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Can life survive a star’s death? Webb telescope can reveal the answer

When stars like our sun die, all that remains is an exposed core — a white dwarf. A planet orbiting a white dwarf presents a promising opportunity to determine if life can survive the death of its star, according to Cornell University researchers.

In a study published in the Astrophysical Journal Letters, they show how NASA’s upcoming James Webb Space Telescope could find signatures of life on Earth-like planets orbiting white dwarfs.

A planet orbiting a small star produces strong atmospheric signals when it passes in front, or “transits,” its host star. White dwarfs push this to the extreme: They are 100 times smaller than our sun, almost as small as Earth, affording astronomers a rare opportunity to characterize rocky planets.

“If rocky planets exist around white dwarfs, we could spot signs of life on them in the next few years,” said corresponding author Lisa Kaltenegger, associate professor of astronomy in the College of Arts and Sciences and director of the Carl Sagan Institute.

Co-lead author Ryan MacDonald, a research associate at the institute, said the James Webb Space Telescope, scheduled to launch in October 2021, is uniquely placed to find signatures of life on rocky exoplanets.

“When observing Earth-like planets orbiting white dwarfs, the James Webb Space Telescope can detect water and carbon dioxide within a matter of hours,” MacDonald said. “Two days of observing time with this powerful telescope would allow the discovery of biosignature gases, such as ozone and methane.”

The discovery of the first transiting giant planet orbiting a white dwarf (WD 1856+534b), announced in a separate paper — led by co-author Andrew Vanderburg, assistant professor at the University of Wisconsin, Madison — proves the existence of planets around white dwarfs. Kaltenegger is a co-author on this paper, as well.

This planet is a gas giant and therefore not able to sustain life. But its existence suggests that smaller rocky planets, which could sustain life, could also exist in the habitable zones of white dwarfs.

“We know now that giant planets can exist around white dwarfs, and evidence stretches back over 100 years showing rocky material polluting light from white dwarfs. There are certainly small rocks in white dwarf systems,” MacDonald said. “It’s a logical leap to imagine a rocky planet like the Earth orbiting a white dwarf.”

The researchers combined state-of-the-art analysis techniques routinely used to detect gases in giant exoplanet atmospheres with the Hubble Space Telescope with model atmospheres of white dwarf planets from previous Cornell research.

NASA’s Transiting Exoplanet Survey Satellite is now looking for such rocky planets around white dwarfs. If and when one of these worlds is found, Kaltenegger and her team have developed the models and tools to identify signs of life in the planet’s atmosphere. The Webb telescope could soon begin this search.

The implications of finding signatures of life on a planet orbiting a white dwarf are profound, Kaltenegger said. Most stars, including our sun, will one day end up as white dwarfs.

“What if the death of the star is not the end for life?” she said. “Could life go on, even once our sun has died? Signs of life on planets orbiting white dwarfs would not only show the incredible tenacity of life, but perhaps also a glimpse into our future.”

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A warm Jupiter orbiting a cool star

A planet observed crossing in front of, or transiting, a low-mass star has been determined to be about the size of Jupiter. While hundreds of Jupiter-sized planets have been discovered orbiting larger sun-like stars, it is rare to see these planets orbiting low-mass host stars and the discovery could help astronomers to better understand how these giant planets form.

“This is only the fifth Jupiter-sized planet transiting a low-mass star that has been observed and the first with such a long orbital period, which makes this discovery really exciting,” said Caleb Cañas, lead author of the paper and a Ph.D. student at Penn State and NASA Earth and Space Science Fellow.

Originally detected by NASA’s Transiting Exoplanet Survey Satellite (TESS) spacecraft, astronomers characterized the planet’s mass, radius, and its orbital period using the Habitable-zone Planet Finder (HPF), an astronomical spectrograph built by a Penn State team and installed on the 10m Hobby-Eberly Telescope at McDonald Observatory in Texas. A paper describing the research appears in the September 2020 issue of the Astronomical Journal and is publicly accessible on arXiv.

“A transiting Jupiter-sized planet is amenable to further observations to see how well the orbit is aligned with the spin-axis of the host star and to constrain how it could have formed,” said Cañas. “Furthermore, the low mass of the host star and the long orbital period result in a Jupiter with a moderate temperature compared to similar planets detected with NASA’s Kepler space telescope.”

The host star, TOI-1899, is a low-mass (M dwarf) star about 419 light years away from Earth. The planet, TOI-1899 b, is two-thirds the mass of Jupiter, ten percent larger in radius than Jupiter, and is 0.16 astronomical units (AU) — a measure defined as the distance between the Earth and the sun — from its host star such that a full year on TOI-1899 takes only 29 Earth days. For comparison, the four other transiting Jupiter-size planets around comparable stars complete their orbits in less than 4 days.

The planet was detected by TESS using the transit method, which searches for stars showing periodic dips in their brightness as a telltale sign of an orbiting object crossing in front of the star and blocking a portion of its light. The signal was later confirmed as a planet using precision observations from the HPF spectrograph that measure the planet’s mass by analyzing how it causes its host start to the wobble.

From a formation and orbital evolution perspective, there is not a clear dividing line between warm Jupiters and the large planets even closer to their host stars, the more commonly discovered hot Jupiters.

“Warm Jupiters like TOI-1899 b orbit surprisingly close to their star,” said Rebekah Dawson, assistant professor of astronomy and astrophysics at Penn State and an author of the paper. “Even though the planet’s orbital period is long compared to many other giant planets detected and characterized through the transit method, it still places the giant planet much closer to its star than we’d expect from classical formation theories. Detailed characterization of their physical and orbital properties, system architecture, and host stars — as the HPF team has done for TOI-1899 b — allow us test theories for how giant planets can form or be displaced so close to their star.”

The Habitable-zone Planet Finder was delivered to the 10m Hobby Eberly Telescope at McDonald Observatory in late 2017, and started full science operations in late 2018. HPF is designed to detect and characterize planets in the Habitable-zone — the region around the star where a planet could sustain liquid water on its surface — around nearby M-dwarf stars, but is also capable of making sensitive measurements for planets outside the habitable zone.

“This warm Jupiter is a compelling target for atmospheric characterization with upcoming missions like the James Webb Space Telescope,” said Suvrath Mahadevan, professor of astronomy and astrophysics at Penn State, the principal investigator of the HPF spectrograph, and an author of the paper. “HPF was critical in helping us to confirm this, but detecting a second transit is important to very precisely pin down its period.”

In addition to data from HPF, additional data were obtained with the 3.5m Telescope at the Kitt Peak National Observatory (KPNO) in Arizona and the 3m Shane Telescope at Lick Observatory for high contrast imaging and photometric observations with the 0.9m WIYN Telescope at KPNO, 0.5 m ARCSAT telescope at Apache Point Observatory, and the 0.43 m telescope at the Richard S. Perkin Observatory in New York.

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Europe’s largest Solar Telescope GREGOR unveils magnetic details of the Sun

The Sun is our star and has a profound influence on our planet, life, and civilization. By studying the magnetism on the Sun, we can understand its influence on Earth and minimize damage of satellites and technological infrastructure. The GREGOR telescope allows scientists to resolve details as small as 50 km on the Sun, which is a tiny fraction of the solar diameter of 1.4 million km. This is as if one saw a needle on a soccer field perfectly sharp from a distance of one kilometer.

“This was a very exciting, but also extremely challenging project. In only one year we completely redesigned the optics, mechanics, and electronics to achieve the best possible image quality.” said Dr. Lucia Kleint, who led the project and the German solar telescopes on Tenerife. A major technical breakthrough was achieved by the project team in March this year, during the lockdown, when they were stranded at the observatory and set up the optical laboratory from the ground up. Unfortunately, snow storms prevented solar observations. When Spain reopened in July, the team immediately flew back and obtained the highest resolution images of the Sun ever taken by a European telescope.

Prof. Dr. Svetlana Berdyugina, professor at the Albert-Ludwig University of Freiburg and Director of the Leibniz Institute for Solar Physics (KIS), is very happy about the outstanding results: “The project was rather risky because such telescope upgrades usually take years, but the great team work and meticulous planning have led to this success. Now we have a powerful instrument to solve puzzles on the Sun.” The new optics of the telescope will allow scientists to study magnetic fields, convection, turbulence, solar eruptions, and sunspots in great detail. First light images obtained in July 2020 reveal astonishing details of sunspot evolution and intricate structures in solar plasma.

Telescope optics are very complex systems of mirrors, lenses, glass cubes, filters and further optical elements. If only one element is not perfect, for example due to fabrication issues, the performance of the whole system suffers. This is similar to wearing glasses with the wrong prescription, resulting in a blurry vision. Unlike for glasses, it is however very challenging to detect which elements in a telescope may be causing issues. The GREGOR team found several of those issues and calculated optics models to solve them. For example, astigmatism is one of such optical problems, which affects 30-60% people’s vision, but also complex telescopes. At GREGOR this was corrected by replacing two elements with so-called off-axis parabolic mirrors, which had to be polished to 6 nm precision, about 1/10000 of the diameter of a hair. Combined with several further enhancements the redesign led to the sharp vision of the telescope. A technical description of the redesign was recently published by the Astronomy & Astrophysics journal in a recent article led by Dr. L. Kleint.

European researchers have access to observations with the GREGOR telescope through national programs and a program funded by the European commission. New scientific observations are starting in September 2020.

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Mystery solved: Bright areas on Ceres come from salty water below

NASA’s Dawn spacecraft gave scientists extraordinary close-up views of the dwarf planet Ceres, which lies in the main asteroid belt between Mars and Jupiter. By the time the mission ended in October 2018, the orbiter had dipped to less than 22 miles (35 kilometers) above the surface, revealing crisp details of the mysterious bright regions Ceres had become known for.

Scientists had figured out that the bright areas were deposits made mostly of sodium carbonate — a compound of sodium, carbon, and oxygen. They likely came from liquid that percolated up to the surface and evaporated, leaving behind a highly reflective salt crust. But what they hadn’t yet determined was where that liquid came from.

By analyzing data collected near the end of the mission, Dawn scientists have concluded that the liquid came from a deep reservoir of brine, or salt-enriched water. By studying Ceres’ gravity, scientists learned more about the dwarf planet’s internal structure and were able to determine that the brine reservoir is about 25 miles (40 kilometers) deep and hundreds of miles wide.

Ceres doesn’t benefit from internal heating generated by gravitational interactions with a large planet, as is the case for some of the icy moons of the outer solar system. But the new research, which focuses on Ceres’ 57-mile-wide (92-kilometer-wide) Occator Crater — home to the most extensive bright areas — confirms that Ceres is a water-rich world like these other icy bodies.

The findings, which also reveal the extent of geologic activity in Occator Crater, appear in a special collection of papers published by Nature Astronomy, Nature Geoscience, and Nature Communications on Aug. 10.

“Dawn accomplished far more than we hoped when it embarked on its extraordinary extraterrestrial expedition,” said Mission Director Marc Rayman of NASA’s Jet Propulsion Laboratory in Southern California. “These exciting new discoveries from the end of its long and productive mission are a wonderful tribute to this remarkable interplanetary explorer.”

Solving the Bright Mystery

Long before Dawn arrived at Ceres in 2015, scientists had noticed diffuse bright regions with telescopes, but their nature was unknown. From its close orbit, Dawn captured images of two distinct, highly reflective areas within Occator Crater, which were subsequently named Cerealia Facula and Vinalia Faculae. (“Faculae” means bright areas.)

Scientists knew that micrometeorites frequently pelt the surface of Ceres, roughing it up and leaving debris. Over time, that sort of action should darken these bright areas. So their brightness indicates that they likely are young. Trying to understand the source of the areas, and how the material could be so new, was a main focus of Dawn’s final extended mission, from 2017 to 2018.

The research not only confirmed that the bright regions are young — some less than 2 million years old; it also found that the geologic activity driving these deposits could be ongoing. This conclusion depended on scientists making a key discovery: salt compounds (sodium chloride chemically bound with water and ammonium chloride) concentrated in Cerealia Facula.

On Ceres’ surface, salts bearing water quickly dehydrate, within hundreds of years. But Dawn’s measurements show they still have water, so the fluids must have reached the surface very recently. This is evidence both for the presence of liquid below the region of Occator Crater and ongoing transfer of material from the deep interior to the surface.

The scientists found two main pathways that allow liquids to reach the surface. “For the large deposit at Cerealia Facula, the bulk of the salts were supplied from a slushy area just beneath the surface that was melted by the heat of the impact that formed the crater about 20 million years ago,” said Dawn Principal Investigator Carol Raymond. “The impact heat subsided after a few million years; however, the impact also created large fractures that could reach the deep, long-lived reservoir, allowing brine to continue percolating to the surface.”

Active Geology: Recent and Unusual

In our solar system, icy geologic activity happens mainly on icy moons, where it is driven by their gravitational interactions with their planets. But that’s not the case with the movement of brines to the surface of Ceres, suggesting that other large ice-rich bodies that are not moons could also be active.

Some evidence of recent liquids in Occator Crater comes from the bright deposits, but other clues come from an assortment of interesting conical hills reminiscent of Earth’s pingos — small ice mountains in polar regions formed by frozen pressurized groundwater. Such features have been spotted on Mars, but the discovery of them on Ceres marks the first time they’ve been observed on a dwarf planet.

On a larger scale, scientists were able to map the density of Ceres’ crust structure as a function of depth — a first for an ice-rich planetary body. Using gravity measurements, they found Ceres’ crustal density increases significantly with depth, way beyond the simple effect of pressure. Researchers inferred that at the same time Ceres’ reservoir is freezing, salt and mud are incorporating into the lower part of the crust.

Dawn is the only spacecraft ever to orbit two extraterrestrial destinations — Ceres and the giant asteroid Vesta — thanks to its efficient ion propulsion system. When Dawn used the last of a key fuel, hydrazine, for a system that controls its orientation, it was neither able to point to Earth for communications nor to point its solar arrays at the Sun to produce electrical power. Because Ceres was found to have organic materials on its surface and liquid below the surface, planetary protection rules required Dawn to be placed in a long-duration orbit that will prevent it from impacting the dwarf planet for decades.

JPL, a division of Caltech in Pasadena, California, manages Dawn’s mission for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. JPL is responsible for overall Dawn mission science. Northrop Grumman in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team.

For a complete list of mission participants, visit:

https://solarsystem.nasa.gov/missions/dawn/overview/

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Ammonia sparks unexpected, exotic lightning on Jupiter

NASA’s Juno spacecraft — orbiting and closely observing the planet Jupiter — has unexpectedly discovered lightning in the planet’s upper atmosphere, according to a multi-institutional study led by the NASA/Jet Propulsion Laboratory (JPL), which includes two Cornell University researchers.

The work was published Aug. 5 in the journal Nature.

Jupiter’s gaseous atmosphere seems placid from a distance, but up close the clouds roil in a turbulent, chemically dynamic realm. As scientists have probed the opaque surface with Juno’s sensitive instrumentation, they’ve learned that Jupiter’s lightning occurs not only deep within the water clouds but also in shallow atmospheric regions (at high altitudes with lower pressure) that feature clouds of ammonia mixed with water.

“On the night side of Jupiter, you see fairly frequent flashes — as if you were above an active thunderstorm on Earth,” said Jonathan I. Lunine, the David C. Duncan Professor in the Physical Sciences and chair of the Department of Astronomy in the College of Arts and Sciences at Cornell University. “You get these tall columns and anvils of clouds, and the lightning is going continuously. We can get some pretty substantial lightning here on Earth, and the same is true for Jupiter.”

The research, “Small Lightning Flashes From Shallow Electrical Storms on Jupiter,” was directed by Heidi N. Becker, the Radiation Monitoring Investigation lead of NASA’s Juno mission. Lunine and doctoral candidate Youry Aglyamov were the two Cornell co-authors in the study.

Previous missions to Jupiter — such as Voyager 1, Galileo and New Horizons — had all observed lightning. But thanks to Juno’s Stellar Reference Unit, a camera designed to detect dim sources of light, the spacecraft’s close observational distance and instrument sensitivity enabled lightning detection at a higher resolution than previously possible.

Ammonia is the key. While there is water and other chemical elements such as molecular hydrogen and helium in Jupiter’s clouds, ammonia is the “antifreeze” that keeps water in those upper atmospheric clouds from freezing entirely.

Lunine notes Aglyamov’s ongoing dissertation work focuses on how lightning is generated under these conditions. The collision of the falling droplets of mixed ammonia and water with suspended water-ice particles constitutes a way to separate charge and produce cloud electrification — resulting in lightning storms in the upper atmosphere.

“The shallow lightning really points to the role of ammonia, and Youry’s models are starting to confirm this,” Lunine said. “This would be unlike any process that occurs on Earth.”

Jupiter’s wild gaseous world fascinates Aglyamov.

“Giant planets in general are a fundamentally different kind of world from Earth and other terrestrial planets,” he said. “There are hydrogen seas transitioning gradually into skies stacked with cloud decks, weather systems the size of the Earth and who-knows-what in the interior.”

The discovery of shallow lightning on Jupiter shifts our understanding of the planet, Aglyamov said.

“Shallow lightning hadn’t really been expected and indicates that there’s an unexpected process causing it,” he said. “It’s one more way in which Juno’s observations show a much more complex atmosphere of Jupiter than had been predicted. We know enough now to ask the right questions about processes going on there, but as Juno shows, we’re in a stage where every answer also tends to multiply the questions.”

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Surprising number of exoplanets could host life

Our solar system has one habitable planet — Earth. A new study shows other stars could have as many as seven Earth-like planets in the absence of a gas giant like Jupiter.

This is the conclusion of a study led by UC Riverside astrobiologist Stephen Kane published this week in the Astronomical Journal.

The search for life in outer space is typically focused on what scientists call the “habitable zone,” which is the area around a star in which an orbiting planet could have liquid water oceans — a condition for life as we know it.

Kane had been studying a nearby solar system called Trappist-1, which has three Earth-like planets in its habitable zone.

“This made me wonder about the maximum number of habitable planets it’s possible for a star to have, and why our star only has one,” Kane said. “It didn’t seem fair!”

His team created a model system in which they simulated planets of various sizes orbiting their stars. An algorithm accounted for gravitational forces and helped test how the planets interacted with each other over millions of years.

They found it is possible for some stars to support as many as seven, and that a star like our sun could potentially support six planets with liquid water.

“More than seven, and the planets become too close to each other and destabilize each other’s orbits,” Kane said.

Why then does our solar system only have one habitable planet if it is capable of supporting six? It helps if the planets’ movement is circular rather than oval or irregular, minimizing any close contact and maintain stable orbits.

Kane also suspects Jupiter, which has a mass two-and-a-half times that of all the other planets in the solar system combined, limited our system’s habitability.

“It has a big effect on the habitability of our solar system because it’s massive and disturbs other orbits,” Kane said.

Only a handful of stars are known to have multiple planets in their habitable zones. Moving forward, Kane plans to search for additional stars surrounded entirely by smaller planets. These stars will be prime targets for direct imaging with NASA telescopes like the one at Jet Propulsion Laboratory’s Habitable Exoplanet Observatory.

Kane’s study identified one such star, Beta CVn, which is relatively close by at 27 light years away. Because it doesn’t have a Jupiter-like planet, it will be included as one of the stars checked for multiple habitable zone planets.

Future studies will also involve the creation of new models that examine the atmospheric chemistry of habitable zone planets in other star systems.

Projects like these offer more than new avenues in the search for life in outer space. They also offer scientists insight into forces that might change life on our own planet one day.

“Although we know Earth has been habitable for most of its history, many questions remain regarding how these favorable conditions evolved with time, and the specific drivers behind those changes,” Kane said. “By measuring the properties of exoplanets whose evolutionary pathways may be similar to our own, we gain a preview into the past and future of this planet — and what we must do to main its habitability.”

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Mars 2020 Perseverance Rover Mission to Red Planet successfully launched

NASA’s Mars 2020 Perseverance rover mission is on its way to the Red Planet to search for signs of ancient life and collect samples to send back to Earth.

Humanity’s most sophisticated rover launched with the Ingenuity Mars Helicopter at 7:50 a.m. EDT (4:50 a.m. PDT) Friday on a United Launch Alliance (ULA) Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida.

“With the launch of Perseverance, we begin another historic mission of exploration,” said NASA Administrator Jim Bridenstine. “This amazing explorer’s journey has already required the very best from all of us to get it to launch through these challenging times. Now we can look forward to its incredible science and to bringing samples of Mars home even as we advance human missions to the Red Planet. As a mission, as an agency, and as a country, we will persevere.”

The ULA Atlas V’s Centaur upper stage initially placed the Mars 2020 spacecraft into a parking orbit around Earth. The engine fired for a second time and the spacecraft separated from the Centaur as expected. Navigation data indicate the spacecraft is perfectly on course to Mars.

Mars 2020 sent its first signal to ground controllers viaNASA’s Deep Space Networkat 9:15 a.m. EDT (6:15 a.m. PDT). However, telemetry (more detailed spacecraft data) had not yet been acquired at that point. Around 11:30 a.m. EDT (8:30 a.m. PDT), a signal with telemetry was received from Mars 2020 by NASA ground stations. Data indicate the spacecraft had entered a state known as safe mode, likely because a part of the spacecraft was a little colder than expected while Mars 2020 was in Earth’s shadow. All temperatures are now nominal and the spacecraft is out of Earth’s shadow.

When a spacecraft enters safe mode, all but essential systems are turned off until it receives new commands from mission control. An interplanetary launch is fast-paced and dynamic, so a spacecraft is designed to put itself in safe mode if its onboard computer perceives conditions are not within its preset parameters. Right now, the Mars 2020 mission is completing a full health assessment on the spacecraft and is working to return the spacecraft to a nominal configuration for its journey to Mars.

The Perseverance rover’s astrobiology mission is to seek out signs of past microscopic life on Mars, explore the diverse geology of its landing site,Jezero Crater, and demonstrate key technologies that will help us prepare for future robotic and human exploration.

“Jezero Crater is the perfect place to search for signs of ancient life,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at the agency’s headquarters in Washington. “Perseverance is going to make discoveries that cause us to rethink our questions about what Mars was like and how we understand it today. As our instruments investigate rocks along an ancient lake bottom and select samples to return to Earth, we may very well be reaching back in time to get the information scientists need to say that life has existed elsewhere in the universe.”

The Martian rock and dust Perseverance’s Sample Caching System collects could answer fundamental questions about the potential for life to exist beyond Earth. Two future missions currently under consideration by NASA, in collaboration with ESA (European Space Agency), will work together to get the samples to an orbiter for return to Earth. When they arrive on Earth, the Mars samples will undergo in-depth analysis by scientists around the world using equipment far too large to send to the Red Planet.

An Eye to a Martian Tomorrow

While most of Perseverance’s seven instruments are geared toward learning more about the planet’s geology and astrobiology, the MOXIE (Mars Oxygen In-Situ Resource Utilization Experiment) instrument’s job is focused on missions yet to come. Designed to demonstrate that converting Martian carbon dioxide into oxygen is possible, it could lead to future versions of MOXIE technology that become staples on Mars missions, providing oxygen for rocket fuel and breathable air.

Also future-leaning is the Ingenuity Mars Helicopter, which will remain attached to the belly of Perseverance for the flight to Mars and the first 60 or so days on the surface. A technology demonstrator, Ingenuity’s goal is a pure flight test — it carries no science instruments.

Over 30 sols (31 Earth days), the helicopter will attempt up to five powered, controlled flights. The data acquired during these flight tests will help the next generation of Mars helicopters provide an aerial dimension to Mars explorations — potentially scouting for rovers and human crews, transporting small payloads, or investigating difficult-to-reach destinations.

The rover’s technologies for entry, descent, and landing also will provide information to advance future human missions to Mars.

“Perseverance is the most capable rover in history because it is standing on the shoulders of our pioneers Sojourner, Spirit, Opportunity, and Curiosity,” said Michael Watkins, director of NASA’s Jet Propulsion Laboratory in Southern California. “In the same way, the descendants of Ingenuity and MOXIE will become valuable tools for future explorers to the Red Planet and beyond.”

About seven cold, dark, unforgiving months of interplanetary space travel lay ahead for the mission — a fact never far from the mind of Mars 2020 project team.

“There is still a lot of road between us and Mars,” said John McNamee, Mars 2020 project manager at JPL. “About 290 million miles of them. But if there was ever a team that could make it happen, it is this one. We are going to Jezero Crater. We will see you there Feb. 18, 2021.”

The Mars 2020 Perseverance mission is part of America’s larger Moon to Mars exploration approach that includes missions to the Moon as a way to prepare for human exploration of the Red Planet. Charged with sending the first woman and next man to the Moon by 2024, NASA will establish a sustained human presence on and around the Moon by 2028 through NASA’s Artemis program.

JPL, which is managed for NASA by Caltech in Pasadena, California, built and will manage operations of the Mars Perseverance rover. NASA’s Launch Services Program, based at the agency’s Kennedy Space Center in Florida, is responsible for launch management, and ULA provided the Atlas V rocket.

Learn more about the Mars 2020 mission at:

https://www.nasa.gov/mars2020

For more about America’s Moon to Mars exploration approach, visit:

https://nasa.gov/topics/moon-to-mars

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‘Lost’ world’s rediscovery is step towards finding habitable planets

The rediscovery of a lost planet could pave the way for the detection of a world within the habitable ‘Goldilocks zone’ in a distant solar system.

The planet, the size and mass of Saturn with an orbit of thirty-five days, is among hundreds of ‘lost’ worlds that University of Warwick astronomers are pioneering a new method to track down and characterise in the hope of finding cooler planets like those in our solar system, and even potentially habitable planets.

Reported in Astrophysical Journal Letters, the planet named NGTS-11b orbits a star 620 light years away and is located five times closer to its sun than Earth is to our own.

The planet was originally found in a search for planets in 2018 by the Warwick-led team using data from NASA’s TESS telescope. This uses the transit method to spot planets, scanning for the telltale dip in light from the star that indicates that an object has passed between the telescope and the star. However, TESS only scans most sections of the sky for 27 days. This means many of the longer period planets only transit once in the TESS data. And without a second observation the planet is effectively lost. The University of Warwick led team followed up one of these ‘lost’ planets using the telescopes at the Next-Generation Transit Survey (NGTS) in Chile and observed the star for seventy-nine nights, eventually catching the planet transiting for a second time nearly a year after the first detected transit.

Dr Samuel Gill from the Department of Physics at the University of Warwick said: “By chasing that second transit down we’ve found a longer period planet. It’s the first of hopefully many such finds pushing to longer periods.

“These discoveries are rare but important, since they allow us to find longer period planets than other astronomers are finding. Longer period planets are cooler, more like the planets in our own Solar System.

“NGTS-11b has a temperature of only 160°C — cooler than Mercury and Venus. Although this is still too hot to support life as we know it, it is closer to the Goldilocks zone than many previously discovered planets which typically have temperatures above 1000°C.”

The Goldilocks zone refers to a range of orbits that would allow a planet or moon to support liquid water: too close to its star and it will be too hot, but too far away and it will be too cold.

Co-author Dr Daniel Bayliss from the University of Warwick said: “This planet is out at a thirty-five days orbit, which is a much longer period than we usually find them. It is exciting to see the Goldilocks zone within our sights.”

Co-author Professor Pete Wheatley from the University of Warwick said: “The original transit appeared just once in the TESS data, and it was our team’s painstaking detective work that allowed us to find it again a year later with NGTS.

“NGTS has twelve state-of-the-art telescopes, which means that we can monitor multiple stars for months on end, searching for lost planets. The dip in light from the transit is only 1% deep and occurs only once every 35 days, putting it out of reach of other telescopes. “

Dr Gill adds: “There are hundreds of single transits detected by TESS that we will be monitoring using this method. This will allow us to discover cooler exoplanets of all sizes, including planets more like those in our own Solar System. Some of these will be small rocky planets in the Goldilocks zone that are cool enough to host liquid water oceans and potentially extraterrestrial life.”

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First measurement of spin-orbit alignment on planet Beta Pictoris b

Astronomers have made the first measurement of spin-orbit alignment for a distant ‘super-Jupiter’ planet, demonstrating a technique that could enable breakthroughs in the quest to understand how exoplanetary systems form and evolved.

An international team of scientists, led by Professor Stefan Kraus from the University of Exeter, has carried out the measurements for the exoplanet Beta Pictoris b — located 63 light years from Earth.

The planet, found in the Pictor constellation, has a mass of around 11 times that of Jupiter and orbits a young star on a similar orbit as Saturn in our solar system.

The study, published today (June 29th 2020) in the Astrophysical Journal Letters, marks the first time that scientists have measured the spin-orbit alignment for a directly-imaged planetary system.

Crucially, the results give a fresh insight into enhancing our understanding of the formation history and evolution of the planetary system.

Professor Kraus said: “The degree to that a star and a planetary orbit are aligned with each other tells us a lot about how a planet formed and whether multiple planets in the system interacted dynamically after their formation.”

Some of the earliest theories of the planet formation process were proposed by prominent 18th century astronomers Kant and Laplace. They noted that the orbits of the solar system planets are aligned with each other, and with the Sun’s spin axis, and concluded that the solar system formed from a rotating and flattened protoplanetary disc.

“It was a major surprise when it was found that more than a third of all close-in exoplanets orbit their host star on orbits that are misaligned with respect to the stellar equator.,” said Prof. Kraus.

“A few exoplanets were even found to orbit in the opposite direction than the rotation direction of the star. These observations challenge the perception of planet formation as a neat and well-ordered process taking place in a geometrically thin and co-planar disc.”

For the study, the researchers devised an innovative method that measures the tiny spatial displacement of less than a billionth of a degree that is caused by Beta Pictoris’ rotation.

The team used the GRAVITY instrument at the VLTI, which combines the light from telescopes separated 140 metres apart, to carry out the measurements. They found that the stellar rotation axis is aligned with the orbital axes of the planet Beta Pictoris b and its extended debris disc.

“Gas absorption in the stellar atmosphere causes a tiny spatial displacement in spectral lines that can be used to determine the orientation of the stellar rotation axis.,” said Dr. Jean-Baptiste LeBouquin, an astronomer at the University of Grenoble in France and a member of the team.

“The challenge is that this spatial displacement is extremely small: about 1/100th of the apparent diameter of the star, or the equivalent to the size of a human footstep on the moon as seen from Earth.”

The results show that the Beta Pictoris system is as well-aligned as our own solar system. This finding favors planet-planet scattering as the cause for the orbit obliquities that are observed in more exotic systems with Hot Jupiters.

However, observations on a large sample of planetary systems will be required to answer this question conclusively. The team proposes a new interferometric instrument that will allow them to obtain these measurements on many more planetary systems that are about to be discovered.

“A dedicated high-spectral resolution instrument at VLTI could measure the spin-orbit alignment for hundreds of planets, including those on long-period orbits.,” said Prof. Kraus, “This will help us to answer the question what dynamical processes shape the architecture of planetary systems.”

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Protecting Earth from asteroid impact with a tethered diversion

Our planet exists within the vicinity of thousands of Near-Earth Objects (NEOs), some of which — Potentially Hazardous Asteroids (PHAs) — carry the risk of impacting Earth causing major damage to infrastructure and loss of life. Methods to mitigate such a collision are highly desirable. A new paper published in EPJ Special Topics, authored by Flaviane Venditti, Planetary Radar Department, Arecibo Observatory, University of Central Florida, Arecibo, suggests the use of a tether assisted system to prevent PHA impact.

The method suggested by Venditti and her colleagues involves using the tether — previously suggested for other uses, such as space/lunar elevators and tethered satellite system — to connect the threatening PHA to another, smaller, asteroid, thus changing the centre of mass of the two and hopefully raising the PHA to a safer orbit.

Each potential PHA impact mitigation method carries with it, its own set of benefits and risks. A considerable risk associated with ‘high-impact’ mitigation techniques, such as the detonation of explosives at the surface of the PHA, is fragmentation. This makes methods which gradually alter the orbit of a PHA, and thus prevent the break up of such an object, look like a less risky prospect. The tether system carries with it little risk of causing fragmentation and smaller pieces of the PHA falling to earth, something which could itself cause widespread damage.

Using the asteroid Bennu as a test subject, the team used computer simulations to calculate the dynamics of such a tether system for a variety of different initial conditions, concluding that it would be feasible for use as a planetary defence system. The team also suggest that the system could be of use in both the study and potential mining of NEOs and other asteroids.

One of the likely drawbacks of such a method is the fact that it could require a longer lead time than many high impact methods which quickly deliver kinetic energy to a PHA to knock it out of orbit. Thus, the continued cataloguing of such objects is needed if such a method is ever to be viable.

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