Watch for the legendary green flash

The green flash image at the top of this post was taken by Jim Grant, an EarthSky friend on Facebook. He captured it off the coast of Ocean Beach, California, and identified it as a mock mirage green flash.

It’s not hard to see a green flash with the eye alone, when sky conditions are right, and when you’re looking toward a very clear and very distant horizon. That’s why those who live near an ocean tend to report green flashes most often. A sea horizon is the best place to see them.

The video below, posted to EarthSky by Vladek in 2016, is an excellent example of the experience of seeing a green flash:

Most people see green flashes just at sunset, at the last moment before the sun disappears below the horizon. Be careful and don’t look too soon. If you do look too soon, the light of the sunset will dazzle (or damage) your eyes, and you’ll miss your green flash chance that day.

But if you wait – looking away until just the thinnest rim of the sun appears above the horizon – that day’s green flash could be yours.

Read more: Is Zubeneschamali a green star?

Of course, the green flash can be seen before sunrise, too, although it’s harder at that time of day to know precisely when to look.

Mock mirage and green flash seen from San Francisco in 2006. Image via Brocken Inaglory/Wikimedia Commons.

There are many different types of green flash. Some describe a streak or ray of the color green … like a green flame shooting up from the sunrise or sunset horizon.

The most common green flash, though – the one most people describe – is a flash of the color green seen when the sun is nearly entirely below the horizon.

Again … you need a distant horizon to see any of these phenomena, and you need a distinct edge to the horizon. That’s why these green flashes, streaks, and rays are most often seen over the ocean. But you can see them over land, too, if your horizon is far enough away.

Pollution or haze on the horizon will hide this instantaneous flash of the color green.

Jim Grant photographed this green flash on April 27, 2012, off the coast of San Diego.

If you’re interested in green flashes, Andrew Young’s green flash page is great. He also has a page of links to pictures of green flashes taken by people from around the globe.

And, of course, Les Cowley at the great website Atmospheric Optics devotes many pages to the green flash phenomenon. Notice the menu bar at the left side of the page; it’ll let you explore many different types of green flashes.

Green flash atop sun pyramid via astrophotographer Colin Legg in Australia.

Bottom line: The green flash is legendary, and some people have told us they thought it was a myth, like a unicorn or a pot of gold at the end of a rainbow. But green flashes are very real. You need a distant and exceedingly clear horizon to see them at the last moment before the sun disappears below the horizon at sunset.

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Can you see a green flash? More tips, plus more pictures

from EarthSky https://ift.tt/31enSo2

The green flash image at the top of this post was taken by Jim Grant, an EarthSky friend on Facebook. He captured it off the coast of Ocean Beach, California, and identified it as a mock mirage green flash.

It’s not hard to see a green flash with the eye alone, when sky conditions are right, and when you’re looking toward a very clear and very distant horizon. That’s why those who live near an ocean tend to report green flashes most often. A sea horizon is the best place to see them.

The video below, posted to EarthSky by Vladek in 2016, is an excellent example of the experience of seeing a green flash:

Most people see green flashes just at sunset, at the last moment before the sun disappears below the horizon. Be careful and don’t look too soon. If you do look too soon, the light of the sunset will dazzle (or damage) your eyes, and you’ll miss your green flash chance that day.

But if you wait – looking away until just the thinnest rim of the sun appears above the horizon – that day’s green flash could be yours.

Read more: Is Zubeneschamali a green star?

Of course, the green flash can be seen before sunrise, too, although it’s harder at that time of day to know precisely when to look.

Mock mirage and green flash seen from San Francisco in 2006. Image via Brocken Inaglory/Wikimedia Commons.

There are many different types of green flash. Some describe a streak or ray of the color green … like a green flame shooting up from the sunrise or sunset horizon.

The most common green flash, though – the one most people describe – is a flash of the color green seen when the sun is nearly entirely below the horizon.

Again … you need a distant horizon to see any of these phenomena, and you need a distinct edge to the horizon. That’s why these green flashes, streaks, and rays are most often seen over the ocean. But you can see them over land, too, if your horizon is far enough away.

Pollution or haze on the horizon will hide this instantaneous flash of the color green.

Jim Grant photographed this green flash on April 27, 2012, off the coast of San Diego.

If you’re interested in green flashes, Andrew Young’s green flash page is great. He also has a page of links to pictures of green flashes taken by people from around the globe.

And, of course, Les Cowley at the great website Atmospheric Optics devotes many pages to the green flash phenomenon. Notice the menu bar at the left side of the page; it’ll let you explore many different types of green flashes.

Green flash atop sun pyramid via astrophotographer Colin Legg in Australia.

Bottom line: The green flash is legendary, and some people have told us they thought it was a myth, like a unicorn or a pot of gold at the end of a rainbow. But green flashes are very real. You need a distant and exceedingly clear horizon to see them at the last moment before the sun disappears below the horizon at sunset.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

Can you see a green flash? More tips, plus more pictures

from EarthSky https://ift.tt/31enSo2

How to spot ISS in your sky

On May 30, 2020, NASA’s SpaceX Demo-2 mission launched successfully. It is the first U.S human spaceflight from U.S. soil since 2011 – on an American rocket and spacecraft – with astronauts Robert Behnken and Douglas Hurley, headed to the International Space Station. Image via NASA.

If you’re looking for information on the SpaceX Crew Dragon launch on Saturday, May 30, 2020 … click here.

The International Space Station (ISS) has been orbiting our planet since 1998. From most locations on Earth, assuming you have clear night skies, you can see ISS for yourself. To us on Earth, it looks like a bright star moving quickly from horizon to horizon. As suddenly as it appears, it disappears. How do you know when to see ISS pass overhead from your location?

NASA has a great tool to help – the Spot the Station program lets you sign up to receive alerts to let you know when ISS will be visible from your location – anywhere in the world. Plus there’s a map-based feature to track when to look for the station as it flies over you in your night sky.

You can also sign up for alerts via email or text message. Typically, alerts are sent out a few times each month when the station’s orbit is near your location. Visit the Spot the Station website to sign up, and see a list of upcoming sighting opportunities.

Wayne Boyd shared his photo of ISS passing over Marstons Mills, Massachusetts,

Patricia Evans in Seabrook, New Hampshire, caught this ISS flyover through clouds on June 9, 2016. She wrote: “It moved quickly and silently overhead towards the east.”

If you sign up for NASA’s Spot the Station service, notices will be sent to you only when ISS will be clearly visible from your location for at least a couple of minutes. If you live north of 51.6 degrees latitude (for example, in Alaska), you will likely have to visit the website to find sighting opportunities because notifications in this region would be rare.

A composite photograph of an International Space Station flyover, taken from the U.K. Image via Dave Walker.

The notices contain information on where to look for ISS in the night sky. Just note where the sun sets and you can easily find the direction where the station will appear (for example, in the southwest or in the northwest). The height at which the station will appear is given in degrees. Just remember that 90 degrees is directly over your head. Any number less than 90 degrees will mean that the station will appear somewhere between the horizon and the 90 degree mark. The station is so bright that it is really hard to miss if you’re looking in the correct direction. Alternatively, you can stretch out your fist at arm’s length toward the horizon, which is equivalent to about 10 degrees. Then, just use the appropriate number of fist-lengths to find the location marker, e.g., four fist-lengths from the horizon would be equivalent to about 40 degrees.

NASA’s Spot the Station program is great. I’ve seen the station fly over many times now, and it’s a pretty amazing experience.

The first module of ISS was launched into space in 1998 and the initial construction of the station took about two years to complete. Human occupation of the station began on November 2, 2000. Since that time, ISS has been continuously occupied. ISS serves as both an orbiting laboratory and a port for international spacecraft. The primary partnering countries involved in operating ISS include the United States, Canada, Japan, several European countries and Russia.

ISS orbits at approximately 220 miles (350 km) above the Earth and it travels at an average speed of 17,227 miles (27,724 km) per hour. ISS makes multiple orbits around the Earth every day.

Photo of the International Space Station taken from the space shuttle Endeavour on May 30, 2011. Image via NASA.

Astronauts Robert Curbeam, Jr. and Christer Fuglesang working on the International Space Station. Image via NASA.

ISS crossing the sky in a long-exposure photograph by Antonín Hušek.

Enjoying EarthSky? Sign up for our free daily newsletter today!

Bottom line: Learn to watch the International Space Station (ISS) moving above your location.

from EarthSky https://ift.tt/3dueKkM

On May 30, 2020, NASA’s SpaceX Demo-2 mission launched successfully. It is the first U.S human spaceflight from U.S. soil since 2011 – on an American rocket and spacecraft – with astronauts Robert Behnken and Douglas Hurley, headed to the International Space Station. Image via NASA.

If you’re looking for information on the SpaceX Crew Dragon launch on Saturday, May 30, 2020 … click here.

The International Space Station (ISS) has been orbiting our planet since 1998. From most locations on Earth, assuming you have clear night skies, you can see ISS for yourself. To us on Earth, it looks like a bright star moving quickly from horizon to horizon. As suddenly as it appears, it disappears. How do you know when to see ISS pass overhead from your location?

NASA has a great tool to help – the Spot the Station program lets you sign up to receive alerts to let you know when ISS will be visible from your location – anywhere in the world. Plus there’s a map-based feature to track when to look for the station as it flies over you in your night sky.

You can also sign up for alerts via email or text message. Typically, alerts are sent out a few times each month when the station’s orbit is near your location. Visit the Spot the Station website to sign up, and see a list of upcoming sighting opportunities.

Wayne Boyd shared his photo of ISS passing over Marstons Mills, Massachusetts,

Patricia Evans in Seabrook, New Hampshire, caught this ISS flyover through clouds on June 9, 2016. She wrote: “It moved quickly and silently overhead towards the east.”

If you sign up for NASA’s Spot the Station service, notices will be sent to you only when ISS will be clearly visible from your location for at least a couple of minutes. If you live north of 51.6 degrees latitude (for example, in Alaska), you will likely have to visit the website to find sighting opportunities because notifications in this region would be rare.

A composite photograph of an International Space Station flyover, taken from the U.K. Image via Dave Walker.

The notices contain information on where to look for ISS in the night sky. Just note where the sun sets and you can easily find the direction where the station will appear (for example, in the southwest or in the northwest). The height at which the station will appear is given in degrees. Just remember that 90 degrees is directly over your head. Any number less than 90 degrees will mean that the station will appear somewhere between the horizon and the 90 degree mark. The station is so bright that it is really hard to miss if you’re looking in the correct direction. Alternatively, you can stretch out your fist at arm’s length toward the horizon, which is equivalent to about 10 degrees. Then, just use the appropriate number of fist-lengths to find the location marker, e.g., four fist-lengths from the horizon would be equivalent to about 40 degrees.

NASA’s Spot the Station program is great. I’ve seen the station fly over many times now, and it’s a pretty amazing experience.

The first module of ISS was launched into space in 1998 and the initial construction of the station took about two years to complete. Human occupation of the station began on November 2, 2000. Since that time, ISS has been continuously occupied. ISS serves as both an orbiting laboratory and a port for international spacecraft. The primary partnering countries involved in operating ISS include the United States, Canada, Japan, several European countries and Russia.

ISS orbits at approximately 220 miles (350 km) above the Earth and it travels at an average speed of 17,227 miles (27,724 km) per hour. ISS makes multiple orbits around the Earth every day.

Photo of the International Space Station taken from the space shuttle Endeavour on May 30, 2011. Image via NASA.

Astronauts Robert Curbeam, Jr. and Christer Fuglesang working on the International Space Station. Image via NASA.

ISS crossing the sky in a long-exposure photograph by Antonín Hušek.

Enjoying EarthSky? Sign up for our free daily newsletter today!

Bottom line: Learn to watch the International Space Station (ISS) moving above your location.

from EarthSky https://ift.tt/3dueKkM

AIM spots season’s 1st Arctic noctilucent clouds

These animated images show AIM’s observations from the first week of the Arctic noctilucent cloud season, which began on May 17, 2020. The colors — from dark blue to light blue and bright white — indicate the clouds’ albedo, which refers to the amount of light that a surface reflects compared to the total sunlight that falls upon it. Things that have a high albedo are bright and reflect a lot of light. Things that don’t reflect much light have a low albedo; they are dark. Image via NASA/ HU/ VT/ CU-LASP/ AIM/ Joy Ng

By Lina Tran/ NASA’s Goddard Space Flight Center

Ice-blue clouds are drifting high above the Arctic, which means the Northern Hemisphere’s noctilucent cloud season is here.

NASA’s AIM – Aeronomy of Ice in the Mesosphere – spacecraft first spotted wisps of these noctilucent, or night-shining, clouds over the Arctic on May 17. In the week that followed, the ghost-like wisps grew into a blur, quickly filling more of the Arctic sky. This is the second-earliest start of the northern season yet observed, and the season is expected to run through mid-August.

The seasonal clouds hover high above the ground, about 50 miles overhead in a layer of the atmosphere called the mesosphere. Most meteors burn up when they reach the mesosphere; there are enough gases there to slough plummeting meteors into nothing more than dust and smoke. Noctilucent clouds form when water molecules congregate around the fine dust and freeze, forming ice crystals. The icy clouds, reflecting sunlight, shine bright blue and white. They first appear in summer — around mid-May in the Northern Hemisphere and mid-November in the Southern — when the mesosphere is most humid, with the season’s heat lofting moisture up to the sky.

Jim Russell is AIM principal investigator at Hampton University in Virginia. He said:

Every year, twice a year, the start of the season is a big event for us. The reason we’re excited is we’re trying to find out what the causes of the season’s starting are and what does it really mean with regard to the larger picture in the atmosphere.

Also known as polar mesospheric clouds (because they tend to huddle around Earth’s poles), these clouds help scientists better understand the mesosphere and how it’s connected to the rest of the atmosphere, weather and climate.

Scientists are eager to see what this Arctic season brings. For the most part, the brilliant clouds usually cling to the polar regions. But sometimes, they stray south. Last year, they were spotted as far south as southern California and Oklahoma — lower latitudes than have ever been seen before, Russell said. The new season is another chance to better understand the fleeting clouds and their possible migration south. Some evidence indicates this could be the result of changing atmospheric conditions. Russell said:

With every year, we get new data to help us put together a picture of the atmosphere.

Botton line: Animated image by NASA’s AIM spacecraft of the 2020 season’s 1st noctilucent, or night-shining, clouds over the Arctic.

Via NASA

from EarthSky https://ift.tt/3cgBRyn

These animated images show AIM’s observations from the first week of the Arctic noctilucent cloud season, which began on May 17, 2020. The colors — from dark blue to light blue and bright white — indicate the clouds’ albedo, which refers to the amount of light that a surface reflects compared to the total sunlight that falls upon it. Things that have a high albedo are bright and reflect a lot of light. Things that don’t reflect much light have a low albedo; they are dark. Image via NASA/ HU/ VT/ CU-LASP/ AIM/ Joy Ng

By Lina Tran/ NASA’s Goddard Space Flight Center

Ice-blue clouds are drifting high above the Arctic, which means the Northern Hemisphere’s noctilucent cloud season is here.

NASA’s AIM – Aeronomy of Ice in the Mesosphere – spacecraft first spotted wisps of these noctilucent, or night-shining, clouds over the Arctic on May 17. In the week that followed, the ghost-like wisps grew into a blur, quickly filling more of the Arctic sky. This is the second-earliest start of the northern season yet observed, and the season is expected to run through mid-August.

The seasonal clouds hover high above the ground, about 50 miles overhead in a layer of the atmosphere called the mesosphere. Most meteors burn up when they reach the mesosphere; there are enough gases there to slough plummeting meteors into nothing more than dust and smoke. Noctilucent clouds form when water molecules congregate around the fine dust and freeze, forming ice crystals. The icy clouds, reflecting sunlight, shine bright blue and white. They first appear in summer — around mid-May in the Northern Hemisphere and mid-November in the Southern — when the mesosphere is most humid, with the season’s heat lofting moisture up to the sky.

Jim Russell is AIM principal investigator at Hampton University in Virginia. He said:

Every year, twice a year, the start of the season is a big event for us. The reason we’re excited is we’re trying to find out what the causes of the season’s starting are and what does it really mean with regard to the larger picture in the atmosphere.

Also known as polar mesospheric clouds (because they tend to huddle around Earth’s poles), these clouds help scientists better understand the mesosphere and how it’s connected to the rest of the atmosphere, weather and climate.

Scientists are eager to see what this Arctic season brings. For the most part, the brilliant clouds usually cling to the polar regions. But sometimes, they stray south. Last year, they were spotted as far south as southern California and Oklahoma — lower latitudes than have ever been seen before, Russell said. The new season is another chance to better understand the fleeting clouds and their possible migration south. Some evidence indicates this could be the result of changing atmospheric conditions. Russell said:

With every year, we get new data to help us put together a picture of the atmosphere.

Botton line: Animated image by NASA’s AIM spacecraft of the 2020 season’s 1st noctilucent, or night-shining, clouds over the Arctic.

Via NASA

from EarthSky https://ift.tt/3cgBRyn

News digest – Pregnancy reprograms breast cells, reducing organ transplant rejection, new uses for malaria drug, and white blood cell-inspired glass robots

Malaria drug used to treat glioblastoma 

One of the most aggressive types of brain cancer could be treated with an already approved malaria drug. Lumefantrine has been proposed in combination with the current  care/treatments – to treat patients with glioblastoma.  This type of brain cancer has a poor survival rate, and it is hoped that lumefantrine will boost the effectiveness of existing treatments. Read more on this at New Atlas 

Scientists unlock potential to reduce transplant rejection 

A new study in the Journal of Clinical Investigation has reported a key molecule that could be responsible for the slow decay of transplanted tissue. The molecules, called HLA antigens, almost always differ between patients (except in the case of identical twins) and are known targets for antibodies which can cause the body to launch an immune response against the foreign tissue. By inhibiting the molecule, scientists believe they could reduce the likelihood of organ rejection in transplant patients. Yale News has the full story.    

Microscopic robots rush against blood to target cancer cells 

The Evening Standard reports on an experimental trial using microscopic glass robots to detect cancerous tissue and deliver chemotherapy drugs to target cancer cells. The tiny spherical devices can move against the flow of blood, allowing them to reach “hard-to-access regions” inside the human body. Tests using mouse blood and artificial blood vessels showed that the robots to effectively target cancer cells in the presence of healthy cells. Read more at New Scientist. 

Younger pregnancy linked to lower risk of breast cancer 

Scientists have found a connection between a lower  risk of breast cancer and the reduced expression of a potent cancer gene in pregnant mice. According to research, breast cells are able to protect themselves from cancer after pregnancy by tucking a potent cancer gene (known as cMYC) away where it cannot cause harm. Breast cells are also able to suspend potential cancer cells in a ‘pre-senescence’ state between living, dying and developing into cancer. More on this at PR Newswire. 

And finally… 

An investigation into the early development of high-grade serous ovarian cancer has found the cells of the oviduct in mice (similar to the fallopian tubes in humans) to be more prone to developing tumours than cells in the outer layers of the ovaries.  Further study into the development and progress of this type of cancer in organoid models is hoped to provide a better understanding of how the disease develops. Read more at News Medical. 

Scarlett Sangster is a writer for PA Media Group

from Cancer Research UK – Science blog https://ift.tt/2M98N1f

Malaria drug used to treat glioblastoma 

One of the most aggressive types of brain cancer could be treated with an already approved malaria drug. Lumefantrine has been proposed in combination with the current  care/treatments – to treat patients with glioblastoma.  This type of brain cancer has a poor survival rate, and it is hoped that lumefantrine will boost the effectiveness of existing treatments. Read more on this at New Atlas 

Scientists unlock potential to reduce transplant rejection 

A new study in the Journal of Clinical Investigation has reported a key molecule that could be responsible for the slow decay of transplanted tissue. The molecules, called HLA antigens, almost always differ between patients (except in the case of identical twins) and are known targets for antibodies which can cause the body to launch an immune response against the foreign tissue. By inhibiting the molecule, scientists believe they could reduce the likelihood of organ rejection in transplant patients. Yale News has the full story.    

Microscopic robots rush against blood to target cancer cells 

The Evening Standard reports on an experimental trial using microscopic glass robots to detect cancerous tissue and deliver chemotherapy drugs to target cancer cells. The tiny spherical devices can move against the flow of blood, allowing them to reach “hard-to-access regions” inside the human body. Tests using mouse blood and artificial blood vessels showed that the robots to effectively target cancer cells in the presence of healthy cells. Read more at New Scientist. 

Younger pregnancy linked to lower risk of breast cancer 

Scientists have found a connection between a lower  risk of breast cancer and the reduced expression of a potent cancer gene in pregnant mice. According to research, breast cells are able to protect themselves from cancer after pregnancy by tucking a potent cancer gene (known as cMYC) away where it cannot cause harm. Breast cells are also able to suspend potential cancer cells in a ‘pre-senescence’ state between living, dying and developing into cancer. More on this at PR Newswire. 

And finally… 

An investigation into the early development of high-grade serous ovarian cancer has found the cells of the oviduct in mice (similar to the fallopian tubes in humans) to be more prone to developing tumours than cells in the outer layers of the ovaries.  Further study into the development and progress of this type of cancer in organoid models is hoped to provide a better understanding of how the disease develops. Read more at News Medical. 

Scarlett Sangster is a writer for PA Media Group

from Cancer Research UK – Science blog https://ift.tt/2M98N1f

On Mars, mud flows like lava

We know that Mars used to be volcanically active in the past. The planet is dotted with enormous now-dormant volcanoes, and the remains of old lava flows can still be seen today. Now, it seems, some of those lava flows weren’t composed of lava at all, but rather mud, according to researchers in Europe. The finding is evidence for what are called sedimentary volcanism, where liquid mud – water-rich sediments – ruptured from Mars’ subsurface, flowing like lava before refreezing. These features have often been seen on Earth, in association with smaller conical hills that resemble mud volcanoes.

The intriguing peer-reviewed results were published in the journal Nature Geoscience on May 20, 2020.

A possible mud volcano on Mars, just one of thousands. Ancient flows from such features and other volcanic spots had previously been assumed to be lava, but a new study suggests that at least in some cases, it was mud instead. That would mean these landforms really are mud volcanoes, not smaller magmatic volcanoes. Image via NASA/ JPL-Caltech/ University of Arizona/ DLR.

From the paper:

Large outflow channels on ancient terrains of Mars have been interpreted as the products of catastrophic flood events. The rapid burial of water-rich sediments after such flooding could have led to sedimentary volcanism, in which mixtures of sediment and water (mud) erupt to the surface.

Tens of thousands of volcano-like landforms populate the northern lowlands … on Mars. However, it is difficult to determine whether the edifices are related to igneous or mud extrusions …

Here we investigate the mechanisms of mud propagation on Mars using experiments performed inside a low-pressure chamber at cold temperatures. We found that low viscosity mud under Martian conditions propagates differently from that on Earth, because of a rapid freezing and the formation of an icy crust. Instead, the experimental mud flows propagate like terrestrial pahoehoe lava flows, with liquid mud spilling from ruptures in the frozen crust, and then refreezing to form a new flow lobe.

We suggest that mud volcanism can explain the formation of some lava-like flow morphologies on Mars, and that similar processes may apply to cryovolcanic extrusions on icy bodies in the solar system.

The low-pressure vacuum chamber used in the experiments. Image via CAS/ Petr Brož/ CC BY-SA 4.0/ DLR.

An example of mud frozen in simulated Mars conditions. The mud froze on the outside but remained liquid on the inside, and formed cavities and shapes similar to lava on Earth. Image via Brož et al./ Nature Geoscience/ CNRS.

The new study was led by researchers from the Institute of Geophysics at the Czech Academy of Sciences (CAS). It involved Lancaster University, the Open University and the Rutherford Appleton Laboratory in the U.K., CNRS in France, DLR and Münster University in Germany, and CEED in Norway.

Ernst Hauber of the DLR Institute of Planetary Research in Berlin-Adlershof said in a statement:

We have long been aware that in the early history of Mars, several billion years ago, large amounts of water were released over a short period of time, eroding very large valleys in the landscape, which have long since dried up. Extensively eroded masses of fragmented rock were transported through these outflow channels and into the northern lowlands of the planet, where they were quickly deposited. Later, these rocky masses were covered by younger sediments and volcanic rocks.

An active mud volcano in Azerbaijan. Image via CAS/ Petr Brož/ CC BY-SA 4.0/ DLR.

Many of the mud flows are found in locations where massive channels were carved by water a few billion years ago. These floods were huge, comparable to the largest floods known on Earth. Water would then seep back into the subsurface, where it could then re-emerge as mud.

How did the researchers determine that some of the lava flows were not really lava, but mud? Lionel Wilson, Emeritus Professor of Earth and Planetary Sciences at Lancaster University, explained:

We performed experiments in a vacuum chamber to simulate the release of mud on Mars. This is of interest because we see many flow-like features on Mars in spacecraft images, but they have not yet been visited by any of the roving vehicles on the surface and there is some ambiguity about whether they are flows of lava or mud.

What they found was quite interesting. Flowing mud on Mars didn’t behave at all like flowing mud on Earth, due to the very thin atmosphere and cold temperatures. The vacuum chamber re-created current Martian conditions. The flowing mud on Mars would freeze quickly and form an icy crust. In the vacuum chamber, the mud flows formed shapes similar to pahoehoe lava, which is common in Hawaii and Iceland. After the mud spilled out of ruptures in the ground, it refroze and formed smooth, undulating surfaces. The outer surface of the mud would freeze on contact with the air, while the inner core remained liquid. This liquid can break the frozen crust to form a new flow lobe that then refreezes.

More conical hills thought to be mud volcanoes, in Coprates Chasma on Mars. Image via Petr Brož/ Mars Reconnaissance Orbiter/ NASA/ JPL/ University of Arizona/ The Conversation.

Rock slab called Old Soaker, found by the Curiosity rover in Gale Crater on Mars, which is covered with what are thought to be mud cracks from when a layer of mud dried out about 3 billion years ago. Image via NASA/ JPL-Caltech/ MSSS.

In another test where the atmospheric pressure was the same as Earth’s, the mud did not form those shapes, even though it was just as cold in the vacuum chamber. Petr Brož, lead author of the new study, said:

Under the low atmospheric pressure of Mars, the mud flows behave in much the same way as pahoehoe, or ‘ropy’, lava, which is familiar from large volcanoes on Hawaii and Iceland. Our experiments show that even a process as apparently simple as the flow of mud – something that many of us have experienced for ourselves since we were children – would be very different on Mars.

Hauber added:

However, the impact of this familiar effect on mud has never been investigated in an experiment before. Once again, it turns out that different physical conditions must always be taken into account when looking at apparently simple surface features on other planets. We now know that we need to consider both mud and lava when analyzing certain flow phenomena.

There are tens of thousands of small conical hills in the northern highlands of Mars that may be mud volcanoes. It isn’t clear whether any of them may still be pumping out mud today, but the findings overall show that mud and wet sediments were common on the planet, at least in the past. In Gale Crater, the Curiosity rover has also found cracked, dried rock slabs that look exactly like dried out mud from the bottom of the lake that used to exist there.

Petr Brož of the Czech Academy of Sciences, lead author of the new study. Image via CAS.

Mars isn’t the only place where this kind of sedimentary volcanism is thought to occur. There is also evidence for a similar process on the dwarf planet Ceres, which may have once had a muddy ocean beneath its outer icy crust. According to Brož:

We suggest that mud volcanism can explain the formation of some lava-like flow morphologies on Mars, and that similar processes may apply to eruptions of mud on icy bodies in the outer solar system, like on Ceres.

Last year it was reported that Ceres likely had subsurface salty muddy meltwater reservoirs that lasted millions of years. The bright spots on Ceres’ surface are now thought to be salt deposits left over from when cryovolcanoes – ice volcanoes – erupted, with the water quickly sublimating away due to the almost complete lack of an atmosphere. Similar features thought to be cryovolcanoes were also discovered on Pluto by the New Horizons spacecraft, and on Saturn’s moon Titan by Cassini. If the flows and conical hills on Mars are really also related to Martian mud, then that would show such processes are common in our solar system (including Earth of course), and could potentially provide valuable clues as to how life originated and evolved on our own planet.

Bottom line: Some features on Mars that were thought to be lava flows may actually be mud flows, according to a new study.

Source: Experimental evidence for lava-like mud flows under Martian surface conditions

Via Lancaster University

Via DLR

from EarthSky https://ift.tt/2AiT7G0

We know that Mars used to be volcanically active in the past. The planet is dotted with enormous now-dormant volcanoes, and the remains of old lava flows can still be seen today. Now, it seems, some of those lava flows weren’t composed of lava at all, but rather mud, according to researchers in Europe. The finding is evidence for what are called sedimentary volcanism, where liquid mud – water-rich sediments – ruptured from Mars’ subsurface, flowing like lava before refreezing. These features have often been seen on Earth, in association with smaller conical hills that resemble mud volcanoes.

The intriguing peer-reviewed results were published in the journal Nature Geoscience on May 20, 2020.

A possible mud volcano on Mars, just one of thousands. Ancient flows from such features and other volcanic spots had previously been assumed to be lava, but a new study suggests that at least in some cases, it was mud instead. That would mean these landforms really are mud volcanoes, not smaller magmatic volcanoes. Image via NASA/ JPL-Caltech/ University of Arizona/ DLR.

From the paper:

Large outflow channels on ancient terrains of Mars have been interpreted as the products of catastrophic flood events. The rapid burial of water-rich sediments after such flooding could have led to sedimentary volcanism, in which mixtures of sediment and water (mud) erupt to the surface.

Tens of thousands of volcano-like landforms populate the northern lowlands … on Mars. However, it is difficult to determine whether the edifices are related to igneous or mud extrusions …

Here we investigate the mechanisms of mud propagation on Mars using experiments performed inside a low-pressure chamber at cold temperatures. We found that low viscosity mud under Martian conditions propagates differently from that on Earth, because of a rapid freezing and the formation of an icy crust. Instead, the experimental mud flows propagate like terrestrial pahoehoe lava flows, with liquid mud spilling from ruptures in the frozen crust, and then refreezing to form a new flow lobe.

We suggest that mud volcanism can explain the formation of some lava-like flow morphologies on Mars, and that similar processes may apply to cryovolcanic extrusions on icy bodies in the solar system.

The low-pressure vacuum chamber used in the experiments. Image via CAS/ Petr Brož/ CC BY-SA 4.0/ DLR.

An example of mud frozen in simulated Mars conditions. The mud froze on the outside but remained liquid on the inside, and formed cavities and shapes similar to lava on Earth. Image via Brož et al./ Nature Geoscience/ CNRS.

The new study was led by researchers from the Institute of Geophysics at the Czech Academy of Sciences (CAS). It involved Lancaster University, the Open University and the Rutherford Appleton Laboratory in the U.K., CNRS in France, DLR and Münster University in Germany, and CEED in Norway.

Ernst Hauber of the DLR Institute of Planetary Research in Berlin-Adlershof said in a statement:

We have long been aware that in the early history of Mars, several billion years ago, large amounts of water were released over a short period of time, eroding very large valleys in the landscape, which have long since dried up. Extensively eroded masses of fragmented rock were transported through these outflow channels and into the northern lowlands of the planet, where they were quickly deposited. Later, these rocky masses were covered by younger sediments and volcanic rocks.

An active mud volcano in Azerbaijan. Image via CAS/ Petr Brož/ CC BY-SA 4.0/ DLR.

Many of the mud flows are found in locations where massive channels were carved by water a few billion years ago. These floods were huge, comparable to the largest floods known on Earth. Water would then seep back into the subsurface, where it could then re-emerge as mud.

How did the researchers determine that some of the lava flows were not really lava, but mud? Lionel Wilson, Emeritus Professor of Earth and Planetary Sciences at Lancaster University, explained:

We performed experiments in a vacuum chamber to simulate the release of mud on Mars. This is of interest because we see many flow-like features on Mars in spacecraft images, but they have not yet been visited by any of the roving vehicles on the surface and there is some ambiguity about whether they are flows of lava or mud.

What they found was quite interesting. Flowing mud on Mars didn’t behave at all like flowing mud on Earth, due to the very thin atmosphere and cold temperatures. The vacuum chamber re-created current Martian conditions. The flowing mud on Mars would freeze quickly and form an icy crust. In the vacuum chamber, the mud flows formed shapes similar to pahoehoe lava, which is common in Hawaii and Iceland. After the mud spilled out of ruptures in the ground, it refroze and formed smooth, undulating surfaces. The outer surface of the mud would freeze on contact with the air, while the inner core remained liquid. This liquid can break the frozen crust to form a new flow lobe that then refreezes.

More conical hills thought to be mud volcanoes, in Coprates Chasma on Mars. Image via Petr Brož/ Mars Reconnaissance Orbiter/ NASA/ JPL/ University of Arizona/ The Conversation.

Rock slab called Old Soaker, found by the Curiosity rover in Gale Crater on Mars, which is covered with what are thought to be mud cracks from when a layer of mud dried out about 3 billion years ago. Image via NASA/ JPL-Caltech/ MSSS.

In another test where the atmospheric pressure was the same as Earth’s, the mud did not form those shapes, even though it was just as cold in the vacuum chamber. Petr Brož, lead author of the new study, said:

Under the low atmospheric pressure of Mars, the mud flows behave in much the same way as pahoehoe, or ‘ropy’, lava, which is familiar from large volcanoes on Hawaii and Iceland. Our experiments show that even a process as apparently simple as the flow of mud – something that many of us have experienced for ourselves since we were children – would be very different on Mars.

Hauber added:

However, the impact of this familiar effect on mud has never been investigated in an experiment before. Once again, it turns out that different physical conditions must always be taken into account when looking at apparently simple surface features on other planets. We now know that we need to consider both mud and lava when analyzing certain flow phenomena.

There are tens of thousands of small conical hills in the northern highlands of Mars that may be mud volcanoes. It isn’t clear whether any of them may still be pumping out mud today, but the findings overall show that mud and wet sediments were common on the planet, at least in the past. In Gale Crater, the Curiosity rover has also found cracked, dried rock slabs that look exactly like dried out mud from the bottom of the lake that used to exist there.

Petr Brož of the Czech Academy of Sciences, lead author of the new study. Image via CAS.

Mars isn’t the only place where this kind of sedimentary volcanism is thought to occur. There is also evidence for a similar process on the dwarf planet Ceres, which may have once had a muddy ocean beneath its outer icy crust. According to Brož:

We suggest that mud volcanism can explain the formation of some lava-like flow morphologies on Mars, and that similar processes may apply to eruptions of mud on icy bodies in the outer solar system, like on Ceres.

Last year it was reported that Ceres likely had subsurface salty muddy meltwater reservoirs that lasted millions of years. The bright spots on Ceres’ surface are now thought to be salt deposits left over from when cryovolcanoes – ice volcanoes – erupted, with the water quickly sublimating away due to the almost complete lack of an atmosphere. Similar features thought to be cryovolcanoes were also discovered on Pluto by the New Horizons spacecraft, and on Saturn’s moon Titan by Cassini. If the flows and conical hills on Mars are really also related to Martian mud, then that would show such processes are common in our solar system (including Earth of course), and could potentially provide valuable clues as to how life originated and evolved on our own planet.

Bottom line: Some features on Mars that were thought to be lava flows may actually be mud flows, according to a new study.

Source: Experimental evidence for lava-like mud flows under Martian surface conditions

Via Lancaster University

Via DLR

from EarthSky https://ift.tt/2AiT7G0

Coronavirus reports – Part 4: “I know I’m in a queue, but things feel uncertain”

We caught up with people living with cancer across the country, to find out how the coronavirus pandemic has been affecting them and their families. 

Paul: “I understand the reasons for the delay and I know I’m in a queue, but things feel uncertain” 

Paul from Enfield, London was diagnosed with both lung and prostate cancer in 2019.  

“I was diagnosed with two cancers at the same time, which I know is very unusual.” Paul, who says he always been pretty active, retired in July 2019 at the age of 66. That’s when investigations for prostate cancer began.  

During a CT scan, doctors picked up something on Paul’s lung, which turn out to be cancer.  

Paul was diagnosed with both lung and prostate cancer in 2019.

“I was not scared when I thought it was just prostate cancer. When they said it was lung cancer too, I had a sudden realisation of being vulnerable. I was a pretty fit bloke. I was very active and think of myself as a young man!” 

Paul had surgery for lung cancer in February and his prognosis is good. “I didn’t need to have any chemotherapy or radiotherapy, I’ll be monitored now for 5 years.” 

But his radiotherapy for prostate cancer has been put on hold due to COVID-19.  

“I am assured the cancer is curable by hormone treatment and radiotherapy, but the radiotherapy was postponed until September.”  

Paul said he was happy with the decision at the time, and he is still having injections to inhibit testosterone. But the delays are starting to worry him.  

“I understand the reasons for the delay and I know I’m in a queue, but things feel uncertain. My CT scan for both cancers has been put on hold too. So, I hope there aren’t any problems because of that delay.” 

“I am currently shielding but I did sign up to the Walk All Over Cancer fundraiser during March  – it was a good challenge and it really helped me.” 

Saima: “It’s very worrying to hear of anything that might hold up new treatments” 

Saima was diagnosed with stage  4 lung cancer in 2018, when she was 29. For her, the coronavirus outbreak moved up her treatment.  

“It has been crazy – as soon as the virus became a pandemic, I had lots of treatment lined up.” Saima’s having ongoing chemotherapy and as the cancer has spread to her brain, she also had a targeted radiotherapy called CyberKnife. “I had four days’ worth of treatment in the first week of lockdown. 

Saima had the CyberKnife treatment at St Barts Hospital in London, “I went to Barts  and they took my temperature on the way in. It was so efficient. There was no one there for anything routine, only compulsory appointments”  

Since then, she’s been told not to leave the house.   

“I am lucky to be in Kent. We have a garden and outdoor space”. Despite this, Saima says mental health is going to be a big issue – “there’s so much trauma happening anyway with cancer and it’s going to have such an impact. It’s too much to think about with COVID-19 risks too”.   

“I’ve spoken to others in the BAME community and I do think there’s still a way to go when it comes to cancer taboos, and educating people about how they can stay safe.” 

A big concern for Saima is also the state of clinical trials, many of which have had to pause recruitment because of the pandemic. “I am stage 4 – to hear of trials being stopped, that is alarming. I need those to keep running to give me hope.  

“It’s very worrying to hear of anything which might hold up any  new cancer treatments being developed.” 

Sophie: “I find it so concerning that this was not a decision I was included in” 

Sophie was diagnosed with breast cancer in 2016. She had surgery and treatment, but the cancer came back in 2018. 

“It had spread to my liver, lungs and spine. I had chemotherapy which worked well but earlier this year, I had a scan that showed it had progressed to the brain.” Sophie’s treatment was changed because of the COVID-19 pandemic. While she’s been switched to a safer option, Sophie says the treatment has a lower chance of working. 

“I was told I could not have the chemo for two reasons – first because they

Sophie was diagnosed with breast cancer in 2016.

said I couldn’t have an IV as there was a risk of getting the virus, and secondly because they wanted to cut down on staff for the COVID wards.” Sophie said she would preferred the treatment with the better prospects, even with the risks.  

“My disease is very progressed and I have been given weeks or months if the chemo doesn’t work. I find it so concerning that this treatment change wasn’t a decision I was included in. Lots of people might die as a result of the impact of COVID-19 on people’s care.”  

“My husband and I have just had a baby through surrogacy too – I have so much to look forward to.” 

Mary: “I was so stressed I wouldn’t get the treatment I needed” 

Mary describes her diagnosis as a “bolt out of the blue”. She was sent for some tests in December 2019, after experiencing heavy periods for the last couple of years. In January, she was set to the Princess of Wales hospital for an appointment, where the doctor told her she had womb cancer.  

“My head was spinning after I heard the word cancer. It was a complete shock.” Mary had been at work that morning and had left her car at the office as she was expecting to be dropped back there after the appointment. “I have not been back.”  

Despite the initial shock, Mary says the NHS have been brilliant. “I had a radical hysterectomy on the 4th February, which was luckily before any talk of lockdown – I am thankful that happened when it did.”  

The operation went well and Mary was in hospital for 3 nights. A few weeks

Mary was diagnosed with womb cancer in 2019.

later, she was told she would need radiotherapy because she had a satellite tumour on her cervix, which she requested to at Velindre Cancer Centre in Cardiff to be nearer family.  

“I went for my planning CT scan the morning that lockdown was announced. I was so stressed that I wouldn’t be able to get the treatment that I needed.” Mary says despite her concerns, the team at the Velindre have been marvellous. “They said they were going to keep going and I started my treatment on the 7th April.” 

A big concern for Mary was travel, but the staff put her at ease. The routine was for her husband Gwyn to drive her in, and they would park the car, ring reception and wait until the team were ready before she went in. She had her temperature taken every day and no visitors were allowed. “It was so professional, and the drive in was much quicker because the roads were so quiet – in fact I felt guilty going in one day as I heard on the radio about people having treatment disrupted and that was not my experience.”   

After four weeks of external beam radiotherapy and one week of brachytherapy, during which Mary says, “all dignity went out the window”, her treatment finished on the 14th May. “The staff were amazing throughout.”  

Mary’s experiencing side effects from the radiotherapy, but overall she’s feeling positive. “I am now looking forward with the support of my family and friends – my eldest was doing her mock A-levels at the time of my diagnosis and is hoping to go to university in September.”  

She’s waiting for follow-up appointments now – which might end up being a phone call. “I’m waiting for a letter about that and a CT scan too.” 

Katie 

Read more coronavirus reports:

• “I should have known when they came back in PPE”
• “We’re ahead when it comes to isolation”
• “I’m taking things week by week”

Thanks to Paul, Saima, Sophie and Mary for sharing their experiences with our Media Volunteer Liaison team. 

If you would like to share your story with us, please visit our website. And you can tell us how COVID-19 is impacting your life with cancer through our survey. 

If you have questions about cancer, you can talk to our nurses Monday to Friday, 9-5pm, on freephone 0808 800 4040. 

from Cancer Research UK – Science blog https://ift.tt/3ddphkR

We caught up with people living with cancer across the country, to find out how the coronavirus pandemic has been affecting them and their families. 

Paul: “I understand the reasons for the delay and I know I’m in a queue, but things feel uncertain” 

Paul from Enfield, London was diagnosed with both lung and prostate cancer in 2019.  

“I was diagnosed with two cancers at the same time, which I know is very unusual.” Paul, who says he always been pretty active, retired in July 2019 at the age of 66. That’s when investigations for prostate cancer began.  

During a CT scan, doctors picked up something on Paul’s lung, which turn out to be cancer.  

Paul was diagnosed with both lung and prostate cancer in 2019.

“I was not scared when I thought it was just prostate cancer. When they said it was lung cancer too, I had a sudden realisation of being vulnerable. I was a pretty fit bloke. I was very active and think of myself as a young man!” 

Paul had surgery for lung cancer in February and his prognosis is good. “I didn’t need to have any chemotherapy or radiotherapy, I’ll be monitored now for 5 years.” 

But his radiotherapy for prostate cancer has been put on hold due to COVID-19.  

“I am assured the cancer is curable by hormone treatment and radiotherapy, but the radiotherapy was postponed until September.”  

Paul said he was happy with the decision at the time, and he is still having injections to inhibit testosterone. But the delays are starting to worry him.  

“I understand the reasons for the delay and I know I’m in a queue, but things feel uncertain. My CT scan for both cancers has been put on hold too. So, I hope there aren’t any problems because of that delay.” 

“I am currently shielding but I did sign up to the Walk All Over Cancer fundraiser during March  – it was a good challenge and it really helped me.” 

Saima: “It’s very worrying to hear of anything that might hold up new treatments” 

Saima was diagnosed with stage  4 lung cancer in 2018, when she was 29. For her, the coronavirus outbreak moved up her treatment.  

“It has been crazy – as soon as the virus became a pandemic, I had lots of treatment lined up.” Saima’s having ongoing chemotherapy and as the cancer has spread to her brain, she also had a targeted radiotherapy called CyberKnife. “I had four days’ worth of treatment in the first week of lockdown. 

Saima had the CyberKnife treatment at St Barts Hospital in London, “I went to Barts  and they took my temperature on the way in. It was so efficient. There was no one there for anything routine, only compulsory appointments”  

Since then, she’s been told not to leave the house.   

“I am lucky to be in Kent. We have a garden and outdoor space”. Despite this, Saima says mental health is going to be a big issue – “there’s so much trauma happening anyway with cancer and it’s going to have such an impact. It’s too much to think about with COVID-19 risks too”.   

“I’ve spoken to others in the BAME community and I do think there’s still a way to go when it comes to cancer taboos, and educating people about how they can stay safe.” 

A big concern for Saima is also the state of clinical trials, many of which have had to pause recruitment because of the pandemic. “I am stage 4 – to hear of trials being stopped, that is alarming. I need those to keep running to give me hope.  

“It’s very worrying to hear of anything which might hold up any  new cancer treatments being developed.” 

Sophie: “I find it so concerning that this was not a decision I was included in” 

Sophie was diagnosed with breast cancer in 2016. She had surgery and treatment, but the cancer came back in 2018. 

“It had spread to my liver, lungs and spine. I had chemotherapy which worked well but earlier this year, I had a scan that showed it had progressed to the brain.” Sophie’s treatment was changed because of the COVID-19 pandemic. While she’s been switched to a safer option, Sophie says the treatment has a lower chance of working. 

“I was told I could not have the chemo for two reasons – first because they

Sophie was diagnosed with breast cancer in 2016.

said I couldn’t have an IV as there was a risk of getting the virus, and secondly because they wanted to cut down on staff for the COVID wards.” Sophie said she would preferred the treatment with the better prospects, even with the risks.  

“My disease is very progressed and I have been given weeks or months if the chemo doesn’t work. I find it so concerning that this treatment change wasn’t a decision I was included in. Lots of people might die as a result of the impact of COVID-19 on people’s care.”  

“My husband and I have just had a baby through surrogacy too – I have so much to look forward to.” 

Mary: “I was so stressed I wouldn’t get the treatment I needed” 

Mary describes her diagnosis as a “bolt out of the blue”. She was sent for some tests in December 2019, after experiencing heavy periods for the last couple of years. In January, she was set to the Princess of Wales hospital for an appointment, where the doctor told her she had womb cancer.  

“My head was spinning after I heard the word cancer. It was a complete shock.” Mary had been at work that morning and had left her car at the office as she was expecting to be dropped back there after the appointment. “I have not been back.”  

Despite the initial shock, Mary says the NHS have been brilliant. “I had a radical hysterectomy on the 4th February, which was luckily before any talk of lockdown – I am thankful that happened when it did.”  

The operation went well and Mary was in hospital for 3 nights. A few weeks

Mary was diagnosed with womb cancer in 2019.

later, she was told she would need radiotherapy because she had a satellite tumour on her cervix, which she requested to at Velindre Cancer Centre in Cardiff to be nearer family.  

“I went for my planning CT scan the morning that lockdown was announced. I was so stressed that I wouldn’t be able to get the treatment that I needed.” Mary says despite her concerns, the team at the Velindre have been marvellous. “They said they were going to keep going and I started my treatment on the 7th April.” 

A big concern for Mary was travel, but the staff put her at ease. The routine was for her husband Gwyn to drive her in, and they would park the car, ring reception and wait until the team were ready before she went in. She had her temperature taken every day and no visitors were allowed. “It was so professional, and the drive in was much quicker because the roads were so quiet – in fact I felt guilty going in one day as I heard on the radio about people having treatment disrupted and that was not my experience.”   

After four weeks of external beam radiotherapy and one week of brachytherapy, during which Mary says, “all dignity went out the window”, her treatment finished on the 14th May. “The staff were amazing throughout.”  

Mary’s experiencing side effects from the radiotherapy, but overall she’s feeling positive. “I am now looking forward with the support of my family and friends – my eldest was doing her mock A-levels at the time of my diagnosis and is hoping to go to university in September.”  

She’s waiting for follow-up appointments now – which might end up being a phone call. “I’m waiting for a letter about that and a CT scan too.” 

Katie 

Read more coronavirus reports:

• “I should have known when they came back in PPE”
• “We’re ahead when it comes to isolation”
• “I’m taking things week by week”

Thanks to Paul, Saima, Sophie and Mary for sharing their experiences with our Media Volunteer Liaison team. 

If you would like to share your story with us, please visit our website. And you can tell us how COVID-19 is impacting your life with cancer through our survey. 

If you have questions about cancer, you can talk to our nurses Monday to Friday, 9-5pm, on freephone 0808 800 4040. 

from Cancer Research UK – Science blog https://ift.tt/3ddphkR

Curiosity rover finds evidence for ancient ice-covered lake on Mars

Artist’s concept of Gale Crater when it was filled by a lake a few billion years ago. The Curiosity rover has now previous evidence for the lake or series of lakes over time, and now a new study suggests that the lake could have been covered by ice during colder climate periods. Image via NASA/ JPL-Caltech/ ESA/ DLR/ FU Berlin/ MSSS.

A few billion years ago, Gale Crater on Mars held a lake or series of lakes. There was even a river that once fed into this lake. That’s the conclusion of scientists working with data from NASA’s Curiosity rover on Mars, which landed inside Gale Crater in August, 2012, and has been exploring the region ever since. Now, a new study of Curiosity data by NASA scientists has added more pieces to the puzzle of what conditions on ancient Mars were like.

NASA announced the study on May 19, 2020. The peer-reviewed paper detailing these findings was published on January 27 in the journal Nature.

The results come from a comprehensive analysis of data from a multi-year experiment onboard the rover, in a chemistry lab called Sample Analysis at Mars (SAM). SAM has been analyzing the chemistry and minerals in rock samples, including organic compounds – the building blocks of life – to determine the habitability of this part of Mars early in its history. This testing has previously confirmed abundant liquid water in the past, as well as a variety of organic molecules preserved in Martian rocks.

Diagram of the proposed carbon cycle on Mars. With little water and no abundant surface life on the planet, the cycle is quite different from the one on Earth. Image via Lance Hayashida/ Caltech/ NASA.

The SAM instrument at Goddard Space Flight Center, before it was placed on Curiosity for the trip to Mars. Image via NASA/ GSFC.

The latest analysis has found evidence for a previous ice-covered lake in Gale Crater, thought to have possibly existed in a colder period between two warmer periods of time. Heather Franz, a geochemist at Goddard Space Flight Center who led the new study, said in a statement:

At some point, Mars’ surface environment must have experienced a transition from being warm and humid to being cold and dry, as it is now, but exactly when and how that occurred is still a mystery.

The evidence supports the idea that Mars’ climate alternated between warmer and colder before finally becoming permanently cold and dry as we see it today. Changes in the axis tilt of the planet and volcanic activity could have played a major part in that instability. Indeed, chemical and mineralogical changes in martian rocks also show this, with some rock layers being formed in warmer conditions, but others in colder climates.

The Quisquiro salt flat in Altiplano, South America. Scientists think this may be similar to the lake(s) that once existed in Gale Crater on Mars. Image via Maksym Bocharov/ NASA.

So how did Franz and her team find the evidence for an ice-covered lake?

Over five years, Curiosity collected 13 rock and dust samples. From these, the gases carbon dioxide and oxygen were extracted inside SAM. Each sample was heated to 1,650 degrees Fahrenheit (900 degrees Celsius), in order to liberate the trapped gases. The temperatures of the SAM oven at the time provided clues as to the kinds of minerals the gases were coming from. This provided insight into Mars’ carbon cycle, where the gas is exchanged between Mars’ subsurface, surface rocks, polar caps, water and atmosphere. While Mars still has a carbon cycle today, it is a lot different than Earth’s, since it has little water and no abundant surface life. As Paul Mahaffy, principal investigator on SAM explained:

Nevertheless, the carbon cycling is still happening and is still important because it’s not only helping reveal information about Mars’ ancient climate. It’s also showing us that Mars is a dynamic planet that’s circulating elements that are the buildings blocks of life as we know it.

Mars doesn’t seem to have a lot of carbonates left – minerals composed of carbon and oxygen – which would be evidence for Mars once having a much thicker atmosphere, probably mostly carbon dioxide like today. Such an atmosphere would be needed to help explain how the planet could have once had long-lasting lakes and rivers. But, even though the carbonates may be sparse where Curiosity landed, the ones it has found so far have provided valuable clues about the ancient martian climate.

Comparison of a carbonate molecule and an oxalate molecule. Image via James Tralie/ NASA/ Goddard Space Flight Center.

By examining the isotopes of the oxygen and carbon dioxide – versions of each element with different molecular masses – scientists can learn what chemical processes were involved in the formation of the rocks, including whether any biological activity might have been involved, as happens on Earth. The analysis showed that in some of the carbonates, the oxygen isotopes were lighter than those found in the martian atmosphere.

Why is that significant? It suggests the carbonates formed in a cold, likely ice-covered, lake. If the carbonates had formed in a warmer lake, then the isotopes should have actually been slightly heavier than the ones from the air. The researchers say that the ice might have sucked up the heavy oxygen isotopes, leaving behind the lighter ones that would eventually be found in the carbonates.

This is puzzling though, because it might mean the atmosphere was still thinner than thought. But without a thicker, warmer atmosphere, how could there have been lakes, rivers and maybe even a northern hemisphere ocean back then, as other other studies have shown?

The answer may be in the form of minerals called oxalates. Franz and her team suggest that some of the carbon may have been stored in oxalates rather than carbonates. The temperatures at which the carbon dioxide was released from some samples inside SAM was too low for carbonates, but just right for oxalates. The ratios of carbon and oxygen isotopes found also support this hypothesis.

Heather Franz at NASA’s Goddard Space Flight Center, who led the new study. Image via NASA/ Goddard Space Flight Center.

If it could be proven that oxalates were involved, that would be intriguing, since they are the most common mineral produced by plant life on Earth, synthesized by the incomplete oxidation of carbohydrates. That in itself wouldn’t prove life on early Mars, however, since they can also be produced by the interaction of carbon dioxide with surface minerals (inorganic or organic catalysts), water and sunlight. This is a process that “mocks” photosynthesis, called abiotic photosynthesis. It may even have paved the way for actual photosynthesis to be utilized by microbes on Earth.

Additional analysis of these and future SAM samples will be necessary to further figure out what role oxalates played, if any. The upcoming Perseverance rover mission to  Jezero Crater, scheduled to launch this summer, should be able to shed more light on the Curiosity findings. Jezero Crater is similar to Gale Crater, in that it also used to contain a lake, and an ancient delta is still clearly visible where a river once emptied into the lake. Perseverance is designed to specifically look for evidence of ancient microbial life on Mars, so it will be very interesting to see what it finds.

Bottom line: A new study of results from the Curiosity rover provides evidence for an ice-covered lake once existing in Gale Crater on Mars.

from EarthSky https://ift.tt/2BdV0UZ

Artist’s concept of Gale Crater when it was filled by a lake a few billion years ago. The Curiosity rover has now previous evidence for the lake or series of lakes over time, and now a new study suggests that the lake could have been covered by ice during colder climate periods. Image via NASA/ JPL-Caltech/ ESA/ DLR/ FU Berlin/ MSSS.

A few billion years ago, Gale Crater on Mars held a lake or series of lakes. There was even a river that once fed into this lake. That’s the conclusion of scientists working with data from NASA’s Curiosity rover on Mars, which landed inside Gale Crater in August, 2012, and has been exploring the region ever since. Now, a new study of Curiosity data by NASA scientists has added more pieces to the puzzle of what conditions on ancient Mars were like.

NASA announced the study on May 19, 2020. The peer-reviewed paper detailing these findings was published on January 27 in the journal Nature.

The results come from a comprehensive analysis of data from a multi-year experiment onboard the rover, in a chemistry lab called Sample Analysis at Mars (SAM). SAM has been analyzing the chemistry and minerals in rock samples, including organic compounds – the building blocks of life – to determine the habitability of this part of Mars early in its history. This testing has previously confirmed abundant liquid water in the past, as well as a variety of organic molecules preserved in Martian rocks.

Diagram of the proposed carbon cycle on Mars. With little water and no abundant surface life on the planet, the cycle is quite different from the one on Earth. Image via Lance Hayashida/ Caltech/ NASA.

The SAM instrument at Goddard Space Flight Center, before it was placed on Curiosity for the trip to Mars. Image via NASA/ GSFC.

The latest analysis has found evidence for a previous ice-covered lake in Gale Crater, thought to have possibly existed in a colder period between two warmer periods of time. Heather Franz, a geochemist at Goddard Space Flight Center who led the new study, said in a statement:

At some point, Mars’ surface environment must have experienced a transition from being warm and humid to being cold and dry, as it is now, but exactly when and how that occurred is still a mystery.

The evidence supports the idea that Mars’ climate alternated between warmer and colder before finally becoming permanently cold and dry as we see it today. Changes in the axis tilt of the planet and volcanic activity could have played a major part in that instability. Indeed, chemical and mineralogical changes in martian rocks also show this, with some rock layers being formed in warmer conditions, but others in colder climates.

The Quisquiro salt flat in Altiplano, South America. Scientists think this may be similar to the lake(s) that once existed in Gale Crater on Mars. Image via Maksym Bocharov/ NASA.

So how did Franz and her team find the evidence for an ice-covered lake?

Over five years, Curiosity collected 13 rock and dust samples. From these, the gases carbon dioxide and oxygen were extracted inside SAM. Each sample was heated to 1,650 degrees Fahrenheit (900 degrees Celsius), in order to liberate the trapped gases. The temperatures of the SAM oven at the time provided clues as to the kinds of minerals the gases were coming from. This provided insight into Mars’ carbon cycle, where the gas is exchanged between Mars’ subsurface, surface rocks, polar caps, water and atmosphere. While Mars still has a carbon cycle today, it is a lot different than Earth’s, since it has little water and no abundant surface life. As Paul Mahaffy, principal investigator on SAM explained:

Nevertheless, the carbon cycling is still happening and is still important because it’s not only helping reveal information about Mars’ ancient climate. It’s also showing us that Mars is a dynamic planet that’s circulating elements that are the buildings blocks of life as we know it.

Mars doesn’t seem to have a lot of carbonates left – minerals composed of carbon and oxygen – which would be evidence for Mars once having a much thicker atmosphere, probably mostly carbon dioxide like today. Such an atmosphere would be needed to help explain how the planet could have once had long-lasting lakes and rivers. But, even though the carbonates may be sparse where Curiosity landed, the ones it has found so far have provided valuable clues about the ancient martian climate.

Comparison of a carbonate molecule and an oxalate molecule. Image via James Tralie/ NASA/ Goddard Space Flight Center.

By examining the isotopes of the oxygen and carbon dioxide – versions of each element with different molecular masses – scientists can learn what chemical processes were involved in the formation of the rocks, including whether any biological activity might have been involved, as happens on Earth. The analysis showed that in some of the carbonates, the oxygen isotopes were lighter than those found in the martian atmosphere.

Why is that significant? It suggests the carbonates formed in a cold, likely ice-covered, lake. If the carbonates had formed in a warmer lake, then the isotopes should have actually been slightly heavier than the ones from the air. The researchers say that the ice might have sucked up the heavy oxygen isotopes, leaving behind the lighter ones that would eventually be found in the carbonates.

This is puzzling though, because it might mean the atmosphere was still thinner than thought. But without a thicker, warmer atmosphere, how could there have been lakes, rivers and maybe even a northern hemisphere ocean back then, as other other studies have shown?

The answer may be in the form of minerals called oxalates. Franz and her team suggest that some of the carbon may have been stored in oxalates rather than carbonates. The temperatures at which the carbon dioxide was released from some samples inside SAM was too low for carbonates, but just right for oxalates. The ratios of carbon and oxygen isotopes found also support this hypothesis.

Heather Franz at NASA’s Goddard Space Flight Center, who led the new study. Image via NASA/ Goddard Space Flight Center.

If it could be proven that oxalates were involved, that would be intriguing, since they are the most common mineral produced by plant life on Earth, synthesized by the incomplete oxidation of carbohydrates. That in itself wouldn’t prove life on early Mars, however, since they can also be produced by the interaction of carbon dioxide with surface minerals (inorganic or organic catalysts), water and sunlight. This is a process that “mocks” photosynthesis, called abiotic photosynthesis. It may even have paved the way for actual photosynthesis to be utilized by microbes on Earth.

Additional analysis of these and future SAM samples will be necessary to further figure out what role oxalates played, if any. The upcoming Perseverance rover mission to  Jezero Crater, scheduled to launch this summer, should be able to shed more light on the Curiosity findings. Jezero Crater is similar to Gale Crater, in that it also used to contain a lake, and an ancient delta is still clearly visible where a river once emptied into the lake. Perseverance is designed to specifically look for evidence of ancient microbial life on Mars, so it will be very interesting to see what it finds.

Bottom line: A new study of results from the Curiosity rover provides evidence for an ice-covered lake once existing in Gale Crater on Mars.

from EarthSky https://ift.tt/2BdV0UZ