Unlike the Hubble Space Telescope, the Cosmic Origins Spectrograph (COS) isn’t designed to capture visual images. Instead, COS is designed to perform spectroscopy, which is the study of the interaction of matter and electromagnetic (EM) radiation. Each object leaves a unique signature on any light that it emits, absorbs, or scatters. By studying that light with a spectrograph we can determine much about the object that interacted with the light, including the object’s temperature, density, velocity, and chemical composition.
The matter involved might be atoms, ions, molecules, or solids, and the radiation involved could be any type of EM wave. When radiation interacts with matter, the radiation’s energy can be absorbed or scattered. Spectroscopic analysis reveals which energies are being absorbed by a given sample, and the resultant profile pinpoints the composition of the matter. Because electrons absorb or emit electromagnetic energy when they shift between levels (from ground state to excited state or vice versa), and because each element has a unique distribution of electrons, spectroscopy can be used to detect the presence of specific elements, the distribution of those elements within a sample, or the relative density of a sample.
A primary objective of the COS mission is to analyze the structure and composition of the large-scale “cosmic web” of galaxies, super-clusters, and gas that make up the universe. By focusing on very distant quasars and analyzing how their light is affected by passing through the web, COS will be able to detect and identify what the cosmic web is made of based on the material’s spectral fingerprints. Spectroscopy can be done for any wavelength of light, but COS is focused on two “energy windows” in the ultraviolet band. In addition to using spectroscopy to analyze the cosmic web, COS will also compare near and far galaxies to help inform models of galactic evolution.
Classroom Activity: Spectra-search
Students (individually or in groups) research the emission spectra of 5 - 10 of the elements on the periodic table. Based on those spectral patterns, students formulate a theory about energy emissions and the other properties of those elements. Students (or groups) present their theory and what they discovered about their chosen elements. Each individual or group also shares at least one new question that came up during the research. The class as a whole discusses those questions and the steps they might take to answer them.
David Leckrone, HST Chief Scientist: COS is the most sensitive spectroscope that we have ever flown in space. Spectroscopes or spectrographs are so important for research. They produce ugly pictures but they are the nuts and bolts of physical science. They put the physics in astrophysics. COS was conceived in the mid 1990s by Dr. Jim Green and his colleagues at the University of Colorado primarily to study the cosmic web which is made up of the largest scale structures of matter in the entire universe. If you want to know what something is made of, how hot it is, how dense it is, how fast its moving in space, how fast its rotating for example, a spectrograph will give you all that information. With COS we can acquire information like that farther out across the universe than we've been able to do before.
Randy Kimble, Project Scientist, HST Development Project: Spectroscopy is taking light from an object and breaking it up into the different colors that that light consists of. Each of the elements, each of the chemical elements, has characteristic wavelengths, characteristic colors at which it emits light when you heat it up or absorbs light. For example if I have a tube full of hydrogen between me and that light, instead of seeing the normal spectrum of that light when I look at it with a spectrograph, I'll see that spectrum but with some of the light taken away at the wavelengths where hydrogen has its characteristic absorptions and so by measuring that the depth of those notches and the velocities and the width of them and so on, you can infer all kinds of things about the physical state of that cloud. COS has taken a really key part of spectroscopic science and said, How can we do that in the absolutely best, most efficient way and that is to measure the properties of the material between the galaxies looking back into the universe. As the galaxies form, there's a lot of material that does not collapse into the galaxies and there's other material that is ejected from galaxies by supernova explosions and so on and so that intergalactic gas, the so-called intergalactic medium, carries a lot of information about the history of the universe.
David Leckrone, HST Chief Scientist:When you couple that story, sort of the global, cosmic process of how you formed a large scale structure of how material is distributed in the universe and what role that played in forming new galaxies and then you use Wide Field Camera 3 to investigate how did the galaxies themselves change internally with time and over space you know looking back through the history of the universe. All of that kind of ties together into the full story of where we came from.
Randy Kimble, Project Scientist, HST Development Project: Its going into the COSTAR slot and so there is nothing whatsoever lost in doing that because COSTAR is not needed anymore. COSTAR was put up in the first servicing mission and it was used to deploy correcting optics in front of some of the first generation instruments, the first generation spectrographs for example. Correcting optics to correct where the spherical aberration that had been inadvertently built into the HST primary mirror. All the more recent instruments include that correction within the new instrument itself. So right now COSTAR doesn't have anything to do. All the other instruments in the so-called axial bays of HST have their own internal correction and so the COSTAR space is freely available and they'll pull that out at no loss of science to HST whatsoever and replace it with this terrific new spectrograph.
Academic standards correlations on Teachers' Domain use the Achievement Standards Network (ASN) database of state and national standards, provided to NSDL projects courtesy of JES & Co.
We assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. If a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by ASN or by Teachers' Domain. We will be adding social studies and arts correlations over the coming year, and also will be increasing the specificity of alignment.