The Telescopes of the Future, and What We Will See Through Them
The Hubble Space Telescope might not make it to 2030. Currently operating 12 years beyond its original 15-year lifespan, Hubble's science operations are slated to end in 2021. A proposed servicing mission could keep the beloved space telescope running even longer, but eventually, the era of Hubble will come to an end.
Fortunately, a number of new telescopes, both in space and on the ground, are currently being developed to probe the cosmos like never before. Here is a look the five scopes we are most excited about.
James Webb Space Telescope
James Webb is the official successor of Hubble, though it will be a very different telescope. Unlike Hubble, James Webb won't orbit the Earth but instead will orbit the sun. The giant space telescope will park about 1.5 million kilometers (932,000 miles) away from the Earth at the second Lagrange point, or L2, and stay on the dark side of the Earth, orbiting the sun along with our planet.
James Webb will have over five times the collecting area of Hubble with a mirror diameter of 6.5 meters compared to Hubble's 2.4 meters. The massive mirror will be able to detect objects 16 times fainter than Hubble. The telescope is so big, that it will need to be folded for launch, and the process to unfold its 18 massive, gold-plated mirrors will take about five months. Because the telescope will sit at such a great distance from the Earth, astronauts will not be able to reach James Webb for repairs or maintenance—at least not with current spaceflight technology—so it's critical that the unfolding, testing and cooling processes go according to plan.
The major difference between James Webb and Hubble, however, is that James Webb will take observations in mostly infrared light, while Hubble is optimized for visible and ultraviolet light. The longer wavelengths of infrared light pass more readily through debris, so James Webb will be able to peer through the gas and dust of stellar nebulae to see the stars and planets forming within.
The infrared capabilities of James Webb will also allow it to peer deeper into the universe than ever before, seeing the light from objects that formed only 100 million years after the Big Bang. That light is so old and has been traveling for so long that it has stretched deep into the infrared part of the spectrum as the universe expands. What exactly James Webb will see when we focus it on the beginning of time is anyone's guess.
Giant Magellan Telescope
James Webb will be big, and it will have the major advantage of operating beyond the Earth's atmosphere, but astronomers are coming up with some incredible ways to make our telescopes on the ground ever more sensitive. The first way to get clear pictures of faint objects, of course, is to increase the size of the telescope, and the aperture of the Giant Magellan Telescope (GMT) will be a gargantuan 24.5 meters in diameter, accounting for a collecting area 80 times that of Hubble and about 15 times that of James Webb. Each of the GMT's seven mirrors will weigh a colossal 15 tons.
Currently under construction in the high Atacama Desert of Chile, the Giant Magellan Telescope is expected to be completed by 2025, though operations could begin sooner with only four of the seven mirrors. Like Hubble, it will take observations in visible light. In space, the GMT would have about 10 times the resolving power of Hubble, but on the ground, the pictures won't be quite so clear. The constantly moving air of the atmosphere warps the light of stars and other objects passing through. This is why stars appear to "twinkle" to the naked eye, but it can be a major complication when trying to get a clear picture through a telescope.
Fortunately, the GMT has some amazing new technology, called adaptive optics, to correct the blurred light that travels through Earth's atmosphere. Secondary mirrors in the telescope will be flexible, and computer-controlled actuators will warp those flexible mirrors hundreds of times per second to correct for the blurred light. The telescope will use six laser beams to produce artificial stars in the sky to calibrate the adaptive optics, just like the European Southern Observatory's Very Large Telescope (VLT). With the help of adaptive optics, GMT will be able to get close to the same resolution as if it were in space, and it should even be able to image planets orbiting other stars—the first pictures of exoplanets.
Wide Field Infrared Survey Telescope
In 2012, the National Reconnaissance Office (NRO) donated two identical space telescopes to NASA. The donated telescopes are the same size as Hubble, though they have a shorter focal length and a wider field of view. They will not be able to peer as deep into the cosmos as Hubble, but they will be able to image a larger area of space at one time.
At the time of the donation, NASA was already considering a Wide Field Infrared Survey Telescope, known as WFIRST. When they received the new space telescopes from the NRO, a plan formed to turn the first of the two scopes into a more powerful version of WFIRST, and the project was formally designated as a NASA mission in February 2016.
Slated for launch in the 2020s, WFIRST will attempt to combine the advantages of the Sloan Digital Sky Survey—observing large swaths of the sky—with Hubble's ability to observe objects at great distances. WFIRST will be able to capture 100 times the area of sky that Hubble can view, with single images containing over a million galaxies, and it will have close to the same resolving power as Hubble thanks to the same type of adaptive optics as GMT—the first time such technology will be used in space.
By taking such huge observations of the sky, WFIRST will be used to measure the effects of dark energy, the expansion of the universe, and the curvature of spacetime with more accuracy than ever before. WFIRST could tell us if dark energy is its own unique form of energy, or if it can be accounted for in the theories of general relativity. The space telescope will also use gravitational lensing techniques to conduct massive exoplanet surveys, possibly discovering many more planets outside our solar system than even the Kepler space telescope, which has already found over 3,000.
Large Synoptic Survey Telescope
The Large Synoptic Survey Telescope (LSST), currently under construction on the Cerro Pachón mountain in northern Chile, will be the first telescope of its kind. With an 8.4-meter primary mirror, LSST is designed to scan the entire southern sky in just a few nights. This can be achieved thanks to the speed with which the telescope will operate as well as an enormous 3.2-gigapixel camera—the largest digital camera ever built, about the size of a car.
LSST is designed to study how the universe changes over time—days, weeks, months, years and eventually decades. Some of the most valuable observations we have are 100-year-old glass astronomical plates because they show us what the sky looked like a century ago. LSST is designed specifically to track changes in the sky so we have a complete record of celestial movement going forward.
Starting in January 2022, LSST will begin a 10 year survey that will take 1,000 pairs of exposures, accounting for 15 terabytes of data, every single night. This is hundreds of times faster than the Sloan Digital Sky Survey, which creates a large map of the universe once per year. LSST will discover high speed objects in our solar system and rogue stars whizzing through the Milky Way.
The speed of LSST will make it perfect for capturing supernovae, the quick and violent deaths of massive stars. The advanced telescope could also become the most sensitive instrument available to find and track near-Earth objects, or NEOs—asteroids that could impact the Earth in the future. In the deep cosmos, LSST will also be able to record the changes in brightness of objects as unseen, massive bodies such as black holes pass nearby, allowing us to create a more complete picture of the sky than ever before.
Five Hundred Meter Aperture Spherical Radio Telescope
The Five hundred meter Aperture Spherical radio Telescope, or FAST, is the largest single-dish radio telescope in the world. FAST was completed September 2016, constructed in a natural depression sinkhole in the Guizhou Province of southwestern China.
With an enormous collecting area of 196,000 square meters, FAST can detect the faintest of radio signals, even operating here on Earth where radio noise is abundant. The telescope has already been contracted by the Breakthrough Listen initiative to search for signals broadcasted by intelligent alien civilizations.
Finding aliens with FAST will certainly require some luck, but the massive radio dish is good for much much more. Astronomers recently pinpointed one of the most mysterious phenomena in the universe, a fast radio burst (FRB), for the first time. The research team discovered that the FRB was coming from a dwarf galaxy that sits three billion light-years away. The distance and origin suggest that the FRB could have been caused by a supermassive black hole ejecting material, a superluminous supernova, or perhaps even a magnetar—a special type of neutron star with an immense magnetic field. Further observations of this FRB and others using radio telescopes around the world will be required to discover what exactly creates a fast radio burst, and FAST is the perfect telescope to assist with such a study.
It also might be the perfect telescope to detect a signal sent home from a spacecraft that we launch to Alpha Centauri, the closest star system to us. Breakthrough Starshot hopes to sent a probe to Alpha Centauri within our lifetimes—a small nanoprobe with a reflective surface that would use photonic propulsion supplied by a laser system on Earth to achieve relativistic speeds in the neighborhood of 20 percent of the speed of light. Such a probe, or host of probes, could reach Alpha Centauri in 20 or 30 years, but it's going to be very difficult to receive a signal back on Earth that tells us our little probe has successfully made the immense journey. The enormous FAST radio dish just might be able to detect such a signal.
All five of these telescopes will be used to achieve some amazing scientific discoveries, refining our models of physics and revealing new ways for us to travel through and explore the cosmos. There are many exciting things we hope to learn from these telescopes, what Space Time's Matt O'Dowd calls "known unknowns." "However," he say, "it's likely that their most exciting revelations will be things we didn't even expect to find—unknown unknowns in the deepest reaches of spacetime."
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