[ and carbonyl sulfide.[1] The mantles of interstellar ice grains are generally amorphous, only becoming crystalline in the presence of a star.[4]]The composition of interstellar ice can be determined through its infrared spectrum. As starlight passes through a molecular cloud containing ice, molecules in the cloud absorb energy. This adsorption occurs at the characteristic frequencies of vibration of the gas and dust. Ice features in the cloud are relatively prominently in this spectra, and the composition of the ice can be determined by comparison with samples of ice materials on Earth.[5] In the sites directly observable from Earth, around 60–70% of the interstellar ice consists of water, which displays a strong emission at 3.05 μm from stretching of the O–H bond.[1]
In September 2012, NASA scientists reported that polycyclic aromatic hydrocarbons (PAHs), subjected to interstellar medium (ISM) conditions, are transformed, through hydrogenation, oxygenation and hydroxylation, to more complex organics - "a step along the path toward amino acids and nucleotides, the raw materials of proteins and DNA, respectively".[1][2] Further, as a result of these transformations, the PAHs lose their spectroscopic signature which could be one of the reasons "for the lack of PAH detection in interstellar ice grains, particularly the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks."[1][2]
Older than the sun
Research published in the journal Science estimates that about 30–50% of the water in the solar system, like the water on Earth, the discs around Saturn, and the meteorites of other planets was already around even before the birth of the sun.[3]
Comet 67P/Churyumov–Gerasimenko {{anchor|Philae}}
On 18 November 2014, spacecraft Philae revealed presence of large amount of water ice on the comet 67P/Churyumov–Gerasimenko, the report stating that "the strength of the ice found under a layer of dust on the first landing site is surprisingly high". The team responsible for the MUPUS (Multi-Purpose Sensors for Surface and Sub-Surface Science) instrument, which hammered a probe into the comet, estimated that the comet is hard as ice. "Although the power of the hammer was gradually increased, we were not able to go deep into the surface," explained Tilman Spohn from the DLR Institute for Planetary Research, who led the research team.[4]
See also
- Amorphous ice
- Heavy water
References
1. ^1 {{cite web |authors=Staff |title=NASA Cooks Up Icy Organics to Mimic Life's Origins|url=http://www.space.com/17681-life-building-blocks-nasa-organic-molecules.html|date=September 20, 2012 |publisher=Space.com |accessdate=September 22, 2012 }}
2. ^1 {{cite journal |last1=Gudipati |first1=Murthy S. |last2=Yang |first2=Rui|title=In-Situ Probing Of Radiation-Induced Processing Of Organics In Astrophysical Ice Analogs—Novel Laser Desorption Laser Ionization Time-Of-Flight Mass Spectroscopic Studies|url=http://iopscience.iop.org/2041-8205/756/1/L24 |date=September 1, 2012 |journal=The Astrophysical Journal Letters |volume=756 |pages=L24 |number=1 |doi=10.1088/2041-8205/756/1/L24|accessdate=September 22, 2012 |bibcode = 2012ApJ...756L..24G }}
3. ^50% of Earth’s water older than the sun and came from interstellar ice, research says
4. ^Philae reveals presence of large amount of water ice on the comet
5. ^1 {{cite book | author=Pirronello, Valerio; Krełowski, Jacek; Manicò, Giulio; North Atlantic Treaty Organization. Scientific Affairs Division | title=Solid state astrochemistry | page=288 | volume=120 | series=NATO science series: Mathematics, physics, and chemistry | publisher=Springer | date=2003 | isbn=978-1-4020-1559-5 }}
6. ^1 {{cite book | author=Greenberg, J. Mayo | date=1991 | chapter=Interstellar Dust-Gas Relationships | page=58 | title=Cosmic rays, supernovae, and the interstellar medium | issue=337 | series=NATO ASI series: Mathematical and physical sciences | editors=Maurice Mandel Shapiro, Rein Silberberg, J. P. Wefel | publisher=Springer | isbn=978-0-7923-1278-9 }}
7. ^1 2 3 {{citation | display-authors=1 | last1=Gibb | first1=E. L. | last2=Whittet | first2=D. C. B. | last3=Boogert | first3=A. C. A. | last4=Tielens | first4=A. G. G. M. | title=eInterstellar Ice: The Infrared Space Observatory Legacy | journal=The Astrophysical Journal Supplement Series | volume=151 | issue=1 | pages=35–73 |date=March 2004 | doi=10.1086/381182 | bibcode=2004ApJS..151...35G }}