Aug 18 2006
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NASA awarded contracts to two companies to develop commercial orbital transportation services for the ISS, creating the possibility of a commercial space transportation industry. The agreements also marked the first time that NASA had hired contractors to build a space transportation system for private-sector use, rather than for government use. Under the agreements, NASA would invest up to US$287 million in Rocketplane Kistler and US$207 million in Space Exploration Technologies Corporation, also known as SpaceX, enabling the two companies to develop a spacecraft that could provide crew and cargo services for the ISS. NASA’s provision of the funds would be contingent on the companies’ completion of designated milestones—including launching and docking a spacecraft with the ISS. According to a NASA official, NASA hoped that private companies would be able to turn low-Earth-orbit services— such as transportation of people or cargo to the ISS—into a profitable venture, thereby enabling NASA to focus on other objectives, such as missions to Mars and the Moon.
NASA, “NASA Selects Crew and Cargo Transportation To Orbit Partners,” news release 06-295, 18 August 2006, http://www.nasa.gov/home/hqnews/2006/aug/HQ_06295_COTS_phase_1.html (accessed 15 March 2010); Mark Carreau, “Two Firms, Both Space Novices, Get Nod from NASA,” Houston Chronicle, 19 August 2006.
Scientists published research on the dimmest stars ever observed in a globular star cluster, including findings that revealed important information about the universe’s age and provided supporting evidence for a theory of star transformation. Harvey B. Richer of the University of British Columbia, and his team of scientists, had used NASA’s HST to observe faint light from white dwarf stars in the cluster NGC 6397. Astronomers often make estimates of the universe’s age based on the age of stars. They are able to determine the age of stars because stars decline in temperature as they exhaust their available energy over their lifetimes. White dwarf stars, which are burned-out relics of stars and cool at predictable rates, are particularly useful for this purpose. However, white dwarves also become less visible as their radiation declines. According to the team’s observations of the light from the white dwarves in NGC 6397, the cluster is almost 12 billion years old. The light from the cluster’s white dwarf stars appears as faint as the light of a birthday candle on the Moon would appear to an observer on Earth. The HST images also revealed that the dimmest white dwarf stars in NGC 6397 have temperatures low enough to cause chemical changes in their atmospheres, making the stars appear blue rather than red. Scientists had theorized the existence of this phenomenon but had never observed it.
NASA, “Hubble Sees Faintest Stars in a Globular Cluster,” news release 06-292, 17 August 2006, http://www.nasa.gov/home/hqnews/2006/aug/HQ_06292_HST_globular_clusters.html (accessed 15 March 2010); Harvey B. Richer et al., “Probing the Faintest Stars in the Globular Star Cluster,” Science 313, no. 5789 (18 August 2006): 936–940, http://www.sciencemag.org/cgi/content/short/313/5789/936 (DOI 10.1126; accessed 29 June 2010).
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