Discoveries of Hubble Telescope Essay

Introduction

The development of space-borne telescopes has heavily influenced our astronomical research and broadened our fundamental understanding of the universe. They have paved the way for astronomers to view and understand the cosmological evolution of galaxies that ground-based telescopes could not fully uncover. In recent years, advancements in space telescopes with the achievements of the Hubble Space Telescope and the upcoming James Webb Space Telescope have revolutionized the data we have in the field of astrophysics. [1] As a result, current and future space exploration operations now rely heavily on space telescopes.

The Need for Telescopes in Space

Initially, the opportunity for space-based research had been restricted by hazy, unclear images produced by ground-based telescopes until the availability of more precise data obtained by space telescopes. [2] Because space telescopes are placed outside of Earth, their observations will not be interfered with by getting absorbed or suffering from scintillation as a result of the Earth’s atmosphere, unlike ground-based telescopes. Their ability to bypass Earth’s atmosphere allows space-based telescopes to make extremely accurate photometric observations at wavelengths unattainable from the ground. The many forms of radiation such as gamma rays, X-rays, and certain parts of ultraviolet cannot be observed from Earth because they are completely blocked out by its atmosphere. Even certain broad bands in the near-infrared would not be able to evade it as they are immediately absorbed by water molecules within Earth’s atmosphere. As a result, with the limited ability to see the entire electromagnetic spectrum our studies will be severely inadequate unless information is to be gathered by space telescopes. [3]

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Moreover, the reduced resolution ground-based telescopes experience when subject to atmospheric distortion is another restraint only space-borne telescopes can fully overcome. This distortion is a result of the constantly fluctuating atmospheric conditions and densities above the ground which reduces the practical resolution of the telescope despite its higher theoretical resolution. Although the application of ground-based adaptive optics imaging has been able to improve the clarity of celestial bodies such as stars, such performing enhancements are not powerful enough to surpass the efficiency of space telescope technology such as the images of the Hubble Space Telescope (HST) can capture. For these reasons, taking telescopes into space beyond the limits of the Earth's atmosphere is the only method to view how the universe appears at various wavelengths and could not otherwise be studied using conventional ground-based telescopes. Hence, HST has been one of the most successfully employed instruments for exoplanet atmosphere studies, which often require precise, near-infrared spectroscopy. [3]

Hubble Space Telescope

Crucial to the pioneering success of space-based technologies, are the accomplishments of the Hubble Space Telescope (HST). Ever since its first space launch in 1990 by NASA, the HST has enabled the detection of some of the most distant galaxies, with its suite of instruments such as the Space Telescope Imaging Spectrograph (STIS), the Near Infrared Camera and MultiObject Spectrometer (NICMOS), the Advanced Camera for Surveys (ACS) and the Cosmic Origins Spectrograph (COS). [5][6] In fact, the technology and discoveries of the large telescope have powerfully evolved our study of the universe and its origins which has arguably been unprecedented since the time of Galileo. [7]

With its advanced picture resolution, Hubble’s countless contribution of images in space include the Orion clusters which are sharply derived from infrared imaging interpretations as well as the sharpest image ever taken of the ‘grand design’ spiral galaxy M81 which is tilted at an oblique angle directly parallel to our line of sight. Hubble has also provided observations of exoplanets in transit with their host stars only made possible because of its impressive imagery stability. In addition, HST has confirmed the existence of black holes and their common positioning within the center of all galaxies, revealed the age of the universe to a close percent as well, and revealed the existence of ‘dark matter’ and ‘dark energy’ taking over approximately 96 percent of the universe. Moreover, the HST has been able to extrapolate data from the Hubble Deep Field and Ultra Deep Field to discern an abundance of a wide range of galaxies of various ages of all which have formed less than a billion years after the Big Bang. [7] [8]

Alongside HST’s astronomical achievements, the space telescope is also serviceable which enables it to maintain durability as well as establish necessary methods to effectively execute future deployment and service missions. Developing such methods provides instrumental experience and assured proficiency in such operational techniques needed to accomplish launches for future space telescopes, especially for the forthcoming James Webb Space Telescope (JWST). With the remarkable tasks Hubble has performed, it would be unfortunate if all its existing observations were to only be seen once. Ultimately, an archive of all of the data HST has accumulated is open to the general public. The readily available information has exponentially facilitated larger use of such information for projects and research other than for the endeavors which it was originally taken for. The use of advanced computing operators has been able to expose previously unknown material in existing observations. Evidently, the legacy of the HST will never be lost and will continue to expand for decades even when it is no longer orbiting space. [6][7][8]

Looking into the Future: James Webb Space Telescope (JWST)

Consequently, the technology and discoveries of Hubble have been able to lay down the groundwork for all future space telescope missions and their potential cosmic breakthroughs. Newly developed by NASA following the Hubble Telescope, a notable mission that is reaching beyond the parameters of image-based wavefront sensing is the James Webb Space Telescope (JWST). While the length of the mission for HST has been 24 to 30 years, the JWST will be shortened to approximately 5 to 10 years. Set to launch in 2021, the JWST is a 6.5-metre diameter space telescope that will act as a successor to the Hubble Space Telescope. As opposed to Hubble’s measurements which sit only at a 2.4 metre diameter, the JWST has a larger optimised mirror with more light-gathering power. As well as that, the JWST will have a longer wavelength coverage of 0.6 - 28.5 μm and a higher range of sensitivity as it is situated further away from Earth. In contrast to Hubble’s tube-enclosed mirrors and instruments, JWST’s mirrors and instruments are open to allow the telescope to cool. Additionally, JWST’s arrangement of 18 Beryllium mirrors will be 2 and a half times more magnified in size than Hubble’s main mirror while also being twice as light. The larger mirror diameter will give JWST a sensitivity 3× greater than HST, which, coupled with its 10× higher spectral resolution, means it will become the unparalleled instrument for exoplanet atmosphere studies. [7][9]

The JWST is primarily an infrared space telescope and its suite of four instruments (NIRCam, NIR Spec, MIRI, and NIRISS) is said to provide a great range of imaging and spectroscopic capabilities. As a result, the telescope should be expected to conduct extended surveys of galaxies in the near-infrared over the redshift range 1 < z < 6 with the use of its powerful 4 instruments. The JWST is also expected to obtain hierarchical merging observations in which dark matter, gas, stars, metals, morphological structures, and active nuclei are built up to form the galaxies we see today. [6] [7]

However, with the JWST situated further away than the Hubble service mission, secure phase retrieval methods are heavily significant throughout its remote orbit within space. The development of new algorithmic data has been currently designed to process a wide spectrum of wavefront aberrations, source characteristics, and vibrational environments in case extreme environmental conditions arise so the JWST’s consistency in performance can be maintained. Because of its versatility, JWST will be used to answer a diverse set of questions from many branches of astronomy, including one of NASA’s broader institutional questions of how the first galaxies in the universe formed, and what the atmospheres of exoplanets are made of. We can therefore expect JWST to revolutionize our understanding of exoplanet atmospheres, and allow us to observe smaller and cooler celestial bodies than has previously been possible. [10]

Conclusion

The productivity and impact of space telescopes have continued to grow ever since the launch of the Hubble Space Telescope. With the continual growth of the next generation of extremely powerful space telescopes, one has been prioritized by the National Research Council to be launched as the complementary and surpassing candidate of the HST. The forthcoming James Webb Space Telescope is expected to serve as the next key program that will yield scientific results for future years to come. Nevertheless, as was the case with the HST, the most exciting discoveries that are likely to be made by JWST cannot be scripted in advance.

References

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3. Melina, R. (2010). Why Are Space Telescopes Better Than Earth-Based Telescopes? Space.com. Retrieved 27 October 2019, from https://www.space.com/8286-space-telescopes-earth-based- telescopes.html
4. What Is the Hubble Space Telescope? (2019). NASA. Retrieved 27 October 2019, from https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-the-hubble-space-telecope- 58.html
5. About the Hubble Space Telescope. (2019). NASA. Retrieved 27 October 2019, from https://www.nasa.gov/mission_pages/hubble/story/index.html
6. Spake, J. (2019). The cold, the hot, and the puffy: atmospheric lessons from three transiting exoplanets. University Of Exeter. Retrieved from https://ore.exeter.ac.uk/repository/handle/10871/38528
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8. FAQ for Scientists Webb Telescope/NASA. (2019). Jwst.nasa.gov. Retrieved 27 October 2019, from https://www.jwst.nasa.gov/content/forScientists/faqScientists.html
9. Database Access - UNSW Library electronic resource. (2019). Link-springer- com.wwwproxy1.library.unsw.edu.au. Retrieved 27 October 2019, from https://link-springer- com.wwwproxy1.library.unsw.edu.au/content/pdf/10.1007%2F978-1-4020-9457-6.pdf
10. THE NEXT GREAT OBSERVATORY: ASSESSING THE JAMES WEBB SPACE TELESCOPE. (2019). Govinfo.gov. Retrieved 27 October 2019, from https://www.govinfo.gov/content/pkg/CHRG- 112hhrg72165/html/CHRG-112hhrg72165.html