Posted on by Nancy Atkinson

LRO Finds Some Surprises on the Moon

Bruno Crater. Taken by: LROC Narrow Camera. Image Credit: NASA/GSFC/Arizona State University

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The Lunar Reconnaissance Orbiter (LRO) is getting the closest look yet at the Moon from orbit, providing crucial insights to help prepare for a possible return of humans to the lunar surface. “There is a lot of natural beauty on the Moon,” said Mike Wargo, NASA’s chief lunar scientist, speaking at the American Geophysical Union meeting on Tuesday. “LRO is collecting data to support a return to the Moon, studying a diverse and representative set of sites selected on scientific, engineering, and resource potential and representative of the wide range of terrains present on the Moon.”

Scientists explained how various instruments on LRO are returning surprising data while helping scientists map the moon in incredible detail and understand the lunar environment.

LROC, or the LRO Camera, has now mapped in high resolution all the Apollo landing sites and 50 sites that were identified by NASA’s Constellation Program to be representative of the wide range of terrains present on the moon.

Some of the most intriguing images revisit the sites of humankind’s first forays beyond Earth orbit.

Enlargement of area surrounding Apollo 11 landing site. Credit: NASA/GSFC/Arizona State University
Enlargement of area surrounding Apollo 11 landing site. Credit: NASA/GSFC/Arizona State University

“Imaging the Apollo landing sites have served a practical purpose,” said Mark Robinson, LROC principal investigator, “as we are using them in lieu of stars to calibrate the LROC Narrow Angle Cameras. Plus these images are much more fun than stars, because we get to see where humans used to walk. It’s also much less stress on the spacecraft because you don’t have to slew in and out to look at the stars.”

Since the locations of the Apollo spacecraft and other hardware left by the astronauts are known to about nine feet absolute accuracy, Robinson said they can tie the Narrow Angle Camera geometric and timing calibration to the coordinates of the Apollo Laser Ranging Retroreflectors and Apollo Lunar Surface Experiments Packages. “This ground truth enables more accurate coordinates to be derived for virtually anywhere on the moon. Scientists are currently analyzing brightness differences of the surface material stirred up by the Apollo astronauts, comparing them with the local surroundings to estimate physical properties of the surface material. Such analyses will provide critical information for interpreting remote sensing data from LRO, as well as from India’s Chandrayaan-1, and Japan’s Kaguya missions.”

Robinson said the soil compacted by the Apollo astronauts and lunar rovers is darker than undisturbed soil. “Disturbing the soil changes the brightness by a factor of two,” he said.

LRO’s Diviner instrument has discovered that the bottoms of polar craters in permanent shadow can be brutally cold. Mid-winter nighttime surface temperatures inside the coldest craters in the north polar region dip down to 26 Kelvin (416 below zero Fahrenheit, or minus 249 degrees Celsius). “These are the coldest temperatures that have been measured thus far anywhere in the solar system. You may have to travel to Kuiper Belt to find temperatures this low” said David Paige, principal investigator for the Diviner Lunar Radiometer Experiment. “The temperatures we are observing both day and night are way cold enough to preserve water ice for extended periods, as well as a wide range of compounds such as carbon dioxide and organic molecules. There could be all kinds of interesting compounds trapped there.”

Paige also noted that it turns out the moon does have seasons. “The Moon has a tilt of 1.54 degrees, so at most latitudes the lunar seasons are hardly noticeable,” he said, “but at Polar Regions, there are significant variation in shadows and temperatures because of this tilt.”

The Cosmic Ray Telescope for the Effects of Radiation, or CRaTER, is measuring the amount of space radiation at the Moon to help determine the level of protection required for astronauts during lengthy expeditions on the moon or to other solar system destinations.

“This surprising solar minimum, or quiet period for the sun regarding magnetic activity, has led to the highest level of space radiation in the form of Galactic Cosmic Rays, or GCRs, fluxes and dose rates during the era of human space exploration,” said Harlan Spence, principal investigator the CRaTER instrument. “The rarest events – cosmic rays with enough energy to punch through the whole telescope – are seen once per second, nearly twice higher than anticipated. Crater radiation measurements taken during this unique, worst-case solar minimum will help us design safe shelters for astronauts.”

GCRs are electrically charged particles – electrons and atomic nuclei – moving at nearly the speed of light into the solar system. Magnetic fields carried by the solar wind deflect many GCRs before they approach the inner solar system. However, the sun is in an unusually long and deep quiet period, and the interplanetary magnetic fields and solar wind pressures are the lowest yet measured, allowing an unprecedented influx of GCRs.

Scientists expected the level of GCRs to drop as LRO got closer to the moon for its mapping orbit. This is because GCRs come from all directions in deep space, but the moon acts as a shield, blocking the particles behind it across about half the sky in close lunar proximity.

“But surprisingly, as we went closer to surface, amount of radiation decrease did not happen as quickly as predicted,” said Spence. “The difference is that the Moon is a source of secondary radiation. This is likely due to interactions between the Galactic Cosmic Rays and the lunar surface. The primary GCRs produce secondary radiation by shattering atoms in the lunar surface material; the lunar surface then becomes a significant secondary source of particles, and the resulting radiation dose is thereby 30-40 percent higher than expected.”

But Spence said the amount of radiation shouldn’t be a showstopper, as far as future human missions to the Moon. The amount of radiation, even at its highest, is comparable to US yearly exposure limits for people with occupational exposure such as x-ray technicians or uranium miners.

The team also wants to see what the radiation environment on the Moon is like during an active solar cycle – but they might have to wait awhile.

“We’re eager to see a big solar flare, so we can evaluate the hazards from solar-generated cosmic rays, but we’ll probably have to wait a couple years until the sun wakes up,” said Spence.

Wargo said the LRO findings emphasizes the importance of engaging the scientific community for exploration. “The work being done in heliophysics areas is important to keeping astronauts safe,” he said, “as well as being able to model the activity of the sun and the generations of energetic solar particles. One of the ‘holy grails’ would be to be able predict the the Sun’s activities and be able to give an ‘all clear’ of how many days when astronauts could be on an EVA and what the likelihood of solar energetic particles being emitted from the sun. The work we are doing to enable exploration is helping our scientific understanding.”

LRO is expected to return more data about the moon than all previous orbital missions combined.

Source: AGU Press conference, press release

Posted on by Jon Voisey

Reexamining a Cataclysm

Image of Earth's Moon centered on the Orientale Basin taken by Galileo Spacecraft.

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One of the legacies of the Apollo program is the rare lunar samples it returned. These samples (along with meteorites that originated from the moon and even one from Mars) can be radiometrically dated, and together they paint a picture a cataclysmic time in the history of our solar system. Over a period of time some 3.8 to 4.1 billion years ago, the moon underwent a fierce period of impacts that was the origin of most of the craters we see today. Paired with the “Nice model” (named after the French university where it was developed, not because it was pleasant in any way), which describes the migration of planets to their current orbits, it is widely held that the migration of Jupiter or one of the other gas giants migrations during this period, caused a shower of asteroids or comets to rain down upon the inner solar system in a time known as the “Late Heavy Bombardment” (LHB).

A new paper by astronomers from Harvard and the University of British Columbia disagrees with this picture. In 2005, Strom et al. published a paper in Science which analyzed the frequency of craters of various sizes on the lunar highlands, Mars, and Mercury (since these are the only rocky bodies in the inner solar system without sufficient erosion to wash away their cratering history). When comparing relatively young surfaces which had been more recently resurfaced to older ones from the Late Heavy Bombardment area, is that there were two separate, but characteristic curves. The one for the LHB era revealed a crater frequency peaking at craters near 100 km (62 miles) in diameter and dropping off rapidly to lower diameters. Meanwhile, the younger surfaces showed a nearly even amount of craters of all sizes measurable. Additionally, the LHB impacts were an order of magnitude more common than the newer ones.

The Strom et al. took this as evidence that two different populations of impactors were at work. The LHB era, they called Population I. The more recent, they called Population II. What they noticed was the current size distribution of main belt asteroids (MBAs) was “virtually identical to the Population 1 projectile size distribution”. Additionally, since the size distribution of the MBA is the same today, this indicated that the process which sent these bodies our way didn’t discriminate based on size, which would weed out that size and alter the distribution we observed today. This ruled out processes such as the Yarkovsky effect but agreed with the gravitational shove as a large body would move through the region. The inverse of this (that a process was selecting rocks to chuck our way based on size) would be indicative of Strom’s Population II objects.

However, in this paper recently uploaded to arXiv, Cuk et al. argue that the dates of many of the regions investigated by Strom et al. cannot be reliably dated and therefore, cannot be used to investigate the nature of the LHB. They suggest that only the Imbrium and Orientale basins, which have their formation dates precisely known from rocks retrieved by Apollo missions, can be used to accurately describe the cratering history during this period.

With this assumption, Cuk’s group reexamined the frequency of crater sizes for just these basins. When this was plotted for these two groups, they found that the power law they used to fit the data had “an index of -1.9 or -2 rather than -1.2 or -1.3 (like the modern asteroid belt)”. As such, they claim, “theoretical models producing the lunar cataclysm by gravitational ejection of main-belt asteroids are seriously challenged.”

Although they call into question Strom et al.’s model, they cannot propose a new one. They suggest some causes that are unlikely, such as comets (which have too low of impact probabilities). One solution they mention is that the population of the asteroid belt has evolved since the LHB which would account for the differences. Regardless, they conclude that this question is more open ended than previously expected and that more work will need to be done to understand this cataclysm.

Posted on by Darnell Clayton

Mini Nuclear Reactors Could Power Space Colonies

Growing up on Star Trek, I was always told that space was the final frontier. What they never told me was that space is about as friendly to the human body as being microwaved alive in a frozen tundra–in essence, shelter is a necessity.

Like any Earthen home or building, an off world shelter on the Moon or Mars will need energy to keep its residents comfortable (not to mention alive), and power outages of any sort will not be tolerated–unless a person desires to be radiated and frozen (which is probably not a great way to “kick the bucket”).

While some may look towards solar power to help keep the lights on and the heat flowing, it may be wiser instead to look at an upcoming “fission battery” from Hyperion Power Generation to power future colonies on the Moon, Mars, and perhaps an plasma rocket powered starship as well.

Originally created by Dr. Otis Peterson while on staff at the Los Alamos National Laboratory in New Mexico, Hyperion Power Generation (which I’ll call HPG for short) has licensed Dr. Peterson’s miniature nuclear reactor which are actually small enough to fit inside a decent sized hot tub.

Despite their small stature (being 1.5 meters by 2.5 meters), one of these mini-reactors could provide enough energy to power 20,000 average sized American homes (or 70 MW’s of thermal energy in geek speak) and can last up to ten years.

Since HPG is designing these mini-nuclear reactors to require little human assistance (the “little” having to do with burying the reactors underground), these “nuclear batteries” would enable NASA (or a wealthy space company) to power an outpost on the Moon or Mars without having to rely upon the Sun’s rays–at least as a primary source for power.

HPG’s mini-reactors could also help power future star ships heading towards Jupiter or Saturn (or even beyond), providing enough energy to not only keep the humans on board alive and comfortable, but provide enough thrust via plasma rockets as well.

Scheduled to be released in 2013, these mini-reactors are priced at around $50 million each, which probably puts it outside the price range of the average private space corporation.

Despite the cost, it may be wise for NASA, the European Space Agency, Japan, India and (if the US is in a really good trusting mood) China to consider installing one (or several) of these mini-reactors for their respective bases, as it could enable humanity to actually do what has been depicted in scifi films and television shows–seek out new homes on new worlds and spread ourselves throughout the universe.

Source: Hyperion Power Generation, Inc., Image Credit: NASA

Posted on by Fraser Cain

Blood Moon



A blood moon is the first full moon after a harvest moon, which is the full moon closest to the fall equinox. Another name for a blood moon is a hunter’s moon.

Before the advent of electricity, farmers used the light of the full moons to get work done. The harvest moon was a time they could dedicate to bringing in their fall harvest. And so a month later is the blood moon, or the hunter’s moon. This was a good time for hunters to shoot migrating birds in Europe, or track prey at night to stockpile food for Winter.

A full moon occurs every 29.5 days, so a blood moon occurs about a month after the harvest moon. A blood moon is just a regular full moon. It doesn’t appear any brighter or redder than any other full moon. The distance between the Earth and the Moon can change over the course of the month. When the moon is at its closest, a full moon can appear 10% larger and 30% brighter than when it’s further away from the Earth.

A blood moon will actually turn red when it matches up with a lunar eclipse. These occur about twice a year, so blood moons match up with lunar eclipses about every 6 years or so. At the time of this writing, the next blood moon lunar eclipse will be in 2015.

We’ve written many articles about the Moon for Universe Today. Here’s an article about the discovery of water on the Moon, and here’s an article about a lava tube on the Moon.

If you’d like more info on the Moon, check out NASA’s Solar System Exploration Guide on the Moon, and here’s a link to NASA’s Lunar and Planetary Science page.

We’ve also done several episodes of Astronomy Cast about the Moon. Here’s a good one, Episode 17: Where Does the Moon Come From?

Posted on by Ryan Anderson

Kaguya Discovers a Lava Tube on the Moon

Image credit: JAXA/SELENE

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Future lunar astronauts may want to brush up on their spelunking skills: the first lava tube has been discovered on the moon.

In a recent paper published in Geophysical Research Letters, Junichi Haruyama and colleagues report that they have discovered a mysterious hole in the lunar surface in high resolution images from the Kaguya spacecraft. The hole is 65 meters in diameter and is located in the volcanic Marius Hills region on the near side of the moon, right in the middle of a long sinuous rille. Sinuous rilles are thought to be formed by flowing lava, either on the surface or in enclosed lava tubes.

Of course, there are a lot of ways to form a hole in the surface of the moon. The most obvious is with an impact: the moon has literally been battered to pieces over the years by rocks from space. Couldn’t this hole be a fresh impact crater? Nope. Haruyama’s team observed the hole nine separate times, at various illumination angles, and even when the sun was almost directly overhead it looked mostly black, suggesting that it is very deep. They calculate a depth of around 88 meters, so the hole is deeper than it is wide. No impact crater is like that.

Four different views of the lava tube skylight at varying sun angles. Arrows indicate the direction of incident sunlight (I) and the viewing direction (V). Image credit: JAXA/SELENE
Four different views of the lava tube skylight at varying sun angles. Arrows indicate the direction of incident sunlight (I) and the viewing direction (V). Image credit: JAXA/SELENE

Another possibility is that the hole is due to some sort of volcanic eruption, but there is no sign of volcanic deposits like lava flows or ash emanating from the hole. The hole is isolated, so it isn’t likely to be due to a fracture in the lunar crust either – you would expect such a fracture to form a chain of holes.

Haruyama’s team concluded that the most likely explanation is that the hole that they discovered is a “skylight” – a location where the roof of a lava tube collapsed, either when the lava filling the tube flowed away, or later in the moon’s history due to an impact, moonquake, or tidal forces from the Earth. If it is a lava tube, their calculations based on the multiple images of the hole show that the tube could be 370 meters across.

Lava tubes are important in understanding how lava was transported on the early moon, but they are not just a scientific curiosity: they may also provide valuable refuges for future human explorers. The surface of the moon is not protected from the harsh radiation of space by a magnetic field or a thick atmosphere, so a long term human presence would be most feasible if astronauts could spend most of their time shielded underground. Digging a hole large enough to fit an entire moon colony in it would be a huge engineering challenge, but lava tubes could provide ready-made locations for a well-shielded base, making future astronauts the most technologically advanced cave-dwellers in history.

Posted on by Nancy Atkinson

Romanian Group Attempts Moon Mission With Giant Balloon

The first attempt to send a rocket to the Moon via balloon hit a snag on Monday. The first test of the Aeronautics and Cosmonautics Romanian Association’s (ARCA) balloon-launched rocket (or “rockoon”) ended in failure when the “inflation arms” used to fill the balloon became entangled in the balloon itself. The arms had to be cut, and the operation – which required the use of a large naval frigate — was curtailed. ARCA hopes to compete in the Google Lunar X PRIZE, and intends on using their unusual rocket system to send an equally unique spherical lunar lander to win a $30 million prize.

Rockoons were tried and then abandoned by the US in the 1950s because they blew off course in windy conditions.

ARCA’s European Lunar Explorer (ELE) is a simple design. The super-huge balloon carrying a system of three rockets will soar to about 11 miles (18 km) up. Then the first two rocket stages will fire and boost the system into low Earth orbit, and use the final stage to boost it to the Moon. The ELE will then travel to the moon and deploy its Lunar Lander, which resembles a knobby rubber ball that uses its own rocket engine to ensure a soft landing. Watch their video of how it all will work below: (If nothing else, watch it for the great music!)

On Monday, the Romanians loaded their prototype moon-balloon rocket onto the a large Romanian naval frigate, the Constanta, which took the entire crew out to the launch site in the Black Sea.

But as the balloon started to inflate, the inflation mechanism arms got tangled, and the entire operation had to be abandoned. The giant black balloon collects heat from the sun instead of using burners like hot-air balloons normally use, so it needs to launch during the day.

The Google Lunar X PRIZE challenges participants to construct a delivery system that will get a rover to the Moon, where the robot has to drive for about 500 meters, take high-resolution pictures of its surroundings, and then send them back home.

Undoubtedly, the ARCA team will try again.

See the images from Monday’s launch attempt.

Google Lunar X PRIZE

Source: Nature Blog

Posted on by Nancy Atkinson

Water on the Moon

Artist concept of the Centaur and LCROSS heading towards the Moon. Credit: NASA

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Water has long been suspected to exist in the permanently shadowed polar craters on the Moon, and now the LCROSS impact has allowed scientists to make a direct and definitive finding of this precious resource in a place NASA and other space agencies are considering exploring with human expeditions. Many say this could be a game-changing discovery for the future of lunar science and exploration. Unlike the previous announcement in September of water on the Moon, where water exists diffusely across the moon as hydroxyl or water molecules adhering to the surface in low concentrations, this new discovery could mean underground reservoirs of water ice. “There is too much water to be just absorbed in the soil,” said Anthony Colaprete of the LCROSS mission at Friday’s press conference. “There has to be real solid ice there. You could melt it and drink it.”

But could you really drink it? “Well, not if it has methanol in it. We need to sort out the flavor of the water,” said Colaprete, “meaning we need to find out if it is water, ice, or vapor. We still need to do that math.”

Colaprete said from the amount of water the spectrometers on the LCROSS spacecraft detected, initial indications are it is ice. However, Colaprete added that the impacting Centaur upper stage didn’t hit appear to hit something hard and frozen, from the images of the crater.

If someone was walking on the Moon and was able to walk in Cabeus crater where the impact took place, would the regolith there look different compared to other places on the Moon? “That’s a good question – and we’ve been talking about that,” Colaprete said. “It would be an interesting place to walk around. With our near infrared camera we can relate the the data to what the human eye can see, and try to understand what the terrain looks like. We never saw the crater floor before impact, but now we can see what the floor looks like.”

Did they find anything else in the plume created by the impact? “We’re seeing a lot of stuff,” Colaprete said. “I think there’s a little bit of everything. We’re seeing other emission lines in the spectroscopic data we haven’t completely identified. We’re still working on those — I don’t know what all else is in there just yet. We’ve been focusing on the water quest so far.”

As to whether they’re seeing any organics, the team couldn’t yet say definitively. Colaprete said they are seeing compounds similar to those seen previously in asteroids and comets.

“This is only another snapshot in time of our understanding of the moon,” said Mike Wargo, NASA’s chief lunar scientist, ” and we’ll be continuing to work to get more details on the water and everything else. We’re not done yet.”

Posted on by Nancy Atkinson

LCROSS Confirms “Buckets” of Water on the Moon



The LCROSS team announced today the mission successfully uncovered water during the Oct. 9, 2009 impacts into the permanently shadowed region of Cabeus cater near the moon’s south pole. “Indeed yes, we found water. We didn’t find just a little bit we found a significant amount,” said Tony Colaprete, principal investigator for LCROSS at a press conference. The team was not able to put a concentration of how much water is held in the lunar regolith, but in a fraction of the 20-30 meter crater the impact made, they were able to observe about 25 gallons (95 liters) of water with spectroscopic data. Colaprete held up a 2-gallon (7 liter) bucket, to demonstrate how much they found.

Data from the down-looking near-infrared spectrometer. The red curve shows how the spectra would look for a "grey" or "colorless" warm (230 C) dust cloud. The yellow areas indicate the water absorption bands. Credit: NASA
Asked if the team had “eureka” moment of when they found the water signature, Colaprete said, “It’s been a ‘holy cow!’ moment every day since impact. About two weeks ago we meet as a team and went through the entire data set. That’s when we came to the conclusion that we definitively found water.”

Colaprete said they also found signatures of other compounds as well, including sodium and carbon dioxide, which they are still analyzing.

While earlier findings this year of water on the Moon with the Moon Mineralogy Mapper on the Chandrayaan-1 spacecraft compared the lunar regolith to being drier than deserts on Earth, at Cabeus crater, there appears to be more.

“If you were standing on the 20 meter ‘beach,’ of the crater we created from the impact, it is wetter than some deserts on Earth,” Colaprete said.

Since the impacts, the LCROSS science team has been working almost nonstop analyzing the huge amount of data the spacecraft collected. The team concentrated on data from the satellite’s spectrometers, which provide the most definitive information about the presence of water. A spectrometer examines light emitted or absorbed by materials that helps identify their composition.

Data from the ultraviolet/visible spectrometer taken shortly after impact showing emission lines (indicated by arrows). These emission lines are diagnostic of compounds in the vapor/debris cloud. Credit: NASA
Data from the ultraviolet/visible spectrometer taken shortly after impact showing emission lines (indicated by arrows). These emission lines are diagnostic of compounds in the vapor/debris cloud. Credit: NASA

The 95 liters was the amount of what was in the field of view of the spectrometers. To find out how much total water is inside the crater will take a “reconstruction” of the crater by the team. “We need to take the amount of ejecta, along with the size of crater and reconstruct the event to understand how it all fits back in the ground to understand everything in its entirety,” said Colaprete. “We know it was important to the public for us to come out with the results, and to provide some sort of quantifiable amount but we still have a lot of work to do to see the total picture.”

The impact created by the LCROSS Centaur upper stage rocket created a two-part plume of material from the bottom of the crater. The first part was a high angle plume about 10-12 meters across of vapor and fine dust and the second a lower angle ejecta curtain of heavier material. This material has not seen sunlight in billions of years.

Colaprete said the crater floor is normally about -230 C, but the impact heated things up to about 1000 K, or 700 C, which is cold for an impact, but what was expected for the low density Centaur rocket that slammed into the Cabeus Crater.

Where the water came from is yet to be determined, whether it was delivered there by comets and meteorite hits or if some process within the Moon or on the surface is creating the water.

Mike Wargo, NASA’s chief lunar scientist, said the cold traps in the permanently shadowed craters of the Moon are like the dusty attics or junk drawers of the solar system. “They collect stuff from the whole evolution of the solar system, at least form the past few billion years. We’re only just begun to tap into our understanding.”

“This has really turned our understanding of lunar water on its head,” said Greg Delory. We should keep our minds open of what this is telling us. It’s not Apollo’s Moon, its our Moon.”

Source: NASA press conference
For more information see NASA’s press release

Posted on by Nancy Atkinson

3-D Virtual Moon Browser from Kaguya Data

JAXA, the Japan Aerospace Exploration Agency has released all the data from the Kaguya mission to the public. One of the ways to view the data is through a very nifty 3-D virtual brower. It only is available in Japanese for now (English version by the end of November, they say) so it is a little difficult to navigate, but once you figure it out, prepare yourself for loads of fun. First, you need Java. Then…

go to this page and download the browser. (If you don’t have Java, when you try to open the download it will ask you if you want to add Java.) When you get everything downloaded and the page opens up, (screenshot of page, above) look for the blue buttons on the top right. If you have a modern PC or laptop, click on the left blue button. If you have an old pre-Intel Mac, click the right blue button. Then again, it takes a while for the data to download. On the left are different data sets you can view from the different instruments. Unless you are familiar with the different instruments, it is kind of a crap shoot as far as what each one is; so just click one and see what comes up. The top one is for Clementine data, but the rest are from the different instruments on Kaguya. The Moon globe will fill in with data, and you can spin around and check out virtually any location on the Moon. It’s pretty wild, and addictive. If you still have a hard time figuring it out, you’ll have to wait for the English version. Or you can go to this page, which is a form where you can request what data you want to see. Enjoy!

Continue reading “3-D Virtual Moon Browser from Kaguya Data”