Space and astronomy news
Modern astronomical telescopes are extraordinarly powerful. And we keep making them more powerful. With telescopes like the Extremely Large Telescope and the Giant Magellan Telescope seeing first light in the coming years, our astronomical observing power will be greater than ever.
But a new commentary says that climate change could limit the power of our astronomical observatories.
Continue reading “Climate Change is Making the Atmosphere Worse for Astronomy”
Japan has suspended its funding contribution to the controversial Thirty Meter Telescope (TMT) in Hawaii. An international consortium is behind the TMT, which was proposed for the summit of Mauna Kea. Mauna Kea is one of the most desirable observing locations on Earth. It’s already host to several observatories, including the Subaru Telescope and the Keck Observatory. The $1.4 billion TMT would be the most powerful telescope there.
Continue reading “Japan Suspends its Funding for the 30-Meter Telescope”
NASA’s Spitzer Space Telescope has reached the end of its life. Its mission was to study objects in the infrared, and it excelled at that since it was launched in 2003. But every mission has an end, and on January 30th 2020, Spitzer shut down.
Continue reading “Good-bye Spitzer. We’ll Miss You But We Won’t Forget You.”
The U.S. House of Representatives have passed a bill to change the name of the Large Synoptic Survey Telescope (LSST.) Instead of that explanatory yet cumbersome name, it will be named after American astronomer Vera Rubin. Rubin is well-known for her pioneering work in discovering dark matter.
Continue reading “Great News! The Large Synoptic Survey Telescope Might be Named for Vera Rubin”You know the drill now. Last week we talked about ancient south African astronomy, and so this week we’ll talk about the modern state of astronomy in the southern part of Africa, which happens to be a great place with nice dark skies and a perfect view into the heart of the galaxy.
Continue reading “Ep. 534: Modern South African Astronomy”
Last week we talked about the ancient astronomy of the American Southwest. But this is actually Pamela’s stomping grounds, and she’s spent many a night perched atop mountains in this region staring in the night sky with gigantic telescopes. How does astronomy get done in this region today?
Continue reading “Ep. 528: Modern Astronomy of the American Southwest”
About 130 million years ago, in a galaxy far away, two neutron stars collided. The cataclysmic crash produced gravitational waves, ripples in the fabric of space and time. This event is now the 5th observation of gravitational waves by the Laser Interferometer Gravitational wave Observatory (LIGO) and Virgo collaboration, and the first detected that was not caused by the collision of two black holes.
But this event — called a kilonova — produced something else too: light, across multiple wavelengths.
Continue reading “First Cosmic Event Observed in Both Gravitational Waves and Light”
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’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.
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:
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.
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.
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.
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 the world’s upcoming Super Telescopes:
It’s easy to forget the impact that the Hubble Space Telescope has had on our state of knowledge about the Universe. In fact, that might be the best measurement of its success: We take the Hubble, and all we’ve learned from it, for granted now. But other space telescopes are being developed, including the WFIRST, which will be much more powerful than the Hubble. How far will these telescopes extend our understanding of the Universe?
“WFIRST has the potential to open our eyes to the wonders of the universe, much the same way Hubble has.” – John Grunsfeld, NASA Science Mission Directorate
The WFIRST might be the true successor to the Hubble, even though the James Webb Space Telescope (JWST) is often touted as such. But it may be incorrect to even call WFIRST a telescope; it’s more accurate to call it an astrophysics observatory. That’s because one of its primary science objectives is to study Dark Energy, that rather mysterious force that drives the expansion of the Universe, and Dark Matter, the difficult-to-detect matter that slows that expansion.
WFIRST will have a 2.4 meter mirror, the same size as the Hubble. But, it will have a camera that will expand the power of that mirror. The Wide Field Instrument is a 288-megapixel multi-band near-infrared camera. Once it’s in operation, it will capture images that are every bit as sharp as those from Hubble. But there is one huge difference: The Wide Field Instrument will capture images that cover over 100 times the sky that Hubble does.
Alongside the Wide Field Instrument, WFIRST will have the Coronagraphic Instrument. The Coronagraphic Instrument will advance the study of exoplanets. It’ll use a system of filters and masks to block out the light from other stars, and hone in on planets orbiting those stars. This will allow very detailed study of the atmospheres of exoplanets, one of the main ways of determining habitability.
WFIRST is slated to be launched in 2025, although it’s too soon to have an exact date. But when it launches, the plan is for WFIRST to travel to the Sun-Earth LaGrange Point 2 (L2.) L2 is a gravitationally balanced point in space where WFIRST can do its work without interruption. The mission is set to last about 6 years.
“WFIRST has the potential to open our eyes to the wonders of the universe, much the same way Hubble has,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate at Headquarters in Washington. “This mission uniquely combines the ability to discover and characterize planets beyond our own solar system with the sensitivity and optics to look wide and deep into the universe in a quest to unravel the mysteries of dark energy and dark matter.”
In a nutshell, there are two proposals for what Dark Energy can be. The first is the cosmological constant, where Dark Energy is uniform throughout the cosmos. The second is what’s known as scalar fields, where the density of Dark Energy can vary in time and space.
Since the 1990s, observations have shown us that the expansion of the Universe is accelerating. That acceleration started about 5 billion years ago. We think that Dark Energy is responsible for that accelerated expansion. By providing such large, detailed images of the cosmos, WFIRST will let astronomers map expansion over time and over large areas. WFIRST will also precisely measure the shapes, positions and distances of millions of galaxies to track the distribution and growth of cosmic structures, including galaxy clusters and the Dark Matter accompanying them. The hope is that this will give us a next level of understanding when it comes to Dark Energy.
If that all sounds too complicated, look at it this way: We know the Universe is expanding, and we know that the expansion is accelerating. We want to know why it’s expanding, and how. We’ve given the name ‘Dark Energy’ to the force that’s driving that expansion, and now we want to know more about it.
Dark Energy and the expansion of the Universe is a huge mystery, and a question that drives cosmologists. (They really want to know how the Universe will end!) But for many of the rest of us, another question is even more compelling: Are we alone in the Universe?
There’ll be no quick answer to that one, but any answer we find begins with studying exoplanets, and that’s something that WFIRST will also excel at.
“WFIRST is designed to address science areas identified as top priorities by the astronomical community,” said Paul Hertz, director of NASA’s Astrophysics Division in Washington. “The Wide-Field Instrument will give the telescope the ability to capture a single image with the depth and quality of Hubble, but covering 100 times the area. The coronagraph will provide revolutionary science, capturing the faint, but direct images of distant gaseous worlds and super-Earths.”
“The coronagraph will provide revolutionary science, capturing the faint, but direct images of distant gaseous worlds and super-Earths.” – Paul Hertz, NASA Astrophysics Division
The difficulty in studying exoplanets is that they are all orbiting stars. Stars are so bright they make it impossible to see their planets in any detail. It’s like staring into a lighthouse miles away and trying to study an insect near the lighthouse.
The Coronagraphic Instrument on board WFIRST will excel at blocking out the light of distant stars. It does that with a system of mirrors and masks. This is what makes studying exoplanets possible. Only when the light from the star is dealt with, can the properties of exoplanets be examined.
This will allow detailed measurements of the chemical composition of an exoplanet’s atmosphere. By doing this over thousands of planets, we can begin to understand the formation of planets around different types of stars. There are some limitations to the Coronagraphic Instrument, though.
The Coronagraphic Instrument was kind of a late addition to WFIRST. Some of the other instrumentation on WFIRST isn’t optimized to work with it, so there are some restrictions to its operation. It will only be able to study gas giants, and so-called Super-Earths. These larger planets don’t require as much finesse to study, simply because of their size. Earth-like worlds will likely be beyond the power of the Coronagraphic Instrument.
These limitations are no big deal in the long run. The Coronagraph is actually more of a technology demonstration, and it doesn’t represent the end-game for exoplanet study. Whatever is learned from this instrument will help us in the future. There will be an eventual successor to WFIRST some day, perhaps decades from now, and by that time Coronagraph technology will have advanced a great deal. At that future time, direct snapshots of Earth-like exoplanets may well be possible.
But maybe we won’t have to wait that long.
There is a plan to boost the effectiveness of the Coronagraph on WFIRST that would allow it to image Earth-like planets. It’s called the EXO-S Starshade.
The EXO-S Starshade is a 34m diameter deployable shading system that will block starlight from impairing the function of WFIRST. It would actually be a separate craft, launched separately and sent on its way to rendezvous with WFIRST at L2. It would not be tethered, but would orient itself with WFIRST through a system of cameras and guide lights. In fact, part of the power of the Starshade is that it would be about 40,000 to 50,000 km away from WFIRST.
Dark Energy and Exoplanets are priorities for WFIRST, but there are always other discoveries awaiting better telescopes. It’s not possible to predict everything that we’ll learn from WFIRST. With images as detailed as Hubble’s, but 100 times larger, we’re in for some surprises.
“This mission will survey the universe to find the most interesting objects out there.” – Neil Gehrels, WFIRST Project Scientist
“In addition to its exciting capabilities for dark energy and exoplanets, WFIRST will provide a treasure trove of exquisite data for all astronomers,” said Neil Gehrels, WFIRST project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This mission will survey the universe to find the most interesting objects out there.”
With all of the Super Telescopes coming on line in the next few years, we can expect some amazing discoveries. In 10 to 20 years time, our knowledge will have advanced considerably. What will we learn about Dark Matter and Dark Energy? What will we know about exoplanet populations?
Right now it seems like we’re just groping towards a better understanding of these things, but with WFIRST and the other Super Telescopes, we’re poised for more purposeful study.
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 (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.
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:
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.