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(3 August 2020 – NASA) As Carl Sagan famously said, “We’re made of star stuff” — but how do stars distribute their essential “stuff” for life into space? NASA’s telescope on an airplane, SOFIA, is finding some answers by watching pulsating stars as they expand and contract, almost like beating hearts.

The Stratospheric Observatory for Infrared Astronomy, SOFIA, examined several types of pulsating stars in our Milky Way galaxy, watching as some spewed carbon, a key ingredient of life as we know it, into interstellar space. Carbon is created deep inside stars through the process of helium fusion. As stars evolve, this carbon can get dredged up to the surface. But it must be forced into space for it to be available as a building block of life.

SOFIA found that some Mira stars, late-stage red giants with especially powerful pulsations, can drive strong stellar winds that eject carbon-rich gas and dust out into interstellar space. On the other hand, stars with much weaker pulsations called semiregular stars, can’t push the wind out as effectively. The Mira stars are therefore responsible for distributing large amounts of carbon into the universe. The research was published in the Astrophysical Journal.

Image of a carbon star known as CW Leonis or IRC+10216 taken by the Herschel Space Observatory. SOFIA found that some carbon stars with especially strong pulsations, called Mira variables, distribute large amounts of carbon to interstellar space where it can be used as a building block for life and other complex structures. (courtesy: ESA/PACS/SPIRE/ Consortia)

“We know that essential chemicals like carbon come from stars,” said Kathleen Kraemer, a scientist at Boston College and lead author of the study. “But these strong pulsations help explain how carbon moves away from stars to where it can evolve into more complex structures, which in the case of Earth, ultimately became DNA, proteins, and fats — life.”

Previous research observed pulsating stars in other galaxies, like the Large Magellanic Cloud, but this research provides new insights into carbon distribution in our own Milky Way galaxy. Understanding the source and delivery of organics in our galaxy is essential to Astrobiology, the study of the origin, evolution and distribution of life in the universe.

SOFIA is a Boeing 747SP jetliner modified to carry a 106-inch diameter telescope. It is a joint project of NASA and the German Aerospace Center, DLR. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart. The aircraft is maintained and operated from NASA’s Armstrong Flight Research Center Building 703, in Palmdale, California.

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Thales Alenia Space will provide the IRIS altimeter for the Copernicus CRISTAL mission

Thales Alenia Space will provide the IRIS altimeter for the

(21 September 2020 – Thales) Thales Alenia Space has today signed a close to €88 million contract with Airbus Defence and Space, prime contractor of the satellite, to develop the two IRIS flight models (Interferometric Radar Altimeter for Ice and Snow) of the Copernicus polaR Ice and Snow Topography ALtimeter (CRISTAL) mission.

The CRISTAL mission is part of the expansion of the Copernicus Space Component programme of the European Space Agency, ESA, in partnership with the European Commission. The European Copernicus flagship programme provides Earth observation and in situ data and a broad range of services for environmental monitoring and protection, climate monitoring, natural disaster assessment to improve the quality of life of European citizens.

The CRISTAL satellite will carry, for the first-time, a dual-frequency Ku/Ka bands radar altimeter to measure and monitor sea-ice thickness and overlying snow depth. Measurements of sea-ice thickness will support maritime operations and they will help in the planning of activities in the polar regions. IRIS will also measure and monitor changes in the height of ice sheets and glaciers around the world, thanks to its interferometric radar mode. IRIS will significantly improve the measurement accuracy of its predecessor SIRAL-2 (a Ku band only altimeter on board ESA’s CryoSat-2 Earth Explorer mission) thanks to the dual frequency operation and by adding the measurement of sea surface height as part of the mission objectives. The CRISTAL global mission is essential to better understand and monitor Earth climate in a context of the rapid climate change.

CRISTAL (courtesy: Airbus Defence and Space)

Hervé Derrey, CEO of Thales Alenia Space declared: “By providing the IRIS altimeter onboard CRISTAL, Thales Alenia Space is pleased to contribute to improve the data already provided by SIRAL-2 on board Cryosat and ensure the continuity of ice monitoring. Polar regions have a real influence on patterns of global climate, thermohaline circulation, and the planetary energy balance. A long-term program to monitor Earth polar ice, ocean and snow topography is therefore of the utmost interest to both operational and scientific users of Arctic and Antarctic measurements.”

Marc-Henri Serre, VP Observation and Science domain, at Thales Alenia Space in France added: “Thales Alenia Space will bring all its expertise and long-standing heritage on space altimetry, and its flight proven heritage acquired with SIRAL-2 to serve this crucial mission to understand and monitor the climate”.

The IRIS altimeter is designed and it will be built from the legacy of several altimeter programs of the Thales Alenia Space product line, including SIRAL-2, Poseidon 4 on board Sentinel-6/Jason-CS, Alti-Ka on the CNES/ISRO satellite, and KaRIn on board the CNES/JPL SWOT satellite. Thales Alenia Space is also the first to have flown an interferometric SAR altimeter (SIRAL) offering a unique expertise in interferometric radar electronics and interferometric antennas.

About industrial contributions for CRISTAL

Thales Alenia Space in France is prime of the IRIS altimeter, with contribution from Thales Alenia Space in Belgium for the Ku and Ka band Solid State Power Amplifiers power supply, Thales Alenia Space in Italy for the Ultra stable Oscillator. Thales Alenia Space in Spain will provide the S-Band transponder (SBT) of the CRISTAL satellite.

Thales Alenia Space: world leader in space altimetry

Thales Alenia Space is a world leader in space altimetry, a technique that lets us study sea surface height, sea ice thickness and river and lake levels, as well as land, ice sheet and seabed topography. The company has provided a whole host of instruments for oceanography, like the Poseidon altimeters on the Topex-Poseidon and Jason 1, 2 and 3 missions for the CNES. Thales Alenia Space also built the AltiKa Ka-band altimeter for the French-Indian SARAL oceanography satellite, and the SIRAL 2 very-high-resolution SAR (synthetic aperture radar) altimeter on ESA’s Cryosat-2 satellite, capable of measuring variations in sea ice thickness and continental ice mass balance with unprecedented accuracy. In addition, Thales Alenia Space supply the SRAL SAR altimeters for Sentinel-3, the SWIM altimeter on the CFOSat satellite for CNES, which measures wave spectra, and the SADKO altimeters on Russia’s GEO-IK satellites.

About Thales Alenia Space

Drawing on over 40 years of experience and a unique combination of skills, expertise and cultures, Thales Alenia Space delivers cost-effective solutions for telecommunications, navigation, Earth observation, environmental management, exploration, science and orbital infrastructures. Governments and private industry alike count on Thales Alenia Space to design satellite-based systems that provide anytime, anywhere connections and positioning, monitor our planet, enhance management of its resources, and explore our Solar System and beyond. Thales Alenia Space sees space as a new horizon, helping to build a better, more sustainable life on Earth. A joint venture between Thales (67%) and Leonardo (33%), Thales Alenia Space also teams up with Telespazio to form the parent companies’ Space Alliance, which offers a complete range of services. Thales Alenia Space posted consolidated revenues of approximately 2.15 billion euros in 2019 and has around 7,700 employees in nine countries.

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Plans underway for new polar ice and snow topography mission

Plans underway for new polar ice and snow topography mission

(21 September 2020 – ESA) Monitoring the cryosphere is essential to fully assess, predict and adapt to climate variability and change. Given the importance of this fragile component of the Earth system, today ESA, along with Airbus Defence and Space and Thales Alenia Space, have signed a contract to develop the Copernicus Polar Ice and Snow Topography Altimeter mission, known as CRISTAL.

Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) mission (courtesy: Airbus)

With a launch planned in 2027, the CRISTAL mission will carry, for the first time on a polar mission, a dual-frequency radar altimeter, and microwave radiometer, that will measure and monitor sea-ice thickness, overlying snow depth and ice-sheet elevations.

These data will support maritime operations in the polar oceans and contribute to a better understanding of climate processes. CRISTAL will also support applications related to coastal and inland waters, as well as providing observations of ocean topography.

The mission will ensure the long-term continuation of radar altimetry ice elevation and topographic change records, following on from previous missions such as ESA’s Earth Explorer CryoSat mission and other heritage missions.

With a contract secured worth € 300 million, Airbus Defence and Space has been selected to develop and build the new CRISTAL mission, while Thales Alenia Space has been chosen as the prime contractor to develop its Interferometric Radar Altimeter for Ice and Snow (IRIS).

ESA’s Director of Earth Observation Programmes, Josef Aschbacher, says, “I am extremely pleased to have the contract signed so we can continue the development of this crucial mission. It will be critical in monitoring climate indicators, including the variability of Arctic sea ice, and ice sheet and ice cap melting.”

The contract for CRISTAL is the second out of the six new high-priority candidate missions to be signed – after the Copernicus Carbon Dioxide Monitoring mission (CO2M) in late-July. The CRISTAL mission is part of the expansion of the Copernicus Space Component programme of ESA, in partnership with the European Commission.

The European Copernicus flagship programme provides Earth observation and in situ data, as well as a broad range of services for environmental monitoring and protection, climate monitoring and natural disaster assessment to improve the quality of life of European citizens.

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Astronomers solve mystery of how planetary nebulae are shaped

Astronomers solve mystery of how planetary nebulae are shaped

(17 September 2020 – Center for Astrophysics | Harvard & Smithsonian) Following extensive observations of stellar winds around cool evolved stars scientists have figured out how planetary nebulae get their mesmerizing shapes.

The findings, published in Science, contradict common consensus, and show that not only are stellar winds aspherical, but they also share similarities with planetary nebulae.

Gallery of stellar winds around cool aging stars, showing a variety of morphologies, including disks, cones, and spirals. The blue color represents material that is coming towards you, red is material that is moving away from you. Image 8, in particular, shows the stellar wind of R Aquilae, which resembles the structure of rose petals. (courtesy: L. Decin, ESO/ALMA)

An international team of astronomers focused their observations on stellar winds—particle flows—around cool red giant stars, also known as asymptotic giant branch (AGB) stars. “AGB stars are cool luminous evolved stars that are in the last stages of evolution just before turning into a planetary nebula,” said Carl Gottlieb, an astronomer at the Center for Astrophysics | Harvard & Smithsonian, and a co-author on the paper. “Through their winds, AGB stars contribute about 85% of the gas and 35% of the dust from stellar sources to the Galactic Interstellar Medium and are the dominant suppliers of pristine building blocks of interstellar material from which planets are ultimately formed.”

Despite being of major interest to astronomers, a large, detailed collection of observational data for the stellar winds surrounding AGB stars—each made using the exact same method—was lacking prior to the study, which resulted in a long-standing scientific misconception: that stellar winds have an overall spherical symmetry. “The lack of such detailed observational data caused us to initially assume that the stellar winds have an overall spherical geometry, much like the stars they surround,” said Gottlieb. “Our new observational data shapes a much different story of individual stars, how they live, and how they die. We now have an unprecedented view of how stars like our Sun will evolve during the last stages of their evolution.”

Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile revealed something strange: the shape of the stellar winds didn’t conform with scientific consensus. “We noticed these winds are anything but round,” said Professor Leen Decin of KU Leuven University in Belgium, and the lead author on the paper. “Some of them are actually quite similar to planetary nebulae.” The new findings may have a significant impact on calculations of galactic and stellar evolution, most pointedly for the evolution of Sun-like stars. “Our findings change a lot,” said Decin. “Since the complexity of stellar winds was not accounted for in the past, any previous estimate of the mass-loss rate of old stars could be wrong by up to a factor of 10.”

The observations revealed many different shapes, further connecting stellar wind formation to that of planetary nebulae. “The winds we observed exhibit various shapes that are similar to planetary nebulae,” said Gottlieb. “Some are disk-like, while others are shaped like eyes, spiral structures, and even arcs.”

Astronomers quickly realized that the shapes weren’t formed randomly, and that companions—low-mass stars and heavy planets—in the vicinity of the AGB stars were influencing the shapes and patterns. “Just like a spoon that you stir in a cup of coffee with some milk can create a spiral pattern, the companion sucks material towards it as it revolves around the star and shapes the stellar wind,” said Decin. “All of our observations can be explained by the fact that the stars have a companion.”

In addition, the study provides a strong foundation for understanding Sun-like stars and the future of the Sun itself. “In about five billion years, the Sun will become more luminous,” said Gottlieb. “Its radius will expand to a length that is comparable to the current distance between the Sun and Earth, and it will enter the AGB phase.” Decin added, “Jupiter or even Saturn—because they have such a big mass—are going to influence whether the Sun spends its last millennia at the heart of a spiral, a butterfly or any of the other entrancing shapes we see in planetary nebulae today. Our current simulations predict that Jupiter and Saturn will create a weak spiral structure in the wind of the Sun once it is an AGB star.”

About Center for Astrophysics | Harvard & Smithsonian

Headquartered in Cambridge, Mass., the Center for Astrophysics | Harvard & Smithsonian (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

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