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Space and ground based astronomy both have their advantages and disadvantages. There are many challenges concerning ground observations that require adapting technologies and oftentimes these challenges can be avoided or overcome by investing in space based astronomy instead. Some of the main challenges to overcome in ground based astronomy are star twinkling, temperature changes, Earth’s gravitational field, and limited angular resolution. Space based astronomy can avoid these challenges, but this type of astronomy also faces some challenges involving high cost issues and its requirement of high quality equipment.
A big problem of observing the sky using a ground based telescope is the phenomenon of star twinkling.
Star twinkling is caused by “space and time variations in chemical and physical properties of the atmosphere that cause variations in the refractive index of different atmospheric regions” [Mat00). Ground based telescopes are required to collect “light over a large area” which leads “to random systematic deviations of light rays”, and thus causing star twinkling to occur [Mat00).
The Earth’s changing climatic temperatures also affect the telescopes. Hot weather causes telescope parts to expand and cold weather causes telescope parts to contract. This constant flux of temperature results in “image distortion” from the telescope [Mat00]. Distorted images can also be caused by Earth’s gravitational field as it “tends to bend the truss structure of large, heavy ground-based telescopes” [Mat00]. The last challenge of ground based astronomy is its limited angular resolution.
However, “a wide range of new techniques, such as mosaic and light-weight mirror, active and adaptive optics” was developed to overcome this issue [Mat00).
Some challenges of ground based astronomy can be overcome by new technologies, but they are still costly and a ground based telescope will never be able to perform in the optimum space conditions that a space based telescope can.
A telescope in space can avoid all of Earth’s temperature fluctuations, the gravitational field, and the atmospheric turbulence that causes star twinkling. However, the complexity of space based astronomy is getting the technology perfect the first time, that is, before sending it into space. Once the telescope is in space, “sending humans to repair or maintain [the telescope] may be costly or impossible” [Kon01). The Hubble Space Telescope created by NASA provides an example of how a mistake can be very detrimental. The telescope “was found to have faulty optics after being launched into orbit and tested in situ for the first time” and “the HST only began returning clear images following a subsequent shuttle repair mission” [Kon01].
Scientists in the space program must make sure that their telescopes, or other technologies that are being sent into space, are perfectly engineered so that a mistake like the Hubble Space Telescope’s first launch will not occur in the future. Although space based astronomy has many advantages over ground based, the high costs of fixing mistakes and perfecting the technology on ground does require some debate when deciding whether space based is actually better than ground based. As technologies continue to advance, ground based astronomy will of course improve, although it is very unlikely that it will ever perform at the same level as space based astronomy.
Infrared astronomy has many advantages over light emitted in other wavelengths, especially over the wavelengths from visible light. Light is emitted in different wavelengths all along the electromagnetic spectrum. “The human eye detects only 1% of light … and so effectively cannot see wavelengths longer” than this [INF13]. Information is sent to us “in the form of electromagnetic information. Much of this information is in the infrared” [INF13]. When observing objects from visible telescopes, much of the mysteries of space are hidden, because the human eye cannot see many wavelengths of light, optical telescopes will not be able to detect these mysteries. However, all objects can be seen in the infrared as long as they have a temperature [INF13]. A downside to infrared observations is that it is not very useful in ground based astronomy, because “only a small amount of … infrared … reaches the Earth’s surface” [INF13).
This is why infrared telescopes are space based and this gives the astronomical world great opportunity to discover distant galaxies among other space phenomenon. An advantage that infrared telescopes have over optical telescopes in space is that the infrared telescopes can see through the regions “hidden from optical telescopes” that “are embedded in dense regions of gas and dust” [INF13). Technology is advancing in the infrared section of astronomy and there are more and more infrared satellite missions. “The first of these satellites – IRAS (Infrared Astronomical Satellite) – detected about 350,000 infrared sources, increasing the number of cataloged astronomical sources by about 70%” [INF13]. In addition to objects being obstructed by dust in space from the visible wavelengths, there are also many objects that are “much too cool and faint to be detected in visible light”, that can be detected through infrared [INF13].
This is another way that infrared telescopes trump optical telescopes in detecting distant galaxies. Since the infrared is able to detect these distant galaxies and the farther a telescope looks into space the further back in time it can see, “astronomers can gather information about the universe as it was a very long time ago and study the early evolution of galaxies” [INF13]. In addition to this, it has been discovered that “all distant galaxies are moving away from us” [INF13]. Since objects moving away from Earth are red shifted, as seen in the Doppler Effect, the only way to study these far away moving galaxies is through infrared technologies.
Optical telescopes are very limited in the amount of sky that they can observe and the detail that they can observe about it. Infrared can reveal “the presence of dust which glows brightly in the infrared” [For13]. As stated before, optical telescopes, and the human eye for that matter, cannot see objects hidden by dust and cannot see the dust itself. A modern example of astronomy reaping the advantages of infrared telescopes is seen in astronomers’ discovery of a new class of galaxies using the Wide-field Infrared Survey Explorer (WISE) from NASA, called “hot dust-obscured galaxies, or ‘hot DOGS”” [Cam12]. First, the astronomers used WISE to survey the sky in four different infrared wavelengths and discovered that these “hot DOGS” were not visible in the shorter wavelengths of infrared, but could only be seen in the longer wavelengths due to the dust that surrounded them [Cam12]. Other astronomers using NASA’s Spitzer Space Telescope believe that they have used this “infrared space observatory” to detect “some of the very first galaxies to have formed” [Gov04]. As illustrated, infrared technologies hold many advantages over optical telescopes from detecting some of the earliest galaxies and discovering and seeing through dust around space objects, to even the detection of more detail around objects that are already visible [INF13). As astronomers continue to explore these advantages of infrared telescopes, more and more magnificent discoveries in space will continue to be brought to light.
The James Webb Space Telescope (JWST) is an ongoing telescope project that has been the focus of controversy of whether or not its construction is worth the cost, but the importance of the telescope and the new information it can bring astronomers and the rest of humanity outweighs all of its costs. The JWST “is a large, infrared optimized space telescope” that is NASA’s second space observatory and telescope that has many goals in its mission that its project designers have ambitiously set [Mag13]. Even the design of the telescope is extremely ambitious. First, all “instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range” [Mag13].
This is completely different than the Hubble Space Telescope’s pure optical telescope abilities. The JWST will have a 6.5 meter primary mirror that will have to have a folding capability, because it is too large and heavy to launch in an open state [Mag131]. These advanced designs, along with the most advanced infrared technologies, are causing NASA to have building delays and extensive cost issues. This is the main source of its debated construction and why astronomers are fighting to keep this project ongoing and on-track for its projected 2018 launch date [Mik11). JWST’s mission is extremely important. It has a five year mission lifetime with a ten year goal [NOR13] and it “will study every phase in the history of our Universe, ranging from … after the Big Bang, to the formation of solar systems capable of supporting life … to the evolution of our own Solar System” [Mag13]. Since the JWST will have the most advanced infrared technologies on board, it will be able to see far into the depths of space and further back into time, spotting light from the very birth of galaxies.
“NASA’s James Webb Space Telescope will peer into the past to a time when new stars and developing galaxies were first beginning to form, measuring and capturing images and spectra of galaxies that formed billions of years ago” [NOR13). This promise of discovery of how the Universe formed with the JWST being able to provide concrete images and information of the now speculative Big Bang theory is what astronomers strive to protect. The telescope will open the door to a part of the universe that has just begun to take shape under humanity’s observations” [See13].
The JWST was debated on whether or not the project should be continued due to its high cost totaling to $6.5 billion [Mik11]. Its launch date was also delayed by three years. However, astronomers fought for JWST, specifically NASA chief Charlie Bolden, who told “members of Congress that the instrument has greater potential for discovery than the iconic Hubble Space Telescope” [Mik11]. Its greater potential comes from its use of infrared technology which includes, four instruments including the Near InfraRed Camera, the Near InfraRed Spectrograph, the Mid-InfraRed Instrument, and the Fine Guidance Sensor/ Near Infrared Imager and Sitless Spectrograph [Mag131].
It can be seen that JWST, although ambitious in design and mission, is achievable. Its infrared technology will reveal new information about the beginning of the Universe and perhaps confirm theories already proposed. Either way, the infrared images that JWST will capture will be far greater than Hubble’s optical images. Infrared can see through the dust of space and can also see farther since it uses the longer wavelengths in the electromagnetic spectrum. When JWST is launched, astronomers will hold their breaths with pure excitement as they wait for the discoveries that JWST is bound to make as it fulfills its mission as NASA’s observatory.
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