"I have looked farther into space than ever a human being did before me."

— William Herschel

Astronomy

NASA still investigating Orion heat shield issues from Artemis 1 moon mission

Space.com - Thu, 04/18/2024 - 6:00am
NASA is still studying the performance of the Orion capsule's heat shield during its reentry to Earth's atmosphere at the end of the Artemis 1 moon mission in late 2022.
Categories: Astronomy

Particles move in beautiful patterns when they have ‘spatial memory’

New Scientist Space - Cosmology - Thu, 04/18/2024 - 6:00am
A mathematical model of a particle that remembers its past so that it never travels the same path twice produces stunningly complex patterns
Categories: Astronomy

Particles move in beautiful patterns when they have ‘spatial memory’

New Scientist Space - Space Headlines - Thu, 04/18/2024 - 6:00am
A mathematical model of a particle that remembers its past so that it never travels the same path twice produces stunningly complex patterns
Categories: Astronomy

Are Titan's Dunes Made of Comet Dust?

Universe Today - Thu, 04/18/2024 - 5:37am

A new theory suggests that Titan’s majestic dune fields may have come from outer space. Researchers had always assumed that the sand making up Titan’s dunes was locally made, through erosion or condensed from atmospheric hydrocarbons. But researchers from the University of Colorado want to know: Could it have come from comets?

The dunes of Titan

When the Cassini spacecraft arrived in orbit around Saturn, nobody had ever seen beneath the thick soupy atmosphere of Titan. So when it dropped the Huygens lander, and began probing Titan with cloud-penetrating radar, scientists were surprised to learn that Titan has a very earth-like appearance. It has a thick nitrogen atmosphere, rain, rivers, oceans and massive dune fields. But unlike the dunes of Earth’s sandy deserts in Namibia and southern Arabia, Titan’s dunes are enormous, and fill massive fields covering more than an eighth of the giant moon’s surface. These dunes are about 100 meters tall, 1 to 2 km wide at the base, and can stretch for hundreds of kilometers in length.

Dunes on Earth are made from sand, which is blown by the wind and heaped into drifts. Individual sand particles are nudged and blown by the wind with enough force to make them bounce and scatter in a process called saltation. If the particles don’t bounce, then they cannot pile up on top of each other, but if the wind is able to lift them off the ground completely then they simply blow away. Saltation depends on the size and mass of the sand particles and the strength of the wind, but also needs the particles to be dry so that they can move freely without sticking together.

Titan’s geology

Titan is the second largest moon in the entire Solar System, beaten only by Ganymede, orbiting Jupiter. It is Saturn’s largest moon, and very old. Unlike most of Saturn’s moons, which were captured over time, Titan would have formed together with Saturn billions of years ago. Despite having so many features in common with Earth, it is a very different place. It is so intensely cold that, instead of water, its rain and rivers are made from liquid hydrocarbons like methane. Water, on the other hand, is frozen into hard ice; rocks on Titan are made from water ice, instead of granite and basalt, and Titan’s equivalent of lava and magma are made from liquid water and ammonia.

This means that sand on Titan is not made from silica eroded from larger rocks, since those materials are not found on the surface. One popular theory is that it could instead be made from ice. When liquid methane rains and flows, it could erode the water-ice bedrock, grinding chunks together to a sand of ice grains. An alternative idea is that the sand particles are instead made from tholins. These are found all over the colder regions of the Solar System, where cold hydrocarbons in comets or the outer atmospheres of planets and moons react with ultraviolet light from the Sun to create complex compounds. Tholins formed in the dry atmosphere of Titan could clump together with static electricity to form small grains of soot that then settle to the ground, creating both dust and sand.

Comet 109P/Swift-Tuttle captured during its last pass by Earth on Nov. 1, 1992. Credit: Gerald Rhemann What do comets have to do with this?

A paper presented at this year’s Lunar and Planetary Science Conference (LPSC) suggests a new idea: What if the sand came from comets? Comets, as we know, are made from materials left over from the creation of the Solar System. Most of the primordial gas and dust that collapsed from an ancient nebula to form the Solar System would have ended up in the Sun, with the bulk of the remains forming the planets. But this would still have left a lot of material floating free, and some of that would have gradually coalesced into lumps of dust and ice, which we see today as comets. When comets are nudged into elliptical orbits and pass through the inner Solar System, some of their ice heats up and sublimates into gas which blows out, carrying dust with it. This dust is scattered throughout the Solar System, concentrated along the various comet’s orbits. Individual grains often collide with the Earth, which we see as meteors, burning high in our atmosphere. Recent surveys in Antarctic ice fields, where there is no surface sand, have found many such particles which have survived atmospheric reentry.

But Earth is not the only place where these grains can end up. According to the researchers, there was a time when a great many comets were passing close by Saturn and its moons. They ran simulations to study the evolution of the Kuiper Belt, using a version of the Nice model. The Nice model, named for the city in which it was first presented, says that the Solar System was originally arranged very differently from how it is today. Over time, the planets migrated to their current locations. During this period, Neptune passed through the Kuiper belt, nudging many comets into new orbits. Many of these comets passed close by Saturn and its moons, and some even collided with the moons. The researchers suggest that much of the sand making up Titan’s dunes may be debris from all these comets.

Artist’s concept of Dragonfly soaring over the dunes of Saturn’s moon Titan. Credit: NASA/Johns Hopkins APL/Steve Gribben

But is it true? This idea does fit with what we currently know, and is supported by computer modelling, but so do the other theories. Fortunately, NASA recently confirmed that the Dragonfly mission will be launched in July 2028. Dragonfly is a lander, which will be sent to Titan. But unlike previous missions, this one is an 8-rotor flying drone. Like the rovers on Mars, it will be able to move to any areas of interest that scientists would like to study further. When it arrives in 2034, it will fly to dozens of locations on Titan’s surface, and should settle the question once and for all: Are the dunes of Titan really built from comet dust?

https://www.hou.usra.edu/meetings/lpsc2024/pdf/1550.pdf

The post Are Titan's Dunes Made of Comet Dust? appeared first on Universe Today.

Categories: Astronomy

Total Totality

APOD - Thu, 04/18/2024 - 4:00am

Total Totality


Categories: Astronomy, NASA

Ancient Maya burned their dead rulers to mark a new dynasty

New Scientist Space - Cosmology - Wed, 04/17/2024 - 8:01pm
In the foundations of a Maya temple, researchers found the charred bones of royal individuals – possibly evidence of a fiery ritual to mark the end of one dynasty and the beginning of another
Categories: Astronomy

Ancient Maya burned their dead rulers to mark a new dynasty

New Scientist Space - Space Headlines - Wed, 04/17/2024 - 8:01pm
In the foundations of a Maya temple, researchers found the charred bones of royal individuals – possibly evidence of a fiery ritual to mark the end of one dynasty and the beginning of another
Categories: Astronomy

The Solar Wind is Stripping Oxygen and Carbon Away From Venus

Universe Today - Wed, 04/17/2024 - 7:55pm

The BepiColombo mission, a joint effort between JAXA and the ESA, was only the second (and most advanced) mission to visit Mercury, the least explored planet in the Solar System. With two probes and an advanced suite of scientific instruments, the mission addressed several unresolved questions about Mercury, including the origin of its magnetic field, the depressions with bright material around them (“hollows”), and water ice around its poles. As it turns out, BepiColombo revealed some interesting things about Venus during its brief flyby.

Specifically, the two probes studied a previously unexplored region of Venus’ magnetic environment when they made their second pass on August 10th, 2021. In a recent study, an international team of scientists analyzed the data and found traces of carbon and oxygen being stripped from the upper layers of Venus’ atmosphere and accelerated to speeds where they can escape the planet’s gravitational pull. This data could provide new clues about atmospheric loss and how interactions between solar wind and planetary atmospheres influence planetary evolution.

The study was led by Lina Hadid, a CNRS researcher at the Plasma Physics Laboratory (LPP) and the Observatoire de Paris. She was joined by researchers from the Institute of Space and Astronautical Science (ISAS) at JAXA, the Max Planck Institute for Solar System Research (MPS), the CNRS Research Institute in Astrophysics and Planetology (IRAP), the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), the Institute for Geophysics and Extraterrestrial Physics (IGEP), the Space Research Institute (SRI), and multiple universities.

Schematic view of planetary material escaping through Venus magnetosheath flank. Credit: Thibaut Roger/Europlanet 2024 RI/Hadid et al.

While Venus does not have an intrinsic magnetic field like Earth, it has a weak magnetic field that results from the interaction of solar wind and electrically charged particles in Venus’ upper atmosphere. Surrounding this “induced magnetosphere” is the “magnetosheath,” a region where the solar wind is slowed and heated. In August 2021, BepliColombo’s two spacecraft – the ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO, aka. Mio) – passed by Venus on the final leg of their journey toward Mercury, using the planet’s gravity to adjust its course and its upper atmosphere to shed speed.

The two spacecraft spent 90 minutes passing through the tail of the magnetosheath and the magnetic regions closest to the Sun. The mission controllers used this opportunity to gather data on the number and mass of charged particles it encountered using Mio‘s Mass Spectrum Analyzer (MSA) and the Mercury Ion Analyzer (MIA), which are part of the probe’s Mercury Plasma Particle Experiment (MPPE). The team also relied on Europlanet’s Sun Planet Interactions Digital Environment on Request (SPIDER) space weather modeling tools to track how atmospheric particles propagated through the magnetosheath.

As Hadid explained in a Europlanet Society release, analysis of this data provides insight into the chemical and physical processes driving atmospheric escape from this region of the magnetosheath:

“This is the first time that positively charged carbon ions have been observed escaping from Venus’s atmosphere. These are heavy ions that are usually slow moving, so we are still trying to understand the mechanisms that are at play. It may be that an electrostatic ‘wind’ is lifting them away from the planet, or they could be accelerated through centrifugal processes.”

In particular, these findings could help scientists to deduce what happened to Venus’ surface water. Like Earth, much of Venus’ surface was once covered in oceans, which disappeared about 700 million years ago. The most widely-held theory is that this coincided with a massive resurfacing event that flooded the atmosphere with carbon dioxide, leading to a runaway Greenhouse Effect that vaporized the oceans. Over time, solar wind stripped away the water, leaving a thick atmosphere over 90 times as dense as Earth’s, and composed of carbon dioxide with smaller amounts of nitrogen and trace gases.

Artist’s impression of Venus with the solar wind flowing around the planet, which has little magnetic protection. Credit: ESA – C. Carreau

Two spacecraft that previously visited Venus – NASA’s Pioneer Venus Orbiter and ESA’s Venus Express -conducted detailed studies of atmospheric loss. However, their orbital paths left some areas unexplored, leaving many questions about the planet’s atmospheric dynamics unanswered. Said Moa Persson, a researcher from the Swedish Institute of Space Physics and a co-author on the study:

“Recent results suggest that the atmospheric escape from Venus cannot fully explain the loss of its historical water content. This study is an important step to uncover the truth about the historical evolution of the Venusian atmosphere, and upcoming missions will help fill in many gaps.”

Over the next decade, several more spacecraft are destined for Venus, including the ESA’s Envision mission, NASA’s Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy (VERITAS) orbiter and Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) probe, and India’s Shukrayaan orbiter. Collectively, these spacecraft will characterize the Venusian environment, magnetosphere, atmosphere, surface, and interior. This research could lead to improved models that predict how once-habitable planets could become hostile to life as we know it.

Further Reading: Euro Planet Society, Nature Astronomy

The post The Solar Wind is Stripping Oxygen and Carbon Away From Venus appeared first on Universe Today.

Categories: Astronomy

Sweden becomes 38th country to sign NASA's Artemis Accords for moon exploration

Space.com - Wed, 04/17/2024 - 6:00pm
Sweden is the latest nation to sign onto NASA's Artemis Accords on April 16, following Switzerland's signing earlier this week.
Categories: Astronomy

What is cloud seeding and did it cause the floods in Dubai?

New Scientist Space - Cosmology - Wed, 04/17/2024 - 5:02pm
Cloud seeding almost certainly did not play a significant role in the flooding on the Arabian peninsula this week – but the heavy rains may have been exacerbated by climate change
Categories: Astronomy

What is cloud seeding and did it cause the floods in Dubai?

New Scientist Space - Space Headlines - Wed, 04/17/2024 - 5:02pm
Cloud seeding almost certainly did not play a significant role in the flooding on the Arabian peninsula this week – but the heavy rains may have been exacerbated by climate change
Categories: Astronomy

Ingenuity team says goodbye to pioneering Mars helicopter

Space.com - Wed, 04/17/2024 - 5:00pm
The Ingenuity Mars helicopter team met one last time on Tuesday (April 16) to oversee a transmission from the little rotorcraft.
Categories: Astronomy

Earth’s Coral Reefs Face a New, Deadly Mass Bleaching. They Can Still Be Saved

Scientific American.com - Wed, 04/17/2024 - 4:30pm

“A mass bleaching event is, by definition, a mass mortality event,” a leading coral reef expert says

Categories: Astronomy

The Solar Eclipse Like We’ve Never Seen it Before

Universe Today - Wed, 04/17/2024 - 4:23pm

You had to be in the right part of North America to get a great view of the recent solar eclipse. But a particular telescope may have had the most unique view of all. Even though that telescope is in Hawaii and only experienced a partial eclipse, its images are interesting.

You had to be in the right part of North America to get a great view of the recent eclipse. Image Credit: DKIST/NSO/NSF/AURA

The Daniel K. Inouye Solar Telescope (DKIST) is at the Haleakala Observatory in Hawaii. With its four-meter mirror, it’s the largest solar telescope in the world. It observes in visible to near-infrared light, and its sole target is the Sun. It can see features on the Sun’s surface as small as 20 km (12 miles.) It began science operations in February 2022, and its primary objective is to study the Sun’s magnetic fields.

This is a collage of solar images captured by the Inouye Solar Telescope. Images include sunspots and quiet regions of the Sun, known as convection cells. (Credit: NSF/AURA/NSO)

Though seeing conditions weren’t perfect during the eclipse and the eclipse was only partial when viewed from Hawaii, the telescope still gathered enough data to create a movie of the Moon passing in front of the Sun. The bumps on the Moon’s dark edge are lunar mountains.

via GIPHY

“The team’s primary mission during Maui’s partial eclipse was to acquire data that allows the characterization of the Inouye’s optical system and instrumentation,” shares National Solar Observatory scientist Dr. Friedrich Woeger.

The Moon plays a critical role in measuring the telescope’s performance. Its edge is well-known and as a dark object in front of the Sun, it acts as a unique tool to measure the Inouye telescope’s performance and to understand the data it collects. Since the telescope has to correct for Earth’s turbulent atmosphere with adaptive optics, the Moon’s known qualities help researchers work with the telescope’s optical elements.

The Daniel Inouye Solar Telescope at the Haleakala Observatory on the Hawaiian island of Maui. Image Credit: DKIST/NSO

“With the Inouye’s high order adaptive optics system operating, the blurring due to the Earth’s atmosphere was greatly reduced, allowing for extremely high spatial resolution images of the moving lunar edge,” said Woeger. “The appearance of the edge is not straight but serrated because of mountain ranges on the Moon!” This serrated dark edge covers the granular convection pattern that governs the “surface of the Sun.”

The Inouye Solar Telescope studies the Sun’s magnetic fields, which drive space weather. What we see in the video is visually interesting, but there’s a lot of data behind it.

It’ll take several months to analyze all of the data it gathered during the eclipse.

The post The Solar Eclipse Like We’ve Never Seen it Before appeared first on Universe Today.

Categories: Astronomy

Boom's XB-1 test plane gets FAA green light for supersonic flight

Space.com - Wed, 04/17/2024 - 4:00pm
Boom Supersonic's XB-1 experimental jet has been cleared for supersonic flight by the FAA.
Categories: Astronomy

A Dengue Fever Outbreak Is Setting Records in the Americas

Scientific American.com - Wed, 04/17/2024 - 3:30pm

At least 2.1 million cases of dengue fever have been reported in North and South America, and this year 1,800 people have died from the mosquito-borne disease

Categories: Astronomy

Amateur Astronomers Caught Sungrazing Comet during Solar Eclipse

Sky & Telescope Magazine - Wed, 04/17/2024 - 3:12pm

Wide-field photos of the total solar eclipse taken by several astronomers along the path of totality, caught a comet approaching the Sun.

The post Amateur Astronomers Caught Sungrazing Comet during Solar Eclipse appeared first on Sky & Telescope.

Categories: Astronomy

Ancient marine reptile found on UK beach may be the largest ever

New Scientist Space - Cosmology - Wed, 04/17/2024 - 3:00pm
The jawbone of an ichthyosaur uncovered in south-west England has been identified as a new species, and researchers estimate that the whole animal was 20 to 25 metres long
Categories: Astronomy

Ancient marine reptile found on UK beach may be the largest ever

New Scientist Space - Space Headlines - Wed, 04/17/2024 - 3:00pm
The jawbone of an ichthyosaur uncovered in south-west England has been identified as a new species, and researchers estimate that the whole animal was 20 to 25 metres long
Categories: Astronomy

Ancient humans lived inside a lava tube in the Arabian desert

New Scientist Space - Cosmology - Wed, 04/17/2024 - 3:00pm
Underground tunnels created by lava flows provided humans with shelter for thousands of years beneath the hot desert landscape of Saudi Arabia
Categories: Astronomy