rich variety of asteroid.
The other meteorite, GRA 06100, rich in iron and nickel, is classified as a chondrite—a rock that has not been altered by melting or other processes since the early days of the solar system. It also has a significant amount of hydrogen-bearing silicates formed by past exposure to water.
To create three-dimensional views of the meteorites, the researchers used the X-ray and neutron beams to image cross-sections of the rocks. Individual images of different cross sections were then combined to create a 3D image, a technique known as tomography or CT scan.
The imaging methods accurately revealed the locations of metal-rich minerals, silicate minerals, water and other hydrogenated compounds in the two meteorites. Neutron imaging pinpointed and characterized the chondrite grains within GRA 06100, which could then be extracted for further study. The 3D imaging can test theories of how water entered the rock and what pathway the liquid took to alter the composition of minerals and become bound in the sample.
Although water accounts for 70% of earth’s surface, exactly how the substance arrived on our planet remains the subject of a longstanding debate. Some planetary scientists suggest that meteorites and comets—icy relics from the frigid, outer solar system—delivered the water, along with the building blocks of proteins essential for life, after our planet’s core had formed. Others suggest that earth acquired the water during its formation 4.5 billion years ago from bits of gas and dust that swaddled the infant sun and glommed together to form our planet.
Water comes in two forms: ordinary water, consisting of hydrogen and oxygen, and heavy water, consisting of deuterium (hydrogen with an added neutron) and oxygen. One way to determine if meteorites were a primary source of terrestrial water is to compare the relative abundance of these two types in the rocks to the relative abundance of the water on and beneath the earth’s surface. Planetary scientists have measured the abundance in some meteorites but need to examine a larger number.
The neutron and X-ray images can assist in these studies. By pinpointing the location of mineral, metal and water deposits locked inside meteorites, the images could guide researchers on how to best slice sections of the rocks so they can measure these abundances as well as the composition of other compounds.
Following this initial trial, the team now plans to use its dual imaging technique to study less familiar meteorites so that their water and mineral content can be mapped in detail for the first time.
Future Space Telescopes Could be 100 Meters Across, Constructed in Space, and Then Bent Into a Precise Shape – Universe Today
It is an exciting time for astronomers and cosmologists. Since the James Webb Space Telescope (JWST), astronomers have been treated to the most vivid and detailed images of the Universe ever taken. Webb‘s powerful infrared imagers, spectrometers, and coronographs will allow for even more in the near future, including everything from surveys of the early Universe to direct imaging studies of exoplanets. Moreover, several next-generation telescopes will become operational in the coming years with 30-meter (~98.5 feet) primary mirrors, adaptive optics, spectrometers, and coronographs.
Even with these impressive instruments, astronomers and cosmologists look forward to an era when even more sophisticated and powerful telescopes are available. For example, Zachary Cordero
of the Massachusetts Institute of Technology (MIT) recently proposed a telescope with a 100-meter (328-foot) primary mirror that would be autonomously constructed in space and bent into shape by electrostatic actuators. His proposal was one of several concepts selected this year by the NASA Innovative Advanced Concepts (NIAC) program for Phase I development.
Corder is the Boeing Career Development Professor in Aeronautics and Astronautics at MIT and a member of the Aerospace Materials and Structures Lab (AMSL) and Small Satellite Center. His research integrates his expertise in processing science, mechanics, and design to develop novel materials and structures for emerging aerospace applications. His proposal is the result of a collaboration with Prof. Jeffrey Lang (from MIT’s Electronics and the Microsystems Technology Laboratories) and a team of three students with the AMSL, including Ph.D. student Harsh Girishbhai Bhundiya.
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Their proposed telescope addresses a key issue with space telescopes and other large payloads that are packaged for launch and then deployed in orbit. In short, size and surface precision tradeoffs limit the diameter of deployable space telescopes to the 10s of meters. Consider the recently-launched James Webb Space Telescope (JWST), the largest and most powerful telescope ever sent to space. To fit into its payload fairing (atop an Ariane 5 rocket), the telescope was designed so that it could be folded into a more compact form.
This included its primary mirror, secondary mirror, and sunshield, which all unfolded once the space telescope was in orbit. Meanwhile, the primary mirror (the most complex and powerful ever deployed) measures 6.5 meters (21 feet) in diameter. Its successor, the Large UV/Optical/IR Surveyor (LUVOIR), will have a similar folding assembly and a primary mirror measuring 8 to 15 meters (26.5 to 49 feet) in diameter – depending on the selected design (LUVOIR-A or -B). As Bhundiya explained to Universe Today via email:
“Today, most spacecraft antennas are deployed in orbit (e.g., Northrop Grumman’s Astromesh antenna) and have been optimized to achieve high performance and gain. However, they have limitations: 1) They are passive deployable systems. I.e. once you deploy them you cannot adaptively change the shape of the antenna. 2) They become difficult to slew as their size increases. 3) They exhibit a tradeoff between diameter and precision. I.e. their precision decreases as their size increases, which is a challenge for achieving astronomy and sensing applications that require both large diameters and high precision (e.g. JWST).”
While many in-space construction methods have been proposed to overcome these limitations, detailed analyses of their performance for building precision structures (like large-diameter reflectors) are lacking. For the sake of their proposal, Cordero and his colleagues conducted a quantitative, system-level comparison of materials and processes for in-space manufacturing. Ultimately, they determined that this limitation could be overcome using advanced materials and a novel in-space manufacturing method called Bend-Forming.
This technique, invented by researchers at the AMSL and described in a recent paper co-authored by Bhundiya and Cordero, relies on a combination of Computer Numerical Control (CNC) deformation processing and hierarchical high-performance materials. As Harsh explained it:
“Bend-Forming is a process for fabricating 3D wireframe structures from metal wire feedstock. It works by bending a single strand of wire at specific nodes and with specific angles, and adding joints to the nodes to make a stiff structure. So to fabricate a given structure, you convert it into bending instructions which can be implemented on a machine like a CNC wire bender to fabricate it from a single strand of feedstock. The key application of Bend-Forming is to manufacture the support structure for a large antenna on orbit. The process is well-suited for this application because it is low-power, can fabricate structures with high compaction ratios, and has essentially no size limit.”
In contrast to other in-space assembly and manufacturing approaches, Bend-Forming is low-power and is uniquely enabled by the extremely low-temperature environment of space. In addition, this technique enables smart structures that leverage multifunctional materials to achieve new combinations of size, mass, stiffness, and precision. Additionally, the resulting smart structures leverage multifunctional materials to achieve unprecedented combinations of size, mass, stiffness, and precision, breaking the design paradigms that limit conventional truss or tension-aligned space structures.
In addition to their native precision, Large Bend-Formed structures can use their electrostatic actuators to contour a reflector surface with sub-millimeter precision. This, said Harsh, will increase the precision of their fabricated antenna in orbit:
“The method of active control is called electrostatic actuation and uses forces generated by electrostatic attraction to precisely shape a metallic mesh into a curved shape which acts as the antenna reflector. We do this by applying a voltage between the mesh and a ‘command surface’ which consists of the Bend-Formed support structure and deployable electrodes. By adjusting this voltage, we can precisely shape the reflector surface and achieve a high-gain, parabolic antenna.”
Harsh and his colleagues deduce that this technique will allow for a deployable mirror measuring more than 100 meters (328 ft) in diameter that could achieve a surface precision of 100 m/m and a specific area of more than 10 m2/kg. This capability would surpass existing microwave radiometry technology and could lead to significant improvements in storm forecasts and an improved understanding of atmospheric processes like the hydrologic cycle. This would have significant implications for Earth Observation and exoplanet studies.
The team recently demonstrated a 1-meter (3.3 ft) prototype of an electrostatically-actuated reflector with a Bend-Formed support structure at the 2023 American Institute of Aeronautics and Astronautics (AIAA) SciTech Conference, which ran from January 23rd to 27th in National Harbor, Maryland. With this Phase I NIAC grant, the team plans to mature the technology with the ultimate aim of creating a microwave radiometry reflector.
Looking ahead, the team plans to investigate how Bend-Forming can be used in geostationary orbit (GEO) to create a microwave radiometry reflector with a 15km (9.3 mi) field of view, a ground resolution of 35km (21.75 mi) and a proposed frequency span of 50 to 56 GHz – the super-high and extremely-high frequent range (SHF/EHF). This will enable the telescope to retrieve temperature profiles from exoplanet atmospheres, a key characteristic allowing astrobiologists to measure habitability.
“Our goal with the NIAC now is to work towards implementing our technology of Bend-Forming and electrostatic actuation in space,” said Harsh. “We envision fabricating 100-m diameter antennas in geostationary orbit with have Bend-Formed support structure and electrostatically-actuated reflector surfaces. These antennas will enable a new generation of spacecraft with increased sensing, communication, and power capabilities.”
Further Reading: NASA
Amateur N.S. astronomer captures magic of the green comet – CBC.ca
Tim Doucette with the Deep Sky Eye Observatory in southwestern Nova Scotia has captured a dazzling time-lapse of the green comet that’s making a rare pass near Earth.
Comet C/2022 E3 (ZTF) making its closest approach to Earth on Wednesday
An amateur astronomer from southwestern Nova Scotia has captured a dazzling time-lapse of the green comet that’s making a rare pass near Earth.
The last time the comet was this close to our planet was 50,000 years ago. Many Canadians are looking up at the stars this week as the comet gets ready to make its closest approach on Wednesday.
Tim Doucette with the Deep Sky Eye Observatory near Yarmouth, N.S., is among them.
He took a two-hour time-lapse of the comet during the early-morning hours of Jan. 28.
“If you’ve got a telescope and you look closely at the comet and the background stars, it’s travelling relative in our sky about one-quarter degrees per hour,” he told CBC Radio’s Mainstreet Halifax. “So within a few minutes you can see that the comet’s actually making motion in the night sky.”
You can listen to Doucette’s full interview with host Jeff Douglas here:
Mainstreet NS8:09Astronomer Tim Doucette captures images of rare green comet
With files from CBC Radio’s Mainstreet Halifax
Kemptville author’s book being sent to the moon
An author from North Grenville, Ont., is going to be part of a small club of authors whose works will be sent to the moon.
Michael Blouin of Kemptville says he’s been interested in space travel since the Apollo 11 mission that landed humans on the moon for the first time.
To be part of a group of hundreds of authors having their work immortalized within the vast expanse of space has him “gobsmacked.”
“I take comfort in the fact that no matter what happens, it looks like my books … will survive and be there,” he said.
“I sometimes wake up at night and say ‘Oh yeah, I’m going to the moon. Wow.’ It’s kind of amazing.”
How it came to be
Blouin said he’s been a lifelong fan of NASA and space exploration, so when the opportunity to get his work in the Writers on the Moon project came up, he had to take it.
Then around the deadline to apply, his house burned down.
Amid the chaos of not having anywhere to live and then moving into his son’s house, he realized he’d missed his chance.
“I had missed the deadline to apply for this program for books to go to the moon by 12 hours and I was just kicking myself,” he said.
“I lost everything and now I’d missed out on my chance to do something I’d always dreamed about doing.”
Luckily a friend and author in Newfoundland, Carolyn R. Parsons, said she had managed to get some of her work included in the project and had enough space on her microdisk to include him as well.
When do the books go?
The NASA launch is scheduled for Feb. 25 at Cape Canaveral in Florida, which will see his book Skin House brought to the stars along with other works of independent fiction.
Blouin is getting the chance to see the launch.
“These launches sometimes get delayed due to technical reasons or due to weather,” he said.
“But I’m hoping to give myself a big enough window that I’ll actually be on site.”
Blouin had some advice for people who aspire to write or create.
“Any young person aspiring in the arts just shouldn’t give up. Keep trying,” he said. “It can be a tough go but it’s worth every moment.”
He’s getting another of his books — I am Billy the Kid — up to the moon in 2024.
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