The HST Key Projects

Before astronomers submitted the first proposals for observing time on the Hubble Space Telescope, the 1983 Space Telescope Advisory Committee recommended that certain ``Key Projects'' be established. These projects would focus on fundamental science objectives which could only be carried out by the HST, but would require a large investment in observing time. Defining these Key Projects was a way of declaring a commitment to address these fundamental science issues at the probable expense of other, smaller, projects. Initially, three Key Projects were defined: the Determination of the Extragalactic Distance Scale, the Quasar Absorption Lines Survey, and the HST Medium Deep Survey. New Key Projects will be defined over the life of HST.

The main goal of the HST Key Project on the Extragalactic Distance Scale is to measure the rate of expansion of the universe (known as the Hubble Constant) to an accuracy of 10%. This is accomplished in part by determining the distance to external galaxies with unprecendented accuracy. The Hubble constant can be used to estimate the age of the universe, and tells us something about the ultimate fate of the universe. There is a Web page for the Extragalactic Distance Scale, for those who which to pursue the topic in greater depth.

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