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One of the most iconic events in history is Apollo 11 landing on the lunar surface. During the descent, astronauts Neil Armstrong and Edwin “Buzz” Aldrin are heard relaying commands and data back and forth to mission control across 385,000 kilometers (240,000 miles) of outer space as the lunar module “Eagle” slowly inched its way into the history books.

In the final moments before touchdown, Aldrin can be heard saying, “Picking up some dust”, followed by large dust clouds shooting outward from underneath from the spacecraft as the exhaust plumes interacted with the lunar surface, more commonly known as brownout or brownout effect. This significantly reduced the visibility for Armstrong and Aldrin as they landed, and while they successfully touched down on the Moon, future astronauts might not be so lucky.

Better understanding brownout is exactly what a team of researchers from South Korea examined in a recent study published in Physics of Fluids as they developed a model to help assess safe and practical means to land a human-piloted spacecraft on a planetary surface.

Brownout is important to understand as humanity continues to venture to other worlds. This begins with the upcoming Artemis missions to the Moon, specifically Artemis III, which is slated to land on the lunar surface sometime in 2025. As Armstrong and Aldrin experienced during the Apollo 11 landing, brownout can significantly hinder a pilot’s visibility.

“Understanding the interaction between the rocket plume and the surface is important for the safety and success of space missions in terms of contamination and erosion, landing accuracy, planetary protection, and engineering design, as well as for scientific understanding and future exploration,” said Dr. Byoung Jae Kim, who is an assistant professor in the School of Mechanical Engineering at Chungnam National University, and a co-author on the study.

For the study, the researchers used computer models to simulate landing on the lunar surface and input data about the rocket, rocket engines, surface topography and composition, all in a near-vacuum. The simulation estimated the size and shape of the exhaust plume and the amount of brownout a pilot would see while descending towards the surface in their spacecraft.

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Exhaust plume-surface interaction, more commonly known as brownout, while landing on the Moon, as depicted in Figure 1 of the study. (Credit: Reproduced with permission from A. Rahimi, O. Ejtehadi, K.H. Lee, R.S. Myong, Acta Astronautica, 175 (2020) 308-326. ©2018 Elsevier.)

In the end, the model showed the researchers that brownout effect for both ascent and descent was greater with small regolith particles as they experienced higher altitudes, whereas larger regolith particles with enlarged bed height (thickness) resulted in more desirable brownout conditions.

“The insights gained from this study of the effects of different parameters on plume-surface interaction can inform the development of more effective and efficient landing technologies,” said Dr. Kim. “The study also sheds light on the festooned scour patterns that can be observed on planetary surfaces, which can provide valuable information for future scientific investigations of planetary bodies.”

Aside from landing spacecraft on planetary bodies, the researchers believe their model can be used for other physics-based application, such as needle-free drug delivery systems. Going forward, the researchers plan to incorporate more data into the simulations, such as solid particle collisions and chemical reactions, in hopes of enhancing the model’s capabilities.

While the study focused on a lunar landing, the Moon and Earth aren’t the only places where brownout is experienced, as severe brownout was observed upon NASA’s Perseverance rover landing on Mars in February 2021, and more recently with NASA’s Mars Ingenuity helicopter. As seen in exclusive NASA video, the Perseverance rover became completely enveloped by Martian dust as the sky crane released it upon touchdown, while the brownout created by Ingenuity was observed to be light and short-lived. With Mars being a far dustier place than the Moon, these experiences demonstrate that brownout could pose

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Transporter-8 Mission

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June 10, 2023

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SpaceX is targeting Monday, June 12 for Falcon 9’s launch of the Transporter-8 mission to low-Earth orbit from Space Launch Complex 4E (SLC-4E) at Vandenberg Space Force Base in California. The 57-minute launch window opens at 2:19 p.m. PT (21:19 UTC). If needed, there is a backup opportunity Tuesday, June 13 with the same window.

The first stage booster supporting this mission previously launched NROL-87, NROL-85, SARah-1, SWOT, and four Starlink missions. Following stage separation, Falcon 9 will land on Landing Zone 4 (LZ-4) at Vandenberg Space Force Base.

Transporter-8 is SpaceX’s eighth dedicated smallsat rideshare mission. There will be 72 payloads on this flight, including CubeSats, MicroSats, a re-entry capsule, and orbital transfer vehicles carrying spacecraft to be deployed at a later time.

A live webcast of this mission will begin about 15 minutes prior to liftoff.

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Triggered Star Birth in the Nessie Nebula

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June 9, 2023

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Star formation is one of the oldest processes in the Universe. In the Milky Way and most other galaxies, it unfolds in cold, dark creches of gas and dust. Astronomers study sites of star formation to understand the process. Even though they know much about it, some aspects remain mysterious. That’s particularly true for the “Nessie Nebula” in the constellation Vulpecula. An international team led by astronomer James Jackson studies the nebula and its embedded star-birth regions. They found that it experienced a domino effect called “triggered star formation.”

“So, one of the interesting and open questions remaining in the field of star formation is, what happens when a star forms and ejects energy into the surrounding medium?” he said. “Does it make new stars, or does it prevent the formation of new stars?”

To answer those questions, Jackson and an international team of observers peered deep into the Nessie Nebula. It’s a so-called “Infrared Dark Cloud” (IRDC) with the official catalog name Lynds 772. Jackson named it the Loch Ness Monster Nebula a few years back. That’s because it resembles a spindly version of the famous and elusive Scottish lake monster. What the team found reveals that triggered star formation actually does take place under special circumstances in this nebula.

Putting the Nessie Nebula in Perspective

In 2013, Dr. Alyssa Goodman of Harvard Center for Astrophysics called the Nessie Nebula one of the “bones” of the Milky Way. That’s because it’s one of many webs of dusty filaments threaded through the galaxy. “It’s possible that the Nessie bone lies within a spiral arm, or that it is part of a web connecting bolder spiral features,” she said, noting that it probably spans at least 80 parsecs long and about a half-parsec wide.

As a galactic “bone”, it’s a prime place to look for triggered star formation. Nessie has a density of about 600 solar masses per parsec across its entire length. It’s also cold, with an average temperature of about 10K. There are many such cold clouds in the Milky Way, notably places like the famous Pillars of Creation or regions in the Carina Nebula.

The Pillars of Creation is another region of cold, dark gas similar to the Nessie Nebula where young stars are forming. Image Credit: NASA/ESA/CSA
The Pillars of Creation is similar to the Nessie Nebula where young stars are forming. Image Credit: NASA/ESA/CSA

A star gets started when gravity pushes the material in the cloud together to form a hot core. Temperatures and pressures rise, and eventually, a star is born. The Nessie Nebula is actually dense enough to form many very high-mass stars, according to Jackson. “By high mass, I mean a star that’s about 8 times the mass of the Sun, or more,” he said. “They have so much more energy than the Sun, and they inject this energy into the surrounding material, and they form these H II bubbles that ionize the gas around them.”

Essentially, those H II bubbles form as stellar winds from the hot young protostars push into surrounding space and photoionize (or heat) the gas there. As they expand, they stir up material around them. That creates a lot of energy. “The question I’m trying to answer is, does this energetic feedback trigger or hinder the formation of other new stars?” said Jackson.

The Domino Effect in the Nessie Nebula

The scenario for triggered star formation requires an almost perfect set of circumstances, starting with the cold dense nebula. Jackson explained that once a star (or group of stars) forms, its H II bubble triggers the birth process of the next star. That process repeats, almost like a domino effect.

So, does this triggered star formation really happen? Jackson pointed out two different scenarios. “If bubbles are just dispersing the gas, then that gas is gone and no stars can form,” he said. “On the other hand, if you have a clump of gas that’s almost ready to make a star, but not quite, can you hit it with an expanding shell and compress it? It could push it over the edge and gravity can take over. Some people say you make new stars and some say you don’t.”

To find out, the team looked at Nessie with the infrared-sensitive SOFIA flying observatory. It allowed them to peer through the clouds of gas and dust at the central region of the nebula. They coupled their observations with radio data from the Australia Telescope Compact Array and the Mopra radio dish. They zeroed in on its most luminous young stellar object, called AGAL337.916-00.477. This high-mass stellar object is part of a cloud in the nebula that has several other high-mass young stellar objects and so-called “dust cores” where the process of star

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New Detailed Images of the Sun from the World’s Most Powerful Ground-Based Solar Telescope

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June 9, 2023

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Our Sun continues to demonstrate its awesome power in a breathtaking collection of recent images taken by the U.S. National Science Foundation’s (NSF’s) Daniel Inouye Solar Telescope, aka Inouye Solar Telescope, which is the world’s largest and most powerful ground-based solar telescope. These images, taken by one of Inouye’s first-generation instruments, the Visible-Broadband Imager (VBI), show our Sun in incredible, up-close detail.

“These images preview the exciting science underway at the Inouye Solar Telescope,” Dr. Alexandra Tritschler, who is a National Solar Observatory Senior Scientist, tells Universe Today. “These images are a small fraction of the data obtained from the first Cycle. They exemplify the many and much broader science objectives and the much more powerful spectroscopy and spectropolarimetry data that now goes along with the images, none of which was available in 2020 when the Inouye Solar Telescope released its first-light images.”

The solar features in Inouye’s images include sunspots which reside in the Sun’s photosphere. These are the dark spots on the Sun’s “surface” and one of the Sun’s most well-known features, often reaching sizes that equal, or even dwarf, the size of the Earth. It is their dark appearance that can be deceiving, however, as sunspots are responsible for solar flares and coronal mass ejections that produce solar storms, which is a type of space weather.

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Image of a sunspot taken by the Inouye Solar Telescope. While they have a dark appearance, sunspots are responsible for solar flares and coronal mass ejections that produce solar storms. Sunspots often reach sizes that equal, or even dwarf, the size of the Earth. (Credit: National Science Foundation (NSF)/Association of Universities for Research in Astronomy, Inc. (AURA)/National Solar Observatory (NSO))
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Image of a sunspot with a light bridge, which is hypothesized to be the beginning stages of a degrading sunspot. (Credit: NSF/AURA/NSO)

Other features from the Inouye images include convection cells, which also reside in the Sun’s photosphere, and consist of upward- and downward-flowing plasma, known as granules or “bubbles”. The last feature in the Inouye images are fibrils, which exist in the Sun’s chromosphere and are produced from the magnetic field interactions within the Sun.

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Image of solar granules or “bubbles”, intergranular lanes, and magnetic elements in the quiet regions of the Sun. In these features, solar plasma rises in the
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