Pascale Ehrenfreund | The George Washington University (original) (raw)

Papers by Pascale Ehrenfreund

Research paper thumbnail of Triple F—a comet nucleus sample return mission

Experimental Astronomy, 2009

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Research paper thumbnail of Small Grains and Large Aromatic Molecules

Chemistry in Space, 1990

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Research paper thumbnail of Solid State Infrared Features: a Diagnostic Tool for Chemical Interactions Between Interstellar Gas and Grains

ESO Astrophysics Symposia, 1996

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Research paper thumbnail of Infrared Properties of Isolated Water Ice

ESO Astrophysics Symposia, 1996

... 969C 969~ ~69~ 9coL~ 8OL~ LOL~ czL~ £9ZL~ Z~L~ (8HOTD)ooc:o~:T=oD:SHOTD:oZH (oD)ooc:o~:1=oD:S... more ... 969C 969~ ~69~ 9coL~ 8OL~ LOL~ czL~ £9ZL~ Z~L~ (8HOTD)ooc:o~:T=oD:SHOTD:oZH (oD)ooc:o~:1=oD:SHOTD:oZH o~:1=8HoTD:ozH 00j:J=Z03:0Z1~1 oI:oT:c~:ct:1=zoJ:zN:zo:oJ: ozH T:cT:c~:oc:I=~oJ:zN:zo:oJ:ozH oz:Ot':ot':T=ZN:ZO:OD:OZH 09:OZ:T=Zo:OJ:OZII oc:oc:I=zo ...

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Research paper thumbnail of Responsible Space Exploration and Use: Balancing Stakeholder Interests

New Space, 2013

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Research paper thumbnail of An ISO View on Interstellar and Cometary Ice Chemistry

Composition and Origin of Cometary Materials, 1999

The ISO-SWS instrument offering a large wavelength coverage and a resolution well adapted to the ... more The ISO-SWS instrument offering a large wavelength coverage and a resolution well adapted to the solid phase has changed our knowledge of the physical-chemical properties of ices in space. The discovery of many new ice features was reported and the comparison with dedicated laboratory experiments allowed the determination of more accurate abundances of major ice components. The presence of CO2 ice has recently been confirmed with the SWS (Short Wavelength Spectrometer) as a dominant ice component of interstellar grain mantles. The bending mode of CO2 ice shows a particular triple-peak structure which provides first evidence for extensive ice segregation in the line-of-sight toward massive protostars. A comparison of interstellar and cometary ices using recent ISO data and ground-based measurements has revealed important similarities but also indicated that comets contain, beside pristine interstellar material, admixtures of processed material. The investigation of molecules in interstellar clouds is essential to reveal the link between dust in the interstellar medium and in the Solar System.

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Research paper thumbnail of Astrobiology --- A Bridge Between Earth Science and Space Exploration

Astrobiology, the study of life in the universe, addresses, as an interdisciplinary science field... more Astrobiology, the study of life in the universe, addresses, as an interdisciplinary science field, many questions that are relevant for sustaining life on planet Earth---and in particular, the relationships between a planet and life, and how each affects the other.

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Research paper thumbnail of Ice Chemistry in Space

Solid State Astrochemistry, 2003

Abstract In this chapter we review the current knowledge on ice chemistry in space. We describe t... more Abstract In this chapter we review the current knowledge on ice chemistry in space. We describe the basic processes of ice formation and destruction on interstellar grains and discuss the role of icy particles as catalysts in dense molecular clouds. In the following ...

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Research paper thumbnail of Window contamination on Expose-R

International Journal of Astrobiology, 2014

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Research paper thumbnail of SMART-1 Impact Ground-based campaign

Based on predictions of impact magnitude and cloud ejecta dynamics, we organized a SMART-1 ground... more Based on predictions of impact magnitude and cloud ejecta dynamics, we organized a SMART-1 ground-based observation campaign to perform coordinated measurements of the impact. Results from the coordinated multi-site campaign will be discussed.

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Research paper thumbnail of From Molecular Clouds to the Origin of Life

Astrobiology, 2002

Contents: The search for large organic molecules in dense clouds. Molecules in protoplanetary dis... more Contents: The search for large organic molecules in dense clouds. Molecules in protoplanetary disks. Diffuse interstellar clouds. The evolution of organic molecules during solar system formation. Implications for the origin of life on Earth.

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Research paper thumbnail of Biota and biomolecules in extreme environments on Earth: implications for life detection on Mars

Life (Basel, Switzerland), 2014

The three main requirements for life as we know it are the presence of organic compounds, liquid ... more The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids) occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to their indispensability for life on Earth, these biomarkers are also prime targets in the search for life on Mars. Biomarkers degrade over time; in situ environmental conditions influence the preservation of those molecules. Nonetheless, upon shielding (e.g., by mineral surfaces), particular biomarkers can persist for billions of years, making them of vital importance in answering questions about the origins and limits of life on early Earth and Mars. The search for organic material and biosignatures on Mars is particularly challenging due to the hostile environment and its effect on organic compounds near the surface. In support of life detect...

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Research paper thumbnail of Cosmic carbon chemistry: from the interstellar medium to the early Earth

Cold Spring Harbor perspectives in biology, 2010

Astronomical observations have shown that carbonaceous compounds in the gas and solid state, refr... more Astronomical observations have shown that carbonaceous compounds in the gas and solid state, refractory and icy are ubiquitous in our and distant galaxies. Interstellar molecular clouds and circumstellar envelopes are factories of complex molecular synthesis. A surprisingly large number of molecules that are used in contemporary biochemistry on Earth are found in the interstellar medium, planetary atmospheres and surfaces, comets, asteroids and meteorites, and interplanetary dust particles. In this article we review the current knowledge of abundant organic material in different space environments and investigate the connection between presolar and solar system material, based on observations of interstellar dust and gas, cometary volatiles, simulation experiments, and the analysis of extraterrestrial matter. Current challenges in astrochemistry are discussed and future research directions are proposed.

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Research paper thumbnail of Composition and Origin of Cometary Materials

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Research paper thumbnail of Circumstellar Variations and Microflaring in FK Comae Berenices: Time-Resolved Balmer Line Spectroscopy

We present results from the analysis of spectra of the fast rotating giant FK Comae Berenices, ob... more We present results from the analysis of spectra of the fast rotating giant FK Comae Berenices, obtained with the recently commissioned ESA-MUSICOS spectrograph at the INT and with the Aurelie spectrograph at the OHP. The Balmer lines broad emission is modelled as arising from structures extending up to 4 stellar radii. The absorption is modelled due to the presence of a shell of cold and dense gas (solar-like filaments), near the corotation radius, covering about 20% of the stellar disc. The extended emission is believed to arise in giant structures reminiscent of active loops or prominences. Time resolved Hα emission spectroscopy indicates that these structures undergo continuous microflaring. Based on data sets from May and November 1996 and May and June 1997, we describe different time scales for variability, from yearly rise of activity to hourly microflares. Based on observations with the ESA-MUSICOS spectrograph at the 2.5 m Isaac Newton Telescope, ING Observatory, Spain and w...

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Research paper thumbnail of Sampling Extreme Life in the Desert: Geochemical Habitats and Biodiversity

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Research paper thumbnail of Habitability in Mars Transient and Local environments: Field Analogue Sample Studies

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Research paper thumbnail of Interstellar Organic Molecules: from Clouds to Solar Nebula

Although laboratory experiments involving energetic processing of simple molecules were able to r... more Although laboratory experiments involving energetic processing of simple molecules were able to reproduce many of the biomolecules that are the building blocks of living organisms impacts of comets and asteroids could have delivered large amounts of organic matter to the early Earth. Volatile cometary matter appears to retain a significant interstellar signature; observations of recent bright comets indicate that they

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Research paper thumbnail of Reactivity Analyzer for Soil, Ices, and Regolith (RASIR)

ABSTRACT The Reactivity Analyzer for Soil, Ices, and Regolith (RASIR) is an integrated microanaly... more ABSTRACT The Reactivity Analyzer for Soil, Ices, and Regolith (RASIR) is an integrated microanalytical system designed to simultaneously measure the organic content and chemical reactivity/toxicity levels of martian surface samples.

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Research paper thumbnail of PEX's Role in Opening Up the Solar System for Scientific Exploration

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Research paper thumbnail of Triple F—a comet nucleus sample return mission

Experimental Astronomy, 2009

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Research paper thumbnail of Small Grains and Large Aromatic Molecules

Chemistry in Space, 1990

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Research paper thumbnail of Solid State Infrared Features: a Diagnostic Tool for Chemical Interactions Between Interstellar Gas and Grains

ESO Astrophysics Symposia, 1996

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Research paper thumbnail of Infrared Properties of Isolated Water Ice

ESO Astrophysics Symposia, 1996

... 969C 969~ ~69~ 9coL~ 8OL~ LOL~ czL~ £9ZL~ Z~L~ (8HOTD)ooc:o~:T=oD:SHOTD:oZH (oD)ooc:o~:1=oD:S... more ... 969C 969~ ~69~ 9coL~ 8OL~ LOL~ czL~ £9ZL~ Z~L~ (8HOTD)ooc:o~:T=oD:SHOTD:oZH (oD)ooc:o~:1=oD:SHOTD:oZH o~:1=8HoTD:ozH 00j:J=Z03:0Z1~1 oI:oT:c~:ct:1=zoJ:zN:zo:oJ: ozH T:cT:c~:oc:I=~oJ:zN:zo:oJ:ozH oz:Ot':ot':T=ZN:ZO:OD:OZH 09:OZ:T=Zo:OJ:OZII oc:oc:I=zo ...

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Research paper thumbnail of Responsible Space Exploration and Use: Balancing Stakeholder Interests

New Space, 2013

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Research paper thumbnail of An ISO View on Interstellar and Cometary Ice Chemistry

Composition and Origin of Cometary Materials, 1999

The ISO-SWS instrument offering a large wavelength coverage and a resolution well adapted to the ... more The ISO-SWS instrument offering a large wavelength coverage and a resolution well adapted to the solid phase has changed our knowledge of the physical-chemical properties of ices in space. The discovery of many new ice features was reported and the comparison with dedicated laboratory experiments allowed the determination of more accurate abundances of major ice components. The presence of CO2 ice has recently been confirmed with the SWS (Short Wavelength Spectrometer) as a dominant ice component of interstellar grain mantles. The bending mode of CO2 ice shows a particular triple-peak structure which provides first evidence for extensive ice segregation in the line-of-sight toward massive protostars. A comparison of interstellar and cometary ices using recent ISO data and ground-based measurements has revealed important similarities but also indicated that comets contain, beside pristine interstellar material, admixtures of processed material. The investigation of molecules in interstellar clouds is essential to reveal the link between dust in the interstellar medium and in the Solar System.

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Research paper thumbnail of Astrobiology --- A Bridge Between Earth Science and Space Exploration

Astrobiology, the study of life in the universe, addresses, as an interdisciplinary science field... more Astrobiology, the study of life in the universe, addresses, as an interdisciplinary science field, many questions that are relevant for sustaining life on planet Earth---and in particular, the relationships between a planet and life, and how each affects the other.

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Research paper thumbnail of Ice Chemistry in Space

Solid State Astrochemistry, 2003

Abstract In this chapter we review the current knowledge on ice chemistry in space. We describe t... more Abstract In this chapter we review the current knowledge on ice chemistry in space. We describe the basic processes of ice formation and destruction on interstellar grains and discuss the role of icy particles as catalysts in dense molecular clouds. In the following ...

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Research paper thumbnail of Window contamination on Expose-R

International Journal of Astrobiology, 2014

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Research paper thumbnail of SMART-1 Impact Ground-based campaign

Based on predictions of impact magnitude and cloud ejecta dynamics, we organized a SMART-1 ground... more Based on predictions of impact magnitude and cloud ejecta dynamics, we organized a SMART-1 ground-based observation campaign to perform coordinated measurements of the impact. Results from the coordinated multi-site campaign will be discussed.

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Research paper thumbnail of From Molecular Clouds to the Origin of Life

Astrobiology, 2002

Contents: The search for large organic molecules in dense clouds. Molecules in protoplanetary dis... more Contents: The search for large organic molecules in dense clouds. Molecules in protoplanetary disks. Diffuse interstellar clouds. The evolution of organic molecules during solar system formation. Implications for the origin of life on Earth.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Biota and biomolecules in extreme environments on Earth: implications for life detection on Mars

Life (Basel, Switzerland), 2014

The three main requirements for life as we know it are the presence of organic compounds, liquid ... more The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids) occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to their indispensability for life on Earth, these biomarkers are also prime targets in the search for life on Mars. Biomarkers degrade over time; in situ environmental conditions influence the preservation of those molecules. Nonetheless, upon shielding (e.g., by mineral surfaces), particular biomarkers can persist for billions of years, making them of vital importance in answering questions about the origins and limits of life on early Earth and Mars. The search for organic material and biosignatures on Mars is particularly challenging due to the hostile environment and its effect on organic compounds near the surface. In support of life detect...

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Research paper thumbnail of Cosmic carbon chemistry: from the interstellar medium to the early Earth

Cold Spring Harbor perspectives in biology, 2010

Astronomical observations have shown that carbonaceous compounds in the gas and solid state, refr... more Astronomical observations have shown that carbonaceous compounds in the gas and solid state, refractory and icy are ubiquitous in our and distant galaxies. Interstellar molecular clouds and circumstellar envelopes are factories of complex molecular synthesis. A surprisingly large number of molecules that are used in contemporary biochemistry on Earth are found in the interstellar medium, planetary atmospheres and surfaces, comets, asteroids and meteorites, and interplanetary dust particles. In this article we review the current knowledge of abundant organic material in different space environments and investigate the connection between presolar and solar system material, based on observations of interstellar dust and gas, cometary volatiles, simulation experiments, and the analysis of extraterrestrial matter. Current challenges in astrochemistry are discussed and future research directions are proposed.

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Research paper thumbnail of Composition and Origin of Cometary Materials

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Research paper thumbnail of Circumstellar Variations and Microflaring in FK Comae Berenices: Time-Resolved Balmer Line Spectroscopy

We present results from the analysis of spectra of the fast rotating giant FK Comae Berenices, ob... more We present results from the analysis of spectra of the fast rotating giant FK Comae Berenices, obtained with the recently commissioned ESA-MUSICOS spectrograph at the INT and with the Aurelie spectrograph at the OHP. The Balmer lines broad emission is modelled as arising from structures extending up to 4 stellar radii. The absorption is modelled due to the presence of a shell of cold and dense gas (solar-like filaments), near the corotation radius, covering about 20% of the stellar disc. The extended emission is believed to arise in giant structures reminiscent of active loops or prominences. Time resolved Hα emission spectroscopy indicates that these structures undergo continuous microflaring. Based on data sets from May and November 1996 and May and June 1997, we describe different time scales for variability, from yearly rise of activity to hourly microflares. Based on observations with the ESA-MUSICOS spectrograph at the 2.5 m Isaac Newton Telescope, ING Observatory, Spain and w...

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Research paper thumbnail of Sampling Extreme Life in the Desert: Geochemical Habitats and Biodiversity

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Habitability in Mars Transient and Local environments: Field Analogue Sample Studies

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Interstellar Organic Molecules: from Clouds to Solar Nebula

Although laboratory experiments involving energetic processing of simple molecules were able to r... more Although laboratory experiments involving energetic processing of simple molecules were able to reproduce many of the biomolecules that are the building blocks of living organisms impacts of comets and asteroids could have delivered large amounts of organic matter to the early Earth. Volatile cometary matter appears to retain a significant interstellar signature; observations of recent bright comets indicate that they

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Reactivity Analyzer for Soil, Ices, and Regolith (RASIR)

ABSTRACT The Reactivity Analyzer for Soil, Ices, and Regolith (RASIR) is an integrated microanaly... more ABSTRACT The Reactivity Analyzer for Soil, Ices, and Regolith (RASIR) is an integrated microanalytical system designed to simultaneously measure the organic content and chemical reactivity/toxicity levels of martian surface samples.

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Research paper thumbnail of PEX's Role in Opening Up the Solar System for Scientific Exploration

Bookmarks Related papers MentionsView impact