Introduction
The Spitzer Space Telescope (Spitzer) is an infrared observatory gadget and program that was launched into the earth’s orbit on 25th August 2003 at 13:35:39 UTC-5 (Romana et al. 2). The telescope was a milestone in astronomy as it is specifically used to study the creation of the universe, creation and advancement of primordial galaxies, chemical evolution of galaxies, and origin of stars and planets (Romana et al. 2). The set up has an 85cm Ritchey-Chretien telescope that is cryogenically cooled and operating at temperatures that are as low as 5.5K. The CTA (Cryogenic Telescope Assembly) contains the CT (Cryogenic Telescope), a liquid Helium Dewar, and SI’s (Science Instruments).
SI’s are three and are also cryogenically cooled and enable imaging and spectroscopy in the ranges of 3-180 m wavelength using their large format detector arrays. The SI’s include (Werner 44):
IRAC (Infra Red Array Camera):- Which operating concurrently on four wavelengths (3.6, 4.5, 5.8, and 8 µm) with each module using 256 X 256 pixel detector. The pair short wavelengths—3.6 and 4.5 µm—use indium antimodine technology while the long wavelength pair --5.8 and 8 µm pair—use arsenic-doped silicon impurity band conduction technology. The shorter wavelengths remain productive even after the liquid Helium has been depleted resulting into the IRAC continuing to operate as the “Spitzer Warm Mission (Romana et al. 2).”
Infrared Spectrograph (IRS):- The device entails 4 units all of which operate at specific wavelengths of 5.3-14µm, 10-19.5 µm, 14-40µm, and 19-37µm using 128X128 pixels.
MIPS (Multiband Imaging Photometer):-Has three detector rays in the far infrared region. The technology used is gallium-doped germanium technology.
These specifics make the Spitzer observations be more sensitive than previous infrared missions.
During the launch of the telescope, the mission was expected to take 2.5 years with an extra five years that was considered before launch. The extra five years was to cater for the on-board helium liquid supply to diminish which happened on 15th May 2009. The telescope cannot be used if the liquid Helium is absent because it is essential in cooling the telescope to very low temperatures that are needed to operate it. This paper entails to highlight the current knowledge of Spitzer telescope in the field of astronomy bringing out the knowledge that remains unanswered. The future of the telescope will also be brought out showing the advances that have resulted usage of the telescope in infrared astronomy observation.
Discussion and Analysis
The Spitzer telescope has enabled astronomers see target planets in other star systems that do not emit enough light to be able to be seen in other wavelengths apart from infrared. The telescope has looked over the thick interstellar dust that covers most of our own Milky Way galaxy, resulting in exposure of structures that were not previously seen. Astronomers have also used the telescope to zero in on huge black holes that are found in centres of dust filled galaxies (Skrutskie 102). The furthest limit of the telescope is the earliest universe, the era when the first galaxies and stars formed. Light from galaxies and stars departed from them in the region of ultraviolet and visible spectrum, but the expansion of space resulted in stretching of light into the infrared region on its way to the earth. Instruments in the Spitzer telescope detect the ancient light, facilitating astronomers to study galaxies whose light left them 12.8 billion years ago, when the universe was 15% of its present size (Skrutskie 102).
The telescope’s cold mission overlap resulted in a great era for exoplanet science. As of early December, 2008, astronomers had found 333 confirmed exoplanets orbiting about 283 nearby planets (Werner 46). Nearly all of the known exoplanets are huge gas planets (“hot Jupiters”) revolving their parent stars (Skrutskie 103). Spitzer telescope enabled the observation of one planet called HD 189733b, which orbits a specific star that is 63 light years from the earth. The same planet radiates most of its light in the infrared region allowing the Spitzer telescope to explore its temperature and structure. Despite the fact that HD 189733b relatively weak glow is lost in the glare of its parent star, the telescope was still able to isolate the planet’s light thanks primarily to the fact that the planets orbit lies edge-on as witnessed from the earth (Massimo et al. 92). With each orbit, the planet transits the mother star and swings around its side before passing behind the star. When the planet disappears from view, the telescope measures the slight drop in the infrared coming from the mother star. The slight blip in the signal ultimately results in a representation of the temperature of the earth’s atmosphere.
The telescope has also contributed to the further understanding of the Milky Way. Spiral arms containing vast amounts of gas and dust dominate images of other galaxies, but obtaining similar images for our Milky Way has been limited by the fact that humans live in the same galaxy. However, infrared astronomy offers a solution as most infrared wavelengths pass through the dust making the Milky Way’s disk visible to the Spitzer telescope. Important advances came during the GLIMPSE survey where a 3000 survey of the inner Milky Way galaxy was done taking about 444,000 images using the IRAC at four different wavelengths (Massimo et al. 93).
Unanswered Question
In infrared astronomy using the Spitzer telescope, there is an unanswered question concerning the finding of black holes. There is an unanswered question about which galaxies contain super-colossal black holes. Until recently, nearly all black holes were seen in galaxies having central concentrations of stars called galactic bulges (Werner 49). For instance, the Milky Way has a central bulge and a super-colossal black hole of 3-4 million solar masses (Werner 49). Researches using the Spitzer telescope have demonstrated that galaxies without bulges can also form black holes. However, the observation leaves a fundamental question that is not answered which is “if galactic bulges do not result in black holes, what does?” Currently, astronomers only speculate with the telescope proving a great avenue of undertaking a complete census of central black holes in nearby galaxies.
Conclusion
The telescope has been a great innovation in infrared exploration resulting in advances in: exoplanet weather reports; finding of black holes in the universe; and in exploring the Milky Way. The telescope has provided the foundation for the launch of the JWST (James Web Space Telescope) in 2013 (Massimo 98). The telescopes light collecting surface will be fifty times that of the Spitzer telescope, resulting in images that would be at higher red shifts than Spitzer can obtain. In the mean time, the use of the telescope is not obsolete as even if the last liquid Helium evaporates, the gadget can still be used to operate two wavelengths at the maximum sensitivity. This is still enough for it to be used to search for other distant galaxies, the Milky Way observations, and exoplanets.
Works Cited
E. A. Romana, et al. "The NASA Spitzer Space Telescope." Review of Scientific Instruments 78.1 (2007): 011302.
Massimo, Marengo, et al. "Observations of Extrasolar Planets During the non-Cryogenic Spitzer Space Telescope Mission." AIP Conference Proceedings 943.1 (2007): 89-100.
M. F. Skrutskie, et al. "The Warm Spitzer Mission: Opportunities to Study Galactic Structure and the Interstellar Medium." AIP Conference Proceedings 943.1 (2007): 101-121.
Werner, Michael. "How the Spitzer Space Telescope unveils the unseen cosmos." Astronomy 37.3 (2009): 44-49.
