This article was updated on the 11th September 2019.
Many different forms of telescope exist, and these differences determine the power of the telescope and the applications they are used for. This article examines some of the different forms of telescope controlled by The North American Space Agency (NASA).
X-rays are a high-energy wavelength in the electromagnetic spectrum. Many stars such as supernova, quasars and galaxies, emit x-rays, and observing these objects in that wavelength will reveal much about them.
Chandra X-Ray Observatory
The Chandra Observatory (formerly called the Advanced X-ray Astrophysics Facility–AXAF) was launched on 23 July 1999 and is the world’s most powerful x-ray telescope to view sources from space. Astronomers must have this observatory in space because the earth’s atmosphere absorbs and blocks celestial x-ray radiation from reaching the ground.
Chandra flies 200 times higher than the Hubble Space Telescope and its orbit takes it one-third of the way to the moon. The cylindrical glass mirrors in the Chandra are the largest of their kind and the smoothest ever created. Chandra and its upper stage is the heaviest payload ever launched on the Space Shuttle.
The Chandra design and development program was managed by Marshall Space Flight Center (MSFC). The observatory’s telescope was tested and certified at the MSFC X-Ray Calibration Facility.
Figure 1. Chandra X-Ray Observatory (Image source NASA)
The Hubble Space Telescope
A new era in astronomy began as Space Shuttle astronauts released the Hubble Space Telescope into orbit on 26 April 1990. With its vantage point above earth’s atmosphere, Hubble has shown the birth and death of stars, colliding galaxies, stellar plumes, gas rings, nebula clouds, comet impacts on Jupiter, and storms on Saturn. This has been with greater clarity and brightness than humans have ever seen before. Hubble is fulfilling its mission to collect knowledge and discover a new perspective of the universe.
The Hubble telescope uses a Cassegrain reflector system that has a hyperbolic-shaped mirror. The design is optimized for focusing the visible spectrum. The development and assembly of the Hubble was directed by MSFC.
Figure 2. Hubble Space Telescope (Image source NASA)
Hobby-Eberly Telescope (HET)
The Hobby-Eberly Telescope (HET) near Ft. Davis, Texas, is a 9m diameter telescope tailored for spectroscopy. It has a special mirror with 91 segments and features an innovative, low-cost tracking system. MSFC is designing a mirror Segment Alignment Maintenance System on the HET to improve the mirror performance.
Figure 3. Hobby-Eberly Telescope (HET). (Image source NASA)
Next Generation Space Telescope
The next space telescopes larger than Hubble will have to be made with special lightweight mirrors. MSFC has tested new materials and assembly techniques to make giant reflectors that will fold up for launch and then open in space. These telescopes will be big enough to allow scientists to see Earth-like planets around other stars.
James Webb Space Telescope (JWST)
The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope, which launched in 2013. JWST looks at the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. JWST peers through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. JWST's instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.
Figure 3. Artistic Impression of James Webb Space Telescope (JWST). (Image source NASA)
JWST has a large mirror which is 6.5 m (21’3’’) in diameter, and a sunshield the size of a tennis court. Both the mirror and sunshade won't fit on the rocket fully open, so both will fold up and open only once. JWST is in outer space and will reside in an orbit about 1.5 million km (1 million miles) from the Earth.