Crew-4 is off to the Station

Name someone who at some point in their life didn’t want to be an astronaut. The answer is no one. Ask any kid what they want to be when they grow up and they all say an astronaut. Being an astronaut is the ultimate dream job for everyone of all ages. Why? Because you get to go to space, and there’s nothing cooler than going into space. For context, even if you’re not a sports fan you have watched the Super Bowl at least once in your life. It is one of the most watched and most lauded sports championship games in the entire world, and yet despite all its media attention and halftime shows and all-time great finishes, the Super Bowl still holds a candle to being able to go to space. Eat your heart out, Tom Brady. Going into space is just awesome, and there’s nothing like it.

Just ask the astronauts of NASA’s SpaceX Crew-4 who blasted off into orbit, and to the International Space Station (ISS), on April 27 at 3:52am EDT (12:52am PDT). They will undoubtedly tell you how awesome it is going to space onboard their Dragon spacecraft. The initial g-forces pushing on their body at liftoff and eventually giving way to the feeling of weightlessness literally minutes later is something they will remember for the rest of their lives.

Crew-4 consists of three NASA astronauts, Mission Commander Kjell Lindgren, Pilot Bob Hines, and Mission Specialist Jessica Watkins, and one European Space Agency astronaut, Mission Specialist Samantha Cristoforetti. The Crew-4 astronauts will spend several months aboard the space station conducting new scientific research in areas such as materials science, health technologies, and plant science to prepare for human exploration beyond low-Earth orbit and to benefit life on Earth.

Lindgren is commander of the Dragon spacecraft and the Crew-4 mission. He is responsible for all phases of flight, from launch to re-entry, and will serve as an Expedition 67 flight engineer. This will be Lindgren’s second spaceflight since becoming an astronaut in 2009. In 2015, he spent 141 days aboard the orbital laboratory as a flight engineer for expeditions 44 and 45. Board certified in emergency medicine, he previously worked at NASA Johnson as a flight surgeon supporting space station training and operations and served as a deputy crew surgeon for space shuttle flight STS-130 and Expedition 24. Lindgren was born in Taipei, Taiwan, and spent most of his childhood in England before graduating from the U.S. Air Force Academy.

Portrait of Expedition 44/45 astronaut Kjell Lindgren in EMU (Credit: NASA/Bill Stafford)

Hines is the pilot of the Dragon spacecraft and second in command for the mission. He is responsible for spacecraft systems and performance. Aboard the station, he will serve as an Expedition 67 flight engineer. This will be his first flight since his selection as an astronaut in 2017. Hines has served more than 22 years in the U.S. Air Force as a test pilot, fighter pilot, and instructor pilot. Before his selection in 2017, he was a research pilot at Johnson.

2017 NASA Astronaut Candidate – Bob Hines. Photo Date: June 6, 2017. Location: Ellington Field – Hangar 276, Tarmac. (Credit: NASA / Robert Markowitz)

Watkins is a mission specialist for Crew-4 and will work closely with the commander and pilot to monitor the spacecraft during the dynamic launch and re-entry phases of flight. Once aboard the station, she will seve as a flight engineer for Expedition 67. Watkins grew up in Lafayette, Colorado, and studied geology at Stanford University, Palo Alto, California, and the University of California, Los Angeles. As a geologist, she studied the surface of Mars and was a science team collaborator at NASA’s Jet Propulsion Laboratory in Pasadena, California, working on the Mars Science Laboratory rover Curiosity. She also was selected as a NASA astronaut in 2017, and this will be her first trip to space.

2017 NASA Astronaut Candidate Jessica Watkins. (Credit: NASA/Bill Stafford)

Cristoforetti will also serve as a mission specialist, working to monitor the Dragon spacecraft during the dynamic launch and re-entry phases of flight. She will serve as a flight engineer for Expedition 67. This will be her second trip to space following five months in 2015 as a flight engineer for Expeditions 42 and 43. Born in Milan, Italy, she was a fighter pilot in the Italian Air Force prior to being selected as an ESA astronaut in 2009. In 2019, she served as commander for NASA’s 23rd Extreme Environment Mission Operations mission on a 10-day stay in Aquarius, the world’s only undersea research station.

European Space Agency astronaut Samantha Cristoforetti, attired in an Extravehicular Mobility Unit (EMU) spacesuit. (Credit: NASA/Robert Markowitz)

Commercial Crew Program and Future Missions

NASA’s Commercial Crew Program (CCP) provides commercially-operated crew transportation service to and from the ISS under a SpaceX contract to NASA and began providing service in 2020 using the Crew Dragon spacecraft. While this latest mission is designated Crew-4, it is actually the fifth crewed mission to the ISS, with the first being Demo-2 that launched NASA astronauts Bob Behnken and Doug Hurley to the ISS in March 2020, followed by Crew-1 (November 2020), Crew-2 (April 2021), and Crew-3 (November 2021). Future planned CCP missions onboard Crew Dragon are Crew-5 (September 2022), Crew-6 (April 2023), and Crew-7 (September 2023). SpaceX is currently contracted up to Crew-9 to ferry astronauts to the ISS, as NASA hopes to maintain an uninterrupted U.S. capability for human access to the ISS.

Logo for NASA’s Commercial Crew Program (Credit: NASA)

Going to space is everyone’s dream, and Crew-4 just became the latest members of humanity to live out that dream. As access to space slowly opens to everyone, it’s only a matter of time until many more Earthlings will be able to live out their own dream as they literally float among the stars while looking down at our precious blue world.

As always, keep doing science & keep looking up!

Sources: NASA Press Release, NASA (1), NASA (2), NASA (3)

Featured Image: A SpaceX Falcon 9 rocket carrying the company’s Crew Dragon spacecraft is launched on NASA’s SpaceX Crew-4 mission to the International Space Station with NASA astronauts Kjell Lindgren, Robert Hines, Jessica Watkins, and ESA (European Space Agency) astronaut Samantha Cristoforetti onboard, Wednesday, April 27, 2022, at NASA’s Kennedy Space Center in Florida. (Credit: NASA/Aubrey Gemignani)

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Antarctica Lost an Ice Shelf, but Gained an Island

Collapsing ice shelves on the eastern coast of Antarctica has revealed something never seen before: a landform that might be an island. But this is not the first newly revealed island off the Antarctic coast. A series of islands have appeared as the ice shelves along the continent’s coastline has disintegrated over the past few years.

The island is visible in the three images, which were taken by Landsat satellites between 1989 and 2022. The landform maintains its shape, even through the ice around it has melted, shifted, and disappeared. With the collapsing ice, scientists think large icebergs likely smashed into the island, but the island maintained its shape.

The eastern coast of Antarctica has lost most of the Glenzer and Conger ice shelves, as seen in these satellite images taken between November 15, 1989 – January 9, 2022. Credit: NASA GSFC/UMBC JCET.

However, scientists are  unsure if there is any solid earth below the mound of snow and ice.

“It is undoubtedly similar to other ice islands, such as Bowman Island (also visible in the image above),” said John Gibson, a scientist with the Australian Antarctic Division, in a post on NASA’s Earth Observatory. Gibson thinks the feature is likely an ice island: a large, heavy cap of ice sitting solidly on an underwater peak.

Gibson called the ice island “self-perpetuating,” meaning that snow and ice accumulating on the island’s surface balances out the amount of melting that occurs underwater. If that balance becomes disrupted by a decrease in snowfall, then the ice island could thin and float away. “The unnamed island is a more-or-less permanent feature of the landscape,” Gibson said, “but may someday detach from the underlying rock and become an iceberg.”

NASA says that elevation data in December 2021 from the Advanced Topographic Laser Altimeter System (ATLAS) on NASA’s Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) shows at least part of the island stands 30 to 35 meters (100 to 115 feet) above the surface of the sea.

NASA says that most of the Glenzer and Conger ice shelves are gone, having collapsed earlier this year. And with further collapse of Antarctic ice shelves due to the warming ocean, more of these islands might be popping up.  

“The discovery of more of them is likely to continue in the years ahead due to shrinking glacial and sea ice,” said Christopher Shuman, a University of Maryland, Baltimore County, glaciologist based at NASA’s Goddard Space Flight Center. “Obviously these are ‘new to us’ features, but we also have more people and more tools to look at the margins of Antarctica now. Several examples do not make a trend, but they do imply that other once-hidden features are likely to be noticed in the years to come.”

Read more about this landform on NASA’s Earth Observatory.

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Solar Power in a Future Martian Lifestyle

An artist’s concept of a future biomanufacturing lab on Mars, powered by photovoltaic (solar power) technology. It will also synthesize food and medicines, and manufacture other needed materials, while recycling waste. (Credit: Davian Ho.)

Sometime in the next couple of decades, humans will head to Mars for long-term missions of more than 400 days. Such lengthy stays mean building Martian cities, complete with safe habitats, labs, and other infrastructure. Future Martians will have to do a lot to survive. They’ll build their cities, make their own food, distill water, create fuel, manufacture medicines, and create other supplies. To do that, they’ll use manufacturing facilities that they bring along. That all requires power. Lots of it. As we all know, Mars is noticeably lacking in obvious ways to make electricity. So, what will our intrepid explorers do to generate power for their new lives on the Red Planet?

This flow chart shows the process humans on Mars will use as they synthesize the materials they need from the raw materials on the planet. The equipment they use will be transported from Earth (at first), but will need reliable power. (Credit: Aaron Berliner and Davian Ho, UC Berkeley)

Mars Needs Power!

Conventional wisdom says that nuclear power units similar to what powers other spacecraft are the best choice. They’re clean, reliable, and long-lasting. The downside is that they weigh a lot. A Mars-bound spacecraft will be very limited in what it can carry. Of course, it’ll have crew and fuel. However, all those people will need supplies, including power units to use on the surface. It turns out that most of the current rockets can only carry about 100 tons (not including fuel). Just one nuclear power plant supplying about a kilowatt of power would be about 9.5 tons. That’s not insurmountable, however. But, mission planners want to minimize a mission’s weight in order to get the most bang for the buck. So, what if there was a lighter alternative to nuclear? Like solar power?

That’s the question a pair of graduate students at the University of California at Berkeley wanted to answer. So, they did a research project looking at future power sources for Martian colonists. Aaron Berliner specializes in nuclear engineering while Anthony Abel is interested in advances in photovoltaic cells for solar power. Together, they analyzed the power needs for a six-person mission staying on Mars for 480 days. In particular, they looked at sites on Mars where solar power might make a lot of sense. And, what they found seems to confound the conventional wisdom.

Future Mars explorers who settle in the mid-latitudes of the planet (shown in yellow) could use photovoltaics for power. Note the locations of other missions previously sent to Mars. Many are also in the same regions and have used solar power for some aspects of their explorations. Credit: Anthony Abel and Aaron Berliner, UC Berkeley)

If our future Martians settle in the mid-latitudes, particularly around the planet’s equatorial regions, solar power stations could trump nuclear. Why is this? First of all, the mid-latitudes get a lot of sunlight, so why not take advantage of that? Second, solar power cells weigh less than nuclear power plants. To get the same power as a nuclear plant, new-generation solar tech would only take up about 8.3 tons of cargo. That’s a significant weight saving over nuclear.

Mars and Next-Gen Solar Power

What kind of power cells are we talking about here? Berliner and Abel looked at systems that use photovoltaic power with electrolysis. That is, they use electricity to split water into hydrogen and oxygen. The students also calculated that some of the energy generated during the daytime would be used to produce hydrogen gas for use in fuel cells. This is roughly similar to the way some homes and businesses here on Earth use solar power to store energy in Powerwalls and batteries for night-time use.

The cool news? All this solar power goodness is possible with current photovoltaic technologies. And, of course, the technology is always improving, so by the time a Mars mission is ready to lift off, whole new versions of today’s solar cells will be ready to use.

“The silicon panels that you have on your roof, with steel construction, glass backing, and so on, just won’t compete with the new and improved nuclear,” said Abel in a press release from UC Berkeley, “But these newer lightweight, flexible panels all of a sudden really, really change that conversation.”

Advantage: Solar Power

The advantages of solar on Mars outweigh the problems. Even though colonists might have to clear the dust off the cells every so often, their lighter weight means that more panels could be sent to Mars. That includes backups for the main systems. As newer, lighter cells come online, solar power could be the main source of power for future Martian colonies. That’s not to say nuclear power won’t be there, too. In the long run, colonists may need every power-generation technology they can get, both for reliability as well as flexibility. And, in the near future, with the need to keep costs down, solar power may well be the way to go.

For more information, the paper that Abel and Berliner wrote is titled “Photovoltaics-Driver Power Production Can Support Human Exploration on Mars”, and published in Frontiers in Astronomy and Space Sciences. Their work was funded by NASA as well as the National Science Foundation.

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Titan is an Alien World, but Surprisingly Familiar

Saturn’s largest moon, Titan, is a fascinating and mysterious world, a world literally shrouded in mystery due to thick clouds that cameras imaging in the visible spectrum cannot penetrate. This was made apparent when NASA’s Pioneer 11 became the first spacecraft to fly past Titan in 1979, and then NASA’s Voyager 1 and 2 in 1980 and 1981, respectively. All three spacecraft were equipped with cameras that were unable to penetrate Titan’s atmosphere of thick clouds, although atmospheric data from Voyager 1 suggested Titan might be the first body, aside from Earth, where liquid might exist on its surface.

Titan’s thick haze layer is shown in this enhanced Voyager 1 image taken on November 12, 1980 at a distance of 435,000 kilometers. (Credit: NASA/JPL)

It wasn’t until the NASA’s Cassini spacecraft had its first encounter with Titan in October 2004 when Saturn’s largest moon was no longer able to hide its secrets beneath the hazy atmosphere. Cassini revealed a world of liquid methane and ethane lakes, sand dunes encircling the equator, and evidence for a possible internal ocean likely comprised of water or ammonia. In December 2004, Cassini released the European Space Agency’s Huygens probe, which had been mounted to the orbiting spacecraft prior to launch. Huygens entered Titan’s atmosphere and landed on the surface in January 2005 after taking 2 hours and 27 minutes to descend through the thick atmosphere, and ultimately operating for an additional one hour and 10 minutes after touchdown. Data during the descent and post-touchdown images revealed rounded rocks and a suite of onboard instruments taught us much about Titan’s atmosphere. Even though Cassini’s mission ended in September 2017 when the spacecraft intentionally plunged into Saturn, scientists continue to pore over scores of data and images that Cassini revealed about Saturn’s largest moon.

These three mosaics of Titan were composed with data from Cassini’s visual and infrared mapping spectrometer taken during the last three Titan flybys, on Oct. 28, 2005 (left), Dec. 26, 2005 (middle), and Jan. 15, 2006 (right). In a new study, researchers have shown how Titan’s distinct dunes, plains, and labyrinth terrains could be formed. (Credit: NASA/JPL/University of Arizona)

Titan is like Earth with its rivers, lakes, and seas filled by rain, but as stated, this is liquid methane and ethane as opposed to liquid water on Earth. Like Earth, Titan also has sand dunes, but they are made of hydrocarbons instead of silicate-based substances. Also, much like Earth, Titan is known for having a seasonal liquid transport cycle, also known as the water cycle on Earth, linking atmosphere, land, and oceans.

A recent study published in Geophysical Research Letters discusses a new model for this transport cycle on Titan, showing how this drives the movements of grains over Titan’s surface.

“Our new model adds a unifying framework that allows us to understand how all of these sedimentary environments work together,” said Dr. Mathieu Lapôtre, an assistant professor of geological sciences at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “If we understand how the different pieces of the puzzle fit together and their mechanisms, then we can start using the landforms left behind by those sedimentary processes to say something about the climate or the geological history of Titan – and how they could impact the prospect for life on Titan.”

While researchers think similar processes on Earth helped form the dunes, plains, and labyrinth terrains on Titan, the sediments on Saturn’s largest moon are composed of solid organic compounds, as opposed to silicate-derived rocks found on Earth, Mars, and Venus. The ability for these organic compounds to grow into sediment grains that can be transported around Titan has left scientists puzzled until now.

Lapôtre and his research team found an answer by studying sediments on Earth called ooids, which are small, spherical grains most often found in shallow tropical seas, such as the Bahamas. These ooids form when calcium carbonate is pulled from the water column and attached in layers around a grain, such as quartz. These ooids form through chemical precipitation, while the simultaneous process of erosion slows the growth as the grains are smashed together by waves and storms. Balancing each other out over time, these two competing mechanisms form a constant grain size – which the research team suggest could also be happening on Titan. While the compounds might differ, this study nonetheless demonstrates that Titan is not that dissimilar from Earth.

“Titan has been viewed as a potential analog to Earth for a variety of reasons,” said Lapôtre. “Notably, its atmosphere is thought to be conducive to the type of prebiotic chemistry that may have given rise to life on Earth. Titan’s modern landscapes are also to a great extent analogous to Earth’s landscapes, with lakes, rivers, and fields of sand dunes. In our study, we proposed a unifying hypothesis to explain how a global sedimentary cycle, driven by Titan’s climate, may generate the observed distribution of Titan’s landscapes. Such models, in turn, will allow us to decipher any sedimentary record on Titan once we get to explore Saturn’s moon in situ. Sedimentary “rocks” (which on Titan could be made of complex organics and ices) offer a prime target to better understand past environmental conditions, and thus, the history of Titan’s surface and atmosphere.”

While Cassini and Huygens were instrumental in teaching more about this mysterious world, NASA’s upcoming Dragonfly mission will deliver an 8-bladed rotorcraft to Titan hopes to further unlock the mysteries of Saturn’s largest moon, and is a mission that Dr. Lapôtre is very excited about.

Dragonfly is a dual-quadcopter lander that would take advantage of the environment on Titan to fly to multiple locations, some hundreds of miles apart, to sample materials and determine surface composition to investigate Titan’s organic chemistry and habitability, monitor atmospheric and surface conditions, image landforms to investigate geological processes, and perform seismic studies. (Credit: NASA)

“Any observations made by Dragonfly will be groundbreaking,” said Lapôtre. “Currently, we only have one picture of Titan’s surface that was acquired from the ground by the Huygens lander in 2005. Everything else we’ve seen of Titan’s surface was from orbit at low resolution. High-resolution ground observations of organic sand grains blown by winds as well as constraints on their chemical composition, for example, will help test our hypothesis.“

Dragonfly is slated to launch in 2027 and arrive at Titan in 2034. During its 2.7-year (32-month) baseline mission, this rotorcraft will sample and examine dozens of promising sites around Saturn’s icy moon and advance our search for the building blocks of life. 

What further secrets will Dragonfly unlock about this alien, but similar, world? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

Sources: Phys.org, NASA Solar System Exploration, European Space Agency, National Oceanic and Atmospheric Administration, Geophysical Research Letters, Stanford Earth, NASA

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A New Kind of Stellar Explosion Has Been Discovered: Micronovae

The most energetic explosions in the Universe come from stars called supernovae. These galactic bombs have the energy of about 10²⁸ mega-tons. After they detonate, the only thing left behind is either a neutron star or black hole. Another type of stellar explosion is known as a nova which has much less energy and covers the surface of a white dwarf.

Now, a team of astronomers recently discovered a new type of stellar explosion akin to supernovae and novae but with much less energy, and they’re calling it a micronova.

There are two types of supernovae, type I and type II. The first type happens in a binary star system, where two stars are gravitationally bound by each other, one being a white dwarf. The white dwarf collects matter from its companion star and eventually explodes, leaving nothing behind. The second type occurs when a star with enough mass, estimated to be in the range of eight to fifteen solar masses, runs out of nuclear fuel and its core collapses. The rebound from the collapse causes its outer layers to expand outward, leaving behind a neutron star or black hole.

A nova also happens on a white dwarf star in a binary star system and when enough material gathers on the surface of the star, a fusion reaction happens causing an explosion that engulfs the whole surface. This blast emits as much energy as our sun releases in 10,000 years.

Novae occurring on white dwarfs in a binary star system cover the entire star’s surface. However, while the newly discovered micronovae are caused by the same thing, these explosions happen when the material accreted onto the white dwarf from its companion accumulate at its magnetic poles. Novae can last for several weeks, but micronovae last only a few hours.

Artist’s impression of a micronova Credit: ESO

While examining data collected from NASA’s Transiting Exoplanet Survey Satellite (TESS), the astronomers “discovered something unusual: a bright flash of optical light lasting for a few hours. Searching further, we found several similar signals,” said Nathalie Degenaar, co-author of the paper recently published in the journal Nature (quoted from source).

They spotted three micronovae with this data. Using the European Southern Observatory’s Very Large Telescope (VLT) they were able to verify one of the star’s status as a white dwarf; the other two were known white dwarfs.

It is unknown how often these micronovae happen. According to Simone Scaringi of Durham University in the UK who is the lead astronomer for the team, “One of the systems shows evidence for micronovae recurring about every 100 days or so. Another target shows the bursts happening about every day on the other hand.” The regularity seems to be tied in to the amount of mass the white dwarf collects over a set amount of time. “The faster recurring system has a much higher mass accretion rate than the other system.”

Continuing on, Scaringi says “It may be that a specific system will show the (recurring) micronovae events only when the material being funneled on to the magnetic poles can remain confined for long enough to reach thermonuclear triggering conditions. In some occasions this may not happen, and material will (evenly) spread around the entire white dwarf surface, potentially building a layer of fresh hydrogen that may grow over time and drive a classical nova.”

“”These events may actually be quite common, but because they are so fast they are difficult to catch in action,” Scaringi explains” (source). In order to answer these questions the team wants to find more of these micronovae outbursts and are looking forward to using data from large-scale surveys combined with rapid response observations from telescopes like the VLT or ESO’s New Technology Telescope.

More:

• ESO.org (source): Astronomers discover micronovae, a new kind of stellar explosion
• NASA: White dwarf stars
• Space.com: What is a supernova?

Header: This artist’s impression shows a two-star system, with a white dwarf (in the foreground) and a companion star (in the background), where micronovae may occur. Credit: Mark Garlick

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Prepare Yourself: New Engineering Images from JWST Will Blow Your Mind

If the phrase “My god, it’s full of stars” was ever appropriate, it’s due to these new images from the James Webb Space Telescope. These are ‘just’ engineering images, mind you, but they are incredible. The number of stars and galaxies visible in each image is just remarkable, not to mention the crisp clarity in the fields of view.

The images were taken by JWST after the completion of the process to fully focus the telescope’s mirror segments. Now the team will begin commissioning the four science instruments, a process that will take about two months to complete. This is the final phase before the observatory will be fully ready to begin its science observations.

In analyzing these new images, the team says the optical performance is better than “the most optimistic predictions.”

“These remarkable test images from a successfully aligned telescope demonstrate what people across countries and continents can achieve when there is a bold scientific vision to explore the universe,” said Lee Feinberg, Webb optical telescope element manager at NASA’s Goddard Space Flight Center.

The alignment of the telescope’s 18 mirror segments means the mirrors are now directing fully focused light down into each instrument, and each instrument is successfully capturing images with the light being delivered to them. The teams said the image quality delivered to all instruments is “diffraction-limited,” meaning that the “fineness of detail that can be seen is as good as physically possible given the size of the telescope.”

The depth quality of these images is just a taste of what’s to come with JWST. Each image is like its own “Deep Field,” – showing innumerable stars and galaxies – like the famous Hubble Deep Field images, but even deeper.

“These images have profoundly changed the way I see the universe,” said Scott Acton, Webb wavefront sensing and controls scientist at Ball Aerospace. “We are surrounded by a symphony of creation; there are galaxies everywhere! It is my hope that everyone in the world can see them.”

As in the image below, which shows even more detail of the observations, the sharpness and clarity remains even when you zoom in. NASA explains the images:

Engineering images of sharply focused stars in the field of view of each instrument demonstrate that the telescope is fully aligned and in focus. For this test, Webb pointed at part of the Large Magellanic Cloud, a small satellite galaxy of the Milky Way, providing a dense field of hundreds of thousands of stars across all the observatory’s sensors. The sizes and positions of the images shown here depict the relative arrangement of each of Webb’s instruments in the telescope’s focal plane, each pointing at a slightly offset part of the sky relative to one another. Webb’s three imaging instruments are NIRCam (images shown here at a wavelength of 2 microns), NIRISS (image shown here at 1.5 microns), and MIRI (shown at 7.7 microns, a longer wavelength revealing emission from interstellar clouds as well as starlight). NIRSpec is a spectrograph rather than imager but can take images, such as the 1.1 micron image shown here, for calibrations and target acquisition. The dark regions visible in parts of the NIRSpec data are due to structures of its microshutter array, which has several hundred thousand controllable shutters that can be opened or shut to select which light is sent into the spectrograph. Lastly, Webb’s Fine Guidance Sensor tracks guide stars to point the observatory accurately and precisely; its two sensors are not generally used for scientific imaging but can take calibration images such as those shown here. This image data is used not just to assess image sharpness but also to precisely measure and calibrate subtle image distortions and alignments between sensors as part of Webb’s overall instrument calibration process. Credit: NASA/STScI

While the mirror is now fully in focus, engineers will still need to make small periodic adjustments to the mirror segments during the lifetime of the mission. Even small changes in temperature or movements of the spacecraft can alter the alignment.

“Our plan is check the alignment every two weeks,” Feinberg told me earlier this year. “But we will take data roughly every two days, and look at it. So, we have the ability to do it even more frequently, but it may be that we’ll find we don’t need to do it every 2 weeks. This is one of the things we are interested to learn — is how frequently we’ll have to update the mirror.”

You can keep track of JWST’s instrument commissioning phase at the Where’s Webb site.

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Amazing! Ingenuity Helicopter Flies to the Perseverance Backshell and Parachute to See Them Close Up

You may recall we reported earlier this month that the Perseverance rover finally spotted its parachute and backshell off in the distance. This is the hardware that safely brought the rover to Mars surface on February 18, 2021.

But now, the incredible Ingenuity helicopter has snapped better images of those items, while it was hovering in the Martian air during its 26^th flight.

And what a mess! The poor backshell crashed to the surface, splitting into pieces.  

This image of Perseverance’s backshell (left of center), supersonic parachute (far right), was collected from an altitude of 26 feet (8 meters) by NASA’s Ingenuity Mars Helicopter during its 26th flight on Mars on April 19, 2022. Credit: NASA/JPL/Caltech

NASA said the backshell, the white, shattered flying-saucer looking piece of equipment, would have impacted the surface at about 126 kph/78 mph – which was the plan all along. Also visible in the photos are the parachute, along with the 80 high-strength suspension lines connecting the backshell to the parachute.  This parachute was the biggest ever deployed on Mars (Perseverance is the largest rover to date). The orange-and-white parachute dimensions are 21.5 meters (70.5 feet) wide.

Perseverance Rover’s Entry, Descent and Landing Profile: This illustration shows the events that occur in the final minutes of the nearly seven-month journey that NASA’s Perseverance rover took to Mars. Credit: NASA/JPL-Caltech.

These items were essential to bring Perseverance safely to the surface, as part of the entry, descent, and landing (EDL) on Mars – otherwise known as the 7 Minutes of Terror. During those seven minutes, the incoming spacecraft carrying the rover comes screaming into Mars atmosphere at nearly 20,000 kph (12,500 mph) experiencing extreme gravitational forces and high temperatures. Through atmospheric resistance (and using small thrusters to keep the lander on target), the heat shield-covered backshell slows the spacecraft to under 1,600 kph (1,000 mph). At that point, it’s safe to deploy the supersonic parachute. The parachute slows the lander enough to where the backshell and parachute are jettisoned, (about 2.1 km 1.3 miles in altitude), allowing a hovering rocket stage called the Sky Crane to gently lower the rover to the surface.

Those seven minutes are fast-paced and stressful, because it all has to happen automatically, with no input from engineers back on Earth.

how it started how it ended pic.twitter.com/suj14iEI8M

— Kevin M. Gill (@kevinmgill) April 27, 2022

NASA engineers love to see these items – even in their crashed state – because it can inform them on how well these pieces of hardware worked, providing valuable insights for future missions. Ingenuity’s 26^th flight on April 19, 2022 provides the perspective engineers were hoping for. In total, Ingenuity took 10 aerial images of the debris field.

One of the upcoming planned missions that will benefit the most from these images is the future Mars Sample Return Lander, which is part of a multimission campaign that would bring Perseverance’s samples of Martian rocks, atmosphere, and sediment back to Earth for detailed analysis. Engineers for this mission actually made a request to the Ingenuity team for these images.  

“NASA extended Ingenuity flight operations to perform pioneering flights such as this,” said Teddy Tzanetos, Ingenuity’s team lead at NASA’s Jet Propulsion Laboratory, in a press release. “Every time we’re airborne, Ingenuity covers new ground and offers a perspective no previous planetary mission could achieve. Mars Sample Return’s reconnaissance request is a perfect example of the utility of aerial platforms on Mars.”

A picture of the Ingenuity helicopter on the surface of Mars, taken by the Perseverance rover. Credit: NASA/JPL/Caltech

NASA said several weeks of analysis will be needed for a final verdict.

“Perseverance had the best-documented Mars landing in history, with cameras showing everything from parachute inflation to touchdown,” said JPL’s Ian Clark, former Perseverance systems engineer and now Mars Sample Return ascent phase lead. “But Ingenuity’s images offer a different vantage point. If they either reinforce that our systems worked as we think they worked or provide even one dataset of engineering information we can use for Mars Sample Return planning, it will be amazing. And if not, the pictures are still phenomenal and inspiring.”

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Ganymede Casts a Long Shadow Across the Surface of Jupiter

What is that large dark smudge on Jupiter’s side? It may remind you of a certain scene from the sci-fi film “2010: The Year We Make Contact,” where a growing black spot appears in Jupiter’s atmosphere.

But this is a real photo, and the dark spot is just an elongated shadow of Ganymede, Jupiter’s largest moon. Just like when Earth’s Moon crosses between our planet and the Sun creating an eclipse for lucky Earthlings, when Jupiter’s moons cross between the gas giant and the Sun, they create shadows too.  

NASA’s Juno spacecraft captured this view of Jupiter during the mission’s 40th close pass by the giant planet on Feb. 25, 2022. This image was taken by the camera on board the spacecraft, JunoCam, and processed by citizen scientist Thomas Thomopoulos. As you may know, JunoCam is a public outreach project, with people around the world actively participating in science investigation. Citizen scientists have processed the stunning images taken by JunoCam, as well as developing time-lapse movies, measuring wind flow, tracking circulation patterns in the circumpolar cyclones, and looking for lightning flashes.

Another citizen scientist/image processer, Brian Swift created the graphic below using JunoCam data, illustrating the approximate geometry of the visible area, projected onto a globe of Jupiter.

Illustration of the approximate geometry of the Ganymede’s shadow projected onto a globe of Jupiter.
Credits: Image data: NASA/JPL-Caltech/SwRI/MSSS, Image processing by Brian Swift © CC BY

At the time this image was taken, the Juno spacecraft was about 44,000 miles (71,000 kilometers) above Jupiter’s cloud tops, at a latitude of about 55 degrees south, and 15 times closer than Ganymede, which orbits about 666,000 miles (1.1 million kilometers) away from Jupiter.

If you were lucky enough  – or unlucky, perhaps due to the conditions on Jupiter – to be observer at Jupiter’s cloud tops within the oval shadow, you would experience a total eclipse of the Sun. NASA says that total eclipses are more common on Jupiter than Earth for several reasons. Jupiter has four large  moons (known as the Galilean satellites) that often pass between Jupiter and the Sun: in seven days, Ganymede transits once; Europa, twice; and Io, four times. And since Jupiter’s moons orbit in a plane close to Jupiter’s orbital plane, the moon shadows are often cast upon the planet.

Jupiter’s moons and their shadows are even visible from even amateur telescopes on Earth. This image was taken by noted astrophotographer John Chumack.  

Jupiter on Sept. 24, 2013 with its moon Europa (at left) casting a pinhead black shadow on Jupiter’s clouds. Credit: John Chumack. See more of John’s images at his website, Galactic Images.

See all of JunoCam’s raw images here, which are available for the public to peruse and process into images. Information about other citizen science projects at NASA can be found here and here.

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A Partial Solar Eclipse Kicks Off the First Eclipse Season of 2022

A remote solar eclipse this coming weekend sets us up for the first total lunar eclipse of 2022.

The first eclipse season for 2022 is nigh. About twice a year, the two nodes where the Moon’s orbit intersects the ecliptic align and an eclipse season occurs, book-ended by one each solar and lunar eclipses spaced about two weeks apart.

An animation for the April 30th partial solar eclipse. NASA/GSFC/AT Sinclair.

The eclipse – This weekend’s brief remote partial solar eclipse ushers in the beginning of the first such season for 2022. The event is a remote one, spanning the southern Pacific Ocean, Easter Island, coastal Antarctica and the southern tip of South America. At its maximum, expect the Sun to be 64% obscured by the Moon over the stretch of ocean between Tierra del Fuego and Antarctica.

The footprint for Saturday’s partial solar eclipse. Credit: Atlas of Solar Eclipses: 2020-2025.

Timing for key moments during the eclipse are in Universal Time (UT):

P1: Start of the partial phases of the eclipse (over the South Pacific): 18:45 UT.

Mid-eclipse: 20:41 UT.

P4: The end of partial phases for the eclipse (near the northern Pacific coast of Chile): 22:38 UT.

Though most of humanity will sit this eclipse out, the region along the coast of Chile and the Andes—to include the Paranal Observatory complex—should see a dramatic ‘horned sunset eclipse.’ sinking into the Pacific.

A sunset partial eclipse, as seen from Santiago, Chile. Credit: Stellarium

Eclipse Safety

Of course, safe solar observing precautions must be practiced during all stages of Saturday’s eclipse. This means using eclipse glasses or filters made for solar observing that fit snugly over the aperture (front) of optics.

Keep an eye out for strange effects during the partial solar eclipse, such as gaps in the tree leaves acting as tiny mini-pinhole projectors, covering the ground with crescent suns.

Sunspot prospects – The Sun has been extremely active as of late, as we head towards the peak for solar sunspot cycle No. 25. As of writing this, there are no less than eight active sunspot regions turned Earthward, making for a photogenic Sun, near mid-partial solar eclipse.

Solar activity as of April 27th. Credit: NASA/SDO

Tales of the Saros

This particular eclipse is member 66 of the 71 eclipses in solar saros cycle series 119. This saros is an old one stretching all the way back to May 15^th 850 AD. The series produced its last annular solar eclipse on May 18, 1950 and is now on the way out, ending with its final shallow partial solar eclipse next century on June 24, (cue Rush) 2112.

An animation for solar eclipse saros 119. Credit: NASA/GSFC/AT Sinclair.

Follow that Moon

The next few mornings sees the slim waning crescent Moon slide by a conga line of planets at dawn, as a prelude to the eclipse. The current lineup includes (in order from the Sun) Jupiter, Venus, Mars and Saturn… Jupiter and Venus will have an especially close 12’ encounter visible worldwide on the morning of the eclipse, April 30^th. The planets continue to shuffle at dawn through May and are joined by Mercury in early June, when you can actually see all of the naked eye planets in order (!) at dawn.

The dawn lunar/planetary lineup over Rome. Credit Gianluca Masi.

The first spotting the Moon on the nights following the eclipse also mark the end of the Muslim month of Ramadan, and the start of the three day celebration of Eid al-Fitr.

But there’s more to come. May 16^th sees the first of two total lunar eclipses for 2022, with both favoring the Americas… and hey, we’re just inside two years ‘til the next total solar eclipse across the United States on April 8^th, 2024.

More to come!

Lead image credit: A dazzling partial solar eclipse. Credit: Dave Dickinson

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In Some Places, Black Holes are Tearing Apart Thousands of Stars at a Time

At the heart of the more massive galaxies in the Universe, there are supermassive black holes (SMBHs) so powerful that they outshine all of the stars in their galactic disks. The core regions of these galaxies are known as Active Galactic Nuclei (AGN), or by their more popular-moniker “quasars.” The ongoing study of these objects has provided a testbed for General Relativity and revealed a great deal about the formation and evolution of galaxies and the large-scale structure of the Universe.

If there’s one thing astronomers have observed repeatedly, it is the fact that these massive black holes have massive appetites. In fact, a new survey of over 100 galaxies by the NASA Chandra X-ray Observatory has shown that some supermassive black holes can consume stars by the thousands! These results indicate that some SMBHs needed to consume amounts of stellar matter rarely (if ever) seen in the Universe to grow and reach the sizes that astronomers see today.

The research team responsible for this discovery was led by Vivienne F. Baldassare, an assistant professor in the Department of Physics and Astronomy at Washington State University (WSU). She was joined by an international team of astrophysicists from The Hebrew University of Jerusalem, Kavli Institute for Particle Astrophysics and Cosmology, the University of Michigan, and Princeton and Columbia University. A paper describing their findings was recently published in The Astrophysical Journal.

The four galaxies, NGC 1385, 1566, 3344, and 6503, observed as part of the Chandra survey. Credit: NASA/CXC/Washington State Univ./V. Baldassare et al. (X-ray); NASA/ESA/STScI (Optical).

Previously, black hole studies have fallen into one of two classes. These include those that deal with smaller “stellar-mass” black holes, which typically weigh 5 to 30 Solar masses, and supermassive black holes, which can weigh millions or even billions of solar masses. In recent years, astronomers have also found evidence that an in-between class exists, known as “intermediate-mass” black holes (IMBHs).

While there have been many instances where black holes were observed consuming stars, there was little evidence it occurred on the kind of scale observed by the Baldassare and her colleagues. This latest study, which relied on Chandra data of dense star clusters in the centers of 108 galaxies, could explain how IMBHs are the result of the runaway growth of a much smaller black hole.

“When stars are so close together like they are in these extremely dense clusters, it provides a viable breeding ground for intermediate-mass black holes,” said Baldassare in a Chandra press release. “And it seems that the denser the star cluster, the more likely it is to contain a growing black hole.”

For decades, scientists have proposed various theories on how SMBHs formed shortly after the Big Bang (about 13.8 billion years ago). These included the idea that they formed from the collapse of a gigantic cloud of gas and dust near the center of a galaxy or that they resulted from oversized stars collapsing directly into a medium-sized back hole that consumed stars and other matter grew over time.

However, both of these theories require conditions that are believed to have existed during the first few hundred million years after the Big Bang. In contrast, Baldassare and her team theorized that the key to the formation of black holes is the density of the star clusters near the center of a galaxy. They further theorized that this density is dependent on how fast the stars in the clusters are moving.

If the density is above a certain threshold, they argue, a stellar-mass black hole at the center of a cluster will rapidly grow as it consumes the stars nearby. After observing the Chandra data, the team found that the star clusters at the center of NGC 1385, 1566, 3344, and 6503 had densities above this threshold and were about twice as likely to contain a growing black hole. As co-author Nicholas C. Stone of the Hebrew University of Jerusalem summarized:

“This is one of the most spectacular examples we’ve seen of the insatiable nature of black holes, because thousands or tens of thousands of stars can be consumed during their growth. The runaway growth only begins slowing down once the supply of stars starts to run dry.”

What’s more, the process suggested by the team’s study can occur at any time in the history of the Universe, implying that IMBHs can form right up until the present day. These results might also explain certain types of gravitational wave (GW) signals detected by the Laser Interferometer Gravitational-wave Observatory (LIGO). In some cases, signals have been detected that appeared to be caused by black holes about 50 to 100 times as massive as the Sun, which most models of stellar collapse do not predict.

Of course, further studies of the centers of active galaxies are needed before any conclusions can be drawn. In the meantime, the team looks forward to additional observations that will test their theory. “Our work doesn’t prove that runaway black hole growth occurs in star clusters,” said co-author Adi Foord from Stanford University. “But with additional X-ray observations and extra theoretical modeling, we could make an even stronger case.”

Further Reading: Chandra

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Webb Has Almost Reached its Final, Coldest Temperature

 

Launched on December 25, 2021 from ESA’s launch site in Kourou, French Guiana aboard an Ariane 5 rocket, the James Webb Space Telescope (JWST) reached its final orbit at the L2 Lagrange point on January 24, 2022. It has since performed several operations to get it ready for its observing mission which should begin in about a month.

As part of getting it ready for its mission, NASA has been cooling off its instruments, such as the Mid-Infrared Instrument (MIRI), to operating temperatures. Now that they have reached that point, all that’s left to cool down are the mirrors.

MIRI is using a closed-cycle gaseous-helium cryocooler to keep its temperature down below 7 kelvin (-447 degrees Fahrenheit, -266 degrees Celsius). However, the telescope’s mirrors and other instruments are being cooled down passively, without any equipment to aid in the process. Their temperature is lowered as heat is radiated out into space.

The secondary mirror, which is held out at the end of its support structure, is ready to go. Being far away from any of the heat sources of the telescope’s instruments, it is currently at 29.4 kelvins. The 18 primary mirror segments are almost cooled down enough to begin observations. Currently their temperatures range from 34.4 to 54.5 kelvins. The team operating the telescope would like to see them cool down another 0.5 to 2 kelvins.

Why is all of this cooling down necessary? JWST will be seeing the infrared part of the electromagnetic spectrum. Infrared light produces heat and if the heat from the telescope’s instruments is not kept below a certain temperature it will interfere with its ability to collect infrared light from the objects it will be attempting to observe.

This image shows the parts of the infrared spectrum that Webb’s instruments can observe. Image: NASA/JWST

The James Webb Space Telescope will be observing in the near- and mid-infrared part of the electromagnetic spectrum. Visible light’s wavelengths tend to bounce off of dust particles, preventing the light from reaching a telescope here on Earth or even a space based observatory. Infrared light has a longer wavelength and is able to get past many more obstacles than visible light, allowing us to capture images that would otherwise not be possible.

Brown dwarfs and protostars are among the objects that JWST will be able to image, along with objects from the early universe such as black holes and some of the first stars to form. The light from those objects in the early universe has redshifted, or stretched out into the infrared part of the spectrum, and the James Webb Space Telescope will allow us to detect them, giving us a better view of this time period and hopefully answering many lingering questions about how our universe works.

More:

• NASA James Webb Space Telescope (source): Is Webb At Its Final Temperature?
• NASA James Webb Space Telescope: About Webb Orbit
• Webbtelescope.org: Beyond Visible Light

Header: NASA’s James Webb Space Telescope, shown in this artist’s conception, will provide more information about previously detected exoplanets. Beyond 2020, many more next-generation space telescopes are expected to build on what it discovers. Credit: NASA

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All Five of Life's Informational Components can Form in Space

On Earth, all life comes down to the polymeric molecules known as deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). These two building blocks contain all of the instructions for every living organism and its many operations. In turn, these are made up of five informational components (nucleobases), which are composed of organic molecules (purines and pyrimidines). For decades, scientists have been scouring meteorite samples for these building blocks.

To date, these efforts have resulted in the detection of three of the five nucleobases within meteorites. However, a recent analysis led by researchers from Hokkaido University, Japan (with support from NASA) has revealed the remaining two nucleobases that have eluded scientists until now. This discovery could help resolve the ongoing debate about whether life on Earth emerged on its own or was assisted by organic compounds deposited by meteorites (aka. panspermia).

The research team was led by Yasuhiro Oba, an associate professor at Hokkaido University’s Institute of Low Temperature Science (ILTS). He was joined by researchers from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Tohoku University, Kyushu University, and the Solar System Exploration Division (SSED) at NASA’s Goddard Space Flight Center in Maryland. The paper that describes their findings recently appeared in the journal Nature Communications.

Peptides could have been transported to the early Earth by meteorites, asteroids, or comets. Credit: © S. Krasnokutski/MPIA Graphics Department

The five nucleobases that make DNA and RNA include adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U), with the bases A, G, C, and T found in DNA while A, G, C, and U are found in RNA. While scientists have found these bases in meteorites before, scientists are uncertain why more types haven’t been discovered so far. As Oba explained in a recent NASA press release:

“I wonder why purines and pyrimidines are exceptional in that they do not show structural diversity in carbonaceous meteorites unlike other classes of organic compounds such as amino acids and hydrocarbons. Since purines and pyrimidines can be synthesized in extraterrestrial environments, as has been demonstrated by our own study, one would expect to find a wide diversity of these organic molecules in meteorites.”

As Oda and his colleagues indicate in their study, this newly discovered pair of nucleobases (cytosine and thymine) may have eluded scientists because they degraded before they could be extracted (owing to their more delicate structure). In earlier experiments, scientists placed grains of meteorite samples in a solution of hot formic acid to extract nucleotides and create a solution (“meteorite tea”) that they would then analyze. As co-author Danny Glavin of NASA’s Goddard Space Flight Center explained:

“We now have evidence that the complete set of nucleobases used in life today could have been available on Earth when life emerged. We study these water extracts since they contain the good stuff, ancient organic molecules that could have been key building blocks for the origin of life on Earth.”

For the sake of their study, the team relied on a “cold brew” rather than a “hot tea” approach. This consisted of using cool water to extract the cytosine and thymine rather than formic acid – which may have destroyed them in previous studies. Second, the team employed more sensitive analytics than previous studies, allowing them to detect smaller amounts of molecules. This allowed the team to detect the fragile cytosine and thymine in their samples of meteorite tea.

While these findings effectively complete the nucleobases that make up all life on Earth, they have not settled the debate just yet. At present, scientists still cannot say for certain if life began in a prebiotic pond billions of years ago or was assisted by organic molecules from space. However, the detection of the remaining two nucleobases and other molecules found in the sample has provided some additional pieces of the puzzle.

For instance, the team detected traces of sugars and bases in the sample, indicating that more fundamental molecules of biology are found in space. Last, but not least, the team’s research has resulted in a new proof of concept technique that has proven more effective at extracting information from asteroids. This will come in handy when NASA’s OSIRIS-REx mission returns samples from the asteroid Bennu next year. 

Further Reading: NASA, Nature Communications

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Hubble has Characterized 25 Hot Jupiters. Here’s What we Know so far

Hot Jupiters are giant exoplanets – even more massive than Jupiter – but they orbit closer to their star than Mercury. When they were first discovered, hot Jupiters were considered oddballs, since we don’t have anything like them in our own Solar System. But they appear to be common in our galaxy. As exoplanets go, they are fairly easy to detect, but because we don’t have up-close experience with them, there are still many unknowns.

A new study used archival data from the Hubble and Spitzer space telescopes to study this class of giant gas exoplanets, and undertook one of the largest surveys ever of exoplanet atmospheres. The researchers said they employed high performance computers to analyses the atmospheres of 25 hot Jupiters using data from about 1,000 hours of telescope observations. Their findings, published in the Astrophysical Journal Supplement Series, help to answer several long-standing questions about hot Jupiters.

“Our paper marks a turning point for the field,” said co-author Dr. Billy Edwards, from University College London (UCL), in a press release. “We are now moving from the characterization of individual exoplanet atmospheres to the characterization of atmospheric populations.”

The international team of astronomers said they combined two techniques – studying information from transits –where the planet passes in front of its star — and eclipses –when the planet passes behind its star. The tools they created were open source and have now been made available to researchers around the world.

Artist’s impression of a “hot Jupiter”, a gas giant that orbits it sun at a fraction of the distance between the Earth and Sun. Credit: ESA/ATG medialab

While we already know the conditions on hot Jupiters are hellish, the new research found that the night and day sides of hot Jupiters are very different from each other, with temperatures plunging by hundreds of degrees from day to night. They found that on average, there was a 1,000 K difference.

They also found that many hot Jupiters have thermally inverted atmospheres, where the upper atmosphere has temperatures that increase with altitude, exactly opposite of Earth’s atmosphere. The research team said this appears to be caused by the presence of metallic elements, such as titanium oxide, vanadium oxide and iron hydride, which absorb the star’s light, heating up the atmosphere.

They also found hot Jupiters contain less water than expected in their atmospheres, which suggests they formed differently than planets with abundant water.

“Many issues such as the origins of water on Earth, the formation of the Moon, and the different evolutionary histories of Earth and Mars, are still unsolved despite our ability to obtain in-situ measurements,” said lead author Dr. Quentin Changeat, also from UCL. “Large exoplanet population studies, such as the one we present here, aim at understanding those general processes.”

More than 5,000 exoplanets that have been discovered, but there is atmospheric data for only about 80, mostly from Hubble and Spitzer. The James Webb Space Telescope, which is undergoing commissioning in space, will have the study of exoplanet atmospheres as one of its areas for priority observing. JWST should be ready to start making observations this summer (2022.)

Lead image caption: Archival observations of 25 hot Jupiters by the NASA/ESA Hubble Space Telescope have been analysed by an international team of astronomers, enabling them to answer open questions important to our understanding of exoplanet atmospheres. Amongst other findings, the team found that the presence of metal oxides and hydrides in the hottest exoplanet atmospheres was clearly correlated with the atmospheres’ being thermally inverted. Credit: ESA/Hubble, N. Bartmann

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Shallow Pockets of Water Under the ice on Europa Could Bring Life Close to its Surface

Beneath the surface of Jupiter’s icy moon Europa, there’s an ocean up to 100 km (62 mi) deep that has two to three times the volume of every ocean on Earth combined. Even more exciting is how this ocean is subject to hydrothermal activity, which means it may have all the necessary ingredients for life. Because of this, Europa is considered one of the most likely places for extraterrestrial life (beyond Mars). Hence, mission planners and astrobiologists are eager to send a mission there to study it closer.

Unfortunately, Europa’s icy surface makes the possibility of sampling this ocean rather difficult. According to the two predominant models for Europa’s structure, the ice sheet could be a few hundred meters to several dozen kilometers thick. Luckily, new research by a team from Stanford University has shown that Europa’s icy shell may have an abundance of water pockets inside, as indicated by features on the surface that look remarkably like icy ridges here on Earth.

The study team was led by Riley Culberg, a Ph.D. candidate and geophysicist at Standford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). He was joined by Dustin Schroeder, an associate professor of geophysics at Stanford Earth; and Gregor Steinbrügge, a former postdoctoral fellow at Stanford Earth, now a planetary scientist at the NASA Jet Propulsion Laboratory. The paper that describes their research and findings recently appeared in the journal Nature Communications.

As they explain in their study, the research was motivated by a similarity the team noticed during a presentation at Standford. While discussing Europa’s double-ridges, Culberg noticed how similar these landforms were to features they had studied extensively in northern Greenland. Between 2015 and 2017, NASA collected ground-penetrating radar data of the region as part of Operation IceBridge, an aerial observation campaign that conducts geophysical studies of the growth and retreat of ice sheets.

This investigation confirmed the existence of a double ridge in northwestern Greenland and provided details of how it evolved. Geophysicists and glacial experts have determined that these features form when water from nearby surface lakes drains into an impermeable layer within the ice sheet. It then refreezes and fractures the ice above, causing it to be forced upward and outwards to create the characteristic double ridge feature on the surface.

The similarities came as a surprise to the team because of how different Earth’s land-based subsurface is compared to Europa’s subsurface ocean of liquid water. “We were working on something totally different related to climate change and its impact on the surface of Greenland when we saw these tiny double ridges – and we were able to see the ridges go from ‘not formed’ to ‘formed,’?” Schroeder said in a recent Stanford News release.

Upon further examination, they found that the M-shaped feature in Greenland could be a miniature version of Europa’s most prominent surface feature. On Europa, double ridges appear as gashes that cut across the surface, with crests reaching nearly 300 m (1,000 ft) tall, separated by valleys about 800 meters (2,625 ft) wide. Scientists have known these features since the Galileo spacecraft took images of the Galilean Moons in the 1990s, leading to the first detailed surface maps.

A double ridge cutting across the surface of Europa is seen in images taken by NASA’s Galileo mission on Feb. 20th, 1997. Credit: NASA/JPL/ASU

Since then, however, scientists have not been able to come up with a definitive explanation of how these features formed. By conducting a comparative analysis between the radar data collected by Operation IceBridge and the geophysical data they had for Europa, the team could conceive a possible answer. As Culberg explained:

“In Greenland, this double ridge formed in a place where water from surface lakes and streams frequently drains into the near-surface and refreezes. One way that similar shallow water pockets could form on Europa might be through water from the subsurface ocean being forced up into the ice shell through fractures – and that would suggest there could be a reasonable amount of exchange happening inside of the ice shell.”

These findings suggest that Europa’s ice shell may be much more dynamic than previously thought, undergoing various geological and hydrological processes. This is supported by other recent findings, such as Hubble’s discovery of plume activity on the surface in 2012, which were later confirmed in 2018 based on a new analysis of Galileo data. A dynamic ice shell model is consistent with the exchange of subsurface water and nutrients from neighboring celestial bodies on the moon’s surface.

Said Steinbrügge, who started working on the project as part of his postdoctoral research at Stanford:

“People have been studying these double ridges for over 20 years now, but this is the first time we were actually able to watch something similar on Earth and see nature work out its magic. We are making a much bigger step into the direction of understanding what processes actually dominate the physics and the dynamics of Europa’s ice shell.”

Artist’s conception of a cryovolcanic eruption on Europa. Credit: Justice Blaine Wainwright

The existence of these pockets is especially good news for the Europa Clipper mission, in which both Schroeder and Steinbrügge will be participants. This robotic orbiter will launch in October 2024, reach the Jovian system by April 2030, and spend the next four years (barring extensions) examining the surface of Europa through a series of flybys. In addition to analyzing Europa’s surface ice and plume activity, it will select landing sites for a possible Europa Lander mission. As Schroeder explained:

“Because it’s closer to the surface, where you get interesting chemicals from space, other moons, and the volcanoes of Io, there’s a possibility that life has a shot if there are pockets of water in the shell. If the mechanism we see in Greenland is how these things happen on Europa, it suggests there’s water everywhere.”

Like Operation IceBridge, the Europa Clipper will rely on an ice-penetrating radar to study the interior structure of Europa’s ice sheet. This instrument is known as the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) and is overseen by a team that includes Schroeder as a co-investigator. This instrument will detect pockets of water using radio waves because of the way water reflects them one thousand times as brightly as ice.

This will allow the REASON team to create a vertical profile that maps the distribution of water pockets in the ice sheet. “We are another hypothesis on top of many – we just have the advantage that our hypothesis has some observations from the formation of a similar feature on Earth to back it up,” Culberg said. “It’s opening up all these new possibilities for a very exciting discovery.”

Artist’s concept of a Europa Clipper mission. Credit: NASA/JPL

Identifying potentially habitable enclaves within the ice sheets also means that any astrobiology missions to Europa won’t need to enter the subsurface ocean to look for signs of life. In addition to increasing accessibility, exploring these pockets dramatically decreases the chances of contaminating potential biospheres in the moon’s interior ocean. As astrobiology missions progress, ensuring the safety of any extraterrestrial life we encounter will be paramount.

“It’s exciting, what it would mean if you have plenty of water within the ice shell,” Steinbrügge added. “It would mean the ice shell on Europa is extremely dynamic. It could facilitate exchange processes between the surface and the subsurface ocean. It could go in both directions.”

The study is yet another indication of how connected the study of Earth and the other Solar planets are. It will also lead to applications that could have significant impacts here at home. “This research will help us either use Earth to understand what we will see on Europa or, when we get to Europa, help us interpret what we see when we get there,” said Schroeder.

Further Reading: NASA, Stanford News, Nature

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