Posted on by Nancy Atkinson

Two New Kinds of Moon Rocks Found

Chandrayaan-1 3D color photo sent by the Moon Mineralogy Mapper. Credit: ISRO

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Scientists analyzing data from the Moon Mineralogy Mapper instrument or M Cubed, on the Chandrayann-1 spacecraft found two different kinds of never-before-seen lunar rocks – one hidden in a basin on the far side of the Moon and the other staring right at us on the near side. Just four minerals — plagioclase feldspar, pyroxene, olivine, and ilmenite — account for 98-99% of the crystalline material of the lunar crust, but the composition of these newly found rocks are two different kinds of spinels, a magnesium spinel and a chromite spinel. The composition and location of these new rock types are extremely puzzling, and lunar scientists are trying to determine more details about these mysterious Moon rocks.

Universe Today talked with Dr. Carle Pieters from Brown University who is the Principal Investigator for M Cubed as well as Dr. Jessica Sunshine from the University of Maryland, a co- investigator with the project.

Universe Today: Dr. Pieters, tell us about the newly found rocks on the far side.

Dr. Carle Pieters: The rock type on the far side of the Moon that is so unusual is a magnesium spinel, which typically has iron, magnesium, and aluminum oxide. In looking in detail at the spectral properties of the Moscoviense Basin on the far side — and in particular the material along the inner-most ring of this basin — we noticed there were a few little areas that were spectroscopically unusual. So, of course we investigated those in more detail. We saw three primary different compositions, and two we understand and had seen elsewhere, and they are rich in iron bearing minerals called pyroxene and olivine, and we saw small areas of these that are widely separated.

But then the third kind of mineral, the magnesium spinel, we had never seen before on the Moon, and what is interesting is not only is there an unusual abundance of this particular mineral, but it also has a lack of the pyroxenes and olivines that we see elsewhere. So there are several mysteries that are interwoven here. One, is why do we have a concentration of this spinel mineral and however it got concentrated in this area, why aren’t the other minerals that we are familiar with also there, because they are not.

So this is a big mystery and it is a very exciting one because now we have to reexamine our understanding of the character of the lunar crust, in particular to the depths that might have been tapped by this enormous basin and that we are now looking at as exposed on the surface.

Universe Today: So, what does this tell you about this region on the Moon?

Pieters: Not only are these unusual areas compositionally, and they are only about a kilometer or two in size, but in every method we’ve been able to look at thus far, in every wavelength and resolution, they have no other distinguishing properties. Typically, on the Moon to indentify an usual composition we look for a fresh crater that has excavated and exposed material on the surface of the Moon. These areas have no fresh craters, no disturbance at all across their surface, even at the highest resolution that is seen with the LROC (Lunar Reconnaissance Orbiter Camera) instrument which measures a half a meter resolution.

These are old surfaces that have been undisturbed but have an extremely unusual composition. And even the space weathering that has occurred on the surface throughout the billions of years of history on the Moon has not erased their unusual compositions. So, they are unusual for the kind of compositions we see, but they are also unusual because they have no identifying property that allows us to identify them in our imagery which is quite unusual for features on the surface of the Moon.

In the dark mantle deposits of the Sinus Aestuum (left), deposits of chromite spinel light up like beacons (right), but the nearby Rima Bode has no spinel. Credit: Jessica Sunshine, University of Maryland

Universe Today: Now let’s move to the near side of the Moon, where Dr. Jessica Sunshine and her team went looking for unusual data.

Dr. Jessica Sunshine: One of the things I was asked to be in charge of was looking for anomalies, things that just didn’t look like the rest of the Moon. And of course you never know what’s going to happen under those circumstances. Carle had already discovered there seemed to be a magnesium spinel on the far side of the Moon and I went looking to see where else it could be. We found that the only place that we had anything that looked like the spinel mineral in the data we had was on the near side and it was an extremely large deposit in the middle of the central nearside, almost exactly dead center at zero-zero. And we started looking a little more carefully and realized that it wasn’t really the same kinds of things that Carle found, which truly was a new rock type on the far side of the Moon, but something really usual about the region.

We had already known the region was full of what we call dark mantle deposits or pyroclastic deposits, which is firefountaining deposits. This came from explosive eruptions of lava and gas over large areas of the Moon, about the size of Massachusetts. And we knew that three of them were there, it just turned out that one of them was compositionally different from the other ones, and in particular it had the kind of spinel which is a chromite, because it has chrome in it, and now we’re busy trying to figure out why this deposit is different from the one next door, and what does it mean. And we’re still working that process out as we speak.

Universe Today: What is it like to find something new like this on the side of the Moon that humans have been able to see for thousands of years?

Sunshine: Yes, I tend to title my talks on the subject something like, “Hidden in Plain Sight” because they are! It’s right there and I think this is a really fascinating part of this because we have been starring at the Moon, as humanity for millennia and if our eyes were slightly different we would see this one really dark spot in the middle of the Moon that is different from anywhere else.

Universe Today: What specifically about the Chandrayaan-1 spacecraft and the Mcubed instrument made these discoveries possible?

Sunshine: M Cubed collects data over a much broader range of light than our human eyes can. We can all see the rainbow, we’re all familiar with that, from blue to red, but there is light at shorter wavelengths, which we call ultraviolet, and particularly for this case, there is light at shorter wavelengths called infrared. M Cubed goes farther into the infrared than humans can see and it is there we are able to see diagnostic fingerprints of different kinds of minerals. So I suspect there are certain kinds of bugs who would look at the Moon and would have known these deposits are there because their vision goes into the infrared!

Universe Today: So, Dr. Pieters, does these new discoveries tell us there are still more mysteries to find on the Moon?

Pieters: Oh, absolutely! We’ve just barely scratched the surface here. This is thrilling from a spectroscapist’s point of view, of course, but also from someone who is trying to understand how planets work, and in particular how this wonderful small body in our neighborhood is telling us about the characteristics of crustal evolution and fundamental properties of planetary surfaces.

You can listen to a version of this interview on the 365 Days of Astronomy podcast and the NASA Lunar Science Institute podcasts

Posted on by Nancy Atkinson

Simple Colors Could Provide First Details of Alien Worlds

At best, the few extrasolar planets we have imaged directly are just points of light. But what can that light tell us about the planet? Maybe more than we thought. As you probably know the, Deep Impact spacecraft flew by comet Hartley 2 today, taking images from only 700 km away. But maneuvering to meet up with the comet is not the only job this spacecraft has been doing. The EPOXI mission also looked for ways to characterize extrasolar planets and the team made a discovery that should help identify distinctive information about extrasolar planets. How did they do it? By using the Deep Impact spacecraft to look at the planets in our very own solar system.

The spacecraft imaged the planetary bodies in our solar system — in particular the Earth, Mars and our Moon — (see here for movies of the Moon transiting Earth) and astronomer Lucy McFadden and UCLA graduate Carolyn Crow compared the reflected red, blue, and green light and grouped the planets according to the similarities they saw. The planets fall into very distinct regions on this plot, where the vertical direction indicates the relative amount of blue light, and the horizontal direction the relative amount of red light.

This suggests that when we do have the technology to gather light from individual exoplanets, astronomers could use color information to identify Earth-like worlds. “Eventually, as telescopes get bigger, there will be the light-gathering power to look at the colors of planets around other stars,” McFadden says. “Their colors will tell us which ones to study in more detail.”

On the plot, the planets cluster into groups based on similarities in the wavelengths of sunlight that their surfaces and atmospheres reflect. The gas giants Jupiter and Saturn huddle in one corner, Uranus and Neptune in a different one. The rocky inner planets Mars, Venus, and Mercury cluster off in their own corner of “color space.”

But Earth really stands out, and its uniqueness comes from two factors. One is the scattering of blue light by the atmosphere, called Rayleigh scattering, after the English scientist who discovered it. The second reason Earth stands out in color is because it does not absorb a lot of infrared light. That’s because our atmosphere is low in infrared-absorbing gases like methane and ammonia, compared to the gas giant planets Jupiter and Saturn.

“It is Earth’s atmosphere that dominates the colors of Earth,” Crow says. “It’s the scattering of light in the ultraviolet and the absence of absorption in the infrared.”

So, this filtering approach could provide a preliminary look at exoplanet surfaces and atmospheres, giving us an inkling of whether the planet is rocky or a gas planet, or what kind of atmosphere it has.

EPOXI is a combination of the names for the two extended mission components for the Deep Impact spacecraft: the first part of the acronym comes from EPOCh, (Extrasolar Planet Observations and Characterization) and the flyby of comet Hartley 2 is called the Deep Impact eXtended Investigation (DIXI).

Posted on by Nancy Atkinson

First Close Images of Hartley 2: It’s a Peanut with Jets

Comet Hartley as seen by the EPOXI spacecraft at closest approach. Credit: NASA

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NASA’s Deep Impact spacecraft came within 700 kilometers (435 miles) of Comet Hartley 2 at 10:01 a.m. EDT (1401 GMT) today, imaging with several cameras. Here are the first pictures released of the closest approach.

The scientific team watched along with viewers online and on NASA TV as the images were returned to Earth, about an hour after the spacecraft made its closest approach. First impressions? It is a peanut with jets.

“This is a type of moment that scientists live for,” said JPL’s Don Yeomans, “to get new results in such a dramatic fashion. The images are clear, taken as spacecraft was approaching, then as it swung past and moved away.”

The Sun is off to right, and visible is the icy surface of the comet throwing dust and gas towards the Sun.


Another view of Comet Hartley 2 during EXPOXI close approach. Credit: NASA

More images will be coming down from the spacecraft and Yeomans said the scientists will be examining Hartley 2, looking for the origination spots of the jets. “Are the jets coming from the surface, or is it coming from well beneath where heat of Sun reaches into the comet? We’ll be looking for how many jets, or if possibly the whole comet outgassing. There is a single obvious jet coming off towards the Sun, but also you can see one at the 7 o’clock position, which was evident in previous images, too.”

Image of Hartley 2 as the EXPOXI spacecraft moved away from comet. Credit:NASA

The spacecraft uses several high-resolution instruments, and one camera can image the entire comet with a resolution of about seven meters (about 23 feet) per pixel. The spacecraft also acquired 199 medium-resolution images.

From previous images taken by EPOXI from a distance and radar images taken from the ground, scientists knew Hartley 2 was a bi-lobate comet, which means peanut- or pickle-shaped. But they didn’t know if it was a solid surface or a contact binary, where two smaller cometesimals were stuck together.

But, Yeomans said, these images show the comet is of a solid, one-piece construction.

EPOXI Principal Investigator Mike A’Hearn agreed. “Every time we go to a comet they are full of big surprises,” he said. “The comets we’ve seen up close all seem to work the same way, but they look very different so there must be some fundamental differences in the ways they work. It could be they came from different parts of the early solar system or that they evolved very differently. Finding out how the solar system formed is really what we want out of this.”

The discoverer of Hartley 2, Malcolm Hartley, was on hand at JPL for the closest approach. He found the comet 26 years ago as a smudge on photographic plates taken at the Siding Spring Observatory in Australia. “I was doing quality control of photographic plates and I noticed faint object with a telltale glow like a comet,” said Hartley, who still works at the same observatory. “It has been very interesting to be here, and it has been interesting for the science team and quite a challenge for the engineers. There’s going to be enough data downloaded to keep researchers busy for several years.”

See the EPOXI website for more images, and more will be coming down from the spacecraft over the next few days.

To see a “quick and dirty” animation of the flyby images, see this link provided by Doug Ellision of Unmanned Spaceflight.com (and JPL).

Posted on by Jason Rhian

Discovery’s Final Mission Scrubbed 24 Hours Due to Weather

The crew of STS-133 will have to wait a little longer for their date with destiny - this time thanks to weather. Photo Credit: NASA/Kim Shiflett

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Discovery’s final flight faced its first hurdle in the form of a fuel leak in its right OMS pod. This problem seemed solved, but using an over-abundance of caution mission managers had the seals around the affected flange replaced. Then unrelated leaks of hydrogen and helium pushed the launch back to Nov. 2 and then Nov. 3. With that problem resolved many thought Discovery’s problems were behind her – enter a voltage issue in the number three engine’s backup control system. This conspired to push the launch back to Nov. 4.

However, in the early morning hours of Nov. 4 it was obvious that Florida’s turbulent weather would not allow a launch on this day and mission managers scrubbed the launch for at least 24 hours. Weather for Friday shows a 70 percent chance of favorable conditions. If Discovery does launch tomorrow, it will take place at 3:04 p.m. EDT.

Discovery’s final mission, STS-133, will deliver the Leonardo Multipurpose Module (PMM) with its cargo – including the first humanoid robot to be sent into space – Robonaut-2 (R2). Also riding along on this mission is the Express Logistics Carrier-4 and spare parts. Like the other remaining shuttle flights, these new components and supplies are designed to leave the space station better prepared for when the space shuttles are retired next year.

The crew of STS-133 will be comprised of Commander Steve Lindsey, Pilot Eric Boe and Mission Specialists; Alvin Drew, Nicole Stott, Tim Kopra and Michael Barratt. All of these astronauts are space flight veterans.

Posted on by Matt Williams

What is Plutonium?

Periodic Table of Elements
Periodic Table of Elements

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The name itself conjures up imagines of mini nukes and sophisticated space-age gadgets doesn’t it? Well for some people it does. For others, Plutonium (Pu, atomic number of 94 on the periodic table of elements) spawns images of nuclear reactors, atomic energy and nuclear waste. All of these are true to an extent, but the reality behind this radioactive element is understandably more complex. For starters, plutonium is a silvery white actinide metal that is radioactive, and hence quite dangerous when exposed to living tissue. It is one of the key ingredients in the making of atomic weapons, but is also produced in nuclear reactors as a result of slow fission. There are also several isotopes of the element, but for our purposes, the most important is Plutonium-239, a fissile isotope that is used for both nuclear power and weapons and has a half-life of 24,100 years.

Plutonium-238 was first discovered as an element on Dec.14th1940, and then chemically identified on February 23rd 1941through the deuteron bombardment of Uranium in a cyclotron by Glenn T. Seaborg and his team of scientists, working out of the University of California in Berkley. The team submitted a paper publishing their findings; however, this paper was retracted when it became clear that Plutonium-239 was a fissile material that could be useful in the construction of an atomic weapon. At this time, the US was deep into the development of an atomic bomb (aka. the Manhattan Project) because it was believed that Germany was doing the same. For this reason, publication of Seaborg’s work was delayed until 1946, a year after the Second World War ended and security surrounding atomic research was no longer a concern. Seaborg decided to name the element after Pluto because of the recent discovery of element 93, Neptunium, and felt that element 94 should accordingly be named after the next planet in the Solar System.

Towards the end of WWII, two nuclear reactors were created which would produce the plutonium used in the construction of “Trinity”, “Fat Man” and other atomic weapons. These were the X-10 Graphite Reactor facility in Oak Ridge (which later became the Oak Ridge National Laboratory) and the Hanford B reactor (built in 1943 and 45 respectively). Large stockpiles were subsequently built up by the US and USSR during the Cold War, and have since become the focus of nuclear proliferation treaty concerns. Today, it is estimated that several tonnes of plutonium isotopes exist in our biosphere, the result of atomic testing during the 1950’s and 60’s.

We have written many articles about Plutonium for Universe Today. Here’s an article about Plutonium shortage in NASA, and here’s an article about Plutonium – 238.

If you’d like more info on Plutonium, check out Wikipedia – Plutonium, and here’s a link to World Nuclear page about Plutonium.

We’ve also recorded an entire episode of Astronomy Cast all about Nuclear Forces. Listen here, Episode 105: The Strong and Weak Nuclear Forces.

Sources:
http://en.wikipedia.org/wiki/Plutonium
http://www.world-nuclear.org/info/inf15.html
http://periodic.lanl.gov/elements/94.html
http://en.wikipedia.org/wiki/Nuclear_proliferation
http://en.wikipedia.org/wiki/Actinide
http://en.wikipedia.org/wiki/Cyclotron

Posted on by Matt Williams

What is a Plutoid?

About Dwarf Planets

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Pluto, we hardly knew ya! Don’t worry, she’s not going anywhere. However, this once happy planet will no longer be listed amongst the “planets” in our solar system. According to International Astronomical Union (IAU), which began meeting in August of 2006, the term Plutoid now applies to Pluto, as well as any other small stellar body that exist beyond the range of Neptune. Arriving at this working definition in 2008, two years after first meeting, the IAU defines the term Plutoids thusly: “Plutoids are celestial bodies in orbit around the Sun at a semimajor axis greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit.”

The reason the IAU began meeting in the first place was to iron out some ambiguities that exist in the terminology of astronomy. For example, thought some might find it shocking, astronomers had never actually come up with a definition of “planet”. Originally, a planet meant a “wandering star” – ie. a star that appeared to move from constellation to constellation. This was the definition used by ancient astronomers, and it applied to the sun and moon as well. However, Copernicus’s heliocentric model changed all that; now it was clear that the Earth was a planet itself and moved around the Sun with the rest of them. In addition, more and planets were being discovered beyond Jupiter, such as Uranus and Neptune, and then between Jupiter and Mars. This included Ceres, Pallas, Vesta, and Juno, but astronomers soon realized that these bodies were far too small to fit with the rest of the planets.

Then came Pluto’s discovery. At the time, scientists thought it to be several times larger than it actually was; accordingly they placed it on the list of planets. Eventually, its true size was realized and other bodies similar to Pluto in size and composition were found far beyond Neptune, in what is known as the Kuiper Belt. Pluto was to these stellar objects what Ceres was to large objects in the asteroid belt – that is to say, comparable in size. Astronomers proposed several names for these objects, but matters did not come to a head until Eris was discovered. This dwarf planet was actually larger than Pluto, 2500 km in diameter, making it twenty-seven percent larger than Pluto.

In the end, the IAU could only resolve this matter by removing Pluto from the list of planets and devising a new category for dwarf planets that could no longer be considered true planets. Plutoid was the result, and now applies to the trans-Neptunian objects of Pluto, Haumea, Makemake, and Eris.

We have written many articles about Plutoid for Universe Today. Here are some facts about Pluto, and here’s an article about why Pluto is no longer a planet.

If you’d like more info on Pluto, check out Hubblesite’s News Releases about Pluto, and here’s a link to NASA’s Solar System Exploration Guide to Pluto.

We’ve also recorded an episode of Astronomy Cast dedicated to Pluto. Listen here, Episode 64: Pluto and the Icy Outer Solar System.

Sources:
http://en.wikipedia.org/wiki/Plutoid
http://astroprofspage.com/archives/1685
http://www.sciencedaily.com/releases/2008/06/080611094136.htm
http://en.wikipedia.org/wiki/Eris_%28dwarf_planet%29

Posted on by Jon Voisey

Hartley 2 Spawns Meteor Shower

Universe Image Gallery

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The comet of the year for 2010 seems to be Hartley 2. Although this comet is receding from Earth now (its closest approach was in the latter half of October) and growing fainter, it seems to have left us with one last hurrah: The spawning a brief meteor shower.


Although other comets, such as 2009 R1 (McNaught) and 2P/Encke have passed earlier this year, none has presented an especially tempting target for amateur astronomers (both McNaught and Encke were too close to the Sun during perihelion to be easily observed). Additionally, Hartley is the target of a flyby of the Deep Impact probe bringing it further attention.

Meanwhile, observationally, the comet has been somewhat difficult to observe. I went out on October 17th to hunt for it with a 4″ telescope, but despite my best efforts, couldn’t find it. Although the comet was predicted to reach 5th magnitude, the growing nucleus has apparently become so diffuse, reaching over 1° in the sky, that it’s hard to spot. Undeterred, I attempted again this past weekend with my 8″ SCT. Again, my attempts were frustrated. Even a 15 second exposure with my camera barely brought out more than a smudge.

Yet that night we observed several bright meteors radiating from near Cassiopeia which is where Hartley had been a few weeks prior. We checked to ensure there weren’t any other annual meteor showers from that region. Sure enough, there weren’t, and we wondered if there might be a connection between Hartley’s passing and the meteors we witnessed.

Sure enough, just such a shower was a predicted possibility. Whether or not the shower would occur would depend on just how much dust Hartley had given off in the past and how diffuse the cloud had grown (on this pass and others) since its closest approach to Earth was still 12 million km. Although the meteors my friends and I witnessed were notable (around 2nd to 3rd magnitude) they came from the wrong direction. Meteors spawning from Hartley should have a radiant in Cygnus, the swan. But while ours may not have caught these “Hartley-ids”, others have been witnessing a far grander show in the past few nights that seem to come from the right direction.

In Seascape California, Helga Cabral caught a bright fireball. “I saw a bright white ball and tail, arcing towards the ocean. It was quite beautiful and it looked like it was headed out to sea and so picture perfect it could have been a movie!” A similar fireball was reported the same night near Boston, Massachusetts by Teresa Witham. The predicted peak of this shower occurs tonight so if you have a chance and clear skies, go out and look. As with most showers, there may be some stragglers just before and after so you may be able to catch some for the next few nights if conditions tonight aren’t favorable.

Meteors from Hartley 2 will have a relatively low velocity upon entering our atmosphere since the comet is traveling roughly in the same direction. As such, the expected velocity as it hits our planet is a mere 7 miles a second. The result of this is that they will likely travel slowly across the sky, taking perhaps as much as a few seconds. In contrast, the Leonid showers coming later this month have a relative velocity of 45 miles per second, which causes the meteors to streak across the entire sky in less than a second. The lower velocity for the Hartley-ids will also mean they won’t undergo as much frictional heating and will likely glow fainter shades of reds and yellows.

Posted on by Nancy Atkinson

Watch Live Coverage of EPOXI’s Hartley 2 Encounter on Nov. 4

Comet 103P/Hartley 2 Animation, created by images taken by Patrick Wiggins, NASA/JPL Solar System Ambassador to Utah. Used by permission.

Watch live coverage of the EPOXI mission’s close flyby of Comet Hartley 2. Live coverage begins on November 4, 2010 at 9:30 a.m. EDT (6:30 a.m. PDT) from mission control at the Jet Propulsion Laboratory. You can watch NASA TV’s Media Channel online at this link, (and make sure you click on the “Media Channel” tab on the right side of the “tv” screen). You can also watch on JPL’s UStream channel online. Coverage includes closest approach, an educational segment, and the return of close-approach images. Emily Lakdawalla of the Planetary Society Blog has posted a very detailed timeline of the encounter.
Continue reading “Watch Live Coverage of EPOXI’s Hartley 2 Encounter on Nov. 4”

Posted on by Nancy Atkinson

Calculate the Effect of an Asteroid Impact on Earth

Impact Earth website

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A 20-km asteroid has just been predicted to hit Earth and you want to know if a. You should run for it, b. You should call Bruce Willis, or c. You can rest easy because your part of the world won’t be affected. All you have to do is input the parameters of the asteroid on the recently updated “Impact Earth” website, and you’ll find out everything about what an impactor will do to Earth, including an estimate of the size of the crater, how far away you’ll need to be in order to avoid being affected by the impact (and if that is possible), tsunami wave height, and other details of the subsequent disaster. The fun part is, you can simulate the destruction of Earth multiple times, without hurting anyone.

The original Impact Earth website was created in 2002 for use by NASA and homeland security. The new version, built in a collaboration between Purdue University and Imperial College London, is more user-friendly for the general public, as well as providing more visual details of an impact. Besides being rather fun to play around with, the website is highly educational about what a various sized impacts would do Earth, depending on if it hit ground or water.

Go play around with it.

Posted on by Nancy Atkinson

It Could Be Our Only Hope for True 3D Holograms

This is great: Now anyone can send holographic appeals to Obi Wan Kenobi just like Princess Leia. A team from the University of Arizona’s College of Optical Sciences has developed a system that can produce truly three-dimensional images and the viewer is not required to wear special 3D glasses. The system allows the projection of a three-dimensional, moving image that refreshes every 2 seconds. So in many respects it would be very similar to R2D2’s projected holographic message in Star Wars.

“Holographic telepresence means we can record a three-dimensional image in one location and show it in another location, in real-time, anywhere in the world,” said Nasser Peyghambarian, who led the research team.
Continue reading “It Could Be Our Only Hope for True 3D Holograms”