Space telescopes

Some graphite-epoxy structures can be tailored to have a zero coefficient of thermal expansion, a big advantage for large antennas that must pass in and out of the sun, yet maintain dimensional stability for accuracy of pointing the signal. For example, a graphite-epoxy truss is used to stabilize and support the Hubble Space Telescope. 

A strong collaboration between micro-optics and astronomy will certainly lead to reach the best scientific return for the lowest cost in next generation astronomical instrumentation for ground-based and space telescopes. 

Infrared detectors can be made with several layer AR coatings, and the detectors for the James Webb Space Telescope, awarded to Rockwell Scientific, specify 4- or 5-layer coatings to achieve QE of 95% over a broad bandpass. 

One of the projects planned for the next decade is Darwin, to be organised by ESA. Darwin will be a flotilla of four or five spacecraft that will search for Earth-like planets around other stars and analyse their atmospheres for the chemical signature of life. Three of the spacecraft will carry 3 1 m space telescopes , which will form the Infrared Space Interferometer IRSI they will be stationed 1.5 million kilometres from Earth, in the opposite direction from the Sun, at the Lagrangian Point L2 (a libration point at which the gravitational forces of the Earth and the sun cancel out). 

R.C. Peterson et al. Mid-Ultraviolet Spectral Templates for Old Stellar Systems . In Space Telescope Science Newsletter 4, 1 (2004)... 

This research has been supported by NASA through Hubble Fellowship grant HST-HF-01151.01-A from the Space Telescope Science Inst., operated by AURA-USA, under NASA contract NAS5-26555. 

Figure 3.12 Line of sight through three Giant Molecular Clouds to the Hubble Space Telescope. (Reproduced by courtesy of StscI and NASA)...

The spectral features observed by astronomers have led to the classification of stars into seven broad classes outlined in Table 4.1, together with their surface temperatures. The highest-temperature class, class O, contains may ionised atoms in the spectrum whereas the older stars in class M have a much lower temperature and many more elements present in the spectrum of the star. Observation of a large number of the stars has lead to extensive stellar catalogues, recently extended by the increased sensitivity of the Hubble Space Telescope. Making sense of this vast quantity of information is difficult but in the early 19th century two astronomers... 

Fig. 3.8. Profiles of interstellar absorption lines observed in the line of sight to the star HD 93521 with the Goddard high resolution spectrograph at the Hubble Space Telescope. Solid lines are theoretical profiles based on cloud velocities indicated by the tick marks at the top dots indicate the data points. After Spitzer and Fitzpatrick (1993). Courtesy Ed Fitzpatrick.

Fig. 8.3. C/O ratio vs. O/H in Galactic and extragalactic H n regions, based on International Ultraviolet Explorer (IUE) and Hubble Space Telescope (HST) observations. After Garnett (2004).

How can absorption and emission spectra be used by the Hubble space telescope to study the structures of stars or other objects found in deep space ... 

Astronomy s new eyes carry code names like HST (Hubble Space Telescope), XMM (X-ray Multi-Mirror) and GRO (Gamma-Ray Observatory). Each wavelength region has its own squadron, extended by future spacecraft that take us ever further towards sensitivity and detailed analysis of images and spectra. 

Optical telescopes with 4 m diameter which had blossomed in many of the world s deserts have now been superseded by the space telescope and 8-m or 10-m telescopes on dry mountain peaks. These giants with their penetrating eye and minuscule field of view are mainly devoted to spectroscopy. 

NASA has formally invited its European counterpart to work on a continuation of the HST and the ESA has accepted. This in no way compromises its own cryostatic project, FIRST (the Far InfraRed Space Telescope). Designed to supersede the highly successful ISO (Infrared Space Observatory), this new space observatory will probe the Universe in the far infrared and submillimetre ranges. It should be recalled that the ESA contributed some 15% of the costs... 

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