formed, and second, they are necessary to make estimates of the likelihood of 

 planet formation. Because of the clouds of dust obscuring star-forming regions, 

 protostellar observations must be made principally at far-infrared and longer 

 wavelengths. Studies of the far-infrared continuum and low-resolution spec- 

 troscopy will help determine the quantity and composition of material available 

 for the formation of planets. High-spectral- and high-spatial-resolution observa- 

 tions at submillimeter and far-infrared wavelengths are needed to identify the 

 molecules present in the gaseous state; these can be used to determine the nature 

 of the physical environment and to investigate the link between organic chemis- 

 try in the dense molecular protostellar clouds and the protostellar nebula. In 

 order for the far-infrared-continuum observations to be sufficiently sensitive, a 

 cryogenically cooled telescope must be employed. Of lesser importance, ultra- 

 violet studies of objects in the late stages of star formation, when the obscuring 

 dust clouds have been blown away, can yield information on the radiation envi- 

 ronment in planetary systems in the era of the origin of life. All of the observa- 

 tions listed here are strongly affected by atmospheric absorption, and thus are 

 best made with orbiting observatories. 



The contribution of biogenic and other heavy elements from stars to the 

 interstellar medium is also of exobiological importance. This happens late in the 

 life of a star, either as grain formation and ejection in the atmospheres of giant 

 stars, or in supernovae ejecta. To a lesser extent, it also occurs during the main- 

 sequence stage of stellar evolution through the action of stellar winds (for exam- 

 ple, the solar wind). Observations of these evolved objects are best made in the 

 visible and near infrared. 



The first-generation instruments on the HST are capable of performing only 

 the ultraviolet and visible observations discussed here. SI RTF is necessary for the 

 other studies mentioned. More detailed work, especially in the high-resolution 

 studies of molecular and atomic lines, requires LDR for its high sensitivity and 

 spatial resolution, which is necessary to determine the composition and structure 

 of matter within these energetic systems. 



6.1 .3 Solar System Observations 



While we recognize the importance of measurements by direct missions to 

 solar system objects, three broad areas of solar system observations have been 

 identified as holding promise for exobiological studies from Earth orbit. These 

 are primarily related to the identification of biogenic elements and complex 

 molecules in primitive bodies and in the atmospheres of the giant planets and 

 satellites. Significant progress is expected, particularly from the use of the HST. 

 Nonetheless, many species of interest will remain undetectable until the develop- 

 ment of sensitive orbiting telescopes and spectrographs for the spectral range 

 from the far-infrared through millimeter wavelengths. 



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