This article originally appeared in the June 2014 issue of Astronomy.
Nearly 30 years ago, the worlds top radio telescope engineers and black-belt radio astronomers haggled over their requirements for an array of antennas that could investigate the deepest, darkest, and coldest places in the universe better than any other telescope ever made.
What they sought sounded like a starry-eyed wish list: 60 or more antennas able to survive blizzards and 100mph (160 km/h) winds yet also able move as fast as missile trackers. And thats not all. Their surfaces cannot deform more than a third the thickness of a human hair. Their electronics cant add noise to the data. Giant trucks must carry the antennas safely for miles across a high-altitude desert without dropping power to the cryogenic receivers. And the array wont work without a supercomputer that can perform 17 quadrillion operations every second.
Fast forward to 2014, and this seemingly fantastical telescope the Atacama Large Millimeter/submillimeter Array (ALMA) is complete. It is a leap in astronomical imaging akin to Galileo Galileis first use of a telescope, and similarly, its technology and early science have changed the business of astronomy forever. Achieving this marvel required the largest ground-based telescope partnership in history, an international collaboration between North America, Europe, East Asia, and Chile that collected $1.3 billion to design and build the worlds most complex astronomical instrument.
Engineering expectations
Radio telescopes gather light with wavelengths from fractions of a millimeter to hundreds of meters. Visible-light waves, by contrast, are only hundreds of nanometers long. Antenna size being equal, a radio telescopes ability to image the universe is to an optical telescopes capacity what finger-painting is to a color photograph.
To gather and focus enough radio waves to achieve similar or better resolution than their optical cousins, radio telescopes must be huge. Earths gravity limits the immensity of a single telescope, but ingenuity can counter that force.
The worlds most versatile radio telescopes are built as reconfigurable arrays of antennas, affording them maximum power and flexibility. Special-purpose supercomputers pair the data from each antenna with that from every other antenna across the array in some cases, up to thousands of miles away to create binocular images of the sky from many different perspectives. The farther apart two antennas are, the greater the resolution of their binocular vision. This groundbreaking technique is known as aperture synthesis and won a Nobel Prize for its pioneer, Sir Martin Ryle.
The resulting data provide often unequalled detail measurements that precisely reveal the spectra (emission of different wavelengths of light), shapes, positions, and distances of objects in space. ALMA, its 66 antennas spread a maximum distance of 9.9 miles (16 kilometers) apart, will have 10 times the resolution of the Hubble Space Telescope when the antennas are observing at their smallest wavelengths.
Unlike its shorter-wavelength cousins, such as Hubble, that collect light as energy packets that hit detectors and form pixels in an image, ALMA must process the light it collects as waves. Each ALMA antenna surface has been painstakingly hand-tuned to accurately reflect light waves as tiny as 400 micrometers long thats about the length a human hair grows in a day. If the dishes have bumps any larger than one-third the diameter of a human hair, then the cosmic waves are scattered away.
Also, submillimeter light waves crash into ALMAs receivers at frequencies as high as the terahertz range 1 trillion per second and no computer (yet) can handle a data stream like that. Therefore, all signals exiting ALMAs receivers have to be mixed with a longer carrier wave. A metronome-like device (called a local oscillator) sends this beat to each antenna.
To ensure these electronics do not introduce any signals of their own during the mix-down process (which electronics naturally do), engineers designed innovative, near-microscopic mixers that can be kept cryogenically cold. To reduce other noise, all eight receivers inside an ALMA antenna chill together in a giant thermos that contains 4-kelvin (452 Fahrenheit) liquid helium, which is bolted behind the dish. This technology has increased receiver sensitivity on Earth fourfold.
The antennas themselves are high-tech art in motion. Engineers from nearly every time zone on Earth came up with three different but equally elegant solutions to the ultimate 12-meter antenna wish list, and the array is an international family of these triplets. Although they look slightly different, ALMAs antennas all share the record-breaking capabilities that astronomers dreamed up 30 years ago.
Read more:
The newest big thing in radio astronomy - Astronomy Magazine
- Astronomy has a bullying and harassment issue: 'Results presented in this report are bleak' - Space.com - May 31st, 2024 [May 31st, 2024]
- WASP-193b: The bizarro, fluffy exoplanet that comes as a surprise - Astronomy Magazine - May 31st, 2024 [May 31st, 2024]
- Next-Generation Radar Will Map Threatening Asteroids - Universe Today - May 31st, 2024 [May 31st, 2024]
- The rush to return humans to the Moon and build lunar bases could threaten opportunities for astronomy - The Conversation - May 31st, 2024 [May 31st, 2024]
- Glimpses of a volcanic world: New telescope images of Jupiter's moon Io rival those from spacecraft - EurekAlert - May 31st, 2024 [May 31st, 2024]
- The Sky This Week from May 31 to June 7: A Jupiter-Mercury conjunction - Astronomy Magazine - May 31st, 2024 [May 31st, 2024]
- Is Pluto a planet? The experts break it down. - Astronomy Magazine - May 31st, 2024 [May 31st, 2024]
- Astronomy Generates Mountains of Data. That's Perfect for AI - Universe Today - May 31st, 2024 [May 31st, 2024]
- The Moon meets Saturn: This Week in Astronomy with Dave Eicher - Astronomy Magazine - May 31st, 2024 [May 31st, 2024]
- What it means for planets to align | Astronomy.com - Astronomy Magazine - May 31st, 2024 [May 31st, 2024]
- The future is bright for astronomy, and very expensive (op-ed) - Space.com - May 31st, 2024 [May 31st, 2024]
- Parade Of Planets And More Your Skywatching Guide To Astronomical Events This June - TRAVEL + LEISURE INDIA - May 31st, 2024 [May 31st, 2024]
- Free astronomy lecture in Lincoln City | Coast Life | newportnewstimes.com - Newport News Times - May 31st, 2024 [May 31st, 2024]
- Venus likely has active volcanoes, flowing streams of lava - Astronomy Magazine - May 31st, 2024 [May 31st, 2024]
- New photos of the dark universe from Euclid are filled with wonder - Astronomy Magazine - May 31st, 2024 [May 31st, 2024]
- James Webb Space Telescope spots the two most distant galaxies ever seen at cosmic dawn - University of Arizona News - May 31st, 2024 [May 31st, 2024]
- Featured speaker to discuss T Coronae Borealis, solar cycle at Quincy Astronomy Club meeting Thursday Muddy ... - Muddy River News - May 31st, 2024 [May 31st, 2024]
- Audience Mesmerized by 3D Shiur on Rambam's Astronomy - Anash.org - Good News - May 31st, 2024 [May 31st, 2024]
- Astronomers Fear Destructive Light Pollution From FCC's 'Single Network Future' - BroadbandBreakfast.com - May 31st, 2024 [May 31st, 2024]
- Caltech's Shri Kulkarni Awarded Shaw Prize in Astronomy For His Ground-Breaking Discoveries - SciTechDaily - May 31st, 2024 [May 31st, 2024]
- Astronomers Spot Epic Flows of Lava Oozing Out of Venus - Futurism - May 31st, 2024 [May 31st, 2024]
- The summer solstice: What is it and when does it occur? - Space.com - May 31st, 2024 [May 31st, 2024]
- 6 Stars Will Soon Be Visible at the Same Time in Rare 'Parade of Planets' - Yahoo News Canada - May 31st, 2024 [May 31st, 2024]
- Astronomy clubs want to help you enjoy the eclipse safely - NPR - March 16th, 2024 [March 16th, 2024]
- You Can See a Rare, Bright Comet This Month. Will It Be Visible During the Solar Eclipse? - Smithsonian Magazine - March 16th, 2024 [March 16th, 2024]
- Solar Eclipse Path Map Shows States Where Sun Will Be Blocked Out - Newsweek - March 16th, 2024 [March 16th, 2024]
- Deep-space astronomy sensor peers into the heart of an atom - Space.com - March 16th, 2024 [March 16th, 2024]
- Physics and Astronomy Colloquium - Professor Paul Cassak; Department of Physics and Astronomy, West Virginia ... - The University of Iowa - March 16th, 2024 [March 16th, 2024]
- United Nations prioritizes discussion of Dark and Quiet Skies - Astrobites - March 16th, 2024 [March 16th, 2024]
- The burning acid behind ant stings was spotted around two stars - WAPT Jackson - March 16th, 2024 [March 16th, 2024]
- The oddities known as Centaurs may sprout their tales after jumping to new orbits - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- Pair of astronomy brothers to host eclipse viewing event - KAIT - March 16th, 2024 [March 16th, 2024]
- How to watch the solar eclipse online - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- How does a black hole get to the center of a galaxy, and does the galaxy revolve around it? - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- The eclipse gives astronomy clubs an opportunity to shine - Voice Of Alexandria - March 16th, 2024 [March 16th, 2024]
- AI 'for all': How access to new models is advancing academic research, from astronomy to education - Source - Microsoft - March 16th, 2024 [March 16th, 2024]
- KU Department of Physics & Astronomy professor receives prestigious NSF award for black hole research - Salina Post - March 16th, 2024 [March 16th, 2024]
- Inspect impressive Mare Imbrium Astronomy Now - Astronomy Now Online - March 16th, 2024 [March 16th, 2024]
- The Sky This Week from March 15 to 22: A conjunction of Venus and Saturn - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- Pons-Brooks and M31 - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- The slightly weird mathematical coincidence behind an eclipse - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- APOD: 2024 March 17 NGC 7714: Starburst after Galaxy Collision - Astronomy Picture of the Day - March 16th, 2024 [March 16th, 2024]
- How to Safely View the Eclipse National Radio Astronomy Observatory - National Radio Astronomy Observatory - March 16th, 2024 [March 16th, 2024]
- NOIRLab releases jaw-dropping images, video of remnants from massive star explosion | Astronomy.com - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- JWST spots oceans' worth of water evaporating from a distant disk - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- Radiation is vaporizing a young star's disk in the Orion Nebula - Astronomy Magazine - March 16th, 2024 [March 16th, 2024]
- APOD: 2024 March 12 A Galaxy Shaped Rocket Exhaust Spiral - Astronomy Picture of the Day - March 16th, 2024 [March 16th, 2024]
- Best laptops for astronomers and astrophotographers in 2024 - Space.com - March 16th, 2024 [March 16th, 2024]
- Why astronomers are worried about 2 major telescopes right now - Space.com - March 16th, 2024 [March 16th, 2024]
- The People Behind Webb | Webb - WebbTelescope.org - March 16th, 2024 [March 16th, 2024]
- X-ray image of universe reveals almost 1 million high-energy objects: 'These are mind-blowing numbers' - Space.com - February 1st, 2024 [February 1st, 2024]
- Galaxy named 'Nube' is almost invisible, baffling astronomers Earth.com - Earth.com - February 1st, 2024 [February 1st, 2024]
- Giant Star Seen 150 Days Before it Exploded as a Supernova - Universe Today - February 1st, 2024 [February 1st, 2024]
- UH astronomer named to prominent national astronomical society | University of Hawaii System News - University of Hawaii - February 1st, 2024 [February 1st, 2024]
- The Art of SeeingStates of Astronomy - Announcements - E-Flux - February 1st, 2024 [February 1st, 2024]
- Pluto isn't really a planet, but it might be Arizona's official state planet - Arizona Mirror - February 1st, 2024 [February 1st, 2024]
- Did You Know? Stars Near and Far Reveal Their Secrets to CSUN Scientists - California State University, Northridge - February 1st, 2024 [February 1st, 2024]
- Top 10 space stories of 2023 - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- How we found the Milky Way's bar: This Week in Astronomy with Dave Eicher - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- The best telescope to use with a smartphone - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- JWST releases 19 awe-inspiring images of spiral galaxies - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- Learning Shines Brightly at SuperKnova National Radio Astronomy Observatory - National Radio Astronomy Observatory - February 1st, 2024 [February 1st, 2024]
- The Crafoord Prize 2024 goes to three ERC grantees for their pioneering contributions to astronomy and mathematics ... - European Research Council - February 1st, 2024 [February 1st, 2024]
- The Moon's south pole is likely not the safest place for manned missions - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- The moon could be perfect for cutting-edge telescopes but not if we don't protect it - Space.com - February 1st, 2024 [February 1st, 2024]
- February Astronomy: Spot the Milky Way and the Zodiacal Light While the Skies Are Darkest - Coachella Valley Independent - February 1st, 2024 [February 1st, 2024]
- You can stream an asteroid whizzing past Earth this weekend - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- Chinese Astronomy at the Royal Observatory | Royal Observatory | Things to do in London - Time Out London - February 1st, 2024 [February 1st, 2024]
- Astronomers in Chile to scour universe with car-sized mega camera - - February 1st, 2024 [February 1st, 2024]
- Dark Matter Might Help Explain How Supermassive Black Holes Can Merge - Universe Today - February 1st, 2024 [February 1st, 2024]
- How far away is the sun? They went on a perilous journey to find out. - National Geographic - February 1st, 2024 [February 1st, 2024]
- Scientists spotted an asteroid hours before it burned up over Germany - Astronomy Magazine - February 1st, 2024 [February 1st, 2024]
- XRISM Unveils the Invisible: A New Era in X-Ray Astronomy - SciTechDaily - January 10th, 2024 [January 10th, 2024]
- New Astronomy Finding Uncovers the Mystery of Star Formation at the Edge of Galaxies - SBU News - Stony Brook News - January 10th, 2024 [January 10th, 2024]
- The Future Of Astronomy Lies In Artificial Intelligence - Forbes - January 10th, 2024 [January 10th, 2024]
- The 'Super Bowl of Astronomy' begins next week in New Orleans - Space.com - January 10th, 2024 [January 10th, 2024]
- Scientific American proposes policing the language of astronomy to make it beautiful and elegant, as well as ... - Why Evolution Is True - January 10th, 2024 [January 10th, 2024]
- 'Blob-like' home of farthest-known fast radio burst is collection of seven galaxies - Northwestern Now - January 10th, 2024 [January 10th, 2024]
- Astronomers revealed mysterious star formation by hearts of molecular clouds - Tech Explorist - January 10th, 2024 [January 10th, 2024]
- Spectroscopic sizing of interstellar icy grains with JWST - Nature.com - January 10th, 2024 [January 10th, 2024]