Letters of Intent for 2015

LoI 2015-221
Focus Meeting: Search for water and life's building blocks in the universe

Date: 3 August 2015 to 6 August 2015
Location: Honolulu, United States
Contact: Sun Kwok (sunkwok@hku.hk)
Coordinating division: Division F Planetary Systems and Bioastronomy
Co-Chairs of SOC: Sun Kwok (University of Hong Kong)
Pascale Ehrenfreund (FWF)
Chair of LOC: ()



*water in the early solar system
*aqueous processes
*water in comets and asteroids
*water on the moon and Mercury
*water on Mars
*water in exoplanetary systems
*water in interstellar clouds and circumstellar envelopes
*synthesis of organic matter in stars and in the interstellar medium
*organic chemistry in the solar nebula
*external delivery of water and organics to Earth
implications on the origin of life on Earth



Water ice seems universal in space and is by far the most abundant condensed-phase species in our universe. It is an essential element for terrestrial life and was observed by numerous ground and space based observations. The Atacama Large Millimeter/submillimeter Array (ALMA) provided evidence for water in the most distant galaxies indicating that water was already present in the early universe. Ultrathin water-rich icy layers cover dust particles within the cold regions of the interstellar medium. Molecular ices are also widespread in the solar system. They cover the poles of terrestrial planets (e.g. Earth, Mars) and most of the outer-solar-system satellites. Smaller solar system bodies, such as comets and Kuiper Belt Objects (KBOs), contain a significant fraction of water ice. Icy particles are also present in planetary atmospheres and play an important role in determining the climate and the environmental conditions on our host planet, Earth. Beneath the ice crust of several moons of Jupiter and Saturn liquid water oceans probably exist. Water represents a crucial solvent for life and prebiotic molecules. Habitability and the origin of life on Earth seem strongly connected to the presence of water. All terrestrial life requires liquid water during some stage of life. Water is characterized by a large heat capacity, high surface tension and is an excellent solvent. D/H ratio of CI chondrites from the outer asteroid belt and from new short-period comet data suggest that these two reservoirs are the principal source of Earth’s water.

Additional to water two more requirements for life as we know it are organic compounds and free energy. Carbon is a key element in the evolution of prebiotic material. Our understanding of the evolution of organic molecules and their journey from molecular clouds to the early solar system and Earth provides important constraints on the emergence of life on Earth and possibly elsewhere. Astronomical observations have shown that carbonaceous matter is ubiquitous in our own as well as distant galaxies and a significant number of molecules that are used in contemporary biochemistry on Earth are found in interstellar and circumstellar regions as well as protoplanetary environments. Currently ~ 180 molecules have been detected in the interstellar and circumstellar gas. Circumstellar envelopes, regarded as the largest factories of carbon chemistry in space, are where small carbon compounds are converted to larger species and into solid organic compounds with mixed aromatic/aliphatic structures. During the formation of the solar system, this interstellar organic material was chemically processed and later integrated in the presolar nebula from which planets and small solar system bodies formed. The remnant planetesimals in the form of comets and asteroids impacted the young planets in the early history of the solar system. The large quantities of extraterrestrial material delivered to young planetary surfaces may have played an important role in life’s origin. Comets, asteroids and their fragments, meteorites are therefore witnesses of the evolving carbon chemistry in space and the processes prevailing at the origin of our solar system.

Several nations are currently engaging in, or planning for, space exploration programs that target the Moon, Mars and near-Earth asteroids, and propose voyages of exploration for robots and humans alike. These journeys seek answers on the origins and evolution of our solar system and life. Europa, Enceladus, and Titan are central objects in the research field of astrobiology representing modern habitats in the outer solar system with conditions that may favor complex organic chemistry and possible life.

Life on Earth is one of the outcomes of the formation and evolution of our solar system and has adapted to every possible environment on planet Earth. Primitive life, in the form of bacteria, emerged approximately 3.5 billion years ago. Despite the original hostile conditions planet Earth was habitable in its early history. All terrestrial planets have been seeded with organic compounds through the impact of small bodies during solar system formation. High molecular diversity and exciting new results concerning the analysis of prebiotic compounds in carbonaceous meteorites thrive the importance to analyse pristine returned samples from asteroids. The question of how life originated on the Earth and whether it exists elsewhere in our solar system has captured human imagination for centuries.

This meeting should bring different communities together to discuss water and organic compounds in the early and current solar system and in exoplanetary systems, and its connections to astrobiology,