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Look up into the rainy sky! What do you see? Well, if its just rained and the sun is once again shining, chances are you see a rainbow. Always a lovely sight isn’t it? But why is it that after a rainstorm, the air seems to catch the light in just the right way to produce this magnificent natural phenomenon? Much like stars, galaxies, and the flight of a bumblebee, some complicated physics underlie this beautiful act of nature. For starters, this effect, where light is broken into the visible spectrum of colors, is known as the Dispersion of Light. Another name for it is the prismatic effect, since the effect is the same as if one looked at light through a prism.
To put it simply, light is transmitted on several different frequencies or wavelengths. What we know as “color” is in reality the visible wavelengths of light, all of which travel at different speeds through different media. In other words, light moves at different speed through the vacuum of space than it does through air, water, glass or crystal. And when it comes into contact with a different medium, the different color wavelengths are refracted at different angles. Those frequencies which travel faster are refracted at a lower angle while those that travel slower are refracted at a sharper angle. In other words, they are dispersed based on their frequency and wavelength, as well as the materials Index of Refraction (i.e. how sharply it refracts light).
The overall effect of this – different frequencies of light being refracted at different angles as they pass through a medium – is that they appear as a spectrum of color to the naked eye. In the case of the rainbow, this occurs as a result of light passing through air that is saturated with water. Sunlight is often referred to as “white light” since it is a combination of all the visible colors. However, when the light strikes the water molecules, which have a stronger index of refraction than air, it disperses into the visible spectrum, thus creating the illusion of a colored arc in the sky.
Now consider a window pane and a prism. When light passes through glass that has parallel sides, the light will return in the same direction that it entered the material. But if the material is shaped like a prism, the angles for each color will be exaggerated, and the colors will be displayed as a spectrum of light. Red, since it has the longest wavelength (700 nanometers) appears at the top of the spectrum, being refracted the least. It is followed shortly thereafter by Orange, Yellow, Green, Blue, Indigo and Violet (or ROY G. GIV, as some like to say). These colors, it should be noted, do not appear as perfectly distinct, but blend at the edges. It is only through ongoing experimentation and measurement that scientists were able to determine the distinct colors and their particular frequencies/wavelengths.
We have written many articles about dispersion of light for Universe Today. Here’s an article about the refractor telescope, and here’s an article about visible light.
Opportunity investigates Tisdale 2 rock showing indications of ancient Martian water flow. NASA's Mars Exploration Rover Opportunity used its front hazard-avoidance camera to take this picture showing the rover's arm extended toward a light-toned rock, "Tisdale 2," during Sol 2695 of the rover's work on Mars (Aug. 23, 2011). The composition of Tisdale 2 is unlike any rock studied by Opportunity since landing 7.5 years ago. It is about 12 inches (30 centimeters) tall. Credit: NASA/JPL-Caltech
Scientists directing NASA’s Mars Opportunity rover gushed with excitement as they announced that the aging robot has discovered a rock with a composition unlike anything previously explored on the Red Planet’s surface – since she landed on the exotic Martian plains 7.5 years ago – and which offers indications that liquid water might have percolated or flowed at this spot billions of years ago.
Barely three weeks ago Opportunity arrived at the rim of the gigantic 14 mile ( 22 km) wide crater named Endeavour after an epic multi-year trek, and for the team it’s literally been like a 2nd landing on Mars – and the equivalent of the birth of a whole new mission of exploration at an entirely ‘new’ landing site.
“This is like having a brand new landing site for our veteran rover,” said Dave Lavery, program executive for NASA’s Mars Exploration Rovers at NASA Headquarters in Washington. “It is a remarkable bonus that comes from being able to rove on Mars with well-built hardware that lasts.”
Opportunity has traversed an incredible distance of 20.8 miles (33.5 km) across the Meridiani Planum region of Mars since landing on January 24, 2004 for a 3 month mission – now 30 times longer than the original warranty.
“Tisdale 2” is the name of the first rock that Opportunity drove to and investigated after reaching Endeavour crater and climbing up the rim at a low ridge dubbed ‘Cape York’.
This rock, informally named "Tisdale 2," was the first rock the NASA's Mars Rover Opportunity examined in detail on the rim of Endeavour crater. It has textures and composition unlike any rock the rover examined during its first 90 months on Mars. Its characteristics are consistent with the rock being a breccia -- a type of rock fusing together broken fragments of older rocks. Image credit: NASA/JPL-Caltech/Cornell/ASU
Endeavour’s rim is heavily eroded and discontinuous and divided into a series of segmented and beautiful mountainous ridges that offer a bonanza for science.
“This is not like anything we’ve ever seen before. So this is a new kind of rock.” said Steve Squyres, principal investigator for Opportunity at Cornell University in Ithaca, N.Y at a briefing for reporters on Sept. 1.
“It has a composition similar to some volcanic rocks, but there’s much more zinc and bromine than we’ve typically seen. We are getting confirmation that reaching Endeavour really has given us the equivalent of a second landing site for Opportunity.”
Tisdale 2 is a flat-topped rock about the size of a footstool that was blasted free by the impact that formed the tennis court sized “Odyssey” crater from which it was ejected.
“The other big take-away message, and this is to me the most interesting thing about Tisdale, is that this rock has a huge amount of zinc in it, way more zinc than we have ever seen in any Martian rock. And we are puzzling, we are thinking very hard over what that means,” Squyres speculated.
Bright veins cutting across outcrop in a section of Endeavour crater's rim called "Botany Bay" are visible in the foreground and middle distance of this view assembled from images taken by the navigation camera on Opportunity during Sol 2,681on Mars (Aug. 9, 2011). Credit: NASA/JPL-Caltech
Squyres said that high levels of zinc and bromine on Earth are often associated with rocks in contact with flowing water and thus experiencing hydrothermal activity and that the impact is the source of the water.
“When you find rocks on Earth that are rich in zinc, they typically form in a place where you had some kind of hydrothermal activity going on, in other words, you have water that gets heated up and it flows through the rocks and it can dissolve out and it can get redeposited in various places,” Squyres explained.
“So this is a clue, not definitive proof yet, but this is a clue that we may be dealing with a hydrothermal system here, we may be dealing with a situation where water has percolated or flowed or somehow moved through these rocks, maybe as vapor, maybe as liquid, don’t know yet.”
“But it has enhanced the zinc concentration in this rock to levels far in excess of anything we’ve ever seen on Mars before. So that’s the beginning of what we expect is going to be a long and very interesting story about these rocks.”
Endeavour crater was chosen three years ago as the long term destination for Opportunity because it may hold clues to a time billions and billions of years ago when Mars was warmer and wetter and harbored an environment that was far more conducive to the formation of life beyond Earth.
Endeavour Crater Panorama from Opportunity, Sol 2681, August 2011
Opportunity arrived at the rim of Endeavour on Sol 2681, August 9, 2011 and climbed up the ridge known as Cape York. Odyssey crater is visible at left. The rover has driven to Tisdale 2 rock at the outskirts of Odyssey to investigate the ejecta blocks which may hold clues to ancient water flow on Mars. Distant portions of Endeavour’s rim - as far as 13 miles away – visible in the background. The rover will likely drive eventually to the Cape Tribulation rim segment at right which holds a mother lode of clay minerals. This photo mosaic was stitched together from raw images taken by Opportunity on Sol 2681.
Mosaic Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Kenneth Kremer
Signatures of clay minerals, or phyllosilicates, were detected at several spots at Endeavour’s western rim by observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard NASA’s Mars Reconnaissance Orbiter (MRO).
“The motherlode of clay minerals is on Cape Tribulation. The exposure extends all the way to the top, mainly on the inboard side,” said Ray Arvidson, the rover’s deputy principal investigator at Washington University in St. Louis.
Opportunity Traverse Map: 2004 to 2011. The yellow line on this map shows where NASA's Mars Rover Opportunity has driven from the place where it landed in January 2004 -- inside Eagle crater, at the upper left end of the track -- to a point approaching the rim of Endeavour crater. The map traces the route through the 2,670th Martian day, or sol, of Opportunity's work on Mars (July 29, 2011). Image credit: NASA/JPL-Caltech/MSSS/NMMNHS.
Phyllosilicates are clay minerals that form in the presence of pH neutral water and which are far more hospitable to the possible genesis of life compared to the sulfate rich rocks studied in the more highly acidic aqueous environments examined by both the Opportunity and Spirit rovers thus far.
“We can get up the side of Cape Tribulation,” said Arvidson. It’s not unlike Husband Hill for Spirit. We need to finish up first at Cape York, get through the martian winter and then start working our way south along Solander Point.
The general plan is that Opportunity will probably spend the next several months exploring the Cape York region for before going elsewhere. “Just from Tisdale 2 we know that we have something really new and different here,” said Squyres.
“On the final traverses to Cape York, we saw ragged outcrops at Botany Bay unlike anything Opportunity has seen so far, and a bench around the edge of Cape York looks like sedimentary rock that’s been cut and filled with veins of material possibly delivered by water,” said Arvidson. “We made an explicit decision to examine ancient rocks of Cape York first.”
So far at least the terrain at Cape York looks safe for driving with good prospects for mobility.
Opportunity approaches Tisdale 2 rock at Endeavour Crater rim
Opportunity Mars rover climbed up the ridge known as Cape York and drove to the flat topped Tisdale 2 rock at upper left to analyze it with the science instruments on the robotic arm. This photo mosaic was stitched together from raw images taken by Opportunity on Sol 2685, August 2011.
Mosaic Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Kenneth Kremer
“The good news is that, as predicted, we have hard packed soils like the plains at Gusev that Spirit saw before getting to the Columbia Hills,” said Arvidson. “The wheel tracks at Cape York are very, very shallow. So if anything we will have some skid going downhill the slopes of 5 to 10 degrees on the inboard side which we can correct for.”
“We are always on the lookout for sand traps. We are particularly sensitized to that after the Spirit situation. So far it’s clear sailing ahead.”
Opportunity will then likely head southwards towards an area dubbed “Botany Bay” and eventually drive some 1.5 km further to the next ridge named Cape Tribulation and hopefully scale the slopes in an uphill search for that mother lode of phyllosilicates.
“My strong hope – if the rover lasts that long – is that we will have a vehicle that is capable of climbing Cape Tribulation just as we climbed Husband Hill with Spirit. So it’s obvious to try if the rover is capable, otherwise we would try something simpler. But even if we lose a wheel we still have a vehicle capable of a lot of science,” Squyres emphasized. “Then we would stick to lower ground and more gently sloping stuff.”
“The clear intention as we finish up at Cape York, and look at what to do next, is that we are going to work our way south. We will focus along the crater’s rim. We will work south along the rim of Endeavour unless some discovery unexpectedly causes us to do something else.”
“We will go where the science takes us !” Squyres stated.
Opportunity is in generally good health but the rover is showing signs of aging.
“All in all, we have a very senior rover that’s showing her age, she has some arthritis and some other issues but generally, she’s in good health, she’s sleeping well at night, her cholesterol levels are excellent and so we look forward to productive scientific exploration for the period ahead,” said John Callas, project manager for Opportunity at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“This has the potential to be the most revealing destination ever explored by Opportunity,” said Lavery. “This region is substantially different than anything we’ve seen before. We’re looking at this next phase of Opportunity’s exploration as a whole new mission, entering an area that is significantly different in the geologic context than anything we’ve seen with the rovers.”
This image taken from orbit shows the path of the path driven by NASA's Mars Exploration Rover Opportunity in the weeks around the rover's arrival at the rim of Endeavour crater. The sol number (number of Martian days since the rover landed on Mars) are indicated along the route. Sol 2674 corresponds to Aug. 2, 2011; Sol 2688 corresponds to Aug. 16, 2011. Image credit: NASA/JPL-Caltech/University of ArizonaElevated Zinc and Bromine in Tisdale 2 Rock on Endeavour Rim. This graphic presents information gained by examining part of the Martian rock called "Tisdale 2" with the alpha particle X-ray spectrometer on Mars rover Opportunity and comparing the composition measured there with compositions of other targets examined by Opportunity and its rover twin, Spirit. The comparison targets are soil in Gusev crater, examined by Spirit; the relatively fresh basaltic rock Adirondack, examined by Spirit; the stony meteorite Marquette examined by Opportunity; and Gibraltar, an example of sulfate-rich bedrock examined by Opportunity. The target area on Tisdale 2, called "Timmins 1," contains elevated levels of bromine (Br), zinc (Zn), phosphorus (P), sulfur (S) and chlorine (Cl) relative to the non-sulfate-rich comparison rocks, and high levels of zinc and phosphorus relative to Gibraltar. Credit: NASA/JPL-Caltech/Cornell/Max Planck Institute/University of Guelph
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For some time, the behavior of light has baffled scientists. Initially, and in accordance with classic physics, light was thought to be a wave, an indefinable form of energy that simply flowed from a heated source. However, with the advent of quantum physics, scientists came to realize that photons, a tiny elementary particle responsible for all forms of electromagnetic radiation, was in fact the source. So you can imagine how confounded they were when, in the course of performing experiments, they discovered that it exhibited the behavior of both a particle and a wave! This rather unique behavior, the ability of light to behave as a wave, even though it is made up of tiny particles, is known as the Diffraction of Light.
By definition, diffraction refers to the apparent bending of waves around small obstacles and the spreading out of waves past small openings. It had long been understood that this is what happens when a wave encounters an obstacle, and by the 17th and 18th centuries, this behavior was observed through experiments involving light. One such physicist who observed this at work was Thomas Young (1773 – 1829), an English polymath who is credited devised the double-slit experiment. In this experiment, Young shone a monochromatic light source (i.e. light of a single color) through an aperture (in this case, a wall with a horizontal slits cut in it) and measured the results on a screen located on the other side. The results were interesting, to say the least. Instead of appearing in the same relative shape as the aperture, the light appeared to be diffracting, implying that it was made up of waves. The experiment was even more interesting when a second slit was cut into the screen (hence the name double-slit). Young, and those who repeated the experiment, found that interference waves resulted, meaning that two propagation waves occurred which then began to interfere with one another.
A more common example comes to us in the form of shadows. Ever notice how the outer edges do not appear solid, but slightly fuzzy instead? This occurs as a result of light bending slightly as it passes around the edge of an object, again, consistent with the behavior of a wave. Similar effects occur when light waves travel through a medium with a varying refractive index, resulting in a spectrum of color or a distorted image. Since all physical objects have wave-like properties at the atomic level, diffraction can be studied in accordance with the principles of quantum mechanics.
We have written many articles about diffraction of light for Universe Today. Here’s an article about visible light, and here’s an article about telescope resolution.
If you’d like more info on diffraction of light, check out these articles:
The Physics of Light: Diffraction Experiments on Diffraction of Light
This view of Earth comes from NASA's Moderate Resolution Imaging Spectroradiometer aboard the Terra satellite
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The planet Earth has three motions: it rotates about its axis, which gives us day and night; it revolves around the sun, giving us the seasons of the year, and through the Milky Way along with the rest of the Solar System. In each case, scientists have striven to calculate not only the time it takes, but the relative velocities involved. When it comes to the Earth rotating on its axis, a process which takes 23 hours, 56 minutes and 4.09 seconds, the process is known as a sidereal day, and the speed at which it moves is known as the Earth’s Angular Velocity. This applies equally to the Earth rotating around the axis of the Sun and the center of the Milky Way Galaxy.
In physics, the angular velocity is a vector quantity which specifies the angular speed of an object and the axis about which the object is rotating. The SI unit of angular velocity is radians per second, although it may be measured in other units such as degrees per second, revolutions per second, etc. and is usually represented by the symbol omega (ω, rarely Ω). A radian, by definition, is a unit which connects the radius of an arc, the length of the arc and the angle subtended by the arc. A full radian is 360 degrees, hence we know that the Earth performs two radians when performing a full rotation around an axis. However, it is sometimes also called the rotational velocity and its magnitude – the rotational speed – is typically measured in cycles or rotations per unit time (e.g. revolutions per minute). In addition, when an object rotating about an axis, every point on the object has the same angular velocity.
Mathematically, the average angular velocity of an object can be represented by the following equation: ωaverage= Δθ/Δt, where ω is the radians/revolutions per second (on average), Δ is the change in quantity, θ is the velocity, and t is time. When calculating the angular velocity of the Earth as it completes a full rotation on its own axis (a solar day), this equation is represented as: ωavg = 2πrad/1day (86400 seconds), which works out to a moderate angular velocity of 7.2921159 × 10-5 radians/second. In the case of a Solar Year, where ωavg = 2πrad/1year (3.2×107 seconds), we see that the angular velocity works out to 2.0×10-7 rad/s.
We have written many articles about the angular velocity of Earth for Universe Today. Here’s an article about angular velocity, and here’s an article about why the Earth rotates.
The book Lunar and Planetary Rovers offers a bit of a primer before NASA's Mars Science Laboratory launches to Mars this November. Image Credit: NASA/Spinger/Praxis
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Ordinarily if a book attempts to cover crewed and unmanned missions – the book is a compilation of space flight history in general. This is not the case when it comes to Springer/Praxis’ offering Lunar and Planetary Rovers. Written by Anthony Young, the book details both crewed (the Apollo “J” missions) and unmanned rovers (Pathfinder, Mars Exploration Rovers and Curiosity). The book is not a perfect blending of the two interconnected, yet separate programs – but it does have much to offer.
First published in 2010, the book is a well-researched, detailed account of the lunar rovers that flew on Apollos 15, 16 and 17 and the robotic explorers that have scoured the face of the red planet – Mars.
Lunar and Planetary Rovers covers both the manned rovers used on the final three Apollo lunar missions and the unmanned rovers used to explore the surface of Mars - under one book. Photo Credit: NASA/Jack Schmitt
Lunar and Planetary Rovers fills a need for an account of efforts to get wheels on other worlds. The book is filled with numerous photographs (both color and black and white) that have never been published before. In terms of the Apollo Program, Lunar and Planetary Rovers is replete with quotes from the astronauts that drove the lunar rovers on the Moon. In terms of the unmanned planetary rovers, the book pulls from the engineers and scientists that made (and make) these machines work.
The book is 305 pages long. It could have stood to be a few pages longer. One glaring omission in the general body of the book is that of the Lunokhods (these amazing machines are mentioned in the appendix of the book). Given that the Lunokhods bridge the gap between the Apollo Program’s manned lunar rovers (in that they both rolled across the lunar regolith) and the robotic planetary rovers – this is a fairly significant gap in coverage of the topic. The book also does not tie these two, separate, programs together very well (the jump from one topic to the other is jarring and not done consistently).
For some reason, Russia's Lunokhod Rover, the first unmanned rover to explore another world, is only mentioned in passing - at the very end of the book. Photo Credit: NASA
Even when one considers this slight flaw – the book still provides an accurate and useful history of rovers. Lunar and Planetary Rovers can be purchased on the secondary market (Amazon) for approximately $5 (that is including shipping and handling) the book is a good buy for those wanting information concerning the topic. For those that are not interested in the traditional, paper, format a Kindle edition is available for around $25.
With the launch of the Mars Science Laboratory (MSL) or Curiosity as it is more commonly known currently scheduled to take place this November – this book serves as a historical reminder as to how the technology employed by Curiosity was both developed and refined.
Lunar and Planetary Rovers details all of the rovers to traverse the surface of the red planet, from the Mars Pathfinder; seen here, to Curiosity - currently set to launch on Nov. 25, 2011. Photo Credit: NASA.gov
Jane Houston Jones from JPL provides information on what’s up for September, focusing on the Moon. The next few days will be a good time to look for the Apollo landing sites — and no, you won’t be able to see any details from Earth, even with a good telescope, but it is fun to try and locate the areas humans have walked on the Moon. Jane shows you how. And of course, the GRAIL mission to the Moon is scheduled to launch on Sept. 8. Learn more about the mission here.
And as a heads up, look for new images of the Apollo landing sites from the Lunar Reconnaissance Orbiter that will be released next week. LRO recently moved closer to the Moon to take new and improved images of these historic sites. We’ll share them as soon as they are available.
Occultation Path For Delta Scorpii - September 3, 2011 Courtesy of IOTA
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Are you ready for a weekend observing treat? Then get out your binoculars, telescopes, or just your eyes as the Moon passes over a bright star. Who, what, when and where? Come on inside and find out…
On September 3, 2001 the dark limb of the Moon will encounter 2.3 magnitude Delta Scorpii. The event can be seen from the eastern and southern United States to northern Venezuela. But don’t be discouraged if you aren’t right in that “zone”. For observers from roughly New York City through central Texas to Baja California, you’ll have an event called a “graze” – where the star will appear to slide along the edge – or just be mighty close.
When do you need to observe? Thankfully the event takes place in the early evening, starting around 10:30 p.m. Eastern Daylight Savings time. But don’t wait until that moment to begin your observations! Get your equipment set up in advance and consult with this IOTA page for precise times and locations.
What do you need to observe an occultation? In this circumstance, the Moon isn’t quite half lit, so the glare won’t be so bad that you can’t observe with your eyes alone. However, a pair of binoculars or a small telescope will make the event far more interesting! For even more fun, take along an accurate watch and time it yourself. If you are in the occultation path, watch to see if Delta disappears and reappears behind a crater rim. Then watch as the whole scene shifts west and the star emerges again!
This main image is a composite of X-rays from Chandra (blue) and optical data from the Hubble Space Telescope (gold) of the spiral galaxy NGC 3393. Meanwhile, the inset box shows the central region of NGC 3993 as observed just by Chandra.
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About 160 million light years away in the constellation of Hydra, spiral galaxy NGC 3393 has been keeping a billion year old secret. It might have a poker face, but it has a pair of black holes up its sleeve…
Using information obtained through NASA’s Chandra X-ray Observatory combined with Hubble Space Telescope imaging, scientists have uncovered first time evidence that NGC 3393 is harboring twin supermassive black holes. Residing only 490 light years apart, the duo may have been the product of a “minor merger” – where a small and large galaxy met. Although the hypothesis of two black holes within one galaxy isn’t new, it has been difficult to prove because the results of two galaxies combining material would result in a rather ordinary looking spiral.
“The current picture of galaxy evolution advocates co-evolution of galaxies and their nuclear massive black holes, through accretion and galactic merging.” says G. Fabbiano, lead author of a recent Nature paper. “Pairs of quasars, each with a massive black hole at the centre of its galaxy, have separations of 6,000 to 300,000 light years and exemplify the first stages of this gravitational interaction.”
If scientific calculations are correct, a smaller galaxy should have contained a smaller mass black hole. This leaves us with an odd situation. If both of these newly discovered black holes have similar mass, shouldn’t the merging pair also be of similar mass? If so, how could a minor merger be the answer?
“The final stages of the black-hole merging process, through binary black holes and final collapse into a single black hole with gravitational wave emission, are consistent with the sub-light-year separation inferred from the optical spectra and light-variability of two such quasars. The double active nuclei of a few nearby galaxies with disrupted morphology and intense star formation demonstrate the importance of major mergers of equal-mass spiral galaxies in this evolution.” says Fabbiano. “Minor mergers of a spiral galaxy with a smaller companion should be a more common occurrence, evolving into spiral galaxies with active massive black-hole pairs, but have hitherto not been seen. The regular spiral morphology and predominantly old circum-nuclear stellar population of this galaxy, and the closeness of the black holes embedded in the bulge, provide a hitherto missing observational point to the study of galaxy/black hole evolution.”
Lay down your bets, gentlemen… It seems the game changes each time it is played!
The timing couldn’t be better. A new supernova, named PTF11kly, which was discovered on August. 24, 2011 is continuing to brighten and should be visible to backyard astronomers this weekend using just a pair of binoculars. It’s not quite naked-eye material but this is an exciting opportunity for amateurs (as well as the pros!) to view a supernova first-hand. Of course, if your backyard is full of light, the best option is to go to an area with darker skies, and you’ll be able to see it much better. Astronomers say PTF11kly will likely continue to shine for some time, and be at its brightest on about Sept. 9, 2011.
In this video Peter Nugent, an astrophysicist from Lawrence Berkeley National Labs explains just how to find this star that exploded about 21 million light years away.
The James Webb Space Telescope.
Image Credit: NASA/JPL
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The James Webb Space Telescope or JWST has long been touted as the replacement for the Hubble Space Telescope. The telescope is considered to be the one of the most ambitious space science projects ever undertaken – this complexity may be its downfall. Cost overruns now threaten the project with cancellation. Despite these challenges, the telescope is getting closer to completion. As it stands now, the telescope has served as a technical classroom on the intricacies involved with such a complex project. It has also served to develop new technologies that are used by average citizens in their daily lives.
Although compared to Hubble, the two telescopes are dissimilar in a number of ways. The JWST is three times as powerful as Hubble in its infrared capabilities. JWST’s primary mirror is 21.3 feet across (this provides about seven times the amount of collecting power that Hubble currently employs).
The JWST’s mirrors were polished using computer modeling guides that allowed engineers to predict that they will enter into the proper alignment when in space. Each of the mirrors on the JWST has been smoothed down to within 1/1000th the thickness of a human hair. The JWST traveled to points across the country to assemble and test the JWST’s various components.
Eventually the mirrors were then sent to NASA’s Marshall Space Flight Center in Huntsville, Alabama. Once there they measured how the mirrors reacted at extremely cold temperatures. With these tests complete, the mirrors were given a thin layer of gold. Gold is very efficient when it comes to reflecting light in the infrared spectrum toward the JWST’s sensors.
A comparison of the primary mirror used by Hubble and the primary mirror array used by the James Webb Space Telescope. Photo Credit: NASA
The telescope’s array of mirrors is comprised of beryllium, which produces a lightweight and more stable form of glass. The JWST requires lightweight yet strong mirrors so that they can retain their shape in the extreme environment of space. These mirrors have to be able to function perfectly in temperatures reaching minus 370 degrees Fahrenheit.
After all of this is done, still more tests await the telescope. It will be placed into the same vacuum chamber that tested the Apollo spacecraft before they were sent on their historic mission’s to the moon. This will ensure that the telescopes optics will function properly in a vacuum.
A life-sized model of the JWST was placed on display in Seattle, Washington - it was several stories tall and weighed several tons. Photo Credit: Rob Gutro/ NASA
With all of the effort placed into the JWST – a lot of spinoff technology was developed that saw its way into the lives of the general populace. Several of these – had to be invented prior to the start of the JWST program.
“Ten technologies that are required for JWST to function did not exist when the project was first planned, and all have been successfully achieved. These include both near and mid-infrared detectors with unprecedented sensitivity, the sunshield material, the primary mirror segment assembly, the NIRSpec microshutter array, the MIRI cryo-cooler, and several more,” said the James Webb Space Telescope’s Deputy Project Scientist Jason Kalirai. Kalirai holds a PhD in astrophysics and carries out research for the Space Telescope Science Institute. “The new technologies in JWST have led to many spinoffs, including the production of new electric motors that outperform common gear boxes, design for high precision optical elements for cameras and cell phones, and more accurate measurements of human vision for people about to undergo Laser Refractive Surgery.”
The James Webb Space Telescope encapsulated atop the Ariane V rocket tapped launch it, next to an early image of the telescope. Image Credit: NASA
If all goes according to plan, the James Webb Space Telescope will be launched from French Guiana atop the European Space Agency’s Arianne V Rocket. The rationale behind the Ariane V’s selection was based on capabilities – and economics.
“The Ariane V was chosen as the launch vehicle for JWST at the time because there was no U.S. rocket with the required lift capacity,” Kalirai said. “Even today, the Ariane V is a better tested vehicle. Moreover, the Ariane is provided at no cost by the Europeans while we would have had to pay for a U.S. rocket.”
It still remains to be seen as to whether or not the JWST will even fly. As of July 6 of this year the project is slated to be cancelled by the United States Congress. The James Webb Space Telescope was initially estimated at costing $1.6 billion. As of this writing an estimated $3 billion has been spent on the project and it is has been estimated that the telescope is about three-quarters complete.
