Posted on by Evan Gough

Rise of the Super Telescopes: The European Extremely Large Telescope

This artist’s rendering of the E-ELT is based on the detailed construction design for the telescope. Image: ESO/L. Calçada/ACe Consortium

We humans have an insatiable hunger to understand the Universe. As Carl Sagan said, “Understanding is Ecstasy.” But to understand the Universe, we need better and better ways to observe it. And that means one thing: big, huge, enormous telescopes.

In this series we’ll look at 6 of the world’s Super Telescopes:

The European Extremely Large Telescope

The European Extremely Large Telescope (E-ELT) is an enormous ‘scope being built by the European Southern Observatory. It’s under construction right now in the high-altitude Atacama Desert of northern Chile. The ESO, with its partners, has built some of the largest and most technically advanced telescopes in the world, like the Atacama Large Millimeter Array (ALMA) and the Very Large Telescope (VLT.) But with a 39 meter primary mirror, the E-ELT will dwarf the other telescopes in the ESO’s fleet.

As Dr Michele Cirasuolo, Programme Scientist for the ELT told Universe Today, “The Extremely Large Telescope (ELT) is the flagship project of the European Southern Observatory (ESO), and when completed in 2024 will be the largest optical/infrared telescope in the world. It represents the next step forward and it will complement the research done with the GMT (Giant Magellan Telescope) and other large telescopes being built.”

This artist’s rendering of the E-ELT shows the 39 meter segmented mirror at the heart of the scope. ESO/L. Calçada/ACe Consortium

The E-ELT is the successor to the Overwhelmingly Large Telescope (OWL), which was the ESO backed away from due to its €1.5 billion price tag. Instead, the ESO focussed on the E-ELT. The site for the E-ELT was selected in 2010, and over the next couple years the design was finalized.

Like other telescopes—including the Keck Telescope—the E-ELT’s primary mirror will be made up of individually manufactured hexagonal segments; 798 of them. The primary mirror will be fitted with edge sensors to ensure that each segment of the mirror is corrected in relation to its neighbours as the scope is aimed or moved, or as it is disturbed by temperature changes, wind, or vibrations.

The E-ELT is actually a 5 mirror system. Along with the enormous primary mirror, and the secondary mirror, there are three other mirrors. An unusual aspect of the E-ELT’s design is its tertiary mirror. This tertiary mirror will give the E-ELT better image quality over a larger field of view than a primary and secondary mirror can.

The ‘scope also has two other mirrors which provide adaptive optics and image stabilization, as well as allowing more large science instruments to be mounted to the ‘scope simultaneously.

This diagram shows the novel 5-mirror optical system of ESO’s Extremely Large Telescope (ELT). Before reaching the science instruments the light is first reflected from the telescope’s giant concave 39-metre segmented primary mirror (M1), it then bounces off two further 4-metre-class mirrors, one convex (M2) and one concave (M3). The final two mirrors (M4 and M5) form a built-in adaptive optics system to allow extremely sharp images to be formed at the final focal plane. Image By ESO – https://www.eso.org/public/images/eso1704a/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=55268266

The Science: What Will the E-ELT Study?

The E-ELT is designed for an ambitious science agenda. One of the most exciting aspects of the E-ELT is its potential to capture images of extra-solar planets. The 39 meter mirror will not only collect more light from distant, faint objects, but will provide an increase in angular resolution. This means that the telescope will be capable of distinguishing objects that are close together.

As Dr. Cirasuolo explains, “This will allow the ELT to image exoplanets nearer to the star they are orbiting. We aim to probe planets in the so called habitable zone (where liquid water could exist on their surfaces) and take spectra to analyse the composition of their atmospheres.”

The E-ELT has other goals as well. It aims to probe the formation and evolution of planetary systems, and to detect water and organic molecules in protoplanetary disks around stars as they form. It will look at some of the most distant objects possible—the first stars, galaxies, and black holes—to try to understand the relationships between them.

The telescope is also designed to study the first galaxies, and to chart their evolution over time. As if this list of science goals isn’t impressive enough, the E-ELT holds out the hope of directly measuring the acceleration in the expansion of the Universe.

This video explains the design of the E-ELT and some of its science goals.

These are all fascinating goals, but for many of us the most compelling question we face is “Are We Alone?” Dr. Cirasuolo feels the same. As he told Universe Today, “The ultimate goal is finding signs of life. Certainly the next generation of telescopes will provide a huge leap forward in our understanding of extra solar planets and for the search for life in the Universe.”

The E-ELT won’t be working alone. Other Super Telescopes, like the Giant Magellan Telescope, the Thirty Meter Telescope, and even the Large Synoptic Survey Telescope, will all be working in conjunction to expand the frontier of knowledge.

It may be a very long time, if ever, before we find life somewhere else in the Universe. But by expanding our knowledge of exo-planets, the E-ELT is going to be a huge part of the ongoing effort. A few years ago, we weren’t even certain that we would find many planets around other stars. Now the discovery of exoplanets is almost commonplace. If the E-ELT lives up to its promise, then capturing actual images of exoplanets may become commonplace as well.

Posted on by Evan Gough

7 Questions For 7 New Planets

Artist's concept of the TRAPPIST-1 star system, an ultra-cool dwarf that has seven Earth-size planets orbiting it. We're going to keep finding more and more solar systemsl like this, but we need observatories like WFIRST, with starshades, to understand the planets better. Credits: NASA/JPL-Caltech
Artist's concept of the TRAPPIST-1 star system, an ultra-cool dwarf that has seven Earth-size planets orbiting it. We're going to keep finding more and more solar systemsl like this, but we need observatories like WFIRST, with starshades, to understand the planets better. Credits: NASA/JPL-Caltech

NASA’s announcement last week of 7 new exoplanets is still causing great excitement. Any time you discover 7 “Earth-like” planets around a distant star, with 3 of them “potentially” in the habitable zone, it’s a big deal. But now that we’re over some of our initial excitement, let’s look at some of the questions that need to be answered before we can all get excited again.

What About That Star?

The star that the planets orbit, called Trappist-1, is a Red Dwarf star, much dimmer and cooler than our Sun. The three potentially habitable planets—TRAPPIST-1e, f, and g— get about the same amount of energy as Earth and Mars do from the Sun, because they’re so close to it. Red Dwarfs are very long-lasting stars, and their lifetimes are measured in the trillions of years, rather than billions of years, like our Sun is.

But Red Dwarfs themselves can have some unusual properties that are problematic when it comes to supporting life on nearby planets.

This illustration shows TRAPPIST-1 in relation to our Sun. Image: By ESO – http://www.eso.org/public/images/eso1615e/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=48532941

Red Dwarfs can be covered in starspots, or what we call sunspots when they appear on our Sun. On our Sun, they don’t have much affect on the amount of energy received by the Earth. But on a Red Dwarf, they can reduce the energy output by up to 40%. And this can go on for months at a time.

Other Red Dwarfs can emit powerful flares of energy, causing the star to double in brightness in mere minutes. Some Red Dwarfs constantly emit these flares, along with powerful magnetic fields.

Part of the excitement surrounding the Trappist planets is that they show multiple rocky planets in orbit around a Red Dwarf. And Red Dwarfs are the most common type of star in the Milky Way. So, the potential for life-supporting, rocky planets just grew in a huge way.

But we don’t know yet how the starspots and flaring of Red Dwarfs will affect the potential habitability of planets orbiting them. It could very well render them uninhabitable.

Will Tidal Locking Affect the Planets’ Habitability?

The planets orbiting Trappist-1 are very likely tidally locked to their star. This means that they don’t rotate, like Earth and the rest of the planets in our Solar System. This has huge implications for the potential habitability of these planets. With one side of the planet getting all the energy from the star, and the other side in perpetual darkness, these planets would be nothing like Earth.

Tidal locking is not rare. For example, Pluto and its moon Charon (above) are tidally locked to each other, as are the Earth and the Moon. But can life appear and survive on a planet tidally locked to its star? Credit: NASA/JHUAPL/SwRI

One side would be constantly roasted by the star, while the other would be frigid. It’s possible that some of these planets could have atmospheres. Depending on the type of atmosphere, the extreme temperature effects of tidal locking could be mitigated. But we just don’t know if or what type of atmosphere any of the planets have. Yet.

So, Do They Have Atmospheres?

We just don’t know yet. But we do have some constraints on what any atmospheres might be.

Preliminary data from the Hubble Space Telescope suggests that TRAPPIST 1b and 1c don’t have extended gas envelopes. All that really tells us is that they aren’t gaseous planets. In any case, those two planets are outside of the habitable zone. What we really need to know is if TRAPPIST 1e, 1f, and 1g have atmospheres. We also need to know if they have greenhouse gases in their atmospheres. Greenhouse gases could help make tidally locked planets hospitable to life.

On a tidally locked planet, the termination line between the sunlit side and the dark side is considered the most likely place for life to develop. The presence of greenhouse gases could expand the habitable band of the termination line and make more of the dark side warmer.

We won’t know much about any greenhouse gases in the atmospheres of these planets until the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (EELT) are operating. Those two ‘scopes will be able to analyze the atmospheres for greenhouse gases. They might also be able to detect biosignatures like ozone and methane in the atmospheres.

We’ll have to wait a while for that though. The JWST doesn’t launch until October 2018, and the EELT won’t see first light until 2024.

Do They Have Liquid Water?

We don’t know for sure if life requires liquid water. We only know that’s true on Earth. Until we find life somewhere else, we have to be guided by what we know of life on Earth. So we always start with liquid water.

A study published in 2016 looked at planets orbiting ultra-cool dwarfs like TRAPPIST-1. They determined that TRAPPIST 1b and 1c could have lost as much as 15 Earth oceans of water during the early hot phase of their solar system. TRAPPIST 1d might have lost as much as 1 Earth ocean of water. If they had any water initially, that is. But the study also shows that they may have retained some of that water. It’s not clear if the three habitable planets in the TRAPPIST system suffered the same loss of initial water. But if they did, they could have retained a similar amount of water.

Artist’s impression of an “eyeball” planet, a water world where the sun-facing side is able to maintain a liquid-water ocean. Credit and Copyright: eburacum45/ DeviantArt

There are still a lot of questions here. The word “habitable” only means that they are receiving enough energy from their star to keep water in liquid form. Since the planets are tidally locked, any water they did retain could be frozen on the planets’ dark side. To find out for sure, we’ll have to point other instruments at them.

Are Their Orbits Stable?

Planets require stable orbits over a biologically significant period of time in order for life to develop. Conditions that change too rapidly make it impossible for life to survive and adapt. A planet needs a stable amount of solar radiation, and a stable temperature, to support life. If the solar radiation, and the planet’s temperature, fluctuates too rapidly or too much due to orbital instability, then life would not be able to adapt to those changes.

Right now, there’s no indication that the orbits of the TRAPPIST 1 planets are unstable. But we are still in the preliminary stage of investigation. We need a longer sampling of their orbits to know for sure.

Pelted by Interlopers?

Our Solar System is a relatively placid place when it comes to meteors and asteroids. But it wasn’t always that way. Evidence from lunar rock samples show that it may have suffered through a period called the “Late Heavy Bombardment.” During this time, the inner Solar System was like a shooting gallery, with Earth, Venus, Mercury, Mars, and our Moon being struck continuously by asteroids.

The cause of this period of Bombardment, so the theory goes, was the migration of the giant planets through the solar system. Their gravity would have dislodged asteroids from the asteroid belt and the Kuiper Belt, and sent them into the path of the inner, terrestrial planets.

We know that Earth has been hit by meteorites multiple times, and that at least one of those times, a mass extinction was the result.

Computer generated simulation of an asteroid strike on the Earth. Credit: Don Davis/AFP/Getty Images

The TRAPPIST 1 system has no giant planets. But we don’t know if it has an asteroid belt, a Kuiper Belt, or any other organized, stable body of asteroids. It may be populated by asteroids and comets that are unstable. Perhaps the planets in the habitable zone are subjected to regular asteroid strikes which wipes out any life that gets started there. Admittedly, this is purely speculative, but so are a lot of other things about the TRAPPIST 1 system.

How Will We Find Out More?

We need more powerful telescopes to probe exoplanets like those in the TRAPPIST 1 system. It’s the only way to learn more about them. Sending some kind of probe to a solar system 40 light years away is something that might not happen for generations, if ever.

Luckily, more powerful telescopes are on the way. The James Webb Space Telescope should be in operation by April of 2019, and one of its objectives is to study exoplanets. It will tell us a lot more about the atmospheres of distant exoplanets, and whether or not they can support life.

Other telescopes, like the Giant Magellan Telescope (GMT) and the European Extremely Large Telescope (E-ELT), have the potential to capture images of large exoplanets, and possibly even Earth-sized exoplanets like the ones in the TRAPPIST system. These telescopes will see their first light within ten years.

This artist’s impression shows the European Extremely Large Telescope (E-ELT) in its enclosure. The E-ELT will be a 39-metre aperture optical and infrared telescope. ESO/L. Calçada

What these questions show is that we can’t get ahead of ourselves. Yes, it’s exciting that the TRAPPIST planets have been discovered. It’s exciting that there are multiple terrestrial worlds there, and that 3 of them appear to be in the habitable zone.

It’s exciting that a Red Dwarf star—the most common type of star in our neighborhood—has been found with multiple rocky planets in the habitable zone. Maybe we’ll find a bunch more of them, and the prospect of finding life somewhere else will grow.

But it’s also possible that Earth, with all of its life supporting and sustaining characteristics, is an extremely unlikely occurrence. Special, rare, and unrepeatable.

Posted on by Evan Gough

Rise of the Super Telescopes: The Overwhelmingly Large Telescope

The 100 meter OWL telescope would have operated in the open air, and then been stored in its enclosure when not in use. Image: ESO Telescope Systems Division

We humans have an insatiable hunger to understand the Universe. As Carl Sagan said, “Understanding is Ecstasy.” But to understand the Universe, we need better and better ways to observe it. And that means one thing: big, huge, enormous telescopes.

In this series we’ll look at 6 of the world’s Super Telescopes:

The Overwhelmingly Large Telescope

The OWL (Overwhelmingly Large Telescope) was a gargantuan telescope proposed by the European Southern Observatory (ESO). The OWL was going to be a 100 meter monstrosity, which would dwarf anything in operation at the time. Sadly, OWL was eventually cancelled.

For now, anyway.

At the time that OWL was first proposed—in the late 1990’s—scientific studies showed that huge telescopes would be necessary to advance our knowledge. OWL promised to help us unlock the mystery of dark matter, peer back in time to witness the birth of the first stars and galaxies, and to directly image the atmospheres of exoplanets. It’s easy to see why people were excited by OWL.

This image simulates the increased resolving power of the OWL compared to its contemporaries. Image: ESO Telescope Systems Division

By 2005, the OWL study was completed and reviewed by a panel of experts. At that time, the concept was validated as a cost-effective way to build an Extremely Large Telescope (ELT). However, as the wheels kept turning, and a price tag of € 1.5 billion was attached to it, the ESO backed away.

OWL’s design called for a 100 meter diameter mirror, built out of 3264 segments. It would have had unequalled light-gathering capacity, and the ability to resolve details down to a milli-arc second. (A milli-arc second is approximately the size of a dime, placed on top of the Eiffel Tower, and viewed from New York City.) That’s extremely impressive to say the least. And OWL would have operated in both visible light and infrared.

Everything about OWL’s design was modular, in an effort to keep costs down. Image: ESO Telescope Systems Division

The problem with OWL was the cost, not the design feasibility. Engineers still think the design is feasible. In fact, the construction of the mirrors was pretty well-understood, and perhaps the most challenging part of the OWL was the adaptive optics required.

It’s a fact of large telescopes that they have to be constantly adjusted to produce sharp images. This requires adaptive optics. The adaptive optics required for OWL would have pushed the state-of-the-art technology at the time.

Adaptive optics is a method of overcoming the distortions that affect light as they pass through Earth’s atmosphere. For extremely sensitive telescopes like the OWL, the atmosphere of Earth is problematic. The photons coming from the distant reaches of the Universe can be garbled by the atmosphere as they approach the telescope. Telescopes are built on mountain-tops to reduce how much atmosphere photons have to travel through, but that’s not enough.

This video explains how adaptive optics work, and how they helped the Keck telescope make new discoveries.

OWL’s mirror segments would have to be aligned to within a fraction of the wavelength (0.0005 mm for visible light) in order for the telescope to deliver good images. OWL’s adaptive optics would have achieved this by adjusting each of OWL’s 3264 segments rapidly, sometimes several times per second.

OWL’s design called for modularity, or “serial, industrialized fabrication of identical building blocks” to reduce costs. The manufacture of extremely large telescopes is expensive, but so are the transportation costs. All of the components have to be built in engineering and manufacturing centres, then shipped to, and assembled on, fairly remote mountain tops. OWL’s components were designed to be shipped in standard shipping containers, which simplified that aspect of its construction.

This graphic shows the sizes of the world’s telescopes superimposed over the OWL. By Cmglee – Own workiThe source code of this SVG is valid., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=33613161

In fact, OWL could have begun operation before all of its mirrors were in place, and would have grown in power as more mirror segments were built and integrated. (Other telescopes, like the Giant Magellan Telescope (GMT) will be in operation before all of the mirrors are installed.)

In the end, OWL’s cost became too great, and the project was cancelled. The ESO moved on to the 39.3 meter European Extremely Large Telescope. But all of the work done on the design of OWL was not lost.

This artist’s impression shows the European Extremely Large Telescope (E-ELT) in its enclosure. The E-ELT will be a 39-metre aperture optical and infrared telescope sited on Cerro Armazones in the Chilean Atacama Desert, 20 kilometres from ESO’s Very Large Telescope on Cerro Paranal, which is visible in the distance towards the left. The design for the E-ELT shown here is preliminary. ESO/L. Calçada

Everything that we learn about telescope design trickles down to our next-generation of telescopes. That’s true whether designs like OWL get built or not. We’ll just keep building on our success, and keep building larger and more powerful telescopes.

The adaptive optics that OWL required were a challenge. But huge advances have been made on that front. And in the way of things, the manufacturing costs have likely come down as well.

OWL itself may never be built, but other ‘scopes are on the way. Telescopes like the James Webb Space Telescope, the Giant Magellan Telescope, and the European Extremely Large Telescope hold the same promise that OWL did.

And in the end, the contributions of those and other ‘scopes might surpass those promised by OWL.

Posted on by Evan Gough

Rise of the Super Telescopes: The Giant Magellan Telescope

The Giant Magellan Telescope is under construction in Chile and should see first light sometime in the early 2020s. Image: Giant Magellan Telescope – GMTO Corporation

We humans have an insatiable hunger to understand the Universe. As Carl Sagan said, “Understanding is Ecstasy.” But to understand the Universe, we need better and better ways to observe it. And that means one thing: big, huge, enormous telescopes.

In this series we’ll look at 6 of the world’s Super Telescopes:

The Giant Magellan Telescope

The Giant Magellan Telescope (GMT) is being built in Chile, at the Las Campanas Observatory, home of the GMT’s predecessors the Magellan Telescopes. The Atacama region of Chile is an excellent location for telescopes because of its superb seeing conditions. It’s a high-altitude desert, so it’s extremely dry and cool there, with little light pollution.

The GMT is being built by the USA, Australia, South Korea, and Brazil. It started facility construction in 2015, and first light should be in the early 2020’s.

The heart of the Giant Magellan Telescope is the segmented primary mirror. Image: Giant Magellan Telescope – GMTO Corporation

Segmented mirrors are the peak of technology when it comes to super telescopes, and the GMT is built around this technology.

The GMT’s primary mirror consists of 7 separate mirrors: one central mirror surrounded by 6 other mirrors. Together they form an optical surface that is 24.5 meters (80 ft.) in diameter. That means the GMT will have a total light collecting area of 368 square meters, or almost 4,000 square feet. The GMT will outperform the Hubble Space Telescope by having a resolving power 10 times greater.

There’s a limit to the size of single mirrors that can be built, and the 8.4 meter mirrors in the GMT are at the limits of construction methods. That’s why segmented systems are in use in the GMT, and in other super telescopes being designed and built around the world.

These mirrors are modern feats of engineering. Each one is made of 20 tons of glass, and takes years to build. The first mirror was cast in 2005, and was still being polished 6 years later. In fact, the mirrors are so massive, that they need 6 months to cool when they come out of casting.

They aren’t just flat, simple mirrors. They’re described as potato chips, rather than being flat. They’re aspheric, meaning the mirrors’ faces have steeply curved surfaces. The mirror’s have to have exactly the same curvature in order to perform together, which requires leading-edge manufacturing. The mirrors’ paraboloidal shape has to be polished to an accuracy greater than 25 nanometers. That’s about 1/25th the wavelength of light itself!

In fact, if you took one of the GMT’s mirrors and spread it out from the east coast to the west coast of the USA, the height of the tallest mountain on the mirror would be only 1/2 of one inch.

The plan is for the Giant Magellan Telescope to begin operation with only four of its mirrors. The GMT will also have an extra mirror built, just for contingencies.

The construction of the GMT’s mirrors required entirely new testing methods and equipment to achieve these demanding accuracies. The entire task fell on the University of Arizona’s Richard F. Caris Mirror Lab.

But GMT is more than just its primary mirror. It also has a secondary mirror, which is also segmented. Each one of the secondary mirror’s segments must work in concert with its matching segment on the primary mirror, and the distance from secondary mirror to primary mirror has to be measured within one part in 500 million. That requires exacting engineering for the steel structure of the body of the telescope.

The engineering behind the GMT is extremely demanding, but once it’s in operation, what will it help us learn about the Universe?

“I think the really exciting things will be things that we haven’t yet though of.” -Dr. Robert Kirshner

The GMT will help us tackle multiple mysteries in the Universe, as Dr. Robert Kirshner, of the Harvard-Smithsonian Center for Astrophysics, explains in this video.

The scientific aims of the GMT are well laid out, and there aren’t really any surprises. The goals of the GMT are to increase our understanding of some fundamental aspects of our Universe:

  • Star, planet, and disk formation
  • Extrasolar planetary systems
  • Stellar populations and chemical evolution
  • Galaxy assembly and evolution
  • Fundamental physics
  • First light and reionization

The GMT will collect more light than any other telescope we have, which is why its development is so keenly followed. It will be the first ‘scope to directly image extrasolar planets, which will be enormously exciting. With the GMT, we may be able to see the color of planets, and maybe even weather systems.

We’re accustomed to seeing images of Jupiter’s storm bands, and weather phenomena on other planets in our Solar System, but to be able to see something like that on extra-solar planets will be astounding. That’s something that even the casual space-interested person will immediately be fascinated by. It’s like science fiction come to life.

Of course, we’re still a ways away from any of that happening. With first light not anticipated until the early 2020’s, we’ll have to be very patient.

Posted on by Evan Gough

Wow, Mars Sure Can Be Pretty

This colorful image of Martian bedrock, punctuated in the center by dunes, is courtesy of the HiRise camera aboard NASA's Mars Reconnaissance Orbiter. Image: NASA/JPL/University of Arizona

For a supposedly dead world, Mars sure provides a lot of eye candy. The High Resolution Imaging Science Experiment (HiRise) aboard NASA’s Mars Reconnaissance Orbiter (MRO) is our candy store for stunning images of Mars. Recently, HiRise gave us this stunning image (above) of colorful, layered bedrock on the surface of Mars. Notice the dunes in the center. The colors are enhanced, which makes the images more useful scientifically, but it’s still amazing.

HiRise has done it before, of course. It’s keen vision has fed us a steady stream of downright jaw-dropping images of Elon Musk’s favorite planet. Check out this image of Gale Crater taken by HiRise to celebrate its 10 year anniversary orbiting Mars. This image was captured in March 2016.

HiRise captured this image of unusual textures on the floor of the Gale Crater, the same crater where the Curiosity rover is working. Image: NASA/JPL-Caltech/Univ. of Arizona

The MRO is approaching its 11 year anniversary around Mars. It has completed over 45,000 orbits and has taken over 216,000 images. The next image is of a fresh impact crater on the Martian surface that struck the planet sometime between July 2010 and May 2012. The impact was in a dusty area, and in this color-enhanced image the fresh crater looks blue because the impact removed the red dust.

This color-enhanced image of a fresh Martian crater was captured by the HiRise camera. Image: NASA/JPL-Caltech/Univ. of Arizona

These landforms on the surface of Mars are still a bit of a mystery. It’s possible that they formed in the presence of an ancient Martian ocean, or perhaps glaciers. Whatever the case, they are mesmerizing to look at.

These odd ridges are still a mystery. Were they formed by glaciers? Oceans? Image: NASA/JPL-Caltech/Univ. of Arizona

Many images of the Martian surface have confounded scientists, and some of them still do. But some, though they look puzzling and difficult to explain, have more prosaic explanations. The image below is a large area of intersecting sand dunes.

What is this? A vast area of Martian rice paddies? Lizard skin? Nope, just an area of intersecting sand dunes. Image: NASA/JPL-Caltech/Univ. of Arizona

The surface of Mars is peppered with craters, and HiRise has imaged many of them. This double crater was caused by a meteorite that split in two before hitting the surface.

This double impact crater was caused by a meteorite that split into two before hitting Mars. Notice how the eroding force of the wind has shaped each crater the same, smoothing one edge and creating dunes in the same place. Image: NASA/JPL-Caltech/Univ. of Arizona

The image below shows gullies and dunes at the Russell Crater. In this image, the field of dunes is about 30 km long. This image was taken during the southern winter, when the carbon dioxide is frozen. You can see the frozen CO2 as white on the shaded side of the ridges. Scientists think that the gullies are formed when the CO2 melts in the summer.

These gullies are on the dunes of Russell Crater on Mars. This image was taken during winter, and the frozen carbon dioxide on the shaded slopes. Credit: NASA/JPL/University of Arizona

The next image is also the Russell Crater. It’s an area of study for the HiRise team, which means more Russell eye candy for us. This images shows the dunes, CO2 frost, and dust devil tracks that punctuate the area.

This image of the Russell Crater, an area of study for HiRise, shows the area covered in dunes, with some frost visible in the lower left. The larger, darker markings are dust devil tracks. Image: By NASA/JPL/University of Arizona – HiRISE, Public Domain, https://commons.wikimedia.org/w/index.php?curid=12015650

One of the main geological features on Mars is the Valles Marineris, the massive canyon system that dwarfs the Grand Canyon here on Earth. HiRise captured this image of delicate dune features inside Valles Marineris.

These delicate dune features formed inside the Valles Mariners, the massive canyon system on Mars. Image: NASA/JPL/University of Arizona

The Mars Reconnaissance Orbiter is still going strong. In fact, it continues to act as a communications relay for surface rovers. The HiRise camera is along for the ride, and if the past is any indication, it will continue to provide astounding images of Mars.

And we can’t seem to get enough of them.

Posted on by Evan Gough

Get Ready for the First Pictures of a Black Hole’s Event Horizon

NASA's Spitzer Space Telescope captured this stunning infrared image of the center of the Milky Way Galaxy, where the black hole Sagitarrius A resides. Credit: NASA/JPL-Caltech

It might sound trite to say that the Universe is full of mysteries. But it’s true.

Chief among them are things like Dark Matter, Dark Energy, and of course, our old friends the Black Holes. Black Holes may be the most interesting of them all, and the effort to understand them—and observe them—is ongoing.

That effort will be ramped up in April, when the Event Horizon Telescope (EHT) attempts to capture our first image of a Black Hole and its event horizon. The target of the EHT is none other than Sagittarius A, the monster black hole that lies in the center of our Milky Way Galaxy. Though the EHT will spend 10 days gathering the data, the actual image won’t be finished processing and available until 2018.

The EHT is not a single telescope, but a number of radio telescopes around the world all linked together. The EHT includes super-stars of the astronomy world like the Atacama Large Millimeter Array (ALMA) as well as lesser known ‘scopes like the South Pole Telescope (SPT.) Advances in very-long-baseline-interferometry (VLBI) have made it possible to connect all these telescopes together so that they act like one big ‘scope the size of Earth.

The ALMA array in Chile. Once ALMA was added to the Event Horizon Telescope, it increased the EHT’s power by a factor of 10. Image: ALMA (ESO/NAOJ/NRAO), O. Dessibourg

The combined power of all these telescopes is essential because even though the EHT’s target, Sagittarius A, has over 4 million times the mass of our Sun, it’s 26,000 light years away from Earth. It’s also only about 20 million km across. Huge but tiny.

The EHT is impressive for a number of reasons. In order to function, each of the component telescopes is calibrated with an atomic clock. These clocks keep time to an accuracy of about a trillionth of a second per second. The effort requires an army of hard drives, all of which will be transported via jet-liner to the Haystack Observatory at MIT for processing. That processing requires what’s called a grid computer, which is a sort of virtual super-computer comprised of 800 CPUs.

But once the EHT has done its thing, what will we see? What we might see when we finally get this image is based on the work of three big names in physics: Einstein, Schwarzschild, and Hawking.

A simulation of what the EHT might show us. Image: Event Horizon Telescope Organization

As gas and dust approach the black hole, they speed up. They don’t just speed up a little, they speed up a lot, and that makes them emit energy, which we can see. That would be the crescent of light in the image above. The black blob would be a shadow cast over the light by the hole itself.

Einstein didn’t exactly predict the existence of Black Holes, but his theory of general relativity did. It was the work of one of his contemporaries, Karl Schwarzschild, that actually nailed down how a black hole might work. Fast forward to the 1970s and the work of Stephen Hawking, who predicted what’s known as Hawking Radiation.

Taken together, the three give us an idea of what we might see when the EHT finally captures and processes its data.

Einstein’s general relativity predicted that super massive stars would warp space-time enough that not even light could escape them. Schwarzschild’s work was based on Einstein’s equations and revealed that black holes will have event horizons. No light emitted from inside the event horizon can reach an outside observer. And Hawking Radiation is the theorized black body radiation that is predicted to be released by black holes.

The power of the EHT will help us clarify our understanding of black holes enormously. If we see what we think we’ll see, it confirms Einstein’s Theory of General Relativity, a theory which has been confirmed observationally over and over. If EHT sees something else, something we didn’t expect at all, then that means Einstein’s General Relativity got it wrong. Not only that, but it means we don’t really understand gravity.

In physics circles they say that it’s never smart to bet against Einstein. He’s been proven right time and time again. To find out if he was right again, we’ll have to wait until 2018.

Posted on by Evan Gough

Earth Just Got A New Continent

This simplified map of the continents shows the new continent Zealandia in grey. Image: Mortimer et. al. 2017, GSA Today.

We tend to lump New Zealand and Australia together. They’re similar culturally and share the same geographical position, relative to North America and Europe, anyway. But according to a new paper published in the Geological Society of America Today, it looks like New Zealand and their neighbor New Caledonia are actually their own continent: ‘Zealandia.’

Continent means something different to geographers and geologists. To be considered a geological continent, like Zealandia, the area in question has to satisfy a few conditions:

  • the land in question has to be higher than the ocean floor
  • it has to include a broad range of siliceous igneous, metamorphic, and sedimentary rocks
  • it has to have thicker crust than the ocean floor that surrounds it
  • it has to have well-defined limits, and be large enough to be considered a continent

In Geology, the first three points are well-understood. But as the authors say in the introduction to their paper, “…the last point—how “major” a piece of continental crust has to be to be called a continent—is almost never discussed… .” Since the Earth has so many micro-continents and continental fragments, defining how large something has to be to be called a continent is challenging. But the researchers did their homework.

They noted that the term “Zealandia” has been used before to describe New Zealand and surrounding regions. But the boundaries were never fully explored. 94% of this new continent is submerged, which helps explain why it’s taken this long to be identified.

This map shows the spatial limits of Zealandia. Note the dotted red line that delineates continental crust from ocean crust. Zealandia is also bisected by a plate boundary between the Pacific Plate and the Australian Plate. Image: Mortimer et. al. 2017, GSA Today

Zealandia seemed to be a collection of broken pieces, but new data collected over the years has challenged that interpretation. Recent satellite data has given us new gravity and elevation maps of the seafloor. This data has shown that Zealandia is a unified region large as large as India.

“This is not a sudden discovery but a gradual realization; as recently as 10 years ago we would not have had the accumulated data or confidence in interpretation to write this paper.”

As the authors point out in their paper, it took a while to determine that Zealandia is a continent. There was no Eureka moment. “This is not a sudden discovery but a gradual realization; as recently as 10 years ago we would not have had the accumulated data or confidence in interpretation to write this paper.”

Besides satisfying our intellectual curiosity about our planet, the discovery is important for other reasons. A proper understanding of the plate structures and continental boundaries is important to other sciences, and may trigger further understandings that we can’t predict yet. It may also point to other areas of research.

Also, many treaties rely on the agreed upon delineation of maritime and continental boundaries, including rights to fish stocks and underground resources. While the recognition of Zealandia seems clear from a scientific standpoint, it remains to be seen if it will be accepted politically.

Posted on by Evan Gough

The Universe Has A Lithium Problem

This illustration shows the evolution of the Universe, from the Big Bang on the left, to modern times on the right. Image: NASA

Over the past decades, scientists have wrestled with a problem involving the Big Bang Theory. The Big Bang Theory suggests that there should be three times as much lithium as we can observe. Why is there such a discrepancy between prediction and observation?

To get into that problem, let’s back up a bit.

The Big Bang Theory (BBT) is well-supported by multiple lines of evidence and theory. It’s widely accepted as the explanation for how the Universe started. Three key pieces of evidence support the BBT:

But the BBT still has some niggling questions.

The missing lithium problem is centred around the earliest stages of the Universe: from about 10 seconds to 20 minutes after the Big Bang. The Universe was super hot and it was expanding rapidly. This was the beginning of what’s called the Photon Epoch.

At that time, atomic nuclei formed through nucleosynthesis. But the extreme heat that dominated the Universe prevented the nuclei from combining with electrons to form atoms. The Universe was a plasma of nuclei, electrons, and photons.

Only the lightest nuclei were formed during this time, including most of the helium in the Universe, and small amounts of other light nuclides, like deuterium and our friend lithium. For the most part, heavier elements weren’t formed until stars appeared, and took on the role of nucleosynthesis.

The problem is that our understanding of the Big Bang tells us that there should be three times as much lithium as there is. The BBT gets it right when it comes to other primordial nuclei. Our observations of primordial helium and deuterium match the BBT’s predictions. So far, scientists haven’t been able to resolve this inconsistency.

But a new paper from researchers in China may have solved the puzzle.

One assumption in Big Bang nucleosynthesis is that all of the nuclei are in thermodynamic equilibrium, and that their velocities conform to what’s called the classical Maxwell-Boltzmann distribution. But the Maxwell-Boltzmann describes what happens in what is called an ideal gas. Real gases can behave differently, and this is what the researchers propose: that nuclei in the plasma of the early photon period of the Universe behaved slightly differently than thought.

This graphics shows the distribution of early primordial light elements in the Universe by time and temperature. Temperature along the top, time along the bottom, and abundance on the side. Image: Hou et al. 2017

The authors applied what is known as non-extensive statistics to solve the problem. In the graph above, the dotted lines of the author’s model predict a lower abundance of the beryllium isotope. This is key, since beryllium decays into lithium. Also key is that the resulting amount of lithium, and of the other lighter nuclei, now all conform to the amounts predicted by the Maxwell-Boltzmann distribution. It’s a eureka moment for cosmology aficionados.

The decay chains of primordial light nuclei in the early days of the Universe. Notice the thin red arrows between Beryllium and Lithium at 10-13, the earliest time shown on this chart. Image: Chou et. al.

What this all means is scientists can now accurately predict the abundance in the primordial universe of the three primordial nuclei: helium, deuterium, and lithium. Without any discrepancy, and without any missing lithium.

This is how science grinds away at problems, and if the authors of the paper are correct, then it further validates the Big Bang Theory, and brings us one step closer to understanding how our Universe was formed.

Eureka!

Posted on by Evan Gough

Dream Chaser Spacecraft May Be Used For Hubble Repair Mission

The Dream Chaser Space System, built by the Sierra Nevada Corporation, may be used for one more servicing mission to the Hubble Space Telescope. Image: By NASA - http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=66081, Public Domain, https://commons.wikimedia.org/w/index.php?curid=27237176

The final servicing mission to the venerable Hubble Space Telescope (HST) was in 2009. The shuttle Atlantis completed that mission (STS-125,) and several components were repaired and replaced, including the installation of improved batteries. The HST is expected to function until 2030 – 2040. With the retiring of the shuttle program in 2011, it looked like the Hubble mission was destined to play itself out.

But now there’s talk of another servicing mission to the Hubble, to be performed by the Dream Chaser Space System.

A view of the Hubble Space Telescope from inside space shuttle Atlantis on mission STS-125 in 2009, the final repair mission. Credit: NASA

The Hubble was originally deployed by the Space Shuttle Discovery in 1990. It was serviced by crew aboard the shuttles 5 times on 5 different shuttle missions. Unlike the other observatories in NASA’s Great Observatories, the Hubble was designed to be serviced during its lifetime.

Those servicing missions, which took place in 1993, 1997, 1999, 2002, and 2009, were complex missions which required coordination between the Kennedy Space Center, Johnson Space Center, and the Goddard Space Flight Center. Grasping Hubble with the robotic Canadarm and placing it inside the shuttle bay was a methodical process. So was the repair and replacement of components, and the testing of components once Hubble was removed from the cargo bay. Though complicated, these missions were ultimately successful, and the Hubble is still operating.

The robotic Canadarm during STS-72, as Space Shuttle Endeavour mission in 1996. Image: By NASA – https://archive.org/details/STS072-722-041, Public Domain, https://commons.wikimedia.org/w/index.php?curid=29803999

A future servicing mission to the Hubble would be a sort of insurance policy in case there are problems with NASA’s new flagship telescope, the James Webb Space Telescope (JWST.) The JWST is due to be launched in 2018, and its capabilities greatly exceed those of the Hubble. But the James Webb’s destination is LaGrange Point 2 (L2), a stable point in space about 1.5 million km (932,000 miles) from Earth. It will enter a halo orbit around L2, which makes a repair mission difficult. Though deployment problems with the JWST could be corrected by visiting spacecraft, the Telescope itself is not designed to be repaired like the Hubble is.

Since the JWST is risky, both in terms of its position in space and its unproven deployment method, some type of insurance policy may be needed to ensure NASA has a powerful telescope operating in space. But without Space Shuttles to visit the Hubble and extend its life, a different vehicle would have to be tasked with any potential future servicing missions. Enter the Dream Chaser Space System (DCSS).

The Dream Chaser Space System is like a smaller Space Shuttle. It can carry seven people into Low-Earth Orbit (LEO). Like the Shuttles, it then returns to Earth and lands horizontally on an airstrip. The DCSS, however, does not have a cargo bay or a robotic arm. If it were used for a Hubble repair mission, all repairs would likely have to be done during spacewalks. The DCSS is designed as a cargo and crew resupply ship for the International Space System. The much larger shuttles were designed with the Hubble in mind, as well as other tasks, like building and servicing the ISS and recovering satellites from orbit.

The DCSS is built by Sierra Nevada Corporation. It will be launched on an Atlas V rocket, and will return to Earth by gliding, where it can land on any commercial runway. The DCSS has its own reaction control system for manoeuvering in space. Like other commercial space ventures, the development of the DCSS has been partly funded by NASA.

The primary mirror of the James Webb Space Telescope is unfolded once it's in space. If it fails to deploy properly, NASA may need to use the Dream Chaser to keep the Hubble Telescope operating instead. Image: NASA/Chris Gunn
The primary mirror of the James Webb Space Telescope. Image: NASA/Chris Gunn

The James Webb has a complex deployment. It will be launched on an Ariane 5 rocket, where it will be folded up in order to fit. The primary mirror on the JWST is made up of 18 segments which must unfold in three sections for the telescope to function. The telescope’s sun shield, which keeps the JWST cool, must also unfold after being deployed. Earlier in the mission, the Webb’s solar array and antennae need to be deployed.

This video shows the deployment of the JWST. It reminds one of a giant insect going through metamorphosis.

If either the mirror, the sunshield, or any of the other unfolding mechanisms fail, then a costly and problematic mission will have to be planned to correct the deployment. If some other crucial part of the telescope fails, then it probably can’t be repaired. NASA needs everything to go well.

People have been waiting for the JWST for a long time. It’s had kind of a tortured path to get this far. We all have our fingers crossed that the mission succeeds. But if there are problems, it may be up to the Hubble to keep doing what it’s always done: provide the kinds of science and stunning images that excites scientists and the rest of us about the Universe.

Posted on by Evan Gough

Chance Discovery Of A Three Hour Old Supernova

Artistic impression of a star going supernova, casting its chemically enriched contents into the universe. Credit: NASA/Swift/Skyworks Digital/Dana Berry

Supernovae are extremely energetic and dynamic events in the universe. The brightest one we’ve ever observed was discovered in 2015 and was as bright as 570 billion Suns. Their luminosity signifies their significance in the cosmos. They produce the heavy elements that make up people and planets, and their shockwaves trigger the formation of the next generation of stars.

There are about 3 supernovae every 100 hundred years in the Milky Way galaxy. Throughout human history, only a handful of supernovae have been observed. The earliest recorded supernova was observed by Chinese astronomers in 185 AD. The most famous supernova is probably SN 1054 (historic supernovae are named for the year they were observed) which created the Crab Nebula. Now, thanks to all of our telescopes and observatories, observing supernovae is fairly routine.

The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer, to show that a superdense neutron star is energizing the expanding Nebula by spewing out magnetic fields and a blizzard of extremely high-energy particles. The Chandra X-ray image is shown in light blue, the Hubble Space Telescope optical images are in green and dark blue, and the Spitzer Space Telescope’s infrared image is in red. The size of the X-ray image is smaller than the others because ultrahigh-energy X-ray emitting electrons radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. The neutron star is the bright white dot in the center of the image.
The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer.

But one thing astronomers have never observed is the very early stages of a supernova. That changed in 2013 when, by chance, the automated Intermediate Palomar Transient Factory (IPTF) caught sight of a supernova only 3 hours old.

Spotting a supernovae in its first few hours is extremely important, because we can quickly point other ‘scopes at it and gather data about the SN’s progenitor star. In this case, according to a paper published at Nature Physics, follow-up observations revealed a surprise: SN 2013fs was surrounded by circumstellar material (CSM) that it ejected in the year prior to the supernova event. The CSM was ejected at a high rate of approximately 10 -³ solar masses per year. According to the paper, this kind of instability might be common among supernovae.

SN 2013fs was a red super-giant. Astronomers didn’t think that those types of stars ejected material prior to going supernova. But follow up observations with other telescopes showed the supernova explosion moving through a cloud of material previously ejected by a star. What this means for our understanding of supernovae isn’t clear yet, but it’s probably a game changer.

Catching the 3-hour-old SN 2013fs was an extremely lucky event. The IPTF is a fully-automated wide-field survey of the sky. It’s a system of 11 CCD’s installed on a telescope at the Palomar Observatory in California. It takes 60 second exposures at frequencies from 5 days apart to 90 seconds apart. This is what allowed it to capture SN 2013fs in its early stages.

The 48 inch telescope at the Palomar Observatory. The IPTF is installed on this telescope. Image: IPTF/Palomar Observatory

Our understanding of supernovae is a mixture of theory and observed data. We know a lot about how they collapse, why they collapse, and what types of supernovae there are. But this is our first data point of a SN in its early hours.

SN 2013fs is 160 million light years away in a spiral-arm galaxy called NGC7610. It’s a type II supernova, meaning that it’s at least 8 times as massive as our Sun, but not more than 50 times as massive. Type II supernovae are mostly observed in the spiral arms of galaxies.

A supernova is the end state of some of the stars in the universe. But not all stars. Only massive stars can become supernova. Our own Sun is much too small.

Stars are like dynamic balancing acts between two forces: fusion and gravity.

As hydrogen is fused into helium in the center of a star, it causes enormous outward pressure in the form of photons. That is what lights and warms our planet. But stars are, of course, enormously massive. And all that mass is subject to gravity, which pulls the star’s mass inward. So the fusion and the gravity more or less balance each other out. This is called stellar equilibrium, which is the state our Sun is in, and will be in for several billion more years.

But stars don’t last forever, or rather, their hydrogen doesn’t. And once the hydrogen runs out, the star begins to change. In the case of a massive star, it begins to fuse heavier and heavier elements, until it fuses iron and nickel in its core. The fusion of iron and nickel is a natural fusion limit in a star, and once it reaches the iron and nickel fusion stage, fusion stops. We now have a star with an inert core of iron and nickel.

Now that fusion has stopped, stellar equilibrium is broken, and the enormous gravitational pressure of the star’s mass causes a collapse. This rapid collapse causes the core to heat again, which halts the collapse and causes a massive outwards shockwave. The shockwave hits the outer stellar material and blasts it out into space. Voila, a supernova.

The extremely high temperatures of the shockwave have one more important effect. It heats the stellar material outside the core, though very briefly, which allows the fusion of elements heavier than iron. This explains why the extremely heavy elements like uranium are much rarer than lighter elements. Only large enough stars that go supernova can forge the heaviest elements.

In a nutshell, that is a type II supernova, the same type found in 2013 when it was only 3 hours old. How the discovery of the CSM ejected by SN 2013fs will grow our understanding of supernovae is not fully understood.

Supernovae are fairly well-understood events, but their are still many questions surrounding them. Whether these new observations of the very earliest stages of a supernovae will answer some of our questions, or just create more unanswered questions, remains to be seen.