![Page 1: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/1.jpg)
Detection of Water ice and Organic Molecules on Asteroids
Humberto Campins- University of Central Florida- Instituto Astrofísica de Canarias, Spain- Observatoire de la Côte d’Azur, France
UCF College of Science Dec. 3, 2010
![Page 2: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/2.jpg)
Ice and Organics on Asteroids: 24 Themis & 65 Cybele
Accepted Sept. 9, 2010
![Page 3: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/3.jpg)
I. Asteroids and the Early Solar System
II. Detection of Water-Ice and Organic Molecules on 24 Themis & 65 Cybele
III. Implications on Origin of Earth’s Water & Life
IV. Conclusions
Outline
![Page 4: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/4.jpg)
V. Conclusions Water-ice and organic molecules detected on two
asteroids so far: 24 Themis and 65 Cybele
Water more abundant on asteroids than expected
Supports proposed asteroidal origin of Earth’s water and organic molecules
Helps understand origin and evolution of life on Earth and possibility of Earth-like planets around other stars
Helps case for NASA’s OSIRIS-Rex mission
![Page 5: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/5.jpg)
I. Asteroids and the Early Solar System
• Planets, asteroids & comets formed from Solar Nebula 4.6 billon years ago
• Planets were transformed extensively • Asteroids & comets are “cosmic fossils” preserving
clues about early solar system
![Page 6: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/6.jpg)
Asteroids and comets accreted at different distances from the Sun
Asteroids: more rock
Comets: more ice
![Page 7: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/7.jpg)
Asteroid Belt
![Page 8: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/8.jpg)
Asteroid Belt
24 Themis
65 Cybele
![Page 9: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/9.jpg)
Largest fragment of a family (~ 2.5 By old) Orbiting near 3.2 AU Diameter ~ 198 km Dark (reflects only 7% of light) Rotation period: 8.4 h
I. Introduction: 24 Themis
![Page 10: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/10.jpg)
Largest of group between 3.3 & 3.7 AU Orbiting near 3.4 AU Diameter ~ 273 km Dark (reflects only 7% of light) Rotation period: 4.0 h
I. Introduction: 65 Cybele
![Page 11: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/11.jpg)
• Themis asteroid family resulted from a large collision and contains two small members that behave like comets
I. Introduction: Themis Family
Elst-Pizarro
176P/Linear
![Page 12: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/12.jpg)
Orbits of the two Themis-family active asteroids not likely to evolve from comets
Spectra of both Themis-family MBCs resemble those of the larger family members and not those of comets
These small asteroids are true members of the Themis family; hence, this family probably contains water-ice
I. Introduction: Themis Family
![Page 13: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/13.jpg)
Infrared Spectra over 7 hours (84% of rotation period)
II. Detection of Water-Ice and Organic Molecules on 24 Themis & 65 Cybele:Rotationally Resolved Observations of 24 Themis
![Page 14: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/14.jpg)
Rotationally Resolved Observations: Ice widespread on 24 Themis
Ice
Infrared Spectra over 7 hours (84% of rotation period)
![Page 15: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/15.jpg)
Something is missing !!!
![Page 16: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/16.jpg)
Something is missing !!!
School of Astronomical Potions
![Page 17: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/17.jpg)
ORGANICS: the missing ingredient
A 5% of “Ice Tholin” added to the mixture of water ice and anhydrous silicate works best!
![Page 18: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/18.jpg)
A 5% of “Ice Tholin” added to the mixture of water ice and anhydrous silicate works best!
ORGANICS: the missing ingredient
![Page 19: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/19.jpg)
Spectra of 24 Themis and 65 Cybele Very Similar
![Page 20: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/20.jpg)
Spectra of 24 Themis and 65 Cybele Very Similar
Ice
![Page 21: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/21.jpg)
Spectra of 24 Themis and 65 Cybele Very Similar
Organics
![Page 22: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/22.jpg)
3.2 3.3 3.4 3.5 3.6
3.2 3.3 3.4 3.5 3.6 wavelength (m)
Exact Composition of Organics is Uncertain:3.4-micron absorption is produced by C-H bond
![Page 23: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/23.jpg)
IV. Implications on Origin of Earth’s Water and life
No Water in Early Earth and Mars
• The solids that formed in the accretion zones of Earth and Mars had a very low water content
• It has been suggested that most of Earth’s water came from asteroids and comets
• More specifically, Morbidelli et al. (2000) suggested Earth’s water came from a single impact with an object formed in the outer asteroid belt
![Page 24: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/24.jpg)
Water in Meteorites
Wet
Dry
![Page 25: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/25.jpg)
• If Earth formed dry where did its water come from?
• The composition of Earth’s water is consistent with asteroidal and cometary contributions
• Main evidence from Deuterium to Hydrogen isotopic ratios (D/H)
IV. (cont.)Implications on Origin of Earth’s Water and life
![Page 26: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/26.jpg)
D/H Ratios10-3
10-4
Earth Oceans
10-5
Solar Nebula
•HB •HY •HA
C Chondrites (H2O-rich meteorites)
Comets
![Page 27: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/27.jpg)
• Water-rich meteorites have the appropriate D/H ratio to be a source of Earth’s Water
• The few comets properly observed have D/H ratios higher than Earth, so comets may have contributed to raise the D/H from the Solar Nebula value
• Asteroids and comets likely brought Earth much of its water….. and more
IV. (cont.)Implications on Origin of Earth’s Water and life
![Page 28: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/28.jpg)
Surface of Early Earth was Molten Rock
IV. Implications on Origin of Earth’s Water and life
![Page 29: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/29.jpg)
• Magma Oceans probably destroyed any primordial organics on Earth
• Meteorites and Comets have significant amounts of organic molecules: – the most primitive meteorites are rich in amino
acids, and – about half of the cometary dust is organic
![Page 30: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/30.jpg)
• Hence, impacts with asteroids and comets, may have also contributed significantly to the organic molecule inventory of early Earth
• The discovery of water ice and organics on 24 Themis and 65 Cybele supports an asteroidal origin of at least some of Earth’s water and organic molecules
IV. Implications on Origin of Earth’s Water and life
![Page 31: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/31.jpg)
Yes, for example:
• 24 Themis is a B-type asteroid, so is near-Earth asteroid 1999RQ36 the target of NASA’s proposed asteroid sample return mission: OSIRIS-Rex
• Our results improve the chances that NASA will choose this mission for full development ($710 million) in June 2011
• UCF is a member of the OSIRIS-Rex team
Any Relevance to Near Earth Asteroids?
![Page 32: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/32.jpg)
V. Conclusions Water-ice and organic molecules detected on two
asteroids so far: 24 Themis and 65 Cybele
Water more abundant on asteroids than expected
Supports proposed asteroidal origin of Earth’s water and organic molecules
Helps understand origin and evolution of life on Earth and possibility of Earth-like planets around other stars
Helps case for NASA’s OSIRIS-Rex mission
![Page 33: Detection of Water ice and Organic Molecules on Asteroids](https://reader036.vdocuments.mx/reader036/viewer/2022062519/568152f0550346895dc10cac/html5/thumbnails/33.jpg)