Grasslands Observatory - Essays - Is the HST Still Doing Good Science?

Is the HST Still Doing Good Science?

By Tim Hunter

Introduction- The Hubble Space Telescope (HST)

The Hubble Space Telescope (HST) is one of the most ambitious scientific and exploratory enterprises in human history. The 2.4 meter Hubble Telescope was launched on April 24,1990 from the Space Shuttle Discovery and deployed on April 25,1990. It cost 1.5 billion US dollars by the time of its launch, and it has required four servicing missions (1993, 1997, 1999, 2002) to correct its initial defective optics and to service and upgrade equipment for routine maintenance and for replacement of obsolete scientific instruments (Hubblesite, 2004). Hubble was designed for a lifetime of 20 years.

HST is a large telescope, but its size is only modest compared to many considerably larger ground based telescopes, several of which are in the 6-10 meter range. The Hubble Telescope’s main usefulness comes from it being above most of the Earth’s atmosphere allowing it to have a far better resolving power than ground based telescopes. It is never bothered by an unsteady atmosphere and cloudy skies.

HST orbits at an altitude of 569 km inclined 28.50 to the equator in a low Earth orbit. The Sun is dangerously too bright for the HST to observe, and HST avoids Mercury and Venus which are close to the Sun. HST has many instruments, but these will not be discussed in this short essay other than to note they cover the ultraviolet through the infrared portions (115-2500 nm) of the electromagnetic spectrum.

The Hubble Space Telescope is controlled from the Space Telescope Science Institute (STScI) in Baltimore, MD. On a daily basis, the HST takes 3 to 5 GB of data. The STScI makes available to the scientific community on a daily basis between 10 to 15 GB of scientific data (HubbleSite, 2004). The statistics for the Hubble Telescope as of March 2000 show it had taken 330, 000 separate images of over 25, 000 astronomical targets. In addition, as of March 2000, the HST data archive consisted of more than 7.3 terabyte of data (HubbleSite, 2004).