Weekly Space Hangout: Feb 28, 2018: Will Kalif’s “See It With A Small Telescope”

Hosts:
Fraser Cain (universetoday.com / @fcain)
Dr. Paul M. Sutter (pmsutter.com / @PaulMattSutter)
Dr. Kimberly Cartier (KimberlyCartier.org / @AstroKimCartier )
Dr. Morgan Rehnberg (MorganRehnberg.com / @MorganRehnberg & ChartYourWorld.org)

Special Guests:
Will Kalif is the author of the new amateur astronomy book titled See it With a Small Telescope.

Announcements:
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!

We record the Weekly Space Hangout every Wednesday at 5:00 pm Pacific / 8:00 pm Eastern. You can watch us live on Universe Today, or the Weekly Space Hangout YouTube page – Please subscribe!

Astronomy Cast Ep. 452: Summer Observing Challenges

Summer is almost here, and for the northern hemisphere, that means warm nights for observing. But what to observe? We’re here with a list of events and targets for you to enjoy over the summer. Get your calendars handy, and start organizing some events with your friends, and then get out there!

Visit the Astronomy Cast Page to subscribe to the audio podcast!

We usually record Astronomy Cast as a live Google+ Hangout on Air every Friday at 1:30 pm Pacific / 4:30 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.

Weekly Space Hangout – May 26, 2017: Stephen Petranek and How We’ll Live On Mars


Host: Fraser Cain (@fcain)

Special Guest:
NAT GEO’s Stephen Petranek is the author of How We’ll Live on Mars (TED Books.) Stephen became a reluctant doomsayer when his earliest TED Talk (10 Ways the World Could End) racked up 1.5 million views. But Petranek is, in fact, an optimist who believes that humanity will escape its predicaments — literally. Within a century, he predicts that humans will have established a city of 80,000 on Mars: and that not only is that plausible, but it’s also inevitable.

Having worked in publishing for four decades — most of it straddling the line with science and technology, Petranek is the former editor-in-chief of Discover magazine, editor of the Washington Post’s magazine, and a renown TED Talk speaker has also given him some unique perspective and insight on the changes that lie ahead and new tools that reflect a potential disruptive shift in how we observe the world around us. Petranek is the editor-in-chief of the Breakthrough Technology Alert, a technology newsletter that ties scientific breakthroughs to investment opportunities.

Guests:
Dr. Kimberly Cartier ( KimberlyCartier.org / @AstroKimCartier )
Nicole Gugliucci (cosmoquest.org / @noisyastronomer)
Paul M. Sutter (pmsutter.com / @PaulMattSutter)

Their stories this week:

Boyajian’s Star is at it again

Q&A about the new dipping event

Familiar Galaxy Shows New Object in the Radio

Gravitational Waves Alter Spacetime?

Defining a new stage of planet formation

We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!

Announcements:

The WSH recently welcomed back Mathew Anderson, author of “Our Cosmic Story,” to the show to discuss his recent update. He was kind enough to offer our viewers free electronic copies of his complete book as well as his standalone update. Complete information about how to get your copies will be available on the WSH webpage – just visit http://www.wsh-crew.net/cosmicstory for all the details.

If you’d like to join Fraser and Paul Matt Sutter on their Tour to Iceland in February 2018, you can find the information at astrotouring.com.

If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!

We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page

Rise of the Super Telescopes: Why We Build Them

This illustration shows what the Giant Magellan Telescope will look like when it comes online. The fifth of its seven mirror segments is being cast now. Each of the segments is a 20 ton piece of glass. Image: Giant Magellan

One night 400 years ago, Galileo pointed his 2 inch telescope at Jupiter and spotted 3 of its moons. On subsequent nights, he spotted another, and saw one of the moons disappear behind Jupiter. With those simple observations, he propelled human understanding onto a path it still travels.

Galileo’s observations set off a revolution in astronomy. Prior to his observations of Jupiter’s moons, the prevailing belief was that the entire Universe rotated around the Earth, which lay at the center of everything. That’s a delightfully childish viewpoint, in retrospect, but it was dogma at the time.

Until Galileo’s telescope, this Earth-centric viewpoint, called Aristotelian cosmology, made sense. To all appearances, we were at the center of the action. Which just goes to show you how wrong we can be.

But once it became clear that Jupiter had other bodies orbiting it, our cherished position at the center of the Universe was doomed.

Galileo Galilei set off a revolution in astronomy when he used his telescope to observe moons orbiting Jupiter. By Justus Sustermans - http://www.nmm.ac.uk/mag/pages/mnuExplore/PaintingDetail.cfm?ID=BHC2700, Public Domain, https://commons.wikimedia.org/w/index.php?curid=230543
Galileo Galilei set off a revolution in astronomy when he used his telescope to observe moons orbiting Jupiter. By Justus Sustermans – http://www.nmm.ac.uk/mag/pages/mnuExplore/PaintingDetail.cfm?ID=BHC2700, Public Domain, https://commons.wikimedia.org/w/index.php?curid=230543

Galileo’s observations were an enormous challenge to our understanding of ourselves at the time, and to the authorities at the time. He was forced to recant what he had seen, and he was put under house arrest. But he never really backed down from the observations he made with his 2 inch telescope. How could he?

Now, of course, there isn’t so much hostility towards people with telescopes. As time went on, larger and more powerful telescopes were built, and we’ve gotten used to our understanding going through tumultuous changes. We expect it, even anticipate it.

In our current times, Super Telescopes rule the day, and their sizes are measured in meters, not inches. And when new observations challenge our understanding of things, we cluster around out of curiosity, and try to work our way through it. We don’t condemn the results and order scientists to keep quiet.

The first of the Super Telescopes, as far as most of us are concerned, is the Hubble Space Telescope. From its perch in Low Earth Orbit (LEO), the Hubble has changed our understanding of the Universe on numerous fronts. With its cameras, and the steady stream of mesmerizing images those cameras deliver, a whole generation of people have been exposed to the beauty and mystery of the cosmos.

The Hubble Space Telescope could be considered the first of the Super Telescopes. In this image it is being released from the cargo bay of the Space Shuttle Discovery in 1990. Image: By NASA/IMAX - http://mix.msfc.nasa.gov/abstracts.php?p=1711, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6061254
The Hubble Space Telescope could be considered the first of the Super Telescopes. In this image it is being released from the cargo bay of the Space Shuttle Discovery in 1990. Image: By NASA/IMAX – http://mix.msfc.nasa.gov/abstracts.php?p=1711, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6061254

Hubble has gazed at everything, from our close companion the Moon, all the way to galaxies billions of light years away. It’s spotted a comet breaking apart and crashing into Jupiter, dust storms on Mars, and regions of energetic star-birth in other galaxies. But Hubble’s time may be coming to an end soon, and other Super Telescopes are on the way.

Nowadays, Super Telescopes are expensive megaprojects, often involving several nations. They’re built to pursue specific lines of inquiry, such as:

  • What is the nature of Dark Matter and Dark Energy? How are they distributed in the Universe and what role do they play?
  • Are there other planets like Earth, and solar systems like ours? Are there other habitable worlds?
  • Are we alone or is there other life somewhere?
  • How do planets, solar systems, and galaxies form and evolve?

Some of the Super Telescopes will be on Earth, some will be in space. Some have enormous mirrors made up of individual, computer-controlled segments. The Thirty Meter Telescope has almost 500 of these segments, while the European Extremely Large Telescope has almost 800 of them. Following a different design, the Giant Magellan Telescope has only seven segments, but each one is over 8 meters in diameter, and each one weighs in at a whopping 20 tons of glass each.

This artistic bird's-eye view shows the dome of the ESO European Extremely Large Telescope (E-ELT) in all its glory, on top of the Chilean Cerro Armazones. The telescope is currently under construction and its first light is targeted for 2024.
This artistic bird’s-eye view shows the dome of the ESO European Extremely Large Telescope (E-ELT) in all its glory, on top of the Chilean Cerro Armazones. The telescope is currently under construction and its first light is targeted for 2024.

Some of the Super Telescopes see in UV or Infrared, while others can see in visible light. Some see in several spectrums. The most futuristic of them all, the Large Ultra-Violet, Optical, and Infrared Surveyor (LUVOIR), will be a massive space telescope situated a million-and-a-half kilometers away, with a 16 meter segmented mirror that dwarfs that of the Hubble, at a mere 2.4 meters.

Some of the Super Telescopes will discern the finest distant details, while another, the Large Synoptic Survey Telescope, will complete a ten-year survey of the entire available sky, repeatedly imaging the same area of sky over and over. The result will be a living, dynamic map of the sky showing change over time. That living map will be available to anyone with a computer and an internet connection.

A group photo of the team behind the Large Synoptic Survey Telescope. The group gathered to celebrate the casting of the 'scope's 27.5 ft diameter mirror. The LSST will create a living, detailed, dynamic map of the sky and make it available to anyone. Image: LSST Corporation
A group photo of the team behind the Large Synoptic Survey Telescope. The group gathered to celebrate the casting of the ‘scope’s 27.5 ft diameter mirror. The LSST will create a living, detailed, dynamic map of the sky and make it available to anyone. Image: LSST Corporation

We’re in for exciting times when it comes to our understanding of the cosmos. We’ll be able to watch planets forming around young stars, glimpse the earliest ages of the Universe, and peer into the atmospheres of distant exoplanets looking for signs of life. We may even finally crack the code of Dark Matter and Dark Energy, and understand their role in the Universe.

Along the way there will be surprises, of course. There always are, and it’s the unanticipated discoveries and observations that fuel our sense of intellectual adventure.

The Super Telescopes are technological masterpieces. They couldn’t be built without the level of technology we have now, and in fact, the development of Super Telescopes help drives our technology forward.

But they all have their roots in Galileo and his simple act of observing with a 2-inch telescope. That, and the curiosity about nature that inspired him.

The Rise of the Super Telescopes Series:

Rise of the Super Telescopes: The Thirty Meter Telescope

As Carl Sagan said, “Understanding is Ecstasy.” But in order 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 six Super Telescopes being built:

The Thirty Meter Telescope

The Thirty Meter Telescope (TMT) is being built by an international group of countries and institutions, like a lot of Super Telescopes are. In fact, they’re proud of pointing out that the international consortium behind the TMT represents almost half of the world’s population; China, India, the USA, Japan, and Canada. The project needs that many partners to absorb the cost; an estimated $1.5 billion.

The heart of any of the world’s Super Telescopes is the primary mirror, and the TMT is no different. The primary mirror for the TMT is, obviously, 30 meters in diameter. It’s a segmented design consisting of 492 smaller mirrors, each one a 1.4 meter hexagon.

The light collecting capability of the TMT will be 10 times that of the Keck Telescope, and more than 144 times that of the Hubble Space Telescope.

But the TMT is more than just an enormous ‘light bucket.’ It also excels with other capabilities that define a super telescope’s effectiveness. One of those is what’s called diffraction-limited spatial resolution (DLSR).

An illustration of the segmented primary mirror of the Thirty Meter Telescope. Image Courtesy TMT International Observatory

When a telescope is pointed at distant objects that appear close together, the light from both can scatter enough to make the two objects appear as one. Diffraction-limited spatial resolution means that when a ‘scope is observing a star or other object, none of the light from that object is scattered by defects in the telescope. The TMT will more easily distinguish objects that are close to each other. When it comes to DLSR, the TMT will exceed the Keck by a factor of 3, and will exceed the Hubble by a factor of 10 at some wavelengths.

Crucial to the function of large, segmented mirrors like the TMT is active optics. By controlling the shape and position of each segment, active optics allows the primary mirror to compensate for changes in wind, temperature, or mechanical stress on the telescope. Without active optics, and its sister technology adaptive optics, which compensates for atmospheric disturbance, any telescope larger than about 8 meters would not function properly.

The TMT will operate in the near-ultraviolet, visible, and near-infrared wavelengths. It will be smaller than the European Extremely Large Telescope (E-ELT), which will have a 39 meter primary mirror. The E-ELT will operate in the optical and infrared wavelengths.

The world’s Super Telescopes are behemoths. Not just in the size of their mirrors, but in their mass. The TMT’s moving mass will be about 1,420 tonnes. Moving the TMT quickly is part of the design of the TMT, because it must respond quickly when something like a supernova is spotted. The detailed science case calls for the TMT to acquire a new target within 5 to 10 minutes.

This requires a complex computer system to coordinate the science instruments, the mirrors, the active optics, and the adaptive optics. This was one of the initial challenges of the TMT project. It will allow the TMT to respond to transient phenomena like supernovae when spotted by other telescopes like the Large Synoptic Survey Telescope.

The Science

The TMT will investigate most of the important questions in astronomy and cosmology today. Here’s an overview of major topics that the TMT will address:

  • The Nature of Dark Matter
  • The Physics of Extreme Objects like Neutron Stars
  • Early galaxies and Cosmic Reionization
  • Galaxy Formation
  • Super-Massive Black Holes
  • Exploration of the Milky Way and Nearby Galaxies
  • The Birth and Early Lives of Stars and Planets
  • Time Domain Science: Supernovae and Gamma Ray Bursts
  • Exo-planets
  • Our Solar System

This is a comprehensive list of topics, to be sure. It leaves very little out, and is a testament to the power and effectiveness of the TMT.

The raw power of the TMT is not in question. Once in operation it will advance our understanding of the Universe on multiple fronts. But the actual location of the TMT could still be in question.

Where Will the TMT Be Built?

The original location for the TMT was Mauna Kea, the 4,200 meter summit in Hawaii. Mauna Kea is an excellent location, and is the home of several telescopes, most notably the Keck Observatory, the Gemini Telescope, the Subaru Telescope, the Canada-France-Hawaii Telescope, and the James Clerk Maxwell Telescope. Mauna Kea is also the site of the westernmost antenna of the Very Long Baseline Array.

The top of Mauna Kea is a prime site for telescopes, as shown in this image. Image Courtesy Mauna Kea Observatories

The dispute between some of the Hawaiian people and the TMT has been well-documented elsewhere, but the basic complaint about the TMT is that the top of Mauna Kea is sacred land, and they would like the TMT to be built elsewhere.

The organizations behind the TMT would still like it to be built at Mauna Kea, and a legal process is unfolding around the dispute. During that process, they identified several possible alternate sites for the telescope, including La Palma in the Canary Islands. Universe Today contacted TMT Observatory Scientist Christophe Dumas, PhD., about the possible relocation of the TMT to another site.

Dr. Dumas told us that “Mauna Kea remains the preferred location for the TMT because of its superb observing conditions, and because of the synergy with other TMT partner facilities already present on the mountain. Its very high elevation of almost 14,000 feet makes it the premier astronomical site in the northern hemisphere. The sky above Mauna Kea is very stable, which allows very sharp images to be obtained. It has also excellent transparency, low light pollution and stable cold temperatures that improves sensitivity for observations in the infrared.”

The preferred secondary site at La Palma is home to over 10 other telescopes, but would relocation to the Canary Islands affect the science done by the TMT? Dr. Dumas says that the Canary Islands site is excellent as well, with similar atmospheric characteristics to Mauna Kea, including stability, transparency, darkness, and fraction of clear-nights.

The Gran Telescopio Canarias (Great Canary Telescope) is the largest ‘scope currently at La Palma. At 10m diameter, it would be dwarfed by the TMT. Image: By Pachango – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6880933

As Dr. Dumas explains, “La Palma is at a lower elevation site and on average warmer than Mauna Kea. These two factors will reduce TMT sensitivity at some wavelengths in the infrared region of the spectrum.”

Dr. Dumas told Universe Today that this reduced sensitivity in the infrared can be overcome somewhat by scheduling different observing tasks. “This specific issue can be partly mitigated by implementing an adaptive scheduling of TMT observations, to match the execution of the most demanding infrared programs with the best atmospheric conditions above La Palma.”

Court Proceedings End

On March 3rd, 44 days of court hearings into the TMT wrapped up. In that time, 71 people testified for and against the TMT being constructed on Mauna Kea. Those against the telescope say that the site is sacred land and shouldn’t have any more telescope construction on it. Those for the TMT spoke in favor of the science that the TMT will deliver to everyone, and the education opportunities it will provide to Hawaiians.

Though construction has been delayed, and people have gone to court to have the project stopped, it seems like the TMT will definitely be built—somewhere. The funding is in place, the design is finalized, and manufacturing of the components is underway. The delays mean that the TMT’s first light is still uncertain, but once we get there, the TMT will be another game-changer, just like the world’s other Super Telescopes.

Rise of the Super Telescopes: The Large Synoptic Survey Telescope

An artist's illustration of the Large Synoptic Survey Telescope with a simulated night sky. The team hopes to use the LSST to further refine their search for hard-surface supermassive objects. Image: Todd Mason, Mason Productions Inc. / LSST 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 Large Synoptic Survey Telescope

While the world’s other Super Telescopes rely on huge mirrors to do their work, the LSST is different. It’s a huge panoramic camera that will create an enormous moving image of the Universe. And its work will be guided by three words: wide, deep, and fast.

While other telescopes capture static images, the LSST will capture richly detailed images of the entire available night sky, over and over. This will allow astronomers to basically “watch” the movement of objects in the sky, night after night. And the imagery will be available to anyone.

The LSST is being built by a group of institutions in the US, and even got some money from Bill Gates. It will be situated atop Cerro Pachon, a peak in Northern Chile. The Gemini South and Southern Astrophysical Research Telescopes are also situated there.

The Camera Inside the ‘Scope

At the heart of the LSST is its enormous digital camera. It weighs over three tons, and the sensor is segmented in a similar way that other Super Telescopes have segmented mirrors. The LSST’s camera is made up of 189 segments, which together create a camera sensor about 2 ft. in diameter, behind a lens that is over 5 ft. in diameter.

Each image that the LSST captures is 40 times larger than the full moon, and will measure 3.2 gigapixels. The camera will capture one of these wide-field images every 20 seconds, all night long. Every few nights, the LSST will give us an image of the entire available night sky, and it will do that for 10 years.

“The LSST survey will open a movie-like window on objects that change brightness, or move, on timescales ranging from 10 seconds to 10 years.” – LSST: FROM SCIENCE DRIVERS TO REFERENCE DESIGN AND ANTICIPATED DATA PRODUCTS

The LSST will capture a vast, movie-like image of over 40 billion objects. This will range from distant, enormous galaxies all the way down to Potentially Hazardous Objects as small as 140 meters in diameter.

The primary-tertiay mirror at its construction facility. Image: LSST

There’s a whole other side to the LSST which is a little more challenging. We get the idea of an in-depth, moving, detailed image of the sky. That’s intuitively easy to engage with. But there’s another side, the data mining challenge.

The Data Challenge

The whole endeavour will create an enormous amount of data. Over 15 terabytes will have to be processed every night. Over its 10 year lifespan, it will capture 60 petabytes of data.

Once data is captured by the LSST, it will travel via two dedicated 40 GB lines to the Data Processing and Archive Center. That Center is a super-computing facility that will manage all the data and make it available to users. But when it comes to handling the data, that’s just the tip of the iceberg.

“LSST is a new way to observe, and gaining knowledge from the Big Data LSST delivers is indeed a challenge.” – Suzanne H. Jacoby, LSST

The sheer amount of data created by the LSST is a challenge that the team behind it saw coming. They knew they would have to build the capacity of the scientific community in advance, in order to get the most out of the LSST.

Handling all of the data from the LSST requires its own infrastructure. Image: LSST

As Suzanne Jacoby, from the LSST team, told Universe today, “To prepare the science community for LSST Operations, the LSST Corporation has undertaken an “Enabling Science” effort which funds the LSST Data Science Fellowship Program (DSFP). This two-year program is designed to supplement existing graduate school curriculum and explores topics including statistics, machine learning, information theory, and scalable programming.”

The Science

The Nature of Dark Matter and Understanding Dark Energy

Contributing to our understanding Dark Energy and Dark Matter is a goal of all of the Super Telescopes. The LSST will map several billion galaxies through time and space. It will help us understand how Dark Energy behaves over time, and how Dark Matter affects the development of cosmic structure.

Cataloging the Solar System

The raw imaging power of the LSST will be a game-changer for mapping and cataloguing our Solar System. It’s thought that the LSST could detect between 60-90% of all potentially hazardous asteroids (PHAs) larger than 140 meters in diameter, as far away as the main asteroid belt. This will not only contribute to NASA’s goal of identifying threats to Earth posed by asteroids, but will help us understand how planets formed and how our Solar System evolved.

Exploring the Changing Sky

The repeated imaging of the night sky, at great depth and with excellent image quality, should tell us a lot about supernovae, variable stars, and possible other events we haven’t even discovered yet. There are always surprising results whenever we build a new telescope or send a probe to a new destination. The LSST will probably be no different.

Milky Way Structure & Formation

The LSST will give us an unprecedented look at the Milky Way. It will survey over half of the sky, and will do so repeatedly. Hundreds of times, in fact. The end result will be an enormously detailed look at the motion of millions of stars in our galaxy.

Open Access

Perhaps the best part of the whole LSST project is that the all of the data will be available to everyone. Anyone with a computer and an internet connection will be able to access LSST’s movie of the Universe. It’s warm and fuzzy, to be sure, to have the results of large science endeavours like this available to anyone. But there’s more to it. The LSST team suspects that the majority of the discoveries resulting from its rich data will come from unaffiliated astronomers, students, and even amateurs.

It was designed from the ground up in this way, and there will be no delay or proprietary barriers when it comes to public data access. In fact, Google has signed on as a partner with LSST because of the desire for public access to the data. We’ve seen what Google has done with Google Earth and Google Sky. What will they come up with for Google LSST?

The Sloan Digital Sky Survey (SDSS), a kind of predecessor to the LSST, was modelled in the same way. All of its data was available to astronomers not affiliated with it, and out of over 6000 papers that refer to SDSS data, the large majority of them were published by astronomers not affiliated with SDSS.

First Light

We’ll have to wait a while for all of this to come our way, though. First light for the LSST won’t be until 2021, and it will begin its 10 year run in 2022. At that time, be ready for a whole new look at our Universe. The LSST will be a game-changer.

Rise of the Super Telescopes: The Overwhelmingly Large Telescope

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.

Rise of the Super Telescopes: The Giant Magellan Telescope

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.

Messier 27 – The Dumbbell Nebula

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the famous and easily-spotted Dumbbell Nebula. Enjoy!

Back in the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of them so that others would not make the same mistake he did. In time, this list would come to include 100 of the most fabulous objects in the night sky.

Known today as the Messier Catalog, this work has come to be viewed as one of the most important milestones in the study of Deep Space Objects. One of these is the famed Dumbbell Nebula – also known as Messier 27, the Apple Core Nebula, and NGC 6853. Because it of its brightness, it is easily viewed with binoculars and amateur telescopes, and was the first planetary Nebula to be discovered by Charles Messier.

Description:

This bright planetary nebula is located in the direction of the Vulpecula constellation, at a distance of about 1,360 light years from Earth. Located within the equatorial plane, this nebula is essentially a dying star that has been ejecting a shell of hot gas into space for roughly 48,000 years.

Picture of M27 processed and combined using IRAF and MaxIm DL by Mohamad Abbas. Credit: Mohamad Abbas
Picture of M27 processed and combined using IRAF and MaxIm DL. Credit: Wikipedia Commons/Mohamad Abbas

The star responsible is an extremely hot blueish subdwarf star, which emits primarily highly energetic radiation in the non-visible part of the electromagnetic spectrum. This energy is absorbed by exciting the nebula’s gas, and then re-emitted by the nebula. Messier 27 particular green glow (hence the nickname “Apple Core Nebula”) is due to the presence of doubly-ionized oxygen in its center, which emits green light at 5007 Angstroms.

For many years I quested to understand the distant and mysterious M27, but no one could answer my questions. I researched it, and learned that it was made up of doubly ionized oxygen. I had hoped that perhaps there was a spectral reason to what I viewed year after year – but still no answer.

Like all amateurs, I became the victim of “aperture fever” and I continued to study M27 with a 12″ telescope, never realizing the answer was right there – I just hadn’t powered up enough. Several years later while studying at the Observatory, I was viewing through a friend’s identical 12″ telescope and, as chance would have it, he was using about twice the magnification that I normally used on the “Dumbbell.”

Imagine my total astonishment as I realized for the very first time that the faint central star had an even fainter companion that made it seem to wink! At smaller apertures or low power, this was not revealed. Still, the eye could “see” a movement within the nebula – the central, radiating star and its companion.

Image from a ground-based telescope at Westview Observatory in Cridersville, OH. Credit: Wikipedia Commons/Charlemagne920
Image from a ground-based telescope at Westview Observatory in Cridersville, OH. Credit: Wikipedia Commons/Charlemagne920

As W.G. Mathews of the University of California put it in his study “Dynamical Evolution of a Model Planetary Nebula”:

“As the gas at the inner edge begins to ionize, the pressure throughout the nebula is equalized by a shock which moves outward through the neutral gas. Later, when about 1/10 of the nebular mass is ionized, a second shock is released from the ionized front, and this shock moves through the neutral shell reaching the outer edge. The density of the HI gas just behind the shock is quite large and the outward gas velocity increases within until it reaches a maximum of 40-80 km per second just behind the shock front. The projected appearance of the nebula during this stage has a double ring structure similar to many observed planetaries.”

R.E. Lupu of John Hopkins has also made studies of motion as well, which they published in a study titled “Discovery of Lyman-alpha Pumped Molecular Hydrogen Emission in the Planetary Nebulae NGC 6853 and NGC 3132“. As they indicated, and found them to “have low surface brightness signatures in the visible and near infrared.”

But, movement or no movement, Messier 27 is known as one of the top “polluters” of the interstellar medium. As Joseph L. Hora ( et al.) of the Harvard-Smithsonian Center for Astrophysics said in his 2008 study “Planetary Nebulae: Exposing the Top Polluters of the ISM“:

“The high mass loss rates of stars in their asymptotic giant branch (AGB) stage of evolution is one of the most important pathways for mass return from stars to the ISM. In the planetary nebulae (PNe) phase, the ejected material is illuminated and can be altered by the UV radiation from the central star. PNe therefore play a significant role in the ISM recycling process and in changing the environment around them…

“A key link in the recycling of material to the Interstellar Medium (ISM) is the phase of stellar evolution from Asymptotic Giant Branch (AGB) to white dwarf star. When stars are on the AGB, they begin to lose mass at a prodigious rate. The stars on the AGB are relatively cool, and their atmospheres are a fertile environment for the formation of dust and molecules. The material can include molecular hydrogen (H2), silicates, and carbon-rich dust. The star is fouling its immediate neighborhood with these noxious emissions. The star is burning clean hydrogen fuel, but unlike a “green” hydrogen vehicle that outputs nothing except water, the star produces ejecta of various types, some of which have properties similar to that of soot from a gas-burning automobile. A significant fraction of the material returned to the ISM goes through the AGB – PNe pathway, making these stars one of the major sources of pollution of the ISM.

“However, these stars are not done with their stellar ejecta yet. Before the slow, massive AGB wind can escape, the star begins a rapid evolution where it contracts and its surface temperature increases. The star starts ejecting a less massive but high velocity wind that crashes into the existing circumstellar material, which can create a shock and a higher density shell. As the stellar temperature increases, the UV flux increases and it ionizes the gas surrounding the central star, and can excite emission from molecules, heat the dust, and even begin to break apart the molecules and dust grains. The objects are then visible as planetary nebulae, exposing their long history of spewing material into the ISM, and further processing the ejecta. There are even reports that the central stars of some PNe may be engaging in nucleosynthesis for purposes of self-enrichment, which can be traced by monitoring the elemental abundances in the nebulae. Clearly, we must assess and understand the processes going on in these objects in order to understand their impact on the ISM, and their influence on future generations of stars.”

Messier 27 and the Summer Triangle. Credit: Wikisky
Messier 27 and the Summer Triangle. Credit: Wikisky

History of Observation:

So, chances are on July 12th, 1764, when Charles Messier discovered this new and fascinating class of objects, he didn’t really have a clue as to how important his observation would be. From his notes of that night, he reports:

“I have worked on the research of the nebulae, and I have discovered one in the constellation Vulpecula, between the two forepaws, and very near the star of fifth magnitude, the fourteenth of that constellation, according to the catalog of Flamsteed: One sees it well in an ordinary refractor of three feet and a half. I have examined it with a Gregorian telescope which magnified 104 times: it appears in an oval shape; it doesn’t contain any star; its diameter is about 4 minutes of arc. I have compared that nebula with the neighboring star which I have mentioned above [14 Vul]; its right ascension has been concluded at 297d 21′ 41″, and its declination 22d 4′ 0″ north.”

Of course, Sir William Herschel’s own curiosity would get the better of him and although he would never publish his own findings on an object previously cataloged by Messier, he did keep his own private notes. Here is an excerpt from just one of his many observations:

“1782, Sept. 30. My sister discovered this nebula this evening in sweeping for comets; on comparing its place with Messier’s nebulae we find it is his 27. It is very curious with a compound piece; the shape of it though oval as M. [Messier] calls it, is rather divided in two; it is situated among a number of small [faint] stars, but with this compound piece no star is visible in it. I can only make it bear 278. It vanishes with higher powers on account of its feeble light. With 278 the division between the two patches is stronger, because the intermediate faint light vanishes more.”

So where did Messier 27 get its famous moniker? From Sir John Herschel, who wrote: “A most extraordinary object; very bright; an unresolved nebula, shaped something like an hour-glass, filled into an oval outline with a much less dense nebulosity. The central mass may be compared to a vertebra or a dumb-bell. The southern head is denser than the northern. One or two stars seen in it.”

It would be several years, and several more historical astronomers, before the true nature of Messier 27 would even be hinted at. At one level, they understood it to be a nebula – but it wasn’t until 1864 when William Huggins came along and began to decode the mystery:

“It is obvious that the nebulae 37 H IV (NGC 3242), Struve 6 (NGC 6572), 73 H IV (NGC 6826), 1 H IV (NGC 7009), 57 M, 18 H. IV (NGC 7662) and 27 M. can no longer be regarded as aggregations of suns after the order to which our own sun and the fixed stars belong. We have with these objects to do no longer with a special modification only of our own type of suns, but find ourselves in the presence of objects possessing a distinct and peculiar plan of structure. In place of an incandescent solid or liquid body transmitting light of all refrangibilities through an atmosphere which intercepts by absorption a certain number of them, such as our sun appears to be, we must probably regard these objects, or at least their photo-surfaces, as enormous masses of luminous gas or vapour. For it is alone from matter in the gaseous state that light consisting of certain definite refrangibilities only, as is the case with the light of these nebulae, is known to be emitted.”

Whether or not you enjoy M27 as one of the most superb planetary nebula in the night sky (or as a science object) you will 100% agree with the words of of Burnham: “The observer who spends a few moments in quiet contemplation of this nebula will be made aware of direct contact with cosmic things; even the radiation reaching us from the celestial depths is of a type unknown on Earth…”

Locating Messier 27:

When you first begin, Messier 27 will seem like such an elusive target – but with a few simple sky “tricks”, it won’t be long until you’ll be finding this spectacular planetary nebula under just about any sky conditions. The hardest part is simply sorting out all the stars in the area to know the right ones to aim at!

The way I found easiest to teach others was to start BIG. The cruciform patterns of the Cygnus and Aquila constellations are easy to recognize and can be seen from even urban locations. Once you’ve identified these two constellations, you’re going smaller by locating Lyra and the tiny kite-shape of Delphinus.

Now you’ve circled the area and the hunt for Vulpecula the Fox begins! What’s that you say? You can’t distinguish Vulpecula’s primary stars from the rest of the field? You’re right. They don’t stand out like they should, and being tempted to simply aim halfway between Albeireo (Beta Cygni) and Alpha Delphini is too much of a span to be accurate. So what are we going to do? Here’s where some patience comes into play.

If you give yourself time, you’ll begin to notice the stars of Sagitta are ever so slightly brighter than the rest of the field stars around it, and it won’t be long until you pick out that arrow pattern. In your mind, measure the distance between Delta and Gamma (the 8 and Y shape on a starfinder map) and then just aim your binoculars or finderscope exactly that same distance due north of Gamma.

The location of M27 in the constellation Vulpecula. Credit: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)
The location of M27 in the constellation Vulpecula. Credit: IAU/Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)

You’ll find M27 every time! In average binoculars it will appear as a fuzzy, out of focus large star in a stellar field. In the finderscope, it may not appear at all… But in a telescope? Be prepared to be blown away! And here are the quick facts on the Dumbbell Nebula to help get you started:

Object Name: Messier 27
Alternative Designations: M27, NGC 6853, The Dumbbell Nebula
Object Type: Planetary Nebula
Constellation: Vulpecula
Right Ascension: 19 : 59.6 (h:m)
Declination: +22 : 43 (deg:m)
Distance: 1.25 (kly)
Visual Brightness: 7.4 (mag)
Apparent Dimension: 8.0×5.7 (arc min)

We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier Objects, , M1 – The Crab Nebula, M8 – The Lagoon Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

Sources:

The Photon Sieve Could Revolutionize Optics

Ever since astronomers first began using telescopes to get a better look at the heavens, they have struggled with a basic conundrum. In addition to magnification, telescopes also need to be able to resolve the small details of an object in order to help us get a better understanding of them. Doing this requires building larger and larger light-collecting mirrors, which requires instruments of greater size, cost and complexity.

However, scientists working at NASA Goddard’s Space Flight Center are working on an inexpensive alternative. Instead of relying on big and impractical large-aperture telescopes, they have proposed a device that could resolve tiny details while being a fraction of the size. It’s known as the photon sieve, and it is being specifically developed to study the Sun’s corona in the ultraviolet.

Basically, the photon sieve is a variation on the Fresnel zone plate, a form of optics that consist of tightly spaced sets of rings that alternate between the transparent and the opaque. Unlike telescopes which focus light through refraction or reflection, these plates cause light to diffract through transparent openings. On the other side, the light overlaps and is then focused onto a specific point – creating an image that can be recorded.

This image shows how the photon sieve brings red laser light to a pinpoint focus on its optical axis, but produces exotic diffraction patterns when viewed from the side. Credits: NASA/W. Hrybyk
Image showing the photon sieve bringing red laser light to a pinpoint focus on its optical axis, and producing exotic diffraction patterns. Credits: NASA/W. Hrybyk

The photon sieve operates on the same basic principles, but with a slightly more sophisticated twist. Instead of thin openings (i.e. Fresnel zones), the sieve consists of a circular silicon lens that is dotted with millions of tiny holes. Although such a device would be potentially useful at all wavelengths, the Goddard team is specifically developing the photon sieve to answer a 50-year-old question about the Sun.

Essentially, they hope to study the Sun’s corona to see what mechanism is heating it. For some time, scientists have known that the corona and other layers of the Sun’s atmosphere (the chromosphere, the transition region, and the heliosphere) are significantly hotter than its surface. Why this is has remained a mystery. But perhaps, not for much longer.

As Doug Rabin, the leader of the Goddard team, said in a NASA press release:

“This is already a success… For more than 50 years, the central unanswered question in solar coronal science has been to understand how energy transported from below is able to heat the corona. Current instruments have spatial resolutions about 100 times larger than the features that must be observed to understand this process.”

With support from Goddard’s Research and Development program, the team has already fabricated three sieves, all of which measure 7.62 cm (3 inches) in diameter. Each device contains a silicon wafer with 16 million holes, the sizes and locations of which were determined using a fabrication technique called photolithography – where light is used to transfer a geometric pattern from a photomask to a surface.

Doug Rabin, Adrian Daw, John O’Neill, Anne-Marie Novo-Gradac, and Kevin Denis are developing an unconventional optic that could give scientists the resolution they need to see finer details of the physics powering the sun’s corona. Other team members include Joe Davila, Tom Widmyer, and Greg Woytko, who are not pictured. Credits: NASA/W. Hrybyk
The Goddard team led by Doug Rabin (left) is working on a new optic device that will drastically reduce the size of telescopes. Credits: NASA/W. Hrybyk

However, in the long-run, they hope to create a sieve that will measure 1 meter (3 feet) in diameter. With an instrument of this size, they believe they will be able to achieve up to 100 times better angular resolution in the ultraviolet than NASA’s high-resolution space telescope – the Solar Dynamics Observatory. This would be just enough to start getting some answers from the Sun’s corona.

In the meantime, the team plans to begin testing to see if the sieve can operate in space, a process which should take less than a year. This will include whether or not it can survive the intense g-forces of a space launch, as well as the extreme environment of space. Other plans include marrying the technology to a series of CubeSats so a two-spacecraft formation-flying mission could be mounted to study the Sun’s corona.

In addition to shedding light on the mysteries of the Sun, a successful photon sieve could revolution optics as we know it. Rather than being forced to send massive and expensive apparatus’ into space (like the Hubble Space Telescope or the James Webb Telescope), astronomers could get all the high-resolution images they need from devices small enough to stick aboard a satellite measuring no more than a few square meters.

This would open up new venues for space research, allowing private companies and research institutions the ability to take detailed photos of distant stars, planets, and other celestial objects. It would also constitute another crucial step towards making space exploration affordable and accessible.

Further Reading: NASA