Why Webb Needs To Chill
Why Webb Needs to Chill
Our massive James Webb Space Telescope is currently being tested to make sure it can work perfectly at incredibly cold temperatures when it’s in deep space.
How cold is it getting and why? Here’s the whole scoop…
Webb is a giant infrared space telescope that we are currently building. It was designed to see things that other telescopes, even the amazing Hubble Space Telescope, can’t see.
Webb’s giant 6.5-meter diameter primary mirror is part of what gives it superior vision, and it’s coated in gold to optimize it for seeing infrared light.
Why do we want to see infrared light?
Lots of stuff in space emits infrared light, so being able to observe it gives us another tool for understanding the universe. For example, sometimes dust obscures the light from objects we want to study – but if we can see the heat they are emitting, we can still “see” the objects to study them.
It’s like if you were to stick your arm inside a garbage bag. You might not be able to see your arm with your eyes – but if you had an infrared camera, it could see the heat of your arm right through the cooler plastic bag.
Credit: NASA/IPAC
With a powerful infrared space telescope, we can see stars and planets forming inside clouds of dust and gas.
We can also see the very first stars and galaxies that formed in the early universe. These objects are so far away that…well, we haven’t actually been able to see them yet. Also, their light has been shifted from visible light to infrared because the universe is expanding, and as the distances between the galaxies stretch, the light from them also stretches towards redder wavelengths.
We call this phenomena “redshift.” This means that for us, these objects can be quite dim at visible wavelengths, but bright at infrared ones. With a powerful enough infrared telescope, we can see these never-before-seen objects.
We can also study the atmospheres of planets orbiting other stars. Many of the elements and molecules we want to study in planetary atmospheres have characteristic signatures in the infrared.
Because infrared light comes from objects that are warm, in order to detect the super faint heat signals of things that are really, really far away, the telescope itself has to be very cold. How cold does the telescope have to be? Webb’s operating temperature is under 50K (or -370F/-223 C). As a comparison, water freezes at 273K (or 32 F/0 C).
How do we keep the telescope that cold?
Because there is no atmosphere in space, as long as you can keep something out of the Sun, it will get very cold. So Webb, as a whole, doesn’t need freezers or coolers - instead it has a giant sunshield that keeps it in the shade. (We do have one instrument on Webb that does have a cryocooler because it needs to operate at 7K.)
Also, we have to be careful that no nearby bright things can shine into the telescope – Webb is so sensitive to faint infrared light, that bright light could essentially blind it. The sunshield is able to protect the telescope from the light and heat of the Earth and Moon, as well as the Sun.
Out at what we call the Second Lagrange point, where the telescope will orbit the Sun in line with the Earth, the sunshield is able to always block the light from bright objects like the Earth, Sun and Moon.
How do we make sure it all works in space?
By lots of testing on the ground before we launch it. Every piece of the telescope was designed to work at the cold temperatures it will operate at in space and was tested in simulated space conditions. The mirrors were tested at cryogenic temperatures after every phase of their manufacturing process.
The instruments went through multiple cryogenic tests at our Goddard Space Flight Center in Maryland.
Once the telescope (instruments and optics) was assembled, it even underwent a full end-to-end test in our Johnson Space Center’s giant cryogenic chamber, to ensure the whole system will work perfectly in space.
What’s next for Webb?
It will move to Northrop Grumman where it will be mated to the sunshield, as well as the spacecraft bus, which provides support functions like electrical power, attitude control, thermal control, communications, data handling and propulsion to the spacecraft.
Learn more about the James Webb Space Telescope HERE, or follow the mission on Facebook, Twitter and Instagram.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
More Posts from Fillthevoid-with-space and Others
Scott Kelly just tweeted this photo of the Moon, Venus, Jupiter and Earth as seen from the International Space Station
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Gretchen: On the International Space Station, you have astronauts from the US and from other English speaking countries and you have cosmonauts from Russia. And obviously it’s very important to get your communication right if you’re on a tiny metal box circling the Earth or going somewhere. You don’t want to have a miscommunication there because you could end up floating in space in the wrong way. And so one of the things that they do on the ISS – so first of all every astronaut and cosmonaut needs to be bilingual in English and Russian because those are the languages of space. Lauren: Yep. Wait, the language of space are English and Russian? I’m sorry, I just said ‘yep’ and I didn’t really think about it, so that’s a fact is it? Gretchen: I mean, pretty much, yeah, if you go on astronaut training recruitment forums, which I have gone on to research this episode… Lauren: You’re got to have a backup job, Gretchen. Gretchen: I don’t think I’m going to become an astronaut, but I would like to do astronaut linguistics. And one of the things these forums say, is, you need to know stuff about math and engineering and, like, how to fly planes and so on. But they also say, you either have to arrive knowing English and Russian or they put you through an intensive language training course. But then when they’re up in space, one of the things that they do is have the English native speakers speak Russian and the Russian speakers speak English. Because the idea is, if you speak your native language, maybe you’re speaking too fast or maybe you’re not sure if the other person’s really understanding you. Whereas if you both speak the language you’re not as fluent in, then you arrive at a level where where people can be sure that the other person’s understanding. And by now, there’s kind of this hybrid English-Russian language that’s developed. Not a full-fledged language but kind of a- Lauren: Space Creole! Gretchen: Yeah, a Space Pidgin that the astronauts use to speak with each other! I don’t know if anyone’s written a grammar of it, but I really want to see a grammar of Space Pidgin.
Excerpt from Episode 1 of Lingthusiasm: Speaking a single language won’t bring about world peace. Listen to the full episode, read the transcript, or check out the show notes. (via lingthusiasm)
Aboard the International Space Station, astronaut Thomas Pesquet of the European Space Agency snapped this photo and wrote, ‘The view at night recently has been simply magnificent: few clouds, intense #aurora. I can’t look away from the windows.'
The dancing lights of the aurora provide stunning views, but also capture the imagination of scientists who study incoming energy and particles from the sun. Aurora are one effect of such energetic particles, which can speed out from the sun both in a steady stream called the solar wind and due to giant eruptions known as coronal mass ejections or CMEs. Credit: NASA/ESA
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
The Moon of Lakes and Rivers - Saturn’s moon Titan
Saturn’s moon Titan is the only world - other than earth - that we know has liquid’s pooled on its surface. Unlike Earth, Titan has lakes of liquid methane - you wouldn’t want to swim in these lakes.
Titan’s “methane cycle” is analogy to Earth’s water cycle. In the 3rd and 4th images above we can see clouds of methane in Titan’s atmosphere. Ever since NASA’s Voyager 1 spacecraft, we have known that the gases that make up Titan’s brown colored haze were hydrocarbons. The atmosphere of Titan is largely nitrogen; minor components lead to the formation of methane–ethane clouds and nitrogen-rich organic smog.
It is thanks to the Cassini spacecraft that we now understand more about the climate of Titan - though we still understand very little!
The Cassini Space craft has mapped most of the Northern polar region of Titan, this is the region that contains almost all of Titan’s lakes. Cassini is systematically sweeping across Titan and mapping the surface of this strange alien world. The image below is an example of Cassini’s mapping process:
Credit: NASA/JPL/Cassini
Spacewalk complete and new astronaut record set! Shane Kimbrough and Peggy Whitson of NASA successfully reconnected cables and electrical connections on an adapter-3 that will provide the pressurized interface between the station and the second of two international docking adapters to be delivered to the complex to support the dockings of U.S. commercial crew spacecraft in the future. The duo were also tasked with installing four thermal protection shields on the Tranquility module of the International Space Station.
Having completed her eighth spacewalk, Whitson now holds the record for the most spacewalks and accumulated time spacewalking by a female astronaut. Spacewalkers have now spent a total of 1,243 hours and 42 minutes outside the station during 199 spacewalks in support of assembly and maintenance of the orbiting laboratory.
Astronaut Thomas Pesquet of ESA posted this image and wrote, ’ Shane and Peggy on their way to their first #spacewalk tasks.’
Credit: ESA/NASA
I found a bizarre open-access, peer-review journal of STEM research. It was hard for me to find anything that pertained to astronomy or any of the stellar studies, but I did find a couple categories I could investigate:
Astrobiology
Astronomical Sciences
Spectroscopy (I didn’t see any astronomical spectroscopy stuff but who knows)
Just looking at the articles popping up suggests that it would take some serious digging to find anything (and I would certainly have to work on my keyword optimization techniques because typing ‘space’ into the search bar got me nothing relevant to my interests), but it’s a new potential resource! And for anyone who wants to find a way to publish in STEM fields, maybe it’s something worth checking out?
When I was in Ireland in 2013, I kept seeing signs for ‘quasar.’ I finally learned that it’s the European way of saying laser tag. It has nothing to do with quasars, which are a specific type of a specific type of galaxy. Listen to this week’s (pretty short) podcast on two types of active galaxies: quasars and blazars.
Below the cut, I have the transcript, sources, music credits, and timeline of people I talked about! If you have suggestions for topics I could cover, please send me a Tumblr message or tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me. Please subscribe on iTunes, rate my podcast and maybe review it, and tell friends if you think they’d like to hear it!
(My thoughts on the next episode are the SOFIA observatory, Chuck Yaeger, or the great Stephen Hawking. The next episode will go up April 2nd.)
Glossary
active galaxy or active galactic nucleus- a galaxy with a small core of emission embedded at the center. This core is typically very variable and very bright compared to the rest of the galaxy. These galaxies emit much more energy than they should; this excess energy is found in the infrared, radio, UV, and X-ray regions of the electromagnetic spectrum.
blazar - a subcategory of active galaxy, it is an extremely bright, distant object, powered by a black hole, which emits massive amounts of energy. It is distinct from a quasar because it is even brighter.
extragalactic objects - objects outside our Milky Way galaxy.
interferometry - a group of techniques to extract information from superimposing electromagnetic waves to create interference. In radio astronomy, this is done by using a wide spread of receivers to look at the same distant object, then bringing that data together with a correlator that can create a larger, clearer picture than an individual radio telescope alone could.
lunar occultations - when stars pass behind the Moon. This is the basis for a method of determining and mapping star positions.
quasar - a subcategory of active galaxy, it is an extremely bright, distant object, powered by a black hole, which emits massive amounts of energy. It is distinct from a blazar because it is less-bright. The name is a contraction of “quasi-stellar radio source” (which is not necessarily true of all quasars—90% are radio-quiet).
torus - a donut shape.
Script/Transcript
Timeline
Walter Baade, German (1893-1960)
Rudolph Minkowski, German-American (1895-1976)
Fritz Zwicky, Swiss (1898-1974)
Gordon Stanley, New Zealander (1921-2001)
John Bolton, English-Australian (1922-1993)
Owen Bruce Slee, Australian (1924-2016)
Allan Rex Sandage, American (1926-2010)
Cyril Hazard, English (1928- )
Maartin Schmidt, Dutch (1929- )
Hong-Yee Chiu, American (1932- )
Stephen Hawking, English (1942 -2018)
Jedidah Isler
Sources
Active Galaxies via NASA (Dec 2016)
Galaxy shapes via Cornell University (April 2000)
Galaxies and Black Holes by David Merritt, published on NED by Caltech and NASA
Cyril Hazard via University of Pittsburgh
The Discovery of Quasars and its Aftermath via Journal of Astronomical History and Heritage (2014)
“Characteristically, Fritz Zwicky (1898–1974; Figure 11) immediately pointed out that ‘All of the five quasi-stellar galaxies described individually by Sandage (1965) evidently belong to the subclass of compact galaxies with pure emission spectra previously discovered and described by the present writer. (Zwicky, 1965: 1293).’ A few years later, Zwicky was less circumspect and wrote: ‘In spite of all these facts being known to him in 1964, Sandage attempted one of the most astounding feats of plagiarism by announcing the existence of a major new component of the Universe: the quasi-stellar galaxies ... Sandage‘s earthshaking discovery consisted in nothing more than renaming compact galaxies, calling them ‘interlopers‘ and quasistellar galaxies, thus playing the interloper himself. (Zwicky and Zwicky, 1971: xix)’”
Lunar occultations via Sky and Telescope
Quasars and Blazars by Matthew Whiting (a chapter in his thesis, What made the quasar blush? Emission mechanisms in optically-red quasars) via the Australia Telescope National Facility (2000)
Jedidah Isler on quasars and blazars via TED Talks (March 2015)
Quasar definition via Space.com (Feb 2018)
Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity
Filler Music: ‘Into The White’ by Pixies off their album Wave of Mutilation.
Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught
What are the most important skills an astronaut should have m?
First of all, the basic requirement is a bachelor’s degree in a STEM field, and 3 years of experience (which can also be substituted for by an advanced degree). Other than that, operational experience (things with a technical/active/hands on nature like flying airplanes, SCUBA diving, taking things apart and putting them back together, basic fix-it skills, etc. etc.) is very important, as this is an integral aspect of every day of a space mission. What we call “expeditionary skills” are also essential, basically the types of things you try to instill in your children, like how to play nicely with others, self care, team care, etc. I like to think about this on the lines of a camping trip and who you would like to have along with you …someone that is competent and can take good care of themselves and their equipment, someone that contributes to the team and helps with group tasks, someone that is good natured and pleasant to be around, etc., someone fun! These things are increasingly important now that we are regularly doing long duration missions (typical International Space Station mission is 6 months). Experience living in extreme/remote/isolated environments with small teams is also useful, as it is similar to what we experience as astronauts.
Haaaaaay I’m on iTunes now! Slightly more convenient to download maybe!
The inner planets and the outer planets all look like stars from Earth. They are strange stars that move in strange ways, but their appearance depends on how they relate to observers on Earth. They are also affected by their position in relation to the Sun. Planets experience eclipses as well when the Sun, Earth, and planet are all aligned; in the inner planets, this is called a transit, and this has been a source of vast information about the solar system and the planets’ places in that system. In the outer planets, this eclipsing is called opposition. You get to hear about both in this week’s podcast!
Below the cut, I have the glossary, transcript, timeline of astronomers, sources, and music credits. I take topic suggestions from Tumblr messages, or you can tweet at me on Twitter at @HDandtheVoid, or you can ask me to my face if you know me. Please subscribe on iTunes, rate my podcast and maybe review it, and tell friends if you think they’d like to hear it!
(My thoughts on the next episode are Chuck Yeager, Edmond Halley, Stephen Hawking and his theories, or famous comets. The next episode will go up later in June!)
Glossary
aphelion - a planet’s most distant position from the Sun
black drop effect - an optical illusion where a planet nearing the edge of the Sun appears to be connected to the Sun’s edge by a black teardrop.
conjunction - when the Earth, Sun, and another planet in the solar system are aligned so that Earth and the planet are on opposite sides of the Sun.
node - the point where another planet’s orbit crosses the plane of Earth’s orbit. The planets’ orbits are tilted at slightly different angles from each other; for example, Mercury’s orbit is inclined 7 degrees compared to Earth’s orbit. Because Mercury orbits the Sun once every 88 days, it crosses Earth’s orbit every 44 days at these nodes.
opposition - when one of the outer planets crosses the plane of Earth’s orbit opposite the Sun.
perihelion - a planet’s closest position to the Sun
retrograde - the apparent motion of a planet in a direction opposite to that of other bodies within its system, as observed from a particular vantage point.
syzygy - the straight line between three celestial bodies, usually the Sun to the Earth to another planetary body.
transit - when one of the inner planets crosses between the plane of Earth’s orbit and the Sun.
Script/Transcript
Timeline
Bernhard Walther, German (1430-1504)
Johannes Regiomontanus, German (1436-1476)
Willibald Pirckheimer, German (1470-1530)
Nicolaus Copernicus, Polish (1473-1543)
Georg Rheticus, Austrian (1514-1574)
Johannes Kepler, German (1571-1630)
Pierre Gassendi, French (1592-1655)
Johannes Hevelius, Polish (1611-1687)
Jeremiah Horrocks, English (1618-1641)
Edmond Halley, English (1656-1742)
Leonhard Euler, Swiss (1707-1783)
Alexandre Guy Pingré, French (1711-1796)
César-François Cassini de Thury, French (1714-1784)
Maximilian Hell, Hungarian (1720-1792)
Jean-Baptiste Chappe d’Auteroche, French (1722-1769)
James Cook, English (1728-1779)
Charles Mason, English (1728-1786)
Jeremiah Dixon, English (1733-1779)
János Sajnovics, Hungarian (1733-1785)
Thomas Hornsby, English (1733-1810)
Charles Green, English (1734-1771)
Joseph Jérôme Lefrançois de Lalande, French (1732-1807)
Jean Guillaume Wallot, French/German (1743-1794)
Christian VII of Denmark, Danish (1749-1808)
Sources
Mercury Solar Transit (image) via NASA
Mercury Transit of the Sun: Why Is It So Rare? via Space.com (May 2016)
The 2016 Transit of Mercury via NASA
Before the Transit of Mercury: forgotten forerunners of an astronomical revolution via The Guardian (May 2016)
Catalog of Venus Transits via NASA’s Fred Espenak
Mars Opposition via NASA
Mars brighter in 2018 than since 2003 via EarthSky (May 2018)
Opposition of Superior Planets via Hong Kong Observatory
Saturn at Opposition via NASA
Earth between sun and Saturn late June via EarthSky (Jun 2018 [not possible because I’m releasing this podcast in May 2018 but okay])
Uranus at opposition via EarthSky (Oct 2017)
Earth passing between Neptune and sun via EarthSky (Sept 2018 [not possible because I’m releasing this podcast in May 2018 but okay])
Anderson, Mark. The Day the World Discovered the Sun. Da Capo Press: Philadelphia, 2012.
“Visionaries like Edmund Halley had in 1716, for instance, argued that the Venus transit could enable science to trace out a map of the solar system accurate to 99.8 percent or better” (191).
Wulf, Andrea. Chasing Venus: The Race to Measure the Heavens. Alfred A. Knopf: New York, 2012.
Intro Music: ‘Better Times Will Come’ by No Luck Club off their album Prosperity
Filler Music: ‘Cannonballs’ by Hey Marseilles off their album To Travels and Trunks.
Outro Music: ‘Fields of Russia’ by Mutefish off their album On Draught
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A podcast project to fill the space in my heart and my time that used to be filled with academic research. In 2018, that space gets filled with... MORE SPACE! Cheerfully researched, painstakingly edited, informal as hell, definitely worth everyone's time.
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