According to the most widely accepted theories, the Moon formed about 4.5 billion years ago after a Mars-sized object (Theia) collided with Earth. After the resulting debris accreted to create the Earth-Moon system, the Moon spent many eons cooling down. This meant that a few billion years ago, lakes of lava were flowing across the surface of the Moon, which eventually hardened to form the vast dark patches (lunar maria) that are still there today.
Thanks to the samples of lunar rock brought back to Earth by China’s Chang’e 5 mission, scientists are learning more about how the Moon formed and evolved. According to a recent study led by the Chinese Academy of Geological Sciences (CGAS), an international team examined these samples to investigate when volcanism on the Moon ended. Their results are not only filling in the gaps of the Moon’s geological history but also of other bodies in the Solar System.
The study, which recently appeared in the journal Science, was led by Xiaochao Che of the Beijing Sensitive High-Resolution Ion Micro Probe Center, located at the CGAS Institute of Geography. He was joined by researchers from the Planetary Science Institute (PSI), McDonnell Center for the Space Sciences, the Swedish Museum of Natural History, Shandong Institute of Geological Sciences, and several universities from the US, UK, and Australia.
Mons Rümker is visible in Oceanus Procellarum in this image taken from the Apollo 15 mission in lunar orbit. Credit: NASA
The samples obtained by the Chang’e-5 rover are the first to be returned to Earth since the Apollo era (45 years ago) and were obtained from the volcanic plain known as Oceanus Procellarum (Latin for “Ocean of Storms”). This lunar region is unique among lunar terrae, as it is believed to have hosted the most recent basalt lava flows on the Moon. Jim Head, a research professor in Brown’s Department of Earth, Environmental and Planetary Sciences, was a co-author on the new study.
The Chang’e-5 spacecraft landed in this region on Dec. 1st, 2020, and managed to collect about 1,730 g (61.1 oz) of lunar rock from this region, including a core sample obtained from a depth of ~1 m (3.3 ft) beneath the surface. As he explained in a recent News from Brown press release:
“These samples come from a region of the Moon that’s been largely unexplored by landed spacecraft. Previous samples from the Apollo missions and the Soviet Luna missions all come from the central and eastern part of the Moon’s near side.
“But it became clear as we collected more remote sensing data that the most recent volcanism on the Moon was absolutely in that western portion, so that region became a prime target for sample collection. Specifically, the samples came from near Mons Rümker, a volcanic mound in the largest of the lunar maria, Oceanus Procellarum.”
Mons Rümker, a volcanic construct in Oceanus Procellarum on the Moon. Mosaic of photos by Lunar Reconnaissance Orbiter, made with Wide Angle Camera. Credit: NASA
The Oceanus Procellarum region is characterized by high concentrations of radioactive elements such as potassium, uranium, and particularly thorium. These generate heat through long-lived radioactive decay and are believed to have played a role in prolonging magmatic activity on the near side of the Moon. After examining the samples through radiometric dating, the team concluded that they were (on average) 2 billion years old.
“However, in these samples, we didn’t actually see an elevated radioactive element composition,” said Head. “If these radioactive
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The Solar Radius Might Be Slightly Smaller Than We Thought
Two astronomers use a pioneering method to suggest that the size of our Sun and the solar radius may be due revision.
Our host star is full of surprises. Studying our Sun is the most essential facet of modern astronomy: not only does Sol provide us with the only example of a star we can study up close, but the energy it provides fuels life on Earth, and the space weather it produces impacts our modern technological civilization.
Now, a new study, titled The Acoustic Size of the Sun suggests that a key parameter in modern astronomy and heliophysics—the diameter of the Sun—may need a slight tweak.
The study out of the University of Tokyo and the Institute of Astronomy at Cambridge was done looking at data from the joint NASA/ESA Solar Heliospheric Observatory (SOHO’s) Michelson Doppler Imager (MDI) imager. The method probes the solar interior via acoustics and a cutting edge field of solar physics known as helioseismology.
A cutaway diagram of the Sun. NASA/ESA/SOHO
‘Hearing’ the Solar Interior
How can you ‘hear’ acoustic waves on the Sun? In 1962, astronomers discovered that patches on the surface of the Sun oscillate, or bubble up and down, like water boiling on a stove top. These create waves that ripple in periodic 5-minute oscillations across the roiling surface of the Sun.
A view of the Sun, courtesy of SOHO’s MDI instrument. Credit: NASA
What’s more, astronomers can use what we see happening on the surface of the Sun to model the solar interior, much like terrestrial astronomers use seismic waves traveling through the Earth to model its core. Thanks to helioseismology, we can even ‘see’ what’s going on on the solar farside, and alert observers of massive sunspots before they rotate into view.
Solar farside modeling using helioseismology. Credit: NSF/GONG
The study looked at p-mode waves as they traversed the solar interior. Previous studies relied on less accurate f-mode waves, which are surface waves considerably shorter than the solar radius.
The study defines the solar radius (half the diameter) as 695,780 kilometers… only slightly smaller than the generally accepted radius of 696,000 kilometers obtained by direct optical measurement. This is only smaller by a few hundredths of a percent, or 100-200 kilometers.
An artist’s conception of SOHO in space. Credit: ESA/SOHO
The solar radius is a deceptively simple but crucial factor in astronomy. The Sun is a glowing ball of hydrogen and helium plasma without a distinct surface boundary. The photosphere—the glowing visible layer we see shining down on us on a sunny day—is what we generally refer to as the surface of the Sun.
The Solar Radius: A Brief
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If Warp Drives are Impossible, Maybe Faster Than Light Communication is Still on the Table?
I’m sure many readers of Universe Today are like me, fans of the science fiction genre. From the light sabres of Star Wars to the neuralyzer of Men in Black, science fiction has crazy inventions aplenty and once science fiction writers dream it, scientists and engineers try and create it. Perhaps the holy grail of science fiction creations is the warp drive from Star Trek and it is fair to say that many have tried to work out if it is even possible to travel faster than the speed of light. To date, alas, to no avail but if the warp drive eludes us, what about faster than light communication!
Let’s start with the warp drive. The concept is a drive that can propel a spacecraft at speeds in excess of the speed of light. According to the Star Trek writers, the speed was described in factors of warp speed where they are converted to multiples of the speed of light by multiplication with the cubic function of the warp factor itself! Got it! Don’t worry, it’s not crucial to this article. Essentially ‘warp 1’ is equivalent to the speed of light, ‘warp 2’ is eight times speed of light and ‘warp 3’ is 27 times the speed of light and so it goes on! Therein lies the problem; achieving faster than light travel.
In attempts to try to understand this, numerous experiments have been undertaken, of note Bill Bertozzi at MIT accelerated electrons and observed them becoming heavier and heavier until they couldn’t be accelerated any more! Once at the speed of light, it takes an infinite amount of energy to accelerate an object further! The maximum speed he achieved was the speed of light. In other experiments, synchronised atomic clocks were taken on board airliners and found that, after travelling at high speed relative to a reference clock on Earth, time had run slower! The upshot is that the faster you go, the slower time passes and at the speed of light, time stops! If time stops, so does speed! hmmmm this is tricky.
The science of faster than light travel aside, In a number of potential warp drive designs have surfaced like the Alcubierre Drive proposed in 1994. However, the common factor to provide the faster than light travel is something called negative energy which is required in copious amounts. The study of quantum mechanics shows that even empty space has energy and anything that has less energy than empty space has ‘negative energy’. The problem (among many) is that no-one knows how to get negative energy in huge amounts to power the warp drives.
Two-dimensional visualization of an Alcubierre drive, showing the opposing regions of expanding and contracting spacetime that displace the central region (Credit : AllenMcC)
It seems the warp drive is some time away yet but what about faster than light communication, could that work? Accelerating macroscopic objects, like spacecraft requires high amounts of negative energy but communication, as a recent paper explains, which operates at much smaller scale requires less energy. Quite a bit less in fact, less than is contained inside a lightning bolt. Perhaps more tantalising is that we may just be able to create small amounts of negative energy using today’s technology.
One of the ways this can be achieved is to ensure the proper configuration and distribution of negative energy to channel communication. The paper proposes a tubular distribution of negative energy in so called hypertubes to enable the acceleration and deceleration of warp bubbles for superluminal communication. Achieving this for long distance communication will require special devices to be designed and built but as the papers author Lorenzo Pieri concludes “it is tantalising to consider the fabrication of microchips capable of superluminal computing”. Yes, that is an exciting proposition but the thought of firing messages out to the cosmos at speeds faster than that of light.. Just wow!
Source : Hyperwave: Hyper-Fast Communication within General Relativity
The post If Warp Drives are Impossible, Maybe Faster Than Light Communication is Still on the Table? appeared first on Universe Today.
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Reader Appreciation Sale: Join The Big Outside for 30% Off
I love the holidays, partly because I make a point of spending a lot of time outside with family and friends. But it’s also a time when I reflect on how much I enjoy my lifestyle—and how much I appreciate readers like you who follow and support my blog. To show my appreciation, I have a special gift for you.
Right now, I’m offering you 30% off the cost of a one-year subscription to The Big Outside.
That means you get full access to all stories at my blog—including my many stories about the trips I’ve taken, with my expert tips on planning them—for $41.97 instead of the usual cost of $59.95 for a full year, or just $3.50 a month.
That’s the biggest discount I offer on a subscription all year—just in time to start researching your trips for next year. Don’t miss out!
Go to my Join page now and click on the Subscribe button under the Annual subscription option (Best Value: $4.99/Month). Enter discount code TBO30 and the price will reset to $41.97. Then just fill out the form and complete the purchase. The 30% discount applies only to a one-year subscription. You also get one free or deeply discounted e-guide, a $12.95 value; I’ll personally email you the discount code for that after you subscribe.
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Michael Lanza of The Big Outside above Macon Lake and Washakie Lake on the Washakie Pass Trail in the Wind River Range, Wyoming.
” data-image-caption=”Me above Macon Lake and Washakie Lake on the Washakie Pass Trail in the Wind River Range, Wyoming; and in Death Hollow in southern Utah (lead photo, above).
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/11/Wind9-53-Me-above-Macon-Lake-and-Washakie-Lake-on-the-Washakie-Pass-Trail-in-the-Wind-River-Range-WY.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/11/Wind9-53-Me-above-Macon-Lake-and-Washakie-Lake-on-the-Washakie-Pass-Trail-in-the-Wind-River-Range-WY.jpg?fit=900%2C600&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/11/Wind9-53-Me-above-Macon-Lake-and-Washakie-Lake-on-the-Washakie-Pass-Trail-in-the-Wind-River-Range-WY.jpg?resize=900%2C600&ssl=1″ alt=”Michael Lanza of The Big Outside above Macon Lake and Washakie Lake on the Washakie Pass Trail in the Wind River Range, Wyoming.” class=”wp-image-61100″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/11/Wind9-53-Me-above-Macon-Lake-and-Washakie-Lake-on-the-Washakie-Pass-Trail-in-the-Wind-River-Range-WY.jpg?resize=1024%2C683&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/11/Wind9-53-Me-above-Macon-Lake-and-Washakie-Lake-on-the-Washakie-Pass-Trail-in-the-Wind-River-Range-WY.jpg?resize=300%2C200&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/11/Wind9-53-Me-above-Macon-Lake-and-Washakie-Lake-on-the-Washakie-Pass-Trail-in-the-Wind-River-Range-WY.jpg?resize=768%2C512&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/11/Wind9-53-Me-above-Macon-Lake-and-Washakie-Lake-on-the-Washakie-Pass-Trail-in-the-Wind-River-Range-WY.jpg?resize=150%2C100&ssl=1 150w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2022/11/Wind9-53-Me-above-Macon-Lake-and-Washakie-Lake-on-the-Washakie-Pass-Trail-in-the-Wind-River-Range-WY.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Me above Macon Lake and Washakie Lake on the Washakie Pass Trail in the Wind River Range, Wyoming; and in Death Hollow in southern Utah (lead photo, above).
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