Spectroscopy - Blog Posts
Black Scientists and Engineers Past and Present Enable NASA Space Telescope
The Nancy Grace Roman Space Telescope is NASA’s next flagship astrophysics mission, set to launch by May 2027. We’re currently integrating parts of the spacecraft in the NASA Goddard Space Flight Center clean room.
Once Roman launches, it will allow astronomers to observe the universe like never before. In celebration of Black History Month, let’s get to know some Black scientists and engineers, past and present, whose contributions will allow Roman to make history.
Dr. Beth Brown
The late Dr. Beth Brown worked at NASA Goddard as an astrophysicist. in 1998, Dr. Brown became the first Black American woman to earn a Ph.D. in astronomy at the University of Michigan. While at Goddard, Dr. Brown used data from two NASA X-ray missions – ROSAT (the ROentgen SATellite) and the Chandra X-ray Observatory – to study elliptical galaxies that she believed contained supermassive black holes.
With Roman’s wide field of view and fast survey speeds, astronomers will be able to expand the search for black holes that wander the galaxy without anything nearby to clue us into their presence.
Dr. Harvey Washington Banks
In 1961, Dr. Harvey Washington Banks was the first Black American to graduate with a doctorate in astronomy. His research was on spectroscopy, the study of how light and matter interact, and his research helped advance our knowledge of the field. Roman will use spectroscopy to explore how dark energy is speeding up the universe's expansion.
NOTE - Sensitive technical details have been digitally obscured in this photograph.
Sheri Thorn
Aerospace engineer Sheri Thorn is ensuring Roman’s primary mirror will be protected from the Sun so we can capture the best images of deep space. Thorn works on the Deployable Aperture Cover, a large, soft shade known as a space blanket. It will be mounted to the top of the telescope in the stowed position and then deployed after launch. Thorn helped in the design phase and is now working on building the flight hardware before it goes to environmental testing and is integrated to the spacecraft.
Sanetra Bailey
Roman will be orbiting a million miles away at the second Lagrange point, or L2. Staying updated on the telescope's status and health will be an integral part of keeping the mission running. Electronics engineer Sanetra Bailey is the person who is making sure that will happen. Bailey works on circuits that will act like the brains of the spacecraft, telling it how and where to move and relaying information about its status back down to Earth.
Learn more about Sanetra Bailey and her journey to NASA.
Dr. Gregory Mosby
Roman’s field of view will be at least 100 times larger than the Hubble Space Telescope's, even though the primary mirrors are the same size. What gives Roman the larger field of view are its 18 detectors. Dr. Gregory Mosby is one of the detector scientists on the Roman mission who helped select the flight detectors that will be our “eyes” to the universe.
Dr. Beth Brown, Dr. Harvey Washington Banks, Sheri Thorn, Sanetra Bailey, and Dr. Greg Mosby are just some of the many Black scientists and engineers in astrophysics who have and continue to pave the way for others in the field. The Roman Space Telescope team promises to continue to highlight those who came before us and those who are here now to truly appreciate the amazing science to come.
To stay up to date on the mission, check out our website and follow Roman on X and Facebook.
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The brown dwarf W1935 is a bit of a mystery. Astronomers using the James Webb Space Telescope picked up glowing methane—a sign that the object’s upper atmosphere is being heated. But the brown dwarf has no host star, so where could the heat be coming from?
In our solar system, Jupiter and Saturn show methane emission due to the presence of auroras—what we call the Northern Lights on Earth. W1935 might also have auroras, which could be powered by energetic particles from a nearby, active moon, like Jupiter’s Io: https://webbtelescope.pub/4aKMkBF
A comparison of available data for Jupiter in 1969 compared to 1996, since then we've learned even more. Paper Link
I’ve been dropping the word ‘spectroscopy’ with only minimal explanation for quite a few episodes now and it’s high time I expanded on this topic. Join me for the double-digit episode of this podcast to learn about the history of spectroscopes and spectroscopy, how it taught us about the Sun and stars, and what advancements were made to take spectroscopes into the 20th century.
Below the cut are sources, music credits, a vocabulary list, a timeline of all the astronomers and chemist and physicists I mention, and the transcript of this episode. Let me know what you think I should research next by messaging me here, tweeting at me at @HDandtheVoid, or asking me to my face if you know me in real life. And please check out the podcast on iTunes, rate it or review it if you’d like, subscribe, and maybe tell your friends about it if you think they’d like to listen!
(My thoughts on the next episode were probes through the ages or the transit of Venus. I could also talk about more modern spectroscopy, and I’m planning to interview a friend after the eclipse next week about her graduate-level research into the history of the universe. Let me know by the 17th and I’ll have the next podcast up on August 28th, barring any new-job-related delays.)
Glossary
absorption lines - dark spectral lines that appear in a spectroscope when a gaseous or burned-up element has light shone through it.
angstrom - a unit of length—one hundred-millionth of a centimeter—that is usually used to express wavelengths and the distances in atoms.
emission lines - bright spectral lines that appear in a spectroscope when you burn an element up.
Fraunhofer lines - a standard set of spectral absorption lines observed by Joseph von Fraunhofer. He mapped 574 lines and designated them alphabetically from red to violet in the spectrum with the letters A through K, with weaker lines assigned other, lowercase letters.
incandescent - luminous or glowing due to intense heat.
spectroscopy - the study of light from an incandescent source (or, more recently, electromagnetic radiation and other radiative energy) that has its wavelength dispersed by a prism or other spectroscopic device that can disperse an object’s wavelength. The spectra of distant astronomical objects like the Sun, stars, or nebulae are patterns of absorption lines that correspond to elements that these objects are made up of. This area of study is the major source of the study of astrophysics as well as advancements in chemistry, astronomy, and quantum mechanics.
Script/Transcript
Sources
Prisms vs. diffraction gratings via CSIRO
Definition of ‘angstrom’ via Encyclopedia Brittanica
Definition of ‘incandescent’ via Merriam-Webster
Current uses of spectroscopy in astronomy
Some past and current satellites with spectroscopic capabilities via a John Hopkin’s professor’s old webpage
Spectral classification of stars via University of Nebraska-Lincoln
Common, A. A. “Astronomy.” In Popular Astronomy 8 (1900), 417-24. Located on Google Books preview.
Hirshfeld, Alan. Starlight Detectives. Bellevue Library Press: NY, 2014.
“the Fraunhofer lines, as they were soon to be called, originate in the sun itself, and are neither optical artifacts of the spectroscope nor the result of selective absorption of sunlight within earth’s atmosphere” (168-9).
“the flame’s radiance did not ‘fill in’ the dark D [sodium] lines , as [Kirchhoff] had expected, but reinforced the absorption of these wavelengths of light” (178).
Kirchhoff: “the dark lines of the solar spectrum … exist in the consequence of the presence, in the incandescent atmosphere of the sun, of those substances which in the spectrum of a flame produce bright lines in the same plane” (178).
“a body with a propensity to emit light at a given wavelength must have an equal propensity to absorb light at that wavelength” (178).
“expresses the wavelength of a spectral line, depending on its derivation angle and the density of grooves in the grating” (187).
“mosaic of the solar spectrum assembled from prints of twenty-eight negatives” (187).
“visual confirmation of the chemical unity of the Sun and stars” (203).
Doppler “claimed in 1842 that the perceived frequency of a wave is altered by one’s state of motion” (209).
“In Doppler’s schema, waves from a steadily approaching source are compressed: as their frequency is increased, their wavelength is shortened. Waves from a steadily receding source are stretched: as their frequency is reduced, their wavelength is elongated” (210).
“Yet history has shown that credit for an evolving theory or field, such as stellar spectrum photography, often goes not to individuals who are first to publish, but to those who most convincingly establish the validity and worth of their results” (223).
“Vogel confirmed that the Sun does not rotate as a solid body; Its rotation rate varies with solar latitude, fastest at the equator, progressively slower towards the poles” (231).
“The deviation of the star’s G line from its solar position revealed the star’s Doppler shift and, via a mathematical formula, its line-of-sight motion” (232).
“What Pickering had accomplished for stellar spectral classification with the Henry Draper project, Campbell had accomplished for stellar radial velocities with the Lick catalog” (233).
Johnson, George. Miss Leavitt’s Stars. Atlas Books: NY, 2005.
“When Kirchhoff and Bunsen made the discovery, the existence of atoms was still controversial. Once they were discovered, the effect could be simply understood: when an atom is energized, its electrons jump into higher orbits. When they fall back down they emit various frequencies of light. Every kind of atom is built a little differently, its electrons arrayed in a specific way, resulting in a characteristic pattern. For similar reasons, if you shine a light through a gaseous substance, like hydrogen or helium, certain colors will be filtered out. The result in this case is a characteristic pattern of black ‘absorption’ lines interrupting the spectrum—another unique chemical fingerprint. (The same colors marked by the absorption lines would appear as bright emission lines if the element was burned.)” (102-103).
Rhodes, Richard. The Making of the Atomic Bomb. 2nd ed. Simon & Schuster: NY, 2012.
Timeline
William Herschel, German/English (1738-1822)
Thomas Melvill, American (1751-1832)
William Hyde Wollaston, English (1766-1828)
David Brewster, Scottish (1781-1868)
Françoise Arago, French (1786-1853)
Joseph von Fraunhofer, Bavarian (1787-1826)
William Henry Fox Talbot, English (1800–1877)
George Airy, English (1801-1892)
Christian Doppler, Austrian (1803-1853)
Robert Wilhelm Bunsen, German (1811-1899)
Anders Ångström, Swedish (1814-1874)
Lewis Morris Rutherfurd, American (1816-1892)
William Allen Miller, English (1817-1870)
Pietro Angelo Secchi, Italian (1818-1878)
Armand-Hippolyte-Louis Fizeau, French (1819-1896)
William Huggins, English (1824-1910)
Gustav Kirchhoff, German (1824-1887)
Giovanni Battista Donati, Italian (1826-1873)
James Clerk Maxwell, Scottish (1831-1879)
Henry Draper, American (1837–1882)
Mary Anna Palmer Draper, American (1839–1914)
Hermann Carl Vogel, German (1841-1907)
Edward Charles Pickering, American (1846–1919)
Margaret Lindsay Huggins, Irish/English (1848-1915)
Henry Augustus Rowland, American (1848-1901)
Williamina “Mina” Fleming, Scottish (1857–1911)
William Wallace Campbell, American (1862-1938)
Annie Jump Cannon, American (1863-1941)
Antonia Maury, American (1866-1952)
Vesto Melvin Slipher, American (1875-1969)
Edwin Hubble, American (1889-1953)
Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity
Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught
This is a Trichroic Beam Splitter.
Using this splitter a white beam of light can be separated into three colours. Red, Blue and Green.
Source