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SPECIAL TOPICS

Astrochemistry

April 2008
 

The baseline time span for this database is (publication years) 1997-2007 from the sixth bimonthly update (an 11-year period). The resulting database contained 989 (10 years) and 338 (2 years) papers; 2,510 authors; 49 nations; 138 journals; and 747 institutions.

Top 20 Papers

  10-year period
  2-year period

Top 20 Overall

  Authors
  Institutions
  Journals
  Nations

Research Front Map

  Extrasolar Planets
  Portable Genetic Analysis Microsystem

Time Series

  1- & 5-year periods

Field Distribution

Interviews

  Interviews, first-person essays, and profiles about people in a wide variety of fields which pertain to this special topic of Astrochemistry.
   

OVERVIEW

Astrobiology is the discipline that explores all aspects of the origin of life in the universe. One of the biggest challenges in astrobiology is the giant step from no life to some life. At the base of that towering cliff stand the astrochemists, who are charged with explaining the formation of organic molecules in interstellar space and the means by which those molecules can be delivered to planetary surfaces without being destroyed.

This month, Special Topics launches into space to check out progress in astrochemistry over the past decade and over the past two years. The key papers in this field involve a sequence of smaller steps. Fundamental data on the origin and abundance of the chemical elements lie at the base, followed by understanding formation mechanisms for hydrocarbon molecules in space. Molecules form in cold dense interstellar clouds, and the observation and identification of interstellar molecules continues apace. But an interstellar cloud cannot produce life as we know it, so the molecules have to be packaged and sent elsewhere.

The first stage of assembly is to condense the organics onto interstellar dust grains or to freeze them in interstellar ices. Either way, the next step is bulking up the dust into asteroids and meteorites, and accreting the ices into comets. Dust formation takes place in the envelopes of low-mass stars. In the final stages of star formation the gaseous and solid phases of the interstellar molecules lie in a disc from which small bodies and planets form.

The final stage of delivery is for the small bodies to bombard the planets. Life on Earth may have arisen after a cataclysmic event 3.9 billion years ago when asteroids and comets pounded the inner solar system. The craters on the Moon and elsewhere are the testimony to this assault.

Evidence of this scenario is sought in meteorites, the oldest solid objects you can hold in your hand. When asteroids hit Mars they expelled stones into planetary orbit, and some of these have landed on Earth, famously Martina meteorite ALH84001, which appears to have fossil bacterial structures. The development of instrumentation to detect biomarkers on Mars is a priority.

Methodology: To construct this database, papers were extracted based on topic-supplied keywords for Astrochemistry. The keywords used were as follows:

(astrobio* OR astrochem*)

The baseline time span for this database is (publication years) 1997-2007 from the sixth bimonthly update (an 11-year period). The resulting database contained 989 (10 years) and 338 (2 years) papers; 2,510 authors; 49 nations; 138 journals; and 747 institutions.

Rankings: Once the database was in place, it was used to generate the lists of top 20 papers (two- and ten-year periods), authors, journals, institutions, and nations, covering a time span of 1997-2007 (sixth bimonthly, an 11-year period).

The top 20 papers are ranked according to total cites. Rankings for author, journal, institution, and country are listed in three ways: according to total cites, total papers, and total cites/paper. The paper thresholds and corresponding percentages used to determine scientist, institution, country, and journal rankings according to total cites/paper, and total papers respectively are as follows:

Entity Authors Institutions Nations Journals
Thresholds 10 7 8 3
Percentage: 1% 10% 50% 20%


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