Telescopes

Earth’s atmosphere which has enabled the mankind and other species to live and survive on this planet has also caused the mankind to think harder about learning our origins and explore the cosmos. The atmosphere on Earth has many drawbacks because of which the earth based telescopes are not as effective as they could be. The clouds, dust, haze, scattering of natural or artificial light are all enemies. Also the atmosphere is transparent to certain wavelengths while for others, the atmosphere is opaque. In order to learn about the cosmos and to have a complete working knowledge of our universe, we had to search for the solutions to these problems and we found one.

Since we can not do anything about the atmosphere, we decided to rise above the atmosphere and send our telescopes into space. Here are a few to read and learn:

• Chandra X-Ray observatorywas launched buy NASA on July 23, 1999 and is named after Indian Astrophysicst and Nobel laureate Subrahmanyam Chandrasekhar for his work in determining the maximum mass of white dwarf stars, leading to greater understanding of high energy astronomical phenomena such as neutron stars and black holes.
• XMM-Newton, also known as the High Throughput X-ray spectroscopy Mission and the X-ray Milti Mirror Mission, is an X-ray space observatory launched by the ESA in December 1999 and as named after Sir Issac Newton. The space coast is tasked with investigating interstellar X-ray sources, performing narrow and broad range spectroscopy and performing the first simultaneous imaging of objects in both X-ray and optical (visible and ultraviolet) wavelengths.
• Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope but it is one of the largest and most versatile, well known both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA’s Great Observatories, along with the Compton Gamma Ray Observatory, the Chandra X-ray Observatory, and the Spitzer Space Telescope. Hubble features a 2.4-meter (7.9 ft) mirror, and its four main instruments observe in the ultraviolet, visible, and near infrared regions of the electromagnetic spectrum. Hubble’s orbit outside the distortion of Earth’s atmosphere allows it to capture extremely high-resolution images with substantially lower background light than ground-based telescopes. It has recorded some of the most detailed visible light images, allowing a deep view into space. Many Hubble observations have led to breakthroughs in astrophysics, such as determining the rate of expansion of the universe.
• Astrosatis India’s first dedicated multi-wavelength space telescope. It was launched on a PSLV-XL on 28 September 2015. With the success of this satellite, ISRO has proposed launching AstroSat-2 as a successor for Astrosat. After the success of the satellite-borne Indian X-ray Astronomy Experiment (IXAE), which was launched in 1996, the Indian Space Research Organization (ISRO) approved further development for a full-fledged astronomy satellite, Astrosat, in 2004. A number of astronomy research institutions in India, and abroad have jointly built instruments for the satellite. Important areas requiring coverage include studies of astrophysical objects ranging from nearby solar system objects to distant stars and objects at cosmological distances; timing studies of variables ranging from pulsations of hot white dwarfs to those of active galactic nuclei can be conducted with Astrosat as well, with time scales ranging from milliseconds to days. Astrosat is a multi-wavelength astronomy mission on an IRS-class satellite into a near-Earth, equatorial orbit. The five instruments on board cover the visible (320–530 nm), near UV (180–300 nm), far UV (130–180 nm), soft X-ray (0.3–8 keV and 2–10 keV) and hard X-ray (3–80 keV and 10–150 keV) regions of the electromagnetic spectrum.
• Transiting Exoplanet Survey Satellite(TESS) is a space telescope for NASA’s Explorers program, designed to search for exoplanets using the transit method in an area 400 times larger than that covered by the Kepler mission. It was launched on April 18, 2018 atop a Falcon 9 rocket and was placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year primary mission, it was expected to find more than 20,000 transiting exoplanets, compared to about 3,800 exoplanets known when it launched. As of 25 March 2020, with about a month to go before the originally planned end of mission, TESS has identified more than 1766 candidate exoplanets, of which 43 have been confirmed so far. The first light image from TESS was taken on August 7, 2018, and released publicly on September 17, 2018. The primary mission objective for TESS is to survey the brightest stars near the Earth for transiting exoplanets over a two-year period. The TESS satellite uses an array of wide-field cameras to perform a survey of 85% of the sky. With TESS, it is possible to study the mass, size, density and orbit of a large cohort of small planets, including a sample of rocky planets in the habitable zones of their host stars. TESS will provide prime targets for further characterization by the James Webb Space Telescope, as well as other large ground-based and space-based telescopes of the future. While previous sky surveys with ground-based telescopes have mainly detected giant exoplanets and the Kepler space telescope has mostly found planets around distant stars that are too faint for characterisation, TESS will find many small planets around the nearest stars in the sky. TESS records the nearest and brightest main sequence stars hosting transiting exoplanets, which are the most favorable targets for detailed investigations.
• Wide-field Infrared Survey Explorer(WISE) is a NASA infrared-wavelength astronomical space telescope launched in December 2009, and placed in hibernation mode in February 2011. It was re-activated in 2013. WISE discovered thousands of minor planets and numerous star clusters. Its observations also supported the discovery of the first Y Dwarf and Earth trojan asteroid. WISE performed an all-sky astronomical survey with images in 3.4, 4.6, 12 and 22 μm wavelength range bands, over ten months using a 40 cm (16 in) diameter infrared telescope in Earth orbit. After its hydrogen coolant depleted, a four-month mission extension called NEOWISE was conducted to search for near-Earth objects such as comets and asteroids using its remaining capability. The All-Sky data including processed images, source catalogs and raw data, was released to the public on March 14, 2012, and is available at the Infrared Science Archive. In August 2013, NASA announced it would reactivate the WISE telescope for a new three-year mission to search for asteroids that could collide with Earth. Science operations and data processing for WISE and NEOWISE take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena.
• James Webb Space Telescope(JWST or “Webb”) is a space telescope that is planned to be the successor to the Hubble Space Telescope. The JWST will provide improved infrared resolution and sensitivity over Hubble, and will enable a broad range of investigations across the fields of astronomy and cosmology, including observing some of the most distant events and objects in the universe, such as the formation of the first galaxies. Other goals include understanding the formation of stars and planets and direct imaging of exoplanets and novas. The primary mirror of the JWST, the Optical Telescope Element, is composed of 18 hexagonal mirror segments made of gold-plated beryllium which combine to create a 6.5-meter (21 ft; 260 in) diameter mirror that is much larger than the Hubble’s 2.4-meter (7.9 ft; 94 in) mirror. Unlike the Hubble, which observes in the near ultraviolet, visible, and near infrared (0.1 to 1 μm) spectra, the JWST will observe in a lower frequency range, from long-wavelength visible light through mid-infrared (0.6 to 28.3 μm), which will allow it to observe high redshift objects that are too old and too distant for the Hubble to observe. The telescope must be kept very cold in order to observe in the infrared without interference, so it will be deployed in space near the Earth–Sun L2 Lagrangian point, and a large sunshield made of silicon- and aluminum-coated Kapton will keep its mirror and instruments below 50 K (−220 °C; −370 °F). The JWST is being developed by NASA—with significant contributions from the European Space Agency and the Canadian Space Agency—and is named for James E. Webb, who was the administrator of NASA from 1961 to 1968 and played an integral role in the Apollo program. Development began in 1996 for a launch that was initially planned for 2007 and a 500 million-dollar budget, but the project has had numerous delays and cost overruns, and underwent a major redesign in 2005. The JWST’s construction was completed in late 2016, after which its extensive testing phase began. In March 2018, NASA delayed the launch after the telescope’s sunshield ripped during a practice deployment. Launch was delayed again in June 2018 following recommendations from an independent review board, and is currently scheduled for March 2021.