Astronomy

SpaceX launched 20 more of its Starlink broadband satellites, including 13 with direct-to-cell capability, from California early Wednesday morning (Sept. 25).

When a massive star explodes as a supernova, it does more than release an extraordinary amount of energy. Supernovae explosions are responsible for creating some of the heavy elements, including iron, which is blasted out into space by the explosion. On Earth, there are two accumulations of the iron isotope Fe60 in sea-floor sediments that scientists trace back about two or three million years ago and about five to six million years ago.

The explosions that created the iron also dosed Earth with cosmic radiation.

In new research submitted to the Astrophysical Journal Letters, scientists examine how much energy reached Earth from these explosions and how that radiation may have affected life on Earth. The paper is titled “Life in the Bubble: How a nearby supernova left ephemeral footprints on the cosmic-ray spectrum and indelible imprints on life.” The lead author is Caitlyn Nojiri from UC Santa Cruz.

“Life on Earth is constantly evolving under continuous exposure to ionizing radiation from both terrestrial and cosmic origin,” the authors write. Terrestrial radiation slowly decreases over billions of years. But not cosmic radiation. The amount of cosmic radiation that Earth is exposed to varies as our Solar System moves through the galaxy. “Nearby supernova (SN) activity has the potential to raise the radiation levels at the surface of the Earth by several orders of magnitude, which is expected to have a profound impact on the evolution of life,” they write.

The authors explain that the two million-year-old accumulation is directly from a supernova explosion, and the older accumulation is from when Earth passed through a bubble.

The bubble in the study’s title comes from a particular type of star called OB stars. OB stars are massive, hot, and short-lived stars that usually form in groups. These stars emit powerful outflowing winds that create “bubbles” of hot gas in the interstellar medium. Our Solar System is inside one of these bubbles, called the Local Bubble, which is almost 1,000 light-years wide and was created several million years ago.

An artist’s conception of the hot local bubble. Image Credit: NASA

The Earth entered the Local Bubble about five or six million years ago, which explains the older Fe60 accumulation. According to the authors, the younger Fe60 accumulation from two or three million years ago is directly from a supernova.

“It is likely that the 60Fe peak at about 2-3 Myr originated from a supernova occurring in the Upper Centaurus Lupus association in Scorpius Centaurus (~140 pc) or the Tucana Horologium association (~70 pc). Whereas the ~ 5-6 Myr peak is likely attributed to the Solar System’s entrance into the bubble,” the authors write.

The left panel shows the Local Bubble and nearby stellar associations, while the right panel shows their galactic coordinates. The right panel also shows a new Galactic bubble discovered in 2018. It’s likely the remnant of an SN that exploded in Upper Centaurus Lupus. Image Credit: Nojiri et al. 2024.

The Local Bubble is not a quiet place. It took multiple supernovae to create it. The authors write that it took 15 SN explosions over the last 15 million years to create the LB. “We know from the reconstruction of the LB history that at least 9 SN exploded during the past 6 Myrs,” they write.

The researchers took all the data and calculated the amount of radiation from multiple SNe in the LB. “It is not clear what would the biological effects of such radiation doses be,” they write, but they do discuss some possibilities.

This figure shows the average dose rate experienced at ground level as a function of the distance to the nearby SN. The average dose is calculated over the first 10 kyr (solid line) and over the first 100 kyr (dashed line) after the SN explosion. It’s not enough to trigger an extinction, but it could’ve driven species diversification. Image Credit: Nojiri et al. 2024.

The radiation dosage may have been strong enough to create double-strand breaks in DNA. This is severe damage and can lead to chromosomal changes and even cell death. But there are other effects in terms of the development of life on Earth.

“Double-strand breaks in DNA can potentially lead to mutations and jump in the diversification of species,” the researchers write. A 2024 paper showed that “the rate of virus diversification in the African Tanganyika lake accelerated 2-3 Myr ago.” Could this be connected to SN radiation?

“It would be appealing to better understand whether this can be attributed to the increase in cosmic-radiation dose we predict to have taking place during that period,” the authors tease.

The SN radiation wasn’t powerful enough to trigger an extinction. But it could’ve been powerful enough to trigger more mutations, which could lead to more species diversification.

Radiation is always part of the environment. It rises and falls as events unfold and as Earth moves through the galaxy. Somehow, it must be part of the equation that created the diversity of life on our planet.

“It is, therefore, certain that cosmic radiation is a key environmental factor when assessing the viability and evolution of life on Earth, and the key question pertains to the threshold for radiation to be a favourable or harmful trigger when considering the evolution of species,” the authors write in their conclusion.

Unfortunately, we don’t clearly understand exactly how radiation affects biology, what thresholds might be in place, and how they might change over time. “The exact threshold can only be established with a clear understanding of the biological effects of cosmic radiation (especially muons that dominate at ground level), which remains highly unexplored,” Nojiri and her co-authors write.

The study shows that, whether we can see it in everyday life or not, or even if we’re aware of it or not, our space environment exerts a powerful force on Earth’s life. SN radiation could’ve influenced the mutation rate at critical times during Earth’s history, helping shape evolution.

Without supernova explosions, life on Earth could look very different. Many things had to go just right for us to be here. Maybe in the distant past, supernova explosions played a role in the evolutionary chain that leads to us.

The post How a Nearby Supernova Left its Mark on Earth Life appeared first on Universe Today.

Astrobiologist Nathalie Cabrol seeks answers to two key questions: Are we alone in the universe? How did life on Earth begin in the first place?

SpaceX and NASA have delayed the Crew-9 astronaut launch from Thursday (Sept. 26) to no earlier than Saturday (Sept. 28) due to a strengthening tropical storm.

STS-128 mission specialist José Hernández waits his turn to enter space shuttle Discovery at NASA's Kennedy Space Center in Florida. In the background are mission specialists Patrick Forrester (left) and Christer Fuglesang (back to camera).

The United States is partnering with India to establish a new factory that will manufacture microchips to enable next-generation technologies for the U.S. Space Force.

Space Marine 2 reminds us how good third-person action games can be.

Dopamine was long thought to play a part in the placebo effect for pain relief, but a new study is questioning its true role

Dopamine was long thought to play a part in the placebo effect for pain relief, but a new study is questioning its true role

Experiment shows that a nuclear explosion could save the planet from a deadly asteroid impact

On June 6th, 2024, the fourth orbital test flight of the Starship successfully lifted off at 07:50 a.m. CT (08:50 a.m. EDT; 06:50 PDT) from SpaceX’s Starbase in Texas. This test was the first time the Starship (SN29) and Super Heavy (BN11) prototypes reentered Earth’s atmosphere and landed successfully. While the SN29 conducted a powered vertical landing before splashing down in the Indian Ocean, the BN11 executed a similar powered landing before splashing down in the Gulf of Mexico. In a recent tweet, Elon Musk shared a photo of the BN11 booster being pulled out of the sea.

Starship Super Heavy Booster Flight 4 pic.twitter.com/EMGpNVn58Q

— Elon Musk (@elonmusk) September 23, 2024

News of the retrieval was posted via Elon Musk’s X account, where he hinted at the possibility of refurbishment and reuse, writing, “Fixer upper.” In addition to being the first flight test in which both vehicles made it back in one piece, this flight was also the first time that a Super Heavy booster simulated a landing at a “virtual tower.” In the future, SpaceX intends to retrieve its boosters by “catching” them with the Orbital Launch Mount tower at their Starbase facility. This is expected to occur for the first time during the fifth integrated flight test, scheduled for no earlier than late November 2024.

The flight test was originally scheduled for September but was delayed by the Federal Aviation Administration (FAA) until November due to environmental complaints and the licensing process. According to statements by the FAA and SpaceX, the company was already authorized to conduct multiple flights using the same mission profile they followed for the fourth flight test. However, adding an attempted “catch” has led the FAA to conduct a more thorough review of the flight and the launch facility.

The post SpaceX Recovers the Super Heavy Booster from Flight 4 appeared first on Universe Today.

SpaceX has stacked and tested its Starship megarocket ahead of the vehicle's fifth flight, which isn't expected to launch until late November.

Florida Surgeon General Joseph Ladapo told Floridians to avoid mRNA vaccines, citing false safety concerns

Researchers have developed a set of hexagon-shaped robotic components that can be snapped together into larger and larger structures. Each one of the component hexagons is made of rigid plates that serve as its exoskeleton. Driven by electricity, the plates can change their shape, shifting from long and narrow to wide and flat at high speed. The combined structures are capable of jumping four times their own body height, then can shape-shift to roll extremely fast, or use multimodal actuation to crawl through confined spaces.

The robotic components were developed at the Max-Planck-Institute for Intelligent Systems (MPI-IS). The modules are made of six lightweight rigid plates made from glass fiber that form a hexagon. Magnets embedded into the plates allows for quick connection to other components as well as providing a shared electrical ground between the modules.

Individual HEXEL modules combine soft artificial muscles with rigid components for fast and large motions. Credit: Zachary Yoder / MPI-IS Ellen Rumley / MPI-IS

The design team integrated artificial “muscles” into the inner joints of the hexagons, called hydraulically amplified self-healing electrostatic (HASEL) muscles. Applying a high voltage to the module causes the muscle to activate, rotating the joints of the hexagon and changing its shape from long and narrow to wide and flat.

“Combining soft and rigid components in this way enables high strokes and high speeds. By connecting several modules, we can create new robot geometries and repurpose them for changing needs,” said  Ellen Rumley, a visiting researcher from the University of Colorado Boulder, in a press release from MPI-IS. Rumley and Zachary Yoder, who are both Ph.D. students working in the Robotic Materials Department, are co-first authors of a new paper, “Hexagonal electrohydraulic modules for rapidly reconfigurable high-speed robots,” published in Science Robotics.

The modules are reconfigurable, with an easy process of attaching or detaching the modules. Chains of modules can be rapidly connected and can operate from one voltage source. The modules can each have their own behaviors, which allows for various operations.

The team created a video to show the various configurations and behaviors that can be created with HEXEL modules. The modules can be seen rolling, dancing, jumping, crawling, and many other motions.  

“In general, it makes a lot of sense to develop robots with reconfigurable capabilities,” said Yoder. “It’s a sustainable design option – instead of buying five different robots for five different purposes, we can build many different robots by using the same components. Robots made from reconfigurable modules could be rearranged on demand to provide more versatility than specialized systems, which could be beneficial in resource-limited environments.”

The post Shape-Shifting Robots Mimic Muscle Movements appeared first on Universe Today.

In the not-so-distant past, the Earth was battered by much more extreme solar storms. Evidence of these storms has come, in particular, from analysing levels of radioactive carbon – known as radiocarbon, or carbon-14 – in tree rings.

In most vertebrates, a pattern of chemical marks on the genome is a reliable indicator of age, but in axolotls this clock seems to stop after the first four years of life

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A preview of Marvel Comics' three "Star Wars: Battle of Jakku" miniseries.

New research is revealing that common sense is a lot more idiosyncratic than we thought, with important implications for tackling political polarisation and the future of AI

New research is revealing that common sense is a lot more idiosyncratic than we thought, with important implications for tackling political polarisation and the future of AI