Space and astronomy news
“Once more, unto the breech…” Ready to brave the February cold and the ongoing arctic polar express? Tonight, North American skywatchers will witness an encore event, as the waxing gibbous Moon crosses the Hyades star cluster and – for a lucky few — occults the bright star Aldebaran. Continue reading “Watch the Moon Beat a Path Across the Hyades Tonight”
Still looking for the right card for your sweetheart this Valentine’s Day? Why not do it in cosmic proportion by getting NASA on your side? The tender-hearted folks at agency may have just what you’re looking for.
The staff at the New Horizons mission headquarters offers two valentines this season that play off Pluto’s heart-shaped, icy plain Tombaugh Regio. While the temperature there hovers around 400 below, you’re guaranteed a 98.6° smile when your sweetie opens the card and sees your love reflected in glittering nitrogen ice.
Pluto not your thing? Select from 12 different Mars e-card love greetings at this NASA site and blow your partner away in a Martian dust devil of love. Many of the heart-shaped features depicted on the cards are genuine features and include collapse pits, craters and mesas.
Even the asteroids send their saucy wishes. Check out the delightful series of valentines from the upcoming OSIRIS-Rex sample return mission to 101955 Bennu, slated to launch in September this year and return a sample of the carbonaceous asteroid to Earth in 2023. If you go this route, I’d complement the card with a meal heavy on edible carbonaceous material at your partner’s favorite restaurant.
Happy Valentine’s Day! Spread the love for a happier planet.
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. His treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come. Thanks to the development of modern telescopes and astronomy, this list was amended by the early 20th century to include the 88 constellation that are recognized by the International Astronomical Union (IAU) today.
Of these, Andromeda is one of the oldest and most widely recognized. Located north of the celestial equator, this constellation is part of the family of Perseus, Cassiopeia, and Cepheus. Like many constellation that have come down to us from classical antiquity, the Andromeda constellation has deep roots, which may go all the way back to ancient Babylonian astronomy.
A massive rogue planet has been discovered in the Beta Pictoris moving group. The planet, called PSO J318.5338-22.8603 (Sorry, I didn’t name it), is over eight times as massive as Jupiter. Because it’s one of the few directly-imaged exoplanets we know of, and is accessible for study by spectroscopy, this massive planet will be extremely important when piecing together the details of planetary formation and evolution.
Most planets outside our solar system are not directly observable. They are discovered when they transit in front of their host star. That’s how the Kepler mission finds exoplanets. After that, their properties are inferred by their gravitational interactions with their star and with any other planets in their system. We can infer a lot, and get quite detailed, but studying planets with spectroscopy is a whole other ball game.
The team of researchers, led by K. Allers of Bucknell University, used the Gemini North telescope, and its Near-Infrared Spectrograph, to find PSO’s radial and rotational velocities. As reported in a draft study on January 20th, PSO J318.5338-22.8603 (PSO from now on…) was confirmed as a member of the Beta Pictoris moving group, a group of young stars with a known age.
The Beta Pictoris moving group is a group of stars moving through space together. Since they are together, they are understood to be formed at the same time, and to have the same age. Confirming that PSO is a member of this group also confirmed PSO’s age.
Once the age of PSO was known, its identity as a planet was confirmed. Without knowing the age, it’s impossible to rule it out as a brown dwarf, a “failed star” that lacked the mass to ignite fusion.
This new rogue planet is 8.3 + or – 0.5 times the mass of Jupiter, and its temperature is about 1130 K. Spectra from the Gemini scope show that PSO rotates at between 5 to 10.2 hours, and that its radial velocity is within the envelope of values for this group. According to the researchers, determining these properties accurately means that PSO J318.5338-22.8603 is “an important benchmark for studies of young, directly imaged planets.”
PSO is in an intermediate position in terms of other planets in the Beta Pictoris moving group. 51 Eridani-b is another directly imaged planet, only slightly larger than Jupiter, discovered in 2014. The third planet in the group is Beta Pictoris b, which is thought to be almost 11 times as massive as Jupiter.
Rogue, or “free-floating” planets like PSO J318.5338-22.8603 are important because they are not near a star. Light from a star dominates the star’s surroundings, and makes it difficult to discern much detail in the planets that orbit the star. Now that PSO is confirmed as a planet, rather than a brown dwarf, studying it will add to our knowledge of planetary formation.
Soon, very soon, Thursday, February 11, at 10:30 Eastern time, we are likely to learn at any one of several press conferences – at the National Press Club in Washington, D.C., in Hannover, Germany, near Pisa in Italy and elswhere – that gravitational waves have been measured directly, for the first time. This would mean the first direct detection of minute distortions of spacetime, travelling at the speed of light, first postulated by Albert Einstein almost exactly 100 years ago.
Time to brush up on your gravitational wave basics: In Gravitational waves and how they distort space, we had a look at what gravitational waves do. In Gravitational wave detectors: How they work we saw how you can measure gravitational waves. Third and final step: What are typical gravitational wave sources? How are these waves produced?
The simplest situation that produces gravitational waves in the cosmos is almost ubiquitous: two or more objects orbiting around each other under their own gravity. The waves they generate are reminiscent to a very slow mixer in the middle of a pool of water: 
This is not something you would see, of course. The wave that is pictured here represents the strength of the minute changes in distance that would be caused by the gravitational wave, just as we’ve seen in Gravitational waves and how they distort space. The animation is courtesy of Sascha Husa of the Universitat de les Illes Balears.
Gravitational waves emitted by orbiting objects carry away energy. Elementary physics tells you that if you remove energy from an orbiting system, the distance between the orbiting objects will shrink, and they will orbit each other faster than before.
In fact, gravitational waves making a binary system of neutron stars speed up was the first evidence for the existence of gravitational waves. The binary neutron star was discovered by Hulse and Taylor in 1974, and the speed-up caused by gravitational waves published by Taylor and Weisberg in 1984, after a careful analysis of seven years’ worth of data. Hulse and Taylor were awarded the Nobel prize in physics in 1993 for their discovery.
Here, in an image from an article by Weisberg 2010, is the match between general relativistic prediction and observation in all its glory (or at least in all its glory up to 2005): 
As the two neutron stars speed up, they will reach the point of closest approach within their orbit earlier and earlier. How much earlier, in seconds, is plotted on the vertical axis, year of measurement on the horizontal axis.
Today’s ground-based detectors cannot detect gravitational waves from all kinds of bodies in mutual orbit. The bodies need to be massive, compact and, crucially, orbit each other quickly enough. For bodies orbiting each other less than a few times per second (very quick, if you are talking about astronomical bodies!), the frequency of the resulting gravitational wave will be too low for ground-based detectors to measure reliably. In the low-frequency regime, below 10–100 Hertz, disturbances caused by undulating motions of the Earth’s surface (“seismic noise”) are dominant, and drown out the minute effects of gravitational waves.
When it comes to gravitational waves from supermassive black holes, or from white dwarfs, we will have to wait for future space-based gravitational wave detectors.
When an orbiting system emits gravitational waves, orbital motion speeds up. And when orbital motion speeds up, the system emits even more energy in form of gravitational wave. This runaway process ends only when the orbiting objects collide and merge.
The final phase is marked by a quick increase in orbital speed, corresponding to ever higher gravitational wave frequency, and ever higher intensity. Here’s what such a signal looks like (image and audio from “Chirping Neutron Stars” on Einstein Online): 
You can see how the frequency and intensity increase right up to time 0, when the two neutron stars collide and merge.
For stellar black holes (with masses between a few and a few dozen solar masses) and neutron stars, in any combination, the frequencies of these gravitational waves are the same as the frequencies of audible sound waves. One can actually represent these changes in frequency as an audible tone, as in this example of two neutron stars merging (Audio © B. Owen, Penn State University):
Here is the same kind of audible representation for the merger of a black hole and a neutron star (© AEI/GEO600):
Sadly, what a gravitational wave detector registers is the combination of this sound plus assorted noise, which sounds like this (© AEI/GEO600):
Colleagues at Cardiff University have made this into a nice online game: Black Hole Hunter. Head over there and see if you can hear the signal beneath the noise!
(And you can hear live chirps by various astrophysicists (and others) under the hashtag #chirpForLIGO on Twitter.)
This kind of signal, from merging stellar black holes or neutron stars (in any combination) is the most promising candidate signal for today’s detectors – and going by the rumors, that is indeed what LIGO appears to have found.
The final part of the signal is interesting for a particular reason: It doesn’t follow from any simple formulae, and can only be modelled with complex computer simulations of such situations known as numerical relativity. If the detectors get a good detection of this very last bit, that will be a good test for current numerical simulations of general relativity!
Chirps are comparatively simple, and likely the first signals to be found.
Another kind of signal that could be found is periodic (or nearly so), and would be produced e.g. if rapidly rotating neutron stars are less than perfectly smooth. No such luck as of yet, though.
Next would come the gravitational wave sources that are somewhat less understood, such as the processes in the interior of supernova explosions. And finally, once numerous signals have been detected, showing the scientists that their detectors are indeed working as they should, there might be the detection of completely unexpected signals. Whenever astronomers have opened a new window to the cosmos – the radio window, infrared window, x-ray window – they have found something new and unexpected. Who can tell what opening the Einstein window, the window of gravitational waves, will teach us about the universe?
Update: Gravitational Waves Discovered
It’s official: this Thursday, February 11, at 10:30 EST, there will be parallel press conferences at the National Press Club in Washington, D.C., in Hannover, Germany, and near Pisa in Italy. Not officially confirmed, but highly probable, is that people running the LIGO gravitational wave detectors will announce the first direct detection of a gravitational wave. The first direct detection of minute distortions of spacetime, travelling at the speed of light, first postulated by Albert Einstein almost exactly 100 years ago. Nobel prize time.
Time to brush up on your gravitational wave basics, if you haven’t done so! In Gravitational waves and how they distort space, I had a look at what gravitational waves do. Now, on to the next step: How can we measure what they do? How do gravitational wave detectors such as LIGO work?
Recall that this is how a gravitational wave will change the distances between particles, floating freely in a circular formation in empty space: 
The wave is moving at right angles to the screen, towards you. I’ve greatly exaggerated the distance changes. For a realistic wave, even the giant distance between the Earth and the Sun would only change by a fraction of the diameter of a hydrogen atom. Tiny changes indeed.
The first unsuccessful attempts to detect gravitational waves in the 1960s tried to measure how they make aluminum cylinders ring like a very soft bell. (Tragic story; Joe Weber [1919-2000], the pioneering physicist behind this, was sure he had detected gravitational waves in this way; after thorough analysis and replication attempts, community consensus emerged that he hadn’t.)
Afterwards, physicists came up with alternative scheme. Imagine that you are replacing the black point in the center of the previous animation with a detector, and the rightmost red particle with a laser light source. Now you send light pulses (represented here by fast red dots) from the light source to the detector; let’s first look at this with the gravitational wave switched off:
Every time a light pulse reaches the detector, an indicator light flashes yellow. The pulses are sent out regularly, they all travel at the same speed, hence they also reach the detector in regular intervals.
If a gravitational wave passes through this system, again from the back and coming towards you, distances will change. Let us keep our camera trained on the detector, so the detector remains where it is. The changing distance to the light source, and also the changing distances between the light pulses, and some of the changes in distance between light pulses and detector or source, are due to the gravitational wave. Here is what that would look like (again, hugely exaggerated): 
Keep your eye on the blinking light, and you will see that its blinking is not so regular any more. Sometimes, the light blinks faster, sometimes slower. This is an effect of the gravitational wave. An effect by which we can hope to detect the gravitational wave.
“We” in this case are the radio astronomers working on what are known as Pulsar Timing Arrays. The sender of regular pulses are pulsars, rotating neutron stars sweeping a radio beam across our antennas like a cosmic lighthouse. The detectors are radio telescopes here on Earth. Detection is anything but easy. With a single pulsar, you’d need to track pulse arrival times with an accuracy of a few billionths of a second over half a year, and make sure you are not being fooled by various other sources of timing variations. So far, no gravitational waves have been detected in this way, although the radio astronomers are keeping at it.
To see how gravitational wave detectors like LIGO work, we need to make things a little more complex.
Here is the basic set-up: Two mirrors, a receiver (or “light detector”), a light source and what is known as a beamsplitter: 
Light is sent into the detector from the (laser) light source LS to the beamsplitter B which, true to its name, sends half of the light on to the mirror M1 and lets the other half through to the mirror M2. At M1 and M2, respectively, the light is reflected back to the beam splitter. There, the light arriving from M1 (or M2) is split again, with half going towards the light detector LD, the other half back in the direction of the light source LS. We will ignore the latter half and pretend, for the sake of our simplified explanation, that all the light reaching B from M1 or M2 goes on to the light detector LD.
(To avoid confusion, I will always refer to LD as the “light detector” and take the unqualified word “detector” to mean the whole setup.)
This setup, by the way, is called a Michelson Interferometer. We’ll see below why it is a good setup for gravitational wave detectors.
In what follows, we will assume that the mirrors and the beam splitter, shown as being suspended, react to the gravitational wave in the same way freely floating particles would react. The key effects are between the mirrors and the beam splitter in what are called the two arms of the detector. Arm length is huge in today’s detectors, running to a few kilometers. In comparison, light source and light detector are very close to the beamsplitter; changes of the distances between these three do not signify.
Next, let us see how light pulses run through this detector. Here is the same setup, seen from above: 
Light source LS, the two mirrors M1 and M2, the beamsplitter B and the light detector LD: all present and accounted for.
Next, we let the light source emit light pulses. For greater clarity, I will make two artificial and unrealistic changes. I will send red and green pulses into the detector, representing the light that goes into the horizontal and the vertical arm, respectively. In reality, there is no distinction, just light apportioned at the beamsplitter. Light running towards M1 will be offset a little to the left, light coming back from M1 to the right, for better clarity. Same goes for M2. This, too, is different in a real detector. That said, here come the light pulses: 
Light starts at the light source to the left. Light that has left the source together, travels together (so green and red pulses are side by side) until the beam splitter. The beam splitter then sends the green pulses on their upward journey and lets the red pulses pass on their way towards the mirror on the right. All the particles that arrive back at the beamsplitter after reflection at M1 or M2. At the beamsplitter, they are directed towards the light detector at the bottom.
In this setup, the horizontal arm is slightly longer than the vertical arm. Red particles have to cover some extra distance. That is why they arrive at the detector a bit later, and we get an alternating rhythm: green, red, green, red, with equal distances in between. This will become important later on.
Here is a diagram, a kind of registration strip, which shows the arrival times for red and green pulses at the light detector (time is measured in “animation frames”): 
The pattern is clear: red and green pulses arrive evenly spaced, one after the other.
Next, let’s switch on our standard gravitational wave (exaggerated, passing through the screen towards you, and so on). Here is the result: 
We have trained our camera on the beamsplitter (so in our image, the beamsplitter doesn’t move). We ignore any slight changes in distance between beamsplitter and light source/light detector. Instead, we focus on the mirrors M1 and M2, which change their distance from the beamsplitter just as we would expect from the earlier animations.
Look at the way the pulses arrive at our light detector: sometimes red and green are almost evenly spaced, sometimes they close together. That is caused by the gravitational wave. Without the wave, we had strict regularity.
Here is the corresponding “registration strip” diagram. You can see that at some times, the light pulses of each color are closer together, at others, farther apart: 
At the time I have marked with a hand-drawn arrow, red and green pulses arrive almost in unison!
The pattern is markedly different from the scenario without a gravitational wave. Detect this change in the pattern, and you have detected the gravitational wave.
If you’ve wondered why detectors like LIGO are called interferometric gravitational wave detectors, we will need to think about waves a bit more. If not, let me just state that detectors like LIGO use the wave properties of light to measure the changes in pulse arrival rate you have seen in the last animation. To skip the details, feel free to jump ahead to the last section, “…and now for something a thousand times more complicated.”
Light is a wave, with crests and troughs corresponding to maxima and minima of the electric and of the magnetic field. While the animations I have shown you track the propagation of light pulses, they can also be used to understand what happens to a light wave in the interferometer. Just assume that each of the moving red and green dots in the detector marks the position of a wave crest.
Particles just add up. Take 2 particle and add 2 particles, and you will end up with 4 particles. But if you add up (combine, superimpose) waves, it depends. Sometimes, one wave plus another wave is indeed a bigger wave. Sometimes, it’s a smaller wave, or no wave at all. And sometimes it’s complicated.
When two waves are in perfect sync, the crests of the one aligning with the crests of the other, and the troughs aligning, too, you indeed get a bigger wave. The following diagram shows at which times the different parts of two light waves arrive at the light detector, and how they add up. (I’ve placed a dot on top of each crest; that is what the dots where meant to signify, after all.) 
On top, the green wave, perfectly aligned with the red wave (which, for clarity, is shown directly below the green wave). Add the two waves up, and you will get the (markedly stronger) blue wave in the bottom panel.
Not so if the two waves are maximally misaligned, the crests of each aligned with the troughs of the other. A crest and a trough cancel each other out. The sum of a wave and a maximally misaligned wave of equal strength is: no wave at all. Here is the corresponding diagram: 
Recall that this was exactly the setup for our gravitational wave detector in the absence of gravitational waves: Red and green pulses with equal spacing; troughs of the one wave perfectly aligned with the crests of the other. The result: No light at the light detector. (For realistic gravitational wave detectors, that is almost true.)
When a gravitational wave passes through the detector, the situation changes. Here is the corresponding pattern of pulse/wave crest arrival times for the animation above: 
The blue pattern, which is the sum of the red and the green, is complex. But it is not a flat line. There is light at the light detector where there was no light before, and the cause of the change is the gravitational wave passing through.
All in all, this makes a (highly simplified) version of how gravitational wave detectors such as LIGO work. Whatever the scientists will report this Thursday, it is based on light signals at the exit of such an interferometric detector.
Real gravitational wave detectors are, of course, much more complicated than that. I haven’t even started talking about the many disturbances scientists need to take into account – and to suppress as far as possible. How do you suspend the mirrors so that (at least for certain gravitational waves) they will indeed be influenced as if they were freely floating particles? How do you prevent seismic noise, cars or trains in the wider neighborhood and so on from moving your mirrors a tiny little bit (either by vibrations or by their own gravity)? What about fluctuations of the laser light?
Gravitational wave hunting is largely a hunt for noise, and for ways of suppressing that noise. The LIGO gravitational wave detectors and their kin are highly complex machines, with hundreds of control circuits, highly elaborate mirror suspensions, the most stable lasers known to physics (and some of the most high-powered). The technology has been contributed by numerous group from all over the world.
But all this is taking us too far, and I refer you to the pages of the detectors and collaborations for additional information:
Pages of the LIGO Scientific Collaboration
You can find some further information about gravitational waves on the Einstein Online website:
Einstein Online: Spotlights on gravitational waves
Update: Gravitational Waves Discovered
In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects in the night sky. In time, he would come to compile a list of approximately 100 of these objects, with the purpose of making sure that astronomers did not mistake them for comets. However, this list – known as the Messier Catalog – would go on to serve a more important function.
In addition to cataloging some of the most beautiful objects in the night sky, this list would come to be an important milestone in the discovery of Deep Sky Objects. The second object to make the list is known as Messier Object 2 (aka. M2 or NGC 7089), one of the largest globular cluster in the Milky Way, and which is located in the constellation Aquarius.
As one of the largest known globular clusters, Messier 2 is a rich, round concentration of gravitationally bound stars that orbits the galactic core. Located about 33,000 light years (10,000 parsecs) from our Solar System, this cluster measures some 175 light-years in diameter and is believed to contain about 150,000 stellar members – including 21 known variable stars. Its brightest stars are red and yellow giant stars.
Because its members are so tightly packed together, it has a density classification of II – which is reserved for clusters that are particularly rich and compact. And like most globular clusters, M2’s central region is highly compressed, measuring just 3.7 light years in diameter. It’s tidal influence, on the other hand, has a radius of 233 light years, beyond which members stars would escape due to the influence of the Milky Way’s tidal forces.
Positioned well beyond the galactic center, M2 is also noted for its elliptical shape, and is believed to be as much as 13 billion years old.
M2 was first discovered by Jean-Dominique Maraldi in 1746 while observing a comet with Jacques Cassini. According to Cassini’s notes, which detail the discovery, the two believed it to be a “nebulous star” at the time:
“On September 11 I have observed another one [nebulous star] for which the right ascension is 320d 7′ 19″ [21h 20m 29s], and the declination 1d 55′ 38″ south, very near to the parallel where the Comet should be. This one is round, well terminated and brighter in the center, about 4′ or 5′ in extent and not a single star around it to a pretty large distance; none can be seen in the whole field of the telescope. This appears very singular to me, for most of the stars one calls nebulous are surrounded by many stars, making one think that the whiteness found there is an effect of the light of a mass of stars too small to be seen in the largest telescopes. I took, at first, this nebula for the comet.”
The object was independently recovered by Charles Messier in 1769, though he too mistook it for something else. In his notes, which were also taken on September 11th (fourteen years later), he described the object as a nebula:
“On September 11, 1760, I discovered in the head of Aquarius a beautiful nebula which doesn’t contain any star; I examined it with a good Gregorian telescope of 30 pouces focal length, which magnified hundred four [104] times; the center is brilliant, and the nebulosity which surrounds it is round; it resembles quite well the beautiful nebula which is located between the head and the bow of Sagittarius: It extends 4 minutes of arc in diameter; one can see it quite well in an ordinary telescope [refractor] of 2 feet [focal length]: I compared its passage of the meridian with that of Alpha Aquarii which is situated on the same parallel; its right ascension was derived at 320d 17′, and its declination at 1d 47′ south. In the night of June 26 and 27, 1764, I reviewed this nebula for a second time; it was the same, with the same appearances. This nebula can be found placed in the chart of the famous Comet of Halley, which I observed at its return in 1759 (b).”
Ultimately, it was William Herschel who finally resolved Messier 2 into the object we recognize today. This took in 1783, where – according to his notes – he was able to resolve individual stars:
“The scattered stars were brought to a good, well determined focus, from which it appears that the central condensed light is owing to a multitude of stars that appeared at various distances behind and near each other. I could actually see and distinguish the stars even in the central mass. The Rev. Mr. Vince, Plumian Professor of Astronomy at Cambridge, saw it in the same telescope as described.”
Messier 2 is located approximately 5 degrees (about 3 finger widths) north of Beta Aquarii, on the same declination as Alpha Aquarii. M2 is sufficiently bright enough to be seen in urban settings where light pollution is a factor, and can alternately be found by looking about 10 degrees (a fist width) south/southwest of Epsilon Pegasi (Enif).
Using binoculars, it will appear as a large, fuzzy ball with little or no resolution. To amateur astronomers using small telescopes, individual stars will be visible around the outer edges, with resolution improving significantly with aperture size of 6” or more. Those with large telescopes, and who are looking for a challenge, should look for a dark dust lane which crosses the north-east edge of this globular cluster.
Of course, John Herschel saw it as “It is like a heap of fine sand!” which is perhaps as apt an description as can be rendered. Through a large telescope, the globular cluster does resemble a glittering mass of sparkling granules.
And for your convenience, here are the vital statistics of this globular cluster:
Object Name: Messier 2
Alternative Designations: NGC 7089, GC 4678, Bode 70
Object Type: Class II Globular Cluster
Constellation: Aquarius
Right Ascension: 21 : 33.5 (h:m)
Declination: -00 : 49 (deg:m)
Distance: 33 (kly)
Visual Brightness: 6.5 (mag)
Apparent Dimension: 16.0 (arc min)
Good luck searching for this and other Deep Sky Objects!
We have written many interesting articles on Messier Objects here at Universe Today. For instance, here’s Tammy Plotner’s Introduction to the Messier Objects, M1 – The Crab Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.
Be to sure to check out our complete Messier Catalog.
For more information, check out the SEDS Messier Database.
Missing out on the morning planetary action?
February sees all five naked eye planets in the dawn sky, though that’s about to change in March. But the good news is, now is the time to hunt for a sometimes planet, sometimes asteroid in the early evening. Continue reading “Vesta Rules the February Dusk Skies”
Ever since the New Horizons spacecraft flew by Pluto in July 2015, people here at Earth have been treated to an endless supply of discoveries about the dwarf planet. These included the first accurate pictures of what Pluto looks like, images of “Pluto’s Heart“, information about the geology and morphology of the surface (and its largest moon, Charon), and information about Pluto’s atmosphere and its escape rate.
And based on the data obtained from images by the New Horizons probe, NASA recently announced that Pluto’s flowing glaciers have numerous hills composed of water ice floating on top of them. Located in the vast ice plain known as “Sputnik Planum” – named after Sputnik One, the first satellite to orbit Earth – these hills measure several kilometers across, and are believed to be fragments that originated from the surrounding uplands.
Continue reading “New Horizons Latest Find: Floating Ice Hills On Pluto!”
NASA GODDARD SPACE FLIGHT CENTER, MD – All 18 of the primary mirrors have been fully installed onto the flight structure of what will become the biggest and most powerful space telescope ever built by humankind – NASA’s James Webb Space Telescope (JWST).
Completion of the huge and complex primary mirror marks a historic milestone and a banner start to 2016 for JWST, commencing the final assembly phase of the colossal observatory that will revolutionize our understanding of the cosmos and our place it in.
After JWST launches in slightly less than three years time, the gargantuan observatory will significantly exceed the light gathering power of the currently most powerful space telescope ever sent to space – NASA’s Hubble!
Indeed JWST is the scientific successor to NASA’s 25 year old Hubble Space Telescope.
Technicians working inside the massive clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, have been toiling around the clock 24/7 to fully install all 18 primary mirror segments onto the mirror holding backplane structure. This author witnessed ongoing work in progress during installation of the last of the primary mirrors.
The engineers and scientists kept up the pace of their assembly work over the Christmas holidays and also during January’s record breaking monster Snowzilla storm, that dumped two feet or more of snow across the Eastern US from Washington DC to New York City and temporarily shut down virtually all travel.
The team used a specialized robotic arm functioning like a claw to meticulously latch on to, maneuver and attach each of the 18 primary mirrors onto the telescope structure.
Each of the 18 hexagonal-shaped primary mirror segments measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms). They are made of beryllium and about the size of a coffee table.
In space, the folded mirror structure will unfold into side by side sections and work together as one large 21.3-foot (6.5-meter) mirror, unprecedented in size and light gathering capability.
The telescopes mirror assembly is comprised of three segments – the main central segment holding 12 mirrors and a pair of foldable outer wing-like segments that hold three mirrors each.
The painstaking assembly work to piece the primary mirrors together began just before the Thanksgiving 2015 holiday, when the first unit was successfully installed onto the central segment of the mirror holding backplane assembly.
One by one the team populated the telescope structure with the primary mirrors at a pace of roughly two per week since the installations started some two and a half months ago.
During the installation process each of the gold coated primary mirrors was covered with a black colored cover to protect them from optical contamination.
The mirror covers will be removed over the summer for testing purposes, said Lee Feinberg, optical telescope element manager at Goddard, told Universe Today.
The two wings were unfolded from their stowed-for-launch configuration to the “deployed” configuration to carry out the mirror installation. They will be folded back over into launch configuration for eventual placement inside the payload fairing of the Ariane V ECA booster rocket that will launch JWST three years from now.
“Scientists and engineers have been working tirelessly to install these incredible, nearly perfect mirrors that will focus light from previously hidden realms of planetary atmospheres, star forming regions and the very beginnings of the Universe,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington, in a statement.
“With the mirrors finally complete, we are one step closer to the audacious observations that will unravel the mysteries of the Universe.”
The mirrors were built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. Ball is the principal subcontractor to Northrop Grumman for the optical technology and lightweight mirror system. The installation of the mirrors onto the telescope structure is performed by Harris Corporation of Rochester, New York. Harris Corporation leads integration and testing for the telescope, according to NASA.
Among the next construction steps are installation of the aft optics assembly and the secondary mirror.
After that the team will install what’s known as the ‘heart of the telescope’ – the Integrated Science Instrument Module ISIM). Then comes acoustic and vibration tests throughout this year. Eventually the finished assembly will be shipped to Johnson Space Center in Houston “for an intensive cryogenic optical test to ensure everything is working properly,” say officials.
The flight structure and backplane assembly serve as the $8.6 Billion Webb telescopes backbone.
The telescope will launch on an Ariane V booster from the Guiana Space Center in Kourou, French Guiana in 2018.
The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).
Webb is designed to look at the first light of the Universe and will be able to peer back in time to when the first stars and first galaxies were forming. It will also study the history of our universe and the formation of our solar system as well as other solar systems and exoplanets, some of which may be capable of supporting life on planets similar to Earth.
“JWST has the capability to look back towards the very first objects that formed after the Big Bang,” said Dr. John Mather, NASA’s Nobel Prize Winning scientist, in a recent exclusive interview with Universe Today at NASA Goddard.
Watch this space for my ongoing reports on JWST mirrors, construction and testing.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
