Asif Bajwa

Astronomy 101

Professor Houser

12/11/2014

James Webb Space Telescope

Since the first astronomers pointed telescopes at the sky, they have sought to see more. See farther and deeper. Space astronomy changed on April 24th 1990 with the launch of the space shuttle Discovery carrying aboard it the Hubble Space Telescope. A lot of people think we launched Hubble into space to get it closer to the stars but the real reason is the Earth's atmosphere both distorts and blocks light coming in from space. In space, beyond the atmosphere, the stars don't twinkle, instead they shine firm. That allows for the sensational images we've become accustomed to seeing from Hubble. But that wasn't Hubble's only benefit, it was also one of NASA's great observatories. There are many of these observatories in space but most are outfitted to answer one or two specific questions. Hubble was designed to be as inclusive as possible, it was supposed to answer as many questions as you could ask. At least as far as its design allowed. And Hubble succeeded very well at that. The Hubble Deep Field, perhaps the most important image ever taken by Hubble, shows us galaxies stretched all the way across the universe, up to ten billion light years away. Light that has taken billions of years to reach us in our corner of the universe, so we see these galaxies not that as they are today but as they were when the light left them. And in the end, after zooming in as much as possible, we see nothing. We've reached the limit of Hubble's vision. To carry us farther, to step past Hubble, we need the James Webb Space Telescope.
James E. Webb, the man whose name NASA chose to give to the successor of the Hubble Space Telescope was a government official who served as the second administrator of NASA from February 1961 to October 1968. “He oversaw NASA from the beginning of the Kennedy administration through the end of the Johnson administration” (history.nasa.gov/biographies), therefore supervising all the pivotal first manned launches. “Webb's vision of a balanced program resulted in a decade of space science research that remains unparalleled today.”(www.nasa.gov/jwst). The Webb Telescope was originally planned to dawn the name Next Generation Space Telescope, or NGST. Personally, I would have liked this name much more considering my adolescent-like fandom of that particular Star Trek series, but the chosen name is well deserved. Webb was the guy who oversaw every operation right up until man set foot on another world for the first time, so naming the Telescope that will usher in a new era of astronomy after him is only fitting.
Webb is a joint project between NASA, ESA and the Canadian Space Agency (CSA). It is scheduled to launch in 2018 on an Ariane 5 ECA rocket from ESA’s spaceport at Kourou in French Guiana. “After launch and after 6 months on a transfer trajectory, the observatory will operate at approximately 1.5 million kilometres from Earth, in an orbit around the second Lagrange point of the Sun-Earth system, L2” (http://webbtelescope.org/webb_telescope/). An enormous amount of the work on the telescope has already been completed. All of Webb's 18 mirror segments have been ground, coated, polished and tested. Its cameras and other instruments are nearing completion or in their final stages. But since Webb will be located a million miles away, it must be perfect before it launches, therefor everything is being meticulously tested. The pieces get tested separately, then together, then as part of the actual telescope. They're tested to make sure they work in the extremes of space and that they can survive the violence of launch. When its time to test them as part of the entire telescope, they're brought to NASA's largest test chamber, a cavern like thermal vacuum chamber at Johnson's Space Center, which has been refitted specially for Webb. It was the same chamber used to famously test the Apollo space vehicles.
There will be four science instruments on Webb, the Near InfraRed Camera (NIRCam), the Near InfraRed Spectrograph (NIRSpec), the Mid-InfraRed Instrument (MIRI), and the Fine Guidance Sensor / Near InfraRed Imager and Slitless Spectrograph (FGS-NIRISS). (http://jwst.nasa.gov/). The four science instruments will be contained within the Integrated Science Instrument Module, or ISIM.

This unit will house these main instruments that will detect light from distant stars and galaxies, and planets orbiting other stars. Several innovative technologies have been developed for Webb. Included is a folding, segmented primary mirror that will essentially 'unbox' itself post launch and later adjust to functional shape. Included in the unpacking process is the sun-shield.“Webb has a sun-shield the size of a tennis court, which is used to keep the telescope and its instruments permanently in the shade where they will cool down to -233ºC.” (http://webbtelescope.org/webb_telescope/). There are “ultra-lightweight beryllium optics” designed to detect and record extremely weak signals, and microshutters that “enable programmable object selection for the spectrograph” (http://jwst.nasa.gov/jwst). Webb's capacities will enable an expansive scope of examinations across numerous sub fields of astronomy. One specific objective includes watching/following the most inaccessible sections of the Universe, past the range of current ground and space based instruments. This includes the first stars, the age of reionization, and the development of the first systems. Another objective is better understanding the formation of stars and planets.
When we turn these instruments on space, they open up the whole universe to us. When we take a gander at the night sky we see stars, planets, worlds and nebulae as visible light. However in the event that we could see in infrared light, the sky would altogether seem very different. Infrared's long wavelengths penetrate clouds of gas and dust. The shorter wavelengths of visible light are stopped and scattered as they fight through collections of particles. “Webb's wavelength range will be from about 0.6 to 28 microns (visible to the mid-infrared light). By comparison, the Hubble Space Telescope observes at 0.1-2.5 microns (ultraviolet to the near infrared)” (http://www.jwst.nasa.gov/). So by detecting infrared light we can see through clouds of dust and gas to warm objects inside, like just forming stars. Objects that don't glow with invisible light of their own like planets, are still warm enough to be detected. And by observing how infrared light from a planets star passes through its atmosphere we gather clues about the planets composition. The dust left behind from distant planets as they form will also help us understand how planets are formed.
“Webb will be the most powerful space telescope ever built, able to detect the light from the first galaxies ever formed and explore planets around distant stars. It will study every phase of our universe's history, ranging from the first luminous glows after the Big Bang, to the formation of stellar systems capable of supporting life on planets like Earth, to the evolution of our own solar system” (http://www.ibtimes.com/). An endeavor of this magnitude is bound to hit a few rough spots along the way and in 2011 that's precisely what happened. The mission has a history of major cost overhauls and was under audit for cancellation by the United States Congress in 2011, after about $3 billion had already been used, and more than 75 percent of its hardware was either underway or undergoing testing. Fortunately, in November 2011, Congress backtracked on arrangements to cross out the Webb Mission and rather chose to cap any additional subsidizing necessary to finish the task at $8 billion.
Every decade, astronomers conduct a survey to determine the astronomy communities top priorities. The James Webb Space Telescope is their number one priority. This is the observatory they want above everything else. I've already explored some of the reasons why, but not the most important reason. If Hubble is any guide, Webb's most important contributions to our understanding of the universe will probably surprise everyone. Because it was designed as a general purpose observatory it is extremely versatile. As Neil Degrasse Tyson said in one of his JWST focused podcasts,“The Webb space telescope will be able to answer the questions we have, and then move on to the questions we haven't yet thought to ask.”

WORKS CITED
"James Webb Space Telescope (JWST) NASA."James Webb Space Telescope (JWST) NASA. Web. 11 Dec. 2014. <http://www.jwst.nasa.gov/>.

"NASA Gets A Budget Increase In Congress' New Spending Bill, James Webb Space Telescope Safe From Cuts."International Business Times. Web. 11 Dec. 2014. <http://www.ibtimes.com/nasa-gets-budget-increase-congress-new-spending-bill-james-webb-space-telescope-safe-cuts-1541344>.

"JWST Factsheet." European Space Agency. Web. 11 Dec. 2014. <http://www.esa.int/Our_Activities/Space_Science/JWST_factsheet>.

"The Webb Space Telescope." HubbleSite. Web. 11 Dec. 2014. <http://webbtelescope.org/webb_telescope/>.