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What is the shortest route to the next stop or the agreed meeting point? Global positioning systems (GPS) have become a routine part of everyday life for most people. Until now, however, the minimum number of GPS satellites needed to determine the exact position of a mobile phone or other navigation device has remained a matter of conjecture. Researchers have now proved that a precise location can be determined in most cases with five or more satellites. At present, we can generally be sure of having contact to only four satellites.

What is the shortest route to the next stop or the agreed meeting point? Global positioning systems (GPS) have become a routine part of everyday life for most people. Until now, however, the minimum number of GPS satellites needed to determine the exact position of a mobile phone or other navigation device has remained a matter of conjecture. Researchers have now proved that a precise location can be determined in most cases with five or more satellites. At present, we can generally be sure of having contact to only four satellites.

Few scientists doubt that Mars was once warm and wet. The evidence for a warm, watery past keeps accumulating, and even healthy skepticism can’t dismiss it. All this evidence begs the next question: what happened to it?

Mars bears the marks of a past when water flowed freely across its surface. There are clear river channels, lakes, and even shorelines. NASA’s Perseverance rover is working its way around Jezero Crater, an ancient paleolake, and finding minerals that can only form in water’s presence. MSL Curiosity has found the same in Gale Crater.

The water that created these landscape features is gone now. Some of it has retreated to the polar caps, where it remains frozen. But aside from that, there are only two places where the remainder of Mars’ ancient water could’ve gone: underground or into space.

Scientists think that there’s water under Mars’ surface. In 2018, researchers found evidence of a large subglacial lake about 1.5 km beneath the southern polar region, though these results have been met with some skepticism. Even if the lake is real, there’s nowhere near enough water there to account for all of Mars’ lost water.

In new research in Science Advances, a team of scientists using data from the Hubble Space Telescope and NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter explain how Mars lost much of its water to space. The research is “Martian atmospheric hydrogen and deuterium: Seasonal changes and paradigm for escape to space.” The lead author is John Clarke, a Professor of Astronomy and the Director of the Center for Space Physics at Boston University.

“Overall, the results presented here offer strong supporting evidence for a warm and wet period with an abundance of water on early Mars and a large amount of water loss into space over the lifetime of the planet.”

John Clarke, Director, Center for Space Physics at Boston University.

“There are only two places water can go. It can freeze into the ground, or the water molecule can break into atoms, and the atoms can escape from the top of the atmosphere into space,” explained Clarke in a press release. “To understand how much water there was and what happened to it, we need to understand how the atoms escape into space.”

The research focuses on two types of hydrogen: what we can call ‘regular’ hydrogen (H) and deuterium (D). Deuterium is hydrogen with a neutron in its nucleus. Water is H2O—two hydrogen atoms bonded to one oxygen atom—and water molecules can contain either hydrogen or deuterium. The neutron contributes additional mass and makes deuterium twice as heavy as hydrogen.

Ultraviolet light from the Sun can split water molecules apart into their constituent hydrogen and oxygen atoms. In an escape-to-space scenario, more of the heavier deuterium is likely to be left behind than hydrogen.

As time passed on Mars and hydrogen kept escaping into space, more of the heavier deuterium was left behind. Over time, this preferential retention shifted the ratio of hydrogen to deuterium in the atmosphere. In this research, Clarke and his co-researchers used MAVEN to see how both atoms escape from Mars currently.

NASA launched MAVEN in 2013, and it reached Martian orbit in 2014. Since then, the capable spacecraft has been observing the Martian atmosphere, making it the first spacecraft dedicated to the task. Its overarching goal is to determine how Mars lost its atmosphere. One of its specific goals is to measure the rate of gas loss from the planet’s upper atmosphere to space and what factors and mechanisms govern the loss.

NASA’s MAVEN spacecraft is depicted in orbit around an artistic rendition of planet Mars, which is shown in transition from its ancient, water-covered past to the cold, dry, dusty world that it has become today. Credit: NASA

MAVEN’s instrument suite contains eight powerful instruments. However, every mission has its tradeoffs, and where MAVEN is concerned, it’s unable to monitor deuterium emissions throughout the entire Martian year. Mars’s orbit is more elliptical than Earth’s. During Martian winter, it travels further from the Sun compared to a circular orbit. During that period, the deuterium emissions are very faint.

This is where the Hubble Space Telescope comes in. It contributed observations from its two high spectral resolution UV instruments, the Goddard High Resolution Spectrograph (GHRS) and the Space Telescope Imaging Spectrograph (STIS). By combining the Hubble observations and the MAVEN data, Clarke and his team monitored deuterium escape for three complete Martian years.

Hubble also contributed data that predates the MAVEN mission. Hubble’s data is critical because the Sun drives the atmospheric escape, and its effect changes throughout the Martian year. The closer Mars is to the Sun, the more rapidly water molecules rise through the atmosphere, where they split apart at high altitudes.

These Hubble images of Mars at aphelion (top) and perihelion (bottom) show how its atmosphere is brighter and more extended when Mars is closer to the Sun. Image Credit: NASA, ESA, STScI, John T. Clarke (Boston University); Processing: Joseph DePasquale (STScI)

The Sun’s effect on the Martian atmosphere is striking.

“In recent years scientists have found that Mars has an annual cycle that is much more dynamic than people expected 10 or 15 years ago,” explained Clarke. “The whole atmosphere is very turbulent, heating up and cooling down on short timescales, even down to hours. The atmosphere expands and contracts as the brightness of the Sun at Mars varies by 40 percent over the course of a Martian year.”

Prior to this research, Mars scientists thought that hydrogen and deuterium atoms slowly diffused upward through the thin atmosphere until they were high enough to escape. But these results change that perspective.

These results show that when Mars is close to the Sun, water molecules rise very rapidly and release their atoms at high altitudes.

“H atoms in the upper atmosphere are lost rapidly by thermal escape in all seasons, and the escape flux is limited by the amount diffusing upward from the lower atmosphere so that the escape flux effectively equals the upward flux,” the authors explain in their research.

It’s different for deuterium atoms, though. “The D escape flux from thermal escape is negligible, in which case an upward flux with the water-based D/H ratio would result in a large surplus of D in the upper atmosphere,” the authors write.

For the D/H ratio to be restored to the measured equilibrium with H near aphelion and to be consistent with observed faster changes in D density near perihelion, something has to boost the escape of D atoms. “In this scenario, the fractionation factor becomes much larger, consistent with a large primordial reservoir of water on Mars,” the authors write. “We consider this to be the likely scenario, while more work is needed to understand the physical processes responsible for superthermal atoms and their escape.”

“Overall, the results presented here offer strong supporting evidence for a warm and wet period with an abundance of water on early Mars and a large amount of water loss into space over the lifetime of the planet,” Clarke and his colleagues write.

The research also reached another conclusion. The upper Martian atmosphere is cold, so most of the atoms need a boost of energy to become superthermal and escape Mars’ gravity. This research shows that solar wind protons can enter the atmosphere and collide with atoms to provide the kick. Sunlight can also provide an energy boost through chemical reactions in the upper atmosphere.

This research doesn’t answer all of our questions about Mars’s lost water, but it makes significant progress, and that’s always welcome.

“The trends reported here represent substantial progress toward understanding the physical processes that govern the escape of hydrogen into space at Mars and our ability to relate these to the isotopic fractionation of D/H and the depth of primordial water on Mars,” the authors write.

How Mars lost its water is one of the big questions in space science right now. It’s about more than just Mars; it can help us understand Earth, Venus, and the rocky exoplanets we find in other habitable zones and how they evolve.

To put it bluntly, Mars lost its water, and Earth didn’t. Why?

We’re inching toward the answer.

The post One Step Closer to Solving the Mystery of Mars’ Lost Water appeared first on Universe Today.

Bands of fast-moving wind that blow west to east around the globe play a crucial role in weather – a poleward shift in parts of these jet streams could cause dramatic changes in weather from the western US to the Mediterranean

Charging new lithium-ion batteries with high currents can significantly increase their total lifespan

A new filtration material might provide a nature-based solution to water contamination by PFAS chemicals. The material, based on natural silk and cellulose, can remove a wide variety of these 'forever' chemicals as well as heavy metals, and its antimicrobial properties can help keep the filters from fouling.

A widely used disinfectant worldwide, chloroxylenol, has been associated with eco-toxicological threats in water environments due to its relatively high chemical stability and massive consumption. Researchers have discovered a promising alternative known as 2,6-dichlorobenzoquinone (2,6-DCQ), which works more effectively in combating certain common bacteria, fungi and viruses, and can be rapidly degraded and detoxified in receiving waters.

An AI-powered tool can distinguish dark matter's elusive effects from other cosmic phenomena, which could bring us closer to unlocking the secrets of dark matter.

An AI-powered tool can distinguish dark matter's elusive effects from other cosmic phenomena, which could bring us closer to unlocking the secrets of dark matter.

An AI-powered tool can distinguish dark matter's elusive effects from other cosmic phenomena, which could bring us closer to unlocking the secrets of dark matter.

A team models the atmospheres of distant planets using neural networks.

Physicists have created a one-dimensional gas out of light. This has enabled them to test theoretical predictions about the transition into this exotic state of matter for the first time. The method used in the experiment by the researchers could be used for examining quantum effects.

A new study has unveiled a new class of quantum critical metal, shedding light on the intricate interactions of electrons within quantum materials. The research explores the effects of Kondo coupling and chiral spin liquids within specific lattice structures.

A new study has unveiled a new class of quantum critical metal, shedding light on the intricate interactions of electrons within quantum materials. The research explores the effects of Kondo coupling and chiral spin liquids within specific lattice structures.

New findings from a global team of expert scientists in academia and industry has generated new research quality standards that will help slash costs and reduce the time it takes to develop advanced nanomedicine treatments and make them available for patients.

Scientists have developed a new tool to help identify optimal photovoltaic (PV) materials capable of maximizing crop growth while generating solar power.

Researchers have discovered compelling evidence suggesting that the supermassive black hole at the center of our Milky Way galaxy, known as Sagittarius A* (Sgr A*), is likely the result of a past cosmic merger. The study builds on recent observations from the Event Horizon Telescope (EHT), which captured the first direct image of Sgr A* in 2022.

Breaching is a common behaviour in a wide range of sharks and rays, and it is thought to have functions related to courtship, birthing and hygiene

https://traffic.libsyn.com/secure/sciencesalon/mss465_Michael_Shermer_2024_09_06.mp3 Download MP3

During a two-hour interview with Tucker Carlson, Darryl Cooper made sensational claims about the Holocaust and World War II, with Carlson calling him “the best and most honest popular historian in the United States.” In this solo episode, Michael Shermer takes a critical look at the pseudohistory and historical revisionism presented by Cooper on Carlson’s show.

Understanding the star formation rate (SFR) in a galaxy is critical to understanding the galaxy itself. Some galaxies are starburst galaxies with extremely high SFRs, some are quenched or quiescent galaxies with very low SFRs, and some are in the middle. Researchers used the JWST to observe a pair of galaxies at Cosmic Noon that are just beginning to merge to see how SFRs vary in different regions of both galaxies.

A rare alignment of massive objects in space allowed astronomers using the James Webb Space Telescope to observe a pair of distant, ancient galaxies that are just beginning to interact and merge. The JWST sees the galaxies as they were about seven billion years ago, near the end of the Universe’s Cosmic Noon. The Cosmic Noon was when star formation was at its peak.

One of the galaxies is a blue, face-on galaxy, and the other is a dusty red, edge-on galaxy. The JWST can only see them because of an intervening galaxy cluster named MACS-J0417.5-1154. It’s a gravitational lens that magnifies the light from the galaxy pair and smears the galaxies’ light into an arc.

Astronomers have found many gravitational lenses and regularly use them to observe objects that are otherwise nearly impossible to see. But this lens is different. It’s a hyperbolic umbilic gravitational lens and produces multiple images of the same objects, where each one has a different magnification and brightness.

“We know of only three or four occurrences of similar gravitational lens configurations in the observable universe, which makes this find exciting, as it demonstrates the power of Webb and suggests maybe now we will find more of these,” said astronomer Guillaume Desprez of Saint Mary’s University in Halifax, Nova Scotia. Desprez works with the CAnadian NIRISS Unbiased Cluster Survey (CANUCS), the team presenting the Webb results.

Not only does the cluster magnify the distant background galaxies, but it also warps their appearance and produces multiple copies. Together with an unrelated one, the galaxies combine to look like a question mark. They’ve been dubbed the Question Mark Galaxy Pair.

False colour images of the Question Mark Pair and MACS J0417.5?1154 (right-hand panel). The left two panels are zoom-in images of four of the multiply lensed images of the Question Mark Pair taken with HST and JWST. By comparing the JWST and HST images, we see how dusty the red edge-on galaxy is as it is barely visible in the HST/ACS imaging. Image Credit: Estrada-Carpenter et al. 2024.

This isn’t the first time astronomers have observed these galaxies. The Hubble observed it previously. But the Hubble and the JWST see things differently. The JWST can see longer wavelengths of infrared light that pass through cosmic dust, while the Hubble only sees the wavelengths of light that get trapped in the dust. So, the Hubble couldn’t detect the question mark shape, whereas the JWST could.

“This is just cool looking. Amazing images like this are why I got into astronomy when I was young,” said astronomer Marcin Sawicki of Saint Mary’s University, one of the lead researchers on the team.

But the question mark shape is just an interesting visual curiosity. The research is about star formation, and these results highlight the JWST’s ability to identify star formation regions in distant galaxies.

“Knowing when, where, and how star formation occurs within galaxies is crucial to understanding how galaxies have evolved over the history of the universe,” said astronomer Vicente Estrada-Carpenter of Saint Mary’s University. Estrada-Carpenter used both Hubble’s ultraviolet and Webb’s infrared data to show where new stars are forming in the galaxies.

The researchers developed a new method to probe SFRs on different timescales of about ten million years and one hundred million years. The ten-million-year timescale relied on H-alpha emission line maps, and the one-hundred-million-year timescale relied on UV observations. H-alpha is sensitive to ten-million-year timescales because it stems from gas around massive, short-lived stars. UV is sensitive to one-hundred-million-year timescales because it originates from longer-lived stars.

Together, the ratio between the two can spatially resolve star formation burstiness.

They found that SFRs decrease at longer distances from the galactic center. That’s not surprising since star-forming gas tends to accumulate near galactic nuclei. However, they also found that overall, the SFR has increased by a factor of 1.6 over the last ~100 Myr, an indication that the galaxies are beginning to merge.

To better understand the merger aspect, the researchers broke the QMP down into segments: blue galaxy bulge and disc, red bulge and disc, and three types of clumps: bursting, equilibrium, and quenching.

This figure from the study shows how the researchers broke the QMP into segments to better understand it. Image Credit: Estrada-Carpenter et al. 2024.

“Both galaxies in the Question Mark Pair show active star formation in several compact regions, likely a result of gas from the two galaxies colliding,” said Estrada-Carpenter. “However, neither galaxy’s shape appears too disrupted, so we are probably seeing the beginning of their interaction with each other.”

They identified twenty star-forming clumps in the galaxy pair, highlighting the JWST’s ability to spatially resolve star formation in distant galaxies. Of those 20, seven were experiencing bursty star formation, 10 were quenching, and three were in equilibrium. The blue face-on galaxy, especially its disk, is mostly in a quenching phase, which makes sense since the JWST is seeing the galaxy pair as they were near the end of Cosmic Noon.

Galaxies grow massive by merging, and one of the JWST’s science goals is to better understand mergers and how they affect star formation. The QMP could be beginning to merge which only increases its value as an observational target.

“What makes the QMP so interesting is that these galaxies are possibly at the beginning of an interaction (as their morphologies do not seem to be disturbed). An interaction between the galaxy pair could lead to a burst of star formation, and this may be the reason why the blue face-on galaxy contains so many clumpy star-forming regions,” the authors write in their paper.

These results are also giving us a look at what our own galaxy was like during Cosmic Noon.

“These galaxies, seen billions of years ago when star formation was at its peak, are similar to the mass that the Milky Way galaxy would have been at that time. Webb is allowing us to study what the teenage years of our own galaxy would have been like,” said Sawicki.

The post JWST Reveals Star Formation at Cosmic Noon appeared first on Universe Today.