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Adaptive Optics: Providing Clarity to Observations ADAPTIVE OPTICS: PROVIDING CLARITY TO OBSERVATIONS IN HAWAII, IS DR PETER WIZINOWICH, BASED AT W. M. KECK OBSERVATORY AN ENGINEER WHO SPECIALISES IN OPTICAL SCIENCES IN ASTROPHYSICS. HIS WORK INVOLVES USING ADAPTIVE OPTICS TO IMPROVE THE IMAGING CAPABILITIES OF SOME OF THE WORLD’S LARGEST TELESCOPES In 1608, Dutch eyeglass maker Hans Earth’s atmosphere blurs astronomical images. technology has developed to an extent where Lippershey patented the world’s first telescope Fortunately, scientists have found a way to Babcock’s proposal could be realised. Initially, (although there is some debate concerning overcome this issue. the technology was limited to using bright stars whether he stole the idea). Lippershey claimed that were relatively close to Earth to measure his device could magnify an image up to three HOW HAVE SCIENTISTS OVERCOME the distortions introduced by the atmosphere, times. While that is hardly a bold claim from THE BLURRING EFFECT OF but in more recent times, lasers have enabled today’s vantage point, it was the first important TURBULENCE? astronomers to observe a much larger part of step towards building the many telescopes Adaptive optics (AO). This is where the sky. that now grace the world; after hearing about deformable mirrors correct the distortion Lippershey’s invention, Galileo designed his caused by atmospheric turbulence so the “The key adaptive optics technologies include own telescope which magnified images up to telescopes can view the skies in much finer low noise, fast readout detectors to measure 20 times, and the field of astronomy was born. detail. Dr Peter Wizinowich, Chief of Technical the light, fast computers to determine the Development at Keck Observatory, is an corrections, and deformable mirrors to make In the 400 years since then, telescopes have engineer who specialises in optical systems the corrections,” explains Peter. “The key become significantly larger. The twin optical in astrophysics. His work focuses on enabling laser technology was to develop a sufficiently and infrared telescopes at the W. M. Keck astrophysics through AO, chiefly by adding bright laser, tuned to the wavelength of sodium Observatory in Hawaii, sit near the top of the new capabilities to one of the world’s largest to excite the sodium atoms in the Earth’s dormant volcano, Maunakea, at an elevation telescopes – the 10-metre Keck I and Keck II mesosphere at an altitude of ~ 90 km to create of 13,600 feet. Both telescopes have a telescopes. the artificial star. In addition, instruments diameter of 10 metres, enabling researchers have been designed to make use of the AO- to observe the universe to a previously WHAT HAS ENABLED THE corrected light, including the development of unimaginable degree. DEVELOPMENT OF ADAPTIVE large format, infrared detectors.” OPTICS? However, while there is a general rule that The concept of AO was proposed in 1951 Keck Observatory became the first in the the larger the telescope, the more detail it by an astronomer named Horace Babcock. world to implement both natural guide should be able to provide, turbulence in the However, it is only in the last few decades that star (1999) and laser guide star (2004) DR PETER WIZINOWICH W. M. Keck Observatory, California Association for Research in Astronomy, Hawaii, USA FIELD OF RESEARCH Optical Science in Astrophysics AO systems on a large telescope. Thus far, of California, Los Angeles (UCLA) Galactic these systems have been used to provide Center Group. Under the leadership of 2020 RESEARCH data for more than 1,000 refereed science Nobel Prize in Physics winner Andrea Ghez, papers. Peter has led the efforts to improve the Group investigates the innermost regions Peter’s work focuses on using and upgrade the systems over the past two of the Milky Way and the supermassive black adaptive optics to improve the decades. hole at its centre, using the highest angular capabilities of some of the world’s resolution possible. largest telescopes. WHAT RESULTS HAVE BEEN MADE POSSIBLE BY AO? Interestingly, Keck Observatory’s AO correct. However, telescopes on Earth are far “A wide range of solar system, galactic, and observations also helped astronomers less expensive and easier to maintain – they extra-galactic science has been facilitated by realise Pluto is not a planet, but rather, a can be larger, quicker to build, longer lasting, the angular resolution provided by powerful dwarf planet. and easier to upgrade. AO systems on a 10-metre telescope,” says Hara Richard Andrew Credit: Photo Peter. “Prior to AO, the angular resolution of “Pluto is located in the Kuiper Belt. Keck AO “Where Keck AO currently works well, at ground-based telescopes was 0.5 arcseconds. measurements revealed the masses of some near-infrared wavelengths, it outperforms Keck AO has improved that resolution by a other Kuiper Belt objects that had moons and the much smaller Hubble Space Telescope factor of 10 and the sensitivity to a faint star were similar in size to Pluto. This led to the (10 metres versus 2.4 metres),” says Peter. by a factor of 100.” discovery of a new class of objects, now called “However, we can’t yet compete with the dwarf planets,” explains Peter. exquisite image quality of Hubble at visible These improvements have led to many wavelengths. One of our ultimate goals is notable results, such as determining there WHERE WILL AO AND RELATED to conceptually have the 10-metre Keck is a supermassive black hole at the centre of RESEARCH LEAD TO IN THE FUTURE? telescopes in space (without actually launching our galaxy with a mass of 4 million suns! The One of the most important reasons for putting them) by having excellent AO-correction at capabilities of Keck Observatory’s telescopes telescopes in space is they are not subject to visible wavelengths.” have led to the creation of the University the atmospheric turbulence that AO seeks to Maunakea hosts some of the most scientifically The 10-metre diameter Keck Observatory telescope The Keck I and Keck II telescopes using their laser productive telescopes in the world, making Hawaii primary mirror consists of 36 hexagonal segments that guide stars to observe the supermassive black hole an international leader in astronomy. Most of are actively controlled with nanometer precision to at the centre of the Milky Way galaxy. The lasers the Maunakea Observatories have optical and work in concert as a single piece of reflective glass. excite sodium atoms in the Earth’s mesosphere to infrared telescopes, but there are also submillimetre create an artificial star that can be used to measure telescopes and a radio telescope. atmospheric turbulence. ABOUT OPTICAL SCIENCE AND ASTROPHYSICS In 1835, the French philosopher Auguste identify the future needs and our technical MINORITIES IN THIS FIELD. HOW Comte said the chemical composition of team to figure out how we are going to meet SUCCESSFUL HAS THIS BEEN? stars could be an example of knowledge that those needs, and then making proposals to “We are already blessed in the Keck might forever be hidden from humankind. both public and private organisations to fund community and the KAPA project leadership However, unbeknownst to him, the these projects,” explains Peter. “We have to have a lot of female astronomers and development of spectroscopy (the study been quite fortunate to have groups support students. Our project scientist, two of the of the absorption and emission of light and us like the W. M. Keck Foundation, the four KAPA key science project leads, and other radiation by matter), was already Gordon and Betty Moore Foundation, the our education lead are women. We would leading to some exciting discoveries. Heising-Simons Foundation, the National like our community and team to include Science Foundation, NASA, and others. more underrepresented people,” says In the two centuries since then, we have Without their support we wouldn’t be able to Peter. “More specifically, we would like to come an incredibly long way. Humankind make our dreams come true.” attract more women, local Hawaii residents, has been on the Moon, rovers have landed and minorities into instrumentation on Mars, telescopes have been put into HOW DOES IT FEEL TO HELP and engineering, and retain them in our space, and observatories around the world CAPTURE IMAGES OF THE community.” are discovering aspects of the universe that UNIVERSE THAT NO ONE ELSE EVER would have defied belief even just a few HAS? To achieve this goal, the AstroTech Summer decades ago. Many of these observations Peter says he feels very lucky to be part of School has been established. Unfortunately, have been made possible by the work of the journey of discovery and to help enable the COVID-19 crisis has led to the scientists like Peter, whose work on adaptive those discoveries. Not an astrophysicist cancellation of the first full event planned for optics has enabled new astrophysics. himself, it is his engineering expertise that 2020, but the team is looking at other ways has enabled plenty of talented and creative to bring students together to support their WHAT DOES PETER FIND MOST people to answer many of the big science future. The summer school aims to introduce CHALLENGING ABOUT HIS WORK? questions. Without the efforts of people late undergraduate and early graduate Peter has been at Keck Observatory for like Peter, it simply would not be possible students to the process of designing and almost 30 years and in that time has to observe our universe in the detail that we building a science instrument by providing overcome many technical and project currently can. extensive hands-on experience. management challenges. “One of the biggest challenges for someone like myself who THE KECK ALL-SKY PRECISION The KAPA project also hosts college wants to see new science capabilities come ADAPTIVE OPTICS (KAPA) PROJECT students from Hawaii through the Akamai to life is finding the funding.
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